Answer:
b. cis test
Explanation:
A test that is used to determine if the mutation associated with a given phenotype is due to mutations in two different genes or due to different alleles of the same gene is called a complementation test.
A complementation test is also called as a cis-trans test.
If the mutations in a complementation test are located on the same position then the genes are termed as being on the cis position otherwise on the trans-position.
A cis test, that is if the genes are located on the same position serves as a control for the complementation test.
The control for a complementation test, which is often omitted, is the b. cis test.
In genetics, the complementation test is used to determine whether two mutations that produce a similar phenotype are in different genes or in different sites within the same gene. The test involves crossing two mutants to see if their offspring have the wild type phenotype, indicating complementary mutations. The control for this test is the cis test, where both mutations are present on the same piece of DNA. This confirms whether the mutations can complement each other when in close proximity, which is necessary for an accurate complementation test. Without this control, one might incorrectly conclude complementation when, in reality, the two mutations could interact in a cis configuration to produce a wild type phenotype.
Explain how a genetic map (in map units) is related to actual physical distance (in base pairs of DNA).
Explanation:
A map unit [or centimorgan (cM)] is a unit for measuring genetic linkage. It is defined as the distance between chromosome positions for which the expected average number of intervening chromosomal crossovers in a single generation is 0.01. Its relation with actual physical distances is inconsistent because the number of base pairs to which it corresponds varies widely across the genome, it also depends on whether the meiosis in which the crossing-over takes place is a part of male or female genes (female genome is 4782 cM long, while the male genome is only 2809 cM long).
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Genetic maps show the relative positions of genes using centimorgans as a measure of the likelihood of recombination, while physical maps show actual distances in base pairs. The conversion between cM and bp varies by organism and chromosome region. Three main methods—cytogenetic, radiation hybrid, and sequence mapping—are used to create physical maps.
A genetic map indicates the relative positions and distances between genetic markers or genes on a chromosome. These distances are expressed in map units or centimorgans (cM), which approximate the probability of recombination occurring between these markers during meiosis. A physical map, on the other hand, provides the actual physical distance between genetic markers, measured in the number of base pairs (bp).
It is essential to understand that one map unit does not correlate to a fixed number of base pairs across all species or even all regions of a chromosome. For example, in Arabidopsis, a model organism in plant biology, 1 cM is roughly equivalent to 150,000 base pairs. This variation is due to differing recombination frequencies across the genome; areas known as 'crossover hot spots' experience more frequent recombination, while regions of heterochromatin may show less. To construct physical maps, methods like cytogenetic mapping, radiation hybrid mapping, and sequence mapping are employed.
Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?
a. The two strands of the double helix would separate.
b. The phosphodiester linkages of the polynucleotide backbone would be broken.
c. The pyrimidines would be separated from the deoxyribose sugars.
d. All bases would be separated from the deoxyribose sugars.
Answer:
The correct answer is option b. "The phosphodiester linkages of the polynucleotide backbone would be broken".
Explanation:
The phosphodiester linkages of the polynucleotide backbone is what binds each nucleotide to each other in the DNA molecules. These linkages are covalent bonds that take place between 3' carbon atom of one sugar molecule and the 5' carbon atom of another. The enzymes that break down DNA catalyze the hydrolysis of the phosphodiester linkage, which results in DNA cleavage within the backbone at specific or unspecific nucleotides.
Final answer:
Enzymes that break down DNA cleave the phosphodiester bonds in the DNA polynucleotide backbone, leading to the degradation of the DNA molecule into its constituent nucleotides. The correct choice is b - the phosphodiester linkages would be broken.
Explanation:
When enzymes that break down DNA are applied to the DNA molecule, they catalyze the hydrolysis of the covalent bonds that join nucleotides together. Specifically, these enzymes target the phosphodiester bonds in the polynucleotide backbone. Hydrolysis of these bonds would lead to a cleavage of the polynucleotide chain. This would result in the degradation of the DNA molecule into its individual nucleotides, where each phosphate group would be associated with a deoxyribose sugar and a nitrogenous base.
The correct answer to the student's question is: b. The phosphodiester linkages of the polynucleotide backbone would be broken. This process is different from denaturation, where hydrogen bonds between complementary bases break; breaking phosphodiester bonds involves a chemical reaction that cleaves the DNA backbone itself.
Enzymes such as nucleases perform this function, specifically endonucleases which cleave phosphodiester linkages within a DNA strand. Conversely, enzymes like DNA ligases can repair these breaks, forming a new phosphodiester linkage, though in this context, we are discussing the breaking of the DNA molecule by hydrolysis, not the joining of fragmented DNA.
Explain how stem cells obtained from IVF leftovers and somatic cell nuclear transfers (SCNT) differ in terms of the sources of their genomes.
Answer:
In in-vitro fertilization, the oocytes from women were taken and inseminated with the donor sperm, post the process of insemination, the oocytes were fertilized successfully and were further allowed to develop into a blastocyst stage.
From the blastocyst, the inner cell masses were extracted, which further produces stem cell lines. From leftover in-vitro fertilization, the extraction of single blastomere becomes very easy.
In SCNT, the nucleus of a somatic cell is administered into the cytoplasm of an enucleated egg that then develops into a zygote and is then permitted to further give rise to a blastocyst stage.
If someone shakes your hand, the proteins that change shape and are responsible for initiating the feeling of this hand touch pressure are called:
a. stretch receptor proteins
b. carboxy receptor proteins
c. cardiac receptor proteins
d. dynamin receptor proteins
Answer:
d. dynamic receptor proteins
Explanation:
In the skin there are several receptor cells that can pick up various stimuli such as temperature, pressure and pain. They can be classified into mechanoreceptor, thermoreceptor and pain receptor cells. When we are dealing with mechanical stimuli like pressure, mechanoreceptors respond to stimuli by sending the signal to the brain.
Light touches on the skin are received by nerve endings called Meissner corpuscles and Merkel discs. Already more intense pressures (such as a handshake) are received by receptors called Pacini corpuscles.
Which of the following is an example of post-transcriptional control of gene expression?
a. the addition of methyl groups to cytosine bases of DNA
b. the binding of transcription factors to a promoter
c. the removal of introns and alternative splicing of exons
d. gene amplification contributing to cancer
Answer:
Option (c).
Explanation:
Transcription may be defined as the process of formation of RNA molecule from the template DNA with the help of enzymes and transcription factors. The transcription occurs in 5' to 3' direction.
Post trancriptional modification occurs in the RNA molecule that plays an important role in transcription as well as translation. The introns are removed from the RNA transcript and exons joined together is known as splicing. The alternative splicing occurs in which different protein isoforms are formed by the single exons.
Thus, the correct answer is option (c).
In four-o'clocks, the allele for red flowers is incompletely dominant over the allele for white flowers, so heterozygotes have pink flowers. What ratios of flower colors would you expect emong the offspring of the following crosses: (a) pink x pink, (b) white x pink, (c) red x red, (d) red x pink, (e) white x white, and (f) red x white? If you specifically wanted to produce pink which of these crosses would be most efficient?
Answer: Crossing red with white is the most efficent way to produce pink flowers.
Explanation:
Let's call the "red" allele R and the "white" allele r. A red flower would have both copies of R, and its genotype would be RR, a white flower would have both copies or r, being rr, and a pink flower would be Rr (heterozygote).
We can represent crosses between individuals by Punnet squares. From pink flowers you can get gametes R and r, from red flowers you can get only R gametes and from white flowers only r. If we put male gametes in the first row and female gametes on the first column, we get the following cases:
a: Crossing pink with pink, we get a ratio of a red flower to a white flower to two pink flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & R & r \\ \ R & RR & Rr \\ \ r & Rr & rr \\ \end{tabular}\end{center}[/tex]
b: Crossing white with pink, we get two pink flowers, and two white flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & r & r \\ \ R & Rr & Rr \\ \ r & rr & rr \\ \end{tabular}\end{center}[/tex]
c: Crossing red with red, we get only red flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & R & R \\ \ R & RR & RR \\ \ R & RR & RR \\ \end{tabular}\end{center}[/tex]
d: Crossing red with pink, we get a ratio of two pink flowers to two red flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & R & R \\ \ R & RR & RR \\ \ r & Rr & Rr \\ \end{tabular}\end{center}[/tex]
e: Crossing white with white, we get only white flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & r & r \\ \ r & rr & rr \\ \ r & rr & rr \\ \end{tabular}\end{center}[/tex]
f: Crossing red with white, we get only pink flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & R & R \\ \ r & Rr & Rr \\ \ r & Rr & Rr \\ \end{tabular}\end{center}[/tex]
Thus crossing red with white is the most efficent way to produce pink flowers.
In four-o'clock flowers, incomplete dominance results in pink flowers when red is crossed with white. The offspring ratios vary with different crosses: pink x pink yields 1 red : 2 pink : 1 white, red x white produces all pink offspring, which is the most efficient cross for producing pink flowers.
Explanation:In four-o'clocks, there is a pattern of inheritance known as incomplete dominance, where the allele for red flowers is incompletely dominant over the allele for white flowers, resulting in pink flowers in heterozygous plants. According to Mendelian genetics, we can predict the outcomes of various crosses.
(a) pink x pink (RW x RW): The expected ratio would be 1 red (RR) : 2 pink (RW) : 1 white (WW).(b) white x pink (WW x RW): The expected ratio would be 1 pink (RW) : 1 white (WW).(c) red x red (RR x RR): All offspring would be red (RR).(d) red x pink (RR x RW): The expected ratio would be 1 red (RR) : 1 pink (RW).(e) white x white (WW x WW): All offspring would be white (WW).(f) red x white (RR x WW): All offspring would be pink (RW).If you specifically wanted to produce pink four-o'clock flowers, the most efficient crosses would be red x white (RR x WW) because all offspring would be pink (RW), and there would be no variation in flower color among the progeny.
Explain how the Lac operon is regulated, including all negative and positive components of regulation.
Explanation:
Three enzymes for lactose metabolism are grouped in the lac operon: lacZ (β-galactosidase), lacY (permease) and lacA (trans-acetylase). The transcription of this operon occurs only when lactose is available to digest, presumably to avoid wasting energy. Apart from these protein-coding genes we have P(promoter), O(operator and CBS(Cap-binding site), sequences that work as binding sites for transcriptional regulation.
Negative components: An important regulator is lacI when four of these molecules assemble they form a repressor, this will bind to the promoter, this won't allow the operon to be transcribed as long as the operator is occupied by a repressor. LacI can also prevent lactose to bind to the operator by binding with it and changing its shape.
Positive components: cAMP binding protein is another molecule that when is bound to CBS improves the chance of RNA polymerase to bind to the promoter to initiate transcription.
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I adden an image that ilustrates what I explained.
Beadle and Tatum used which of the following organisms to support their one gene - one enzyme concept?
a. escherichia coli
b. drosophila
c. neurospora
d. salmonella
e. homo sapien
Answer:
Neurospora.
Explanation:
Beadle and Tatum experiment shows one gene one enzyme hypothesis. According to this, a single enzyme is encoded by each gene. This idea is not accepted in today's world.
Beadle and Tatum performed experiment on the neurospora. They chosed neurospora in their experiment because neurospora shows the fast life cycle with alternation of generation. The genetic experiments can be easily performed on neurospora.
Thus, the correct answer is option (c).
A researcher conducted crosses between two different strains of Drosophila. When true-breeding flies with singed bristles (s) and normal wings (L) were crossed to true-breeding flies with normal bristles (S) and vestigial wings (l), all F1 offspring had normal wings and normal bristles. The F1 offspring were crossed to flies with singed bristles and vestigial wings. Which F2 offspring is/are recombinant?
The best way of solving this is to draw a Punnett square.
You know the F0 had one parent with singed bristles (s), and normal wings (L), and the other parent is normal bristles (S) with vestigial wings (l).
If you do the cross ssLL x SSll you'll find 100% of the offspring is F1: SsLl, this means, all of them show the dominant traits: normal wings and normal bristles.
If you cross two parents from F1 to have F2, you'll find:
SsLl x SsLl = SSLL + SslL + sSlL+ ssll = 25% SSLL,all dominant traits. 50% SsLl is a recessive trait carrier but shows dominant traits. 25% ssll this one has all recessive alleles, which means, it will show vestigial wings and signed bristles.
The recombinant F2 offspring in this genetic cross of Drosophila are those that do not exhibit the parental trait combinations. Therefore, singed bristles/normal wings and normal bristles/vestigial wings are considered recombinant offspring. Option C is correct.
A researcher crossed true-breeding Drosophila flies with singed bristles (s) and normal wings (L) with true-breeding flies having normal bristles (S) and vestigial wings (l). The F1 offspring all had normal wings and normal bristles, indicating that these traits are dominant. When these F1 flies were crossed with flies having singed bristles and vestigial wings, the F2 generation showed various combinations of these traits.The F2 progeny would exhibit the following combinations: normal bristles/normal wings, singed bristles/vestigial wings, normal bristles/vestigial wings, and singed bristles/normal wings. The recombinant offspring are those that do not exhibit the parental combinations of traits. Thus, the recombinant F2 offspring would be singed bristles/normal wings and normal bristles/vestigial wings.Complete question as follows:
A researcher conducted crosses between two different strains of Drosophila. When true-breeding flies with singed bristles (s) and normal wings (L) were crossed to true-breeding flies with normal bristles (S) and vestigial wings (l), all F1 offspring had normal wings and normal bristles. The F1 offspring were crossed to flies with singed bristles and vestigial wings. Which F2 offspring is/are recombinant?
A.Singed bristles/vestigial wings only
B.Singed bristles/normal wings only
C.Singed bristles/normal wings and normal bristles/vestigial wings
D.Singed bristles/vestigial wings and normal bristles/normal wings
How are transfusion reactions type II responses? What happens in a transfusion reaction?
Answer:
Explained
Explanation:
Type II response can be defined as an antibody-dependent process in which specific antibodies bind to antigens and results in tissue damage. Transfusion reaction is a type II response because here the mismatched RBC's are rapidly destroyed by specific preformed antibodies (anti-ABO or -Rh) and complement.
Transfusion reactions takes place when incompatible blood products are transfused into a patient's circulation. This triggers the patient's immune system and consequently donor RBC's are destroyed by antibodies in the recipient's circulation. This is usually seen when antigen-positive donor RBC's are transfused into a patient who has preformed antibodies to that antigen.
Uterine muscle responsiveness to oxytocin
a. is enhanced by an increased in estrogen/progesterone ratio
b. is prevented by high prostaglandin levels during pregnancy
c. is decreased by down-regulation of oxytocin receptors during the third trimester
d. is enhanced by decreased estrogen/progesterone ratio
e. is independent of estrogen/progesterone ratio
Answer:
a. is enhanced by an increased in estrogen/progesterone ratio
Explanation:
The average duration of human pregnancy is about 9 months or we can say 38 weeks/266 days. This period is called as the gestation period. At the end of pregnancy vigorous contraction of the uterus result in expulsion or delivery of the baby. It is called parturition. Parturition is a neuroendocrine mechanism.
During pregnancy uterine contractions are inhibited due to the high progesterone levels. Progesterone maintains the endometrium and prevents contraction of myometrium. At the end of last trimester, the progesterone levels plateau and then drops whereas estrogen levels continue to rise.
As a result the E/P ratio increases which makes the myometrium more sensitive to contraction stimuli.
The decreases levels of progesterone may lead to Braxton Hicks contraction which is nothing but false labor. Meanwhile, oxytocin hormone is secreted by the posterior pituitary gland which induces the contraction of myometrium.
This family of bacteria is often associated with urinary tract infections?
A) Listeria
B) Salmonella
C) Proteus
Answer:
The correct answer is C) Proteus
Explanation:
Proteus comes under the family Enterobacteriaceae and is often associated with urinary tract infections in animals and humans. These bacteria are often the part of intestine but become pathogenic when enter into urinary tract.
Proteus mirabilis is a gram negative anaerobic bacteria present as normal flora of intestine known to cause urinary tract infections in humans but most of the urinary tract infection is caused by E. coli.
When these bacteria get into the blood stream they can cause systemic inflammatory response syndrome and sepsis which has very high mortality rate.
Final answer:
The family of bacteria often associated with urinary tract infections is Proteus. While not included in the options, Escherichia coli is the most common cause of UTIs.
Explanation:
The family of bacteria often associated with urinary tract infections (UTIs) is Proteus. Among the options given, Proteus specifically refers to a genus of bacteria that can cause infection in the urinary tract. While not included in the given options, it is noteworthy that Escherichia coli is actually the most common cause of UTIs. Bacteria from the genus Proteus are known for their ability to produce a strong odor and have the ability to form stones in the kidney due to the production of urease, causing further complications.
If you are about to fight or flight a dog that wants to bite you, the cellular signal inside your body that will trigger a signaling network for this response is called:
a. NADH
b. connexon
c. estrogen
d. adrenaline
Answer:
D. Adrenaline
Explanation:
Adrenaline hormone is secreted by adrenal medulla during stressful conditions. The hormone is involved in preparing the body for stressful conditions by intensifying the sympathetic response.
If a person is chased by a dog, the adrenaline hormone is released from the adrenal medulla. The hormone triggers the preganglionic neurons of the sympathetic division of the autonomous nerve system to generate the flight or flight response.
Adrenaline increases the heart rate, blood pressure, and blood flow to skeletal muscles and adipose tissues. The hormone also triggers the dilation of airways and increases the blood levels of glucose and fatty acids.
A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have
a. T2 protein and T4 DNA.
b. T2 protein and T2 DNA.
c. T4 protein and T4 DNA.
d. T4 protein and T2 DNA.
Answer:
Option (a).
Explanation:
Virus are the acellular organism and can only acts as living organism when present inside the host organism. Virus can have DNA or RNA as their genetic material.
The bacteria is infected with T2 phage protein coat and T4 phage DNA. As only DNA can acts as the genetic material and can be inherited to the next generation. The new phages has the T4 DNA as their genetic material and T2 phage protein coat.
Thus, the correct answer is option (a).
Answer:
Option (a).
Explanation:
Albino rabbits (lacking pigment) are homozygous for the recessive c allele (C allows pigment formation). Rabbits homozygous for the recessive b allele make brown pigment, while those with at least one copy of B make black pigment. True-breeding brown rabbits were crossed to albinos, which were BB. F1 rabbits, which were all black, were crossed to the double recessive (bb cc). The progeny obtained were 34 black, 66 brown, and 100 albino. a. What phenotypic proportions would have been expected if the b and c loci were unlinked? b. How far apart are the two loci?
Answer:
a. If the b and c loci were unliked the expected phenotypic proportions would be:
- 1/4 Brown
- 1/4 Black
- 1/2 Albino
b. The estimated distance between the two loci is equal to 17 centimorgans (cM).
Explanation:
a. If the loci b and c are unlinked or they are not in the same chromosome, it means that b and c are segregated independently (following Mendel's laws). So, the first step is to state the genotypes of the rabbits.
Albino rabbits are homozygous for c (cc)
Brown rabbits are homozygous for b (bb).
Black rabbits have a copy of B (Bb or BB).
But, rabbits have the two genes (b and c), so they could be:
Albino: BBcc/Bbcc/bbcc.
Brown: bbCC/bbCc
Black: BBCC/BBCc/BbCC/BbCc
A cross was made with true-breeding brown rabbits( that means "pure" or homocygotes) bbCC and albino BBcc.
So, we have :
bbCC X BBcc
This is a dihybrid cross with only one possible genotype in F1: BbCc. -> Black rabbits.
After this, these rabbits (BbCc) were crossed with double recessive (albino) rabbits, like this:
BbCc X bbcc
To know the possible outcomes of F2, it is necessary to make a Punnett square 4x4. Following the independent assortment principle, we will have the following possible gametes:
Black Rabbits: Cb, CB, cB,cb.
Double recessive rabbits: cb, cb, cb, cb.
After doing the Punnett square, we will have 4 possible genotypes and 3 possible phenotypes in F2:
1. bbCc = Brown
2 BbCc = Black
3. Bbcc= Albino
4. bbcc= Albino
That means:
1. 1/4 Brown
2. 1/4 Black
3. 1/2 Albino
b. To estimate the distance between the two loci is necessary to use the data provided in the question.
In this case, we are assuming that b and c are in the same chromosome, so they don't follow Mendel's laws. The first step is to know which are the initial genotypes.
The initial cross was between a brown rabbit (bbCC ) and an albino rabbit (BBcc). If the two genes are linked, we can say that in the brown rabbit bC are always together and in the albino Bc will be together, because they're linked.
F1 will be black rabbits bCBc, (remember bC and Bc go always together).
So, after this, a new cross was made with a double recessive:
bCBc X bcbc
The possible outcomes are:
bCbc Brown
bCbc Brown
Bcbc Albino
Bcbc Albino
As you see, there are not black rabbits, so to find black rabbits, we need to find a BCbc genotype. This genotype can be produced by recombination or crossingover in the same chromosome in parentals. So, the distance between two loci is equal to the proportion of individuals with a recombinant genotype, in this case, BCbc or black rabbits.
So, we have:
34 black
66 brown
100 albino
Total: 200
D[tex]Distance=\frac{Recombinants}{Total } *100= \frac{34}{200}*100= 17 cM[/tex]
Estimated distances are measured in centimorgans (cM).
Your digestive system is equipped with a diversity of enzymes that
break the polymers in your food down to monomers that your cells can
assimilate. A generic name for a digestive enzyme is hydrolase. What is
the chemical basis for that name?
Answer:
Enzymes are named according to the reaction they catalyze. Polymers are made of subunits joined together by different types of bonds, forming a macromolecule.
Hydrolases are used by the organism to catalyze the hydrolysis of polymers so they can be easily manipulated as monomers. Hydrolysis means reacting with water, water can break the bonds of different polymers turning it into its constitutive monomers.
Describe the four ways that drugs can affect a person's nervous system.
Answer:
Four ways by which drugs can affect the nervous system are as follows:
Drugs like heroin can mimics the chemical structure of the neurotransmitters. They causes the excess activation of neurons in the brains and affect the nervous system.
Some drugs also mimics the neurotransmitter but causes the abnormal messages sent through the brain. Their mimicry of neurotransmitters cannot activate the neuron but causes the interruption and wrong messaging in the nervous system.
Drugs like cocaine causes the stimulation of release of large number of neurotransmitters. This causes the prevention of recycling of brain chemicals and disturbs the neuron communication.
Some drugs causes the inhibition of release of neurotransmitters in the brain. This stops the signalling of the nervous system and interrupts the chemical messages of the body.
Besides a high voltage shock, what is another method to make E. coli competent to take up "naked" DNA?
a. high concentrations of calcium ions followed by high temperature
b. high concentrations of calcium ions and several hours on ice
c. large amounts of DNA added directly to a bacterial culture growing at 37C
d. high concentrations of minerals followed by high temperature
e. a high voltage shock is the only way to make E. coli competent
Answer:
The correct answer is a. high concentrations of calcium ions followed by high temperature.
Explanation:
Apart from high voltage shock, calcium chloride heat shock method can be used to make E. coli competent to take up naked DNA. As both DNA and lipids contain phosphorus and phosphorus contains negative charge, therefore, ice-chilled CaCl₂ makes cation bridge between phosphorylated lipid of cell membrane and phosphorus present in the DNA.
This allows the naked DNA to attach to the cell surface of bacteria. Then cells are given heat shock which creates gaps(holes) in the membrane and makes the cells competent to take up the naked DNA by these holes.
Then the transformed cells can be selected by screening methods like growing transformed cells on media containing a suitable antibiotics.
E. coli cells can be made competent to take up DNA by incubating with calcium ions and then applying heat shock, which allows DNA to enter the cells through pores formed in the membrane. So the correct option is a.
Explanation:Besides a high voltage shock, another method to make E. coli competent to take up DNA is by using high concentrations of calcium ions followed by a heat shock. This process involves incubating E. coli cells with an ice-cold solution of 50 mM calcium chloride at 4°C for 30 minutes, which allows the DNA molecules to attach to the cell exterior. Following this, the cells are briefly incubated at 42°C, which causes the formation of pores in the membrane, allowing DNA to enter the cell.
Which of the following does not occur during mitosis?
a. condensation of the chromosomes
b. replication of the DNA
c. separation of sister chromatids
d. spindle formation
Answer:
Option (b).
Explanation:
Mitosis may be defined as the process of cell division in which a single parent cell divides into two cells. This division is known as reduction division because the chromosome number remains the same.
The chromosome condensation, spindle formation and sister chromatid separation occurs in mitosis. The replication of DNA occurs in the synthesis phase of cell cycle not during the process of mitosis.
Thus, the correct answer is option (b).
Replication of the DNA does not occur during mitosis.
Explanation:The correct answer is b. replication of the DNA. DNA replication occurs during interphase, which is the phase before mitosis. During mitosis, the DNA has already been replicated and is condensed into visible chromosomes. The other events listed in the options all occur during mitosis: condensation of the chromosomes, separation of sister chromatids, and spindle formation.
Because of gall stones, Fred had his gallbladder surgically removed. Which of the following is the most likely side effect?
a. difficulty with protein digestion
b. difficulty with feces production
c. difficulty with vitamin B12 absorption
d. difficulty with fat digestion
e. difficulty with bile production
Answer:
d. difficulty with fat digestion
Explanation:
The gallbladder is an accessory gland that stores bile produced in the liver, so option "e" is not possible. Bile is a type of enzyme that helps to break down fats which makes option "d" as the best option. Protein digestion is mainly by different enzymes known as proteases. Feces are formed in the short intestine.
One theory of human evolution suggests that Homo erectus evolved directly into Homo sapiens (humans), after which point Homo erectus became extinct. If this is true, humans arose by ________.
a. allopatric speciation
b. cladogenesis
c. anagenesis
d. parapatric speciation
Answer:
The correct answer will be option-C.
Explanation:
The evolution of human species in which one species transformed into another species evolves by a mechanism known as anagenesis.
Anagenesis is the mechanism of evolution which transform one species into a different species within a lineage. This process is slow and takes time to form species, therefore, is also known as gradualism or phyletic transformation.
The Homo sapiens evolved from Homo erectus where Homo sapiens overwrites the ancestral species and caused the species to become extinct.
Thus, Option-C is the correct answer.
Write down symbols for the alleles. (These may be given in the problem.) When represented by single letters, the dominant allele is uppercase and the recessive is lowercase.
Answer: A (uppercase letter) is used to refer to dominant alleles.
a (lowecase letter) is used to refer to recessive alleles.
Explanation:
Alleles are different forms of a gene, and they can be dominant or recessive. Each gene codes for a specific trait.
Diploid organisms, such as human beings, have two alleles for each gene. If an organism is heterozygous for a certain trait, it means it has one dominant and one recessive allele. And since the dominant allele masks the effects of the other one, the dominant trait is expressed in the phenotype. So, dominant alleles show their effect even if the organisms only has one copy of it.
If an organisms is homozygous, it has two dominant alleles or two recessive alleles. Then it can be homozygous dominant, where both are dominant alleles; or homozygous recessive where both are recessive. Recessive alleles only show their effect if the organisms has two copies of it.
For example, if we want to study the gene that codes for hair color, we could say that dominat allele "A" codes for brown hair, and recessive allele "a" codes for blonde hair. If a person has brown hair, the genotype could be either AA or Aa, becuase AA is homozygous dominant and it has two copies of brown color. And Aa is heterozyogus, but the person only needs one copy of the allele to be expressed. On the other hand, if the person has blonde hair, the genotype can only be aa because recessive alleles only show their effect if there are two copies of the allele.
In genetics, alleles are symbolized by letters, with uppercase for dominant alleles and lowercase for recessive alleles. A homozygous dominant genotype is written with two uppercase letters (VV), a homozygous recessive with lowercase (vv), and a heterozygous genotype combines both (Vv).
Explanation:Understanding Allele Symbols in Genetics
In genetics, the symbols for alleles are represented by letters, with the dominant allele typically denoted by an uppercase letter and the recessive allele by a lowercase letter. For instance, in the example of pea plant flower color, if violet is the dominant trait, then 'V' would symbolize the dominant allele, while 'v' would represent the recessive allele for a white flower color. Therefore, a homozygous dominant pea plant with violet flowers would have the genotype 'VV', a homozygous recessive plant with white flowers would be 'vv', and a heterozygous pea plant with violet flowers would have the genotype 'Vv'.
Dominance was discovered by Mendel, who observed that certain traits, like the height in pea plants, showed a dominant and recessive pattern. A plant with genotype 'TT' (tall) would be homozygous dominant, while 'tt' (dwarf) would indicate a homozygous recessive plant. A heterozygous plant with the genotype 'Tt' would also be tall, displaying the dominant trait. Furthermore, when two heterozygous pea plants are crossed (Tt x Tt), Mendel deduced a characteristic 3:1 ratio of dominant to recessive phenotypes in the offspring.
In mechanism, photophosphorylation is most similar to
a. substrate-level phosphorylation in glycolysis.
b. oxidative phosphorylation in cellular respiration.
c. carbon fixation.
d. reduction of NADP+.
Answer:
b. oxidative phosphorylation in cellular respiration.
In mechanism, photophosphorylation is most similar to oxidative phosphorylation in cellular respiration. Both processes involve establishing a proton gradient across a membrane to generate ATP.
Explanation:In the biological process of energy production, photophosphorylation parallels most closely to oxidative phosphorylation in cellular respiration as option b suggests.
During oxidative phosphorylation, electron transport chain drives the creation of a proton gradient across a membrane, and the subsequent flow of protons down this gradient is used to power ATP production. Similarly, during photophosphorylation, the energy of sunlight is used to generate a proton gradient, which again drives the synthesis of ATP. So, in essence, both processes use a membrane-bound proton gradient to drive ATP synthesis.
This is different from substrate-level phosphorylation, carbon fixation and the reduction of NADP+. Substrate-level phosphorylation refers to direct ATP production during a specific reaction in the metabolic pathway, while carbon fixation is the process of converting CO2 into organic compounds; and the reduction of NADP+ is about adding electrons to NADP+ to convert it to its reduced form, NADPH.
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Variant Creutzfeldt-Jakob disease, listeriosis, anthrax, and E.coli 0157-H7 infections all have which of the following in common?
a. All four diseases can be transmitted from cattle to humans
b. All four diseases are caused by bacteria
c. All four diseases can be treated with antibiotics
d. All of the above are true for all four diseases.
Answer:
A. All four diseases can be transmitted from cattle to humans
Explanation:
Variant Creutzefeldt Jakob disease (VCJD) is a brain disease caused by a mutated protein (prion).
This particular type of CJD can be caused by eating beef from animals that were infected with bovine spongiform encephalopathy.
Listeriosis is caused by a bacteria called Listeria monocytogenes
Listeriosis often occurs through digesting contaminated foods such as raw meat, beef or dairy products.
E.coli-0157:H7
E. coli is a bacteria that occurs naturally in the digestive system of humans and animals.
However, it can be disease causing once it spreads to other parts of the body.
There are different strains of E.coli.
E.coli 0157:H7 is a dangerous strain to humans and is found in the manure of cattle, dogs and geese.
People can become sick with this by eating raw contaminated meat.
Anthrax
Anthrax is caused by a bacteria called Bacillus Anthracis.
Anthrax mainly affects livestock (cattle) and wild animals.
Anthrax is transmitted to humans by direct contact with an infected animal.
Tom's brother suffers from phenylketonuria (PKU), a recessive disorder. Tom and the brothers' parents do not have PKU. What are the chances that Tom is a carrier of the recessive PKU allele?
a. 1/4
b. 1/3
c. 1/2
d. 2/3
e. 4/3
Final answer:
Tom has a 2/3 chance of being a carrier of the recessive PKU allele.
Explanation:
To determine the chance that Tom is a carrier of the recessive PKU allele, we need to understand the inheritance pattern of PKU. PKU is a recessive disorder, which means that an individual needs to inherit two copies of the recessive allele to have the disorder. Since Tom's parents do not have PKU, they must be carriers of the recessive allele. This means that each parent has one copy of the recessive allele and one copy of the dominant allele.
If both parents are carriers, there are four possible combinations of alleles that they can pass on to their offspring: two dominant alleles (NN), one dominant allele and one recessive allele (Nn), one recessive allele and one dominant allele (nN), and two recessive alleles (nn).
Since Tom does not have PKU, we know that his genotype is either NN or Nn. The chance that Tom is a carrier of the recessive PKU allele is 2/3, which corresponds to the possibility of him having the Nn genotype. Therefore, the correct answer is d. 2/3.
Josey wants to look at the cells of an onion under a light microscope. She peels off a thin, transparent layer of onion and places it on a
microscope slide. Josey places the sample on the microscope stage, looks through the eyepiece, and adjusts the stage to focus the image
However, she is unable to see any details of the cells.
Which of the following possible solutions could possibly help Josey to see the onion cells in detail?
A. Josey should use a thicker piece of onion for her sample
B. Josey shouldhplace her onion sample in a vacuum.
C. Josey should place a drop of water on her sample
D. Josey should apply a stain, such as iodine, to her sample
Answer:
D
Explanation:
A cell and its organelles are usually transparent hence hard to discern without staining. There are different staining techniques that are useful for viewing various type of cells and organelles depending on which stain they pick up well. In this case of an onion, the starch molecules in the onion will take up the iodine and improve visualization. This due to the fact that iodine molecules get emended in the structure of the amylose and amylopectin molecules of starch causing starch molecules to turn blue lack (due to a change in light absorption spectra of the complex).
Final answer:
Josey should try applying a stain, such as iodine, to her onion sample to see the cells in detail. Using a thicker piece of onion, placing the sample in a vacuum, or adding a drop of water can also improve visibility, but applying a stain is the most effective solution.
Explanation:
To see the onion cells in detail, Josey should try applying a stain to her sample. Stains like iodine can help to make the cells more visible under the microscope. By adding a stain, the cells will appear darker or have a different color, making it easier to see their structures and details.
Using a thicker piece of onion for the sample or placing the sample in a vacuum will not help Josey see the onion cells in detail. A thicker piece of onion will not necessarily enhance the visibility of the cells, and placing the sample in a vacuum is not necessary for observing cells under a light microscope.
Adding a drop of water to the sample can actually help improve the visibility of the cells. Water can help to enhance the contrast between the cells and the microscope slide, making the cells easier to see.
Microphylls are found in which plant group?
a. lycophytes
b. liverworts
c. ferns
d. hornworts
Answer:
a. lycophytes is the correct answer.
Explanation:
Microphylls are found in lycophytes.
lycophyte is a vascular plant, they have a unique type of leaves called microphylls.
The lycophytes belong to the division of Lycophyta, they are seedless plants and have vascular tissue.
The leaves(microphylls) present in the lycophyte have a single vein that is unbranched and narrow, which provides the water to the leaf and supplies nutrients to other parts of the plant.
Microphylls, which are characterized by a single vascular vein, are found primarily in lycophytes. Lycophytes are an ancient group of vascular plants and include species like club mosses and quillworts.
Explanation:Microphylls are a specific type of leaf that are typically characterized by only having a single vascular strand or vein. This contrasts with megaphylls, which usually have multiple veins. The answer to which plant group microphylls are found in is a. lycophytes.
Lycophytes are one of the oldest groups of vascular plants and are recognized by their microphyllous leaves. Notable examples of lycophytes include club mosses, quillworts, and spike mosses. The presence of microphylls is a defining characteristic of this plant group.
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What is the total number of ATPs produced by cellualar metabolism (per glucose molecule)?
Answer:
38 ATP
Explanation:
One molecule of glucose on complete breakdown yields 38 ATP. The break up of APT production at different steps of cellular respiration is given below:
Glycolysis yields 4 ATP and 2 NADH is produced, but 2ATP is used. Net gain of 2ATP. During formation of Acetyl CoA, 2 NADH is produced. During Krebs cycle 2 ATP, 6 NADH, 2 FADH₂ are produced. During Electron transport chain, reduced coenzymes NADH and FADH₂ oxidised to release ATP.Each NADH releases 3 ATP and each FADH₂ releases 2 ATP. Altogether 10 NADH is produced which yield 30 ATP and 2 FADH₂ yields 4 ATP.
Therefore, on complete oxidation of one molecule of glucose yields 38 ATP.
How many possible open reading frames (frames without stop codons) are there that extend through the following sequence? 5'... CTTACAGTTTATTGATACGGAGAAGG... 3' 3'... GAATGTCAAATAACTATGCCTCTTCC... 5'
According to the DNA sequence shown in the question above, we can see that there are 3 reading frames without stop codons.
You can find this answer as follows:
Isolate the 5'-3' Sequence: You will not need the 3'-5' Sequence, so you will need to isolate the 5'-3' Sequence. In this, you should observe the sequence of nitrogenous bases, identify the codons (set of three nitrogenous bases) and create three sequences. The first sequence will exclude the first nucleotide, the second sequence will exclude the second nucleotide, and the third sequence will exclude nothing. Based on this, you will have the three sequences below:5'... C TTA CAG TTT ATT GAT ACG GAG AAG G... 3' (no stop codon)
5'... CT TAC AGT TTA TTG ATA CGG AGA AGG... 3' (no stop codon)
5'... CTT ACA GTT TAT TGA TAC GGA GAA GG... 3' (with stop codons)
Create complementary sequences: You should do this based on the complementarity of the nitrogenous bases. In this case, it is necessary to remember that Adenine (A) is complemented by Thymine (T), Guanine (G) is complemented by cytosine (C), and vice versa. In this case, you will have the following sequences:3'... GAA TGT CAA ATA ACT ATG CCT CTT CC... 5'
3'... GA ATG TCA AAT AAC TAT GCC TCT TCC... 5'
3'... G AAT GTC AAA TAA CTA TGC CTC TTC C... 5'
Identify the inverse complement: Still taking into account the complementarity of the nitrogenous bases, you should find the inverse complementary sequences. In this case, you will find the sequences:CCT TCT CCG TAT CAA TAA ACT GTA AG (with stop codon)
CC TTC TCC GTA TCA ATA AAC TGT AAG (no stop codon)
C CTT CTC CGT ATC AAT AAA CTG TAA G (with stop codons)
From this, we can see which sequences have one of the stop codons, which are TAA, TAG, TGA. As you can see, only the first two frames of the 5'-3' sequences and the first two frames of the inverse sequences do not have these codons, so it is possible to observe 3 open reading frames without stop codons.
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The query's genetic sequence potentially has three different open reading frames, starting from the first, second or third position. However, without specific information about the position of the start codon AUG and the stop codons, we can't definitively verify how many open reading frames extend through this sequence.
Explanation:In genetics, the concept of an open reading frame (ORF) is of immense importance. An ORF is a sequence of DNA or RNA that could be potentially translated to give a protein. Understanding the open reading frames in a genetic sequence helps us predict how that sequence might be translated into amino acids.
For the given sequence, we can have three ORFs since you can start reading the sequence from three different positions (first, second, or third nucleotide) until you run into a stop codon. However, without knowing the exact position of the start and stop codons in this specific sequence, we cannot accurately say exactly how many open reading frames might extend through it.
The concept of AUG start codon used to initiate translation and stop codons that terminate protein synthesis are essential for determining open reading frames. The sequence AUG signifies the beginning of an ORF.
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With respect to angiosperms, which of the following is incorrectly paired with its chromosome count?
a. egg—n
b. megaspore—2n.
c. microspore—n
d. zygote—2n
Answer:
Megaspore—2n.
Explanation:
Angiosperms are the fruit bearing plants and reproduce by the process of sexual reproduction. The chromosome number are specific at each stage of the cell cycle of the angiosperms.
Microspores , egg are haploid. Zygote is diploid in nature. Megaspores get germinate into the female gametophytes and these are haploid in nature. Megaspores are also haploid in angiosperms.
Thus, the correct answer is option (b).
The description 'megaspore—2n' is INCORRECTLY paired with its chromosome count.
In plants (including angiosperms) the egg cell is the haploid (n) female gamete.
After fertilization, the egg cell forms a diploid (2n) zygote that subsequently develops the embryo inside the ovule.
A microspore is a haploid (n) cell that gives a male gametophyte.
In conclusion, the description 'megaspore—2n' is INCORRECTLY paired with its chromosome count.
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