Answer:
A nucleosome forms hydrogen bonds with the phosphodiester backbone and with the bases through the minor groove. The histone-fold hydrogen bonds with both the A: T enriched bases and the phosphodiester backbone. The histone-fold domains' association with the minor groove is responsible for the majority of the associations in the nucleosome.
Final answer:
A nucleosome forms hydrogen bonds primarily with the phosphodiester backbone of DNA, facilitated by interactions at the L1-L2 loops and αl helices, including minor groove entry by arginine side chains from histone folds. These arrangements enable efficient DNA packaging and sequence-independent binding necessary for nucleosome function.
Explanation:
A nucleosome forms hydrogen bonds with the phosphodiester backbone of DNA. These interactions are fundamental for DNA packaging within the nucleus, ensuring DNA is wrapped around histone proteins to form nucleosomes. The L1-L2 loops at the ends of each histone dimer and the αl helices at the center of the DNA binding site are primary contact points, where hydrogen bonds are formed between amino acids of the histones and the phosphate backbone of DNA. Additionally, arginine side chains from histone folds enter the minor groove of DNA, influencing the DNA's structural dynamics within the nucleosome.
These interactions allow nucleosomes to bind to DNA in a non-sequence-specific manner, which is crucial for their role in DNA packaging and regulation. The presence of water-mediated interactions and the flexibility in binding accommodate the DNA's varying sequences and structures, enabling nucleosomes to organize DNA efficiently within the cell nucleus.
Which (if any) of the following statements regarding staphylococcal food-borne illness is not correct? If all of the statements are correct, choose the final answer.
a. the disease is caused by ingestion of a toxin
b. the bacterium that causes the disease is often normal flora in the nose of asymptomatic carriers.
c. the bacterium that causes the disease also causes pus forming wound infections, which can transmit the disease to food.
d. cooking contaminated food to kill the bacteria will prevent transmission of the disease
e. all of the above statements regarding staphylococcal food-borne illness are correct
Answer:
d. cooking contaminated food to kill the bacteria will prevent transmission of the disease
Explanation:
Staphylococcus is an opportunistic pathogen that normally inhabits our skin and respiratory tract. When this bacteria grows in food it produces different enterotoxins, which are stable at high temperatures. That is why if a food is contaminated with this bacterium, it is possible that it already contains enterotoxin and when it is reheated or cooked, even though the bacteria is killed, the toxin will remain active and will generate the disease.
why is it important to stain youngcultures of bacteria with
the grain stain?
Answer:
Because older cultures of gram-positive bacteria tend to lose their ability to retain crystal-violet in the peptidoglycan of their cell walls and can be confused with gram-negative bacteria.
Explanation:
Gram staining is used to differentiate between two major groups of bacteria. Gram-positive and gram-negative, these bacteria differ in the amount of peptidoglycan in their cell walls. Gram-positive bacteria have a higher amount of peptidoglycan, which absorbs the violet crystal complex used in gram staining, staining them purple/violet. Old cultures of gram-positive bacteria tend to lose the ability to retain the violet crystal and are stained by safranine, staining them red/pink and appear to be gram-negative.
What is the difference between Southern and Northern hybridizations?
a. southern blots hybridize a DNA probe to a digested DNA sample but northern blots hybridize a DNA probe to, usually, mRNA
b. southern blots use an RNA probe to hybridize to DNA but northern blots use an RNA probe to hybridize to RNA
c. southern blots determine if a particular gene is being expressed but northern blots determina the homology between mRNA and a DNA probe
d. southern blots determine the homology between mRNA and a DNA probe but northern blots determine if a particular gene is being expressed
e. southern and northern blots are essentially the same technique performed in different hemispheres of the world.
Answer:
a. southern blots hybridize a DNA probe to a digested DNA sample but northern blots hybridize a DNA probe to, usually, mRNA
Explanation:
Both techniques are quite similar. The main objective of this technique is to identified specific either DNA or mRNA molecules. Hybridization is the process of forming a double - stranded DNA molecule between a single-stranded DNA probe and a single-stranded target DNA (which is the fragment that wants to be found. Northern blotting targets mRNA while Southern blotting targets DNA sequences.
When the his—Salmonella strain used in the Ames test is exposed to substance X, no his+ revertants are seen. If, however, rat liver supernatant is added to the cells along with substance X, revertants do occur. Is substance X a potential carcinogen for human cells? Explain.
Answer:
The test, which is used to examine the tendency of generating mutagens by a chemical is termed as the Ames test. The procedure is primarily used in bacteria to see whether the given chemical results in mutations in the DNA of the organism being examined.
The positive test demonstrates that the chemical is mutagenic and can function as a carcinogen, this is due to the fact that cancer is associated with the mutation. The performed experiment in the given case indicates that substance X is a potential carcinogen.
As the rat liver supernatant exhibited the enzymes, which transformed the substance X into mutagen. This led to the origination of his + revertants. The human liver possesses identical enzymes, which process the substance and transforms them into other components. This can cause mutation in human cells and can result in cancer.
If substance X does not cause his+ revertants in the Ames test alone but does when rat liver supernatant is added, it suggests substance X is metabolized to a mutagenic or potentially carcinogenic form. Hence, substance X could be a potential carcinogen for human cells.
In the Ames test, the his—Salmonella strain is used to test the mutagenicity or potential carcinogenicity of substances. If substance X does not cause any his+ revertants in the presence of the Salmonella strain alone but does when rat liver supernatant is added, it suggests that substance X is being metabolized by the liver enzymes to a mutagenic or potentially carcinogenic form. Therefore, substance X could be a potential carcinogen for human cells as well.
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A group of paleontologists have discovered a new fossil animal resembling a horse with intact DNA in the fossil. The fossil animal is theorized to have a phylogenetic relationship with a horse. What is the most appropriate method for determining if a close relation existed between these two species? A : Morphological studies B : Biochemical estimation C : Genetic analysis D : Physiological studies
The correct answer is C. Genetic analysis
Explanation:
In biology, two organisms have a phylogenetic relationship if they share a common ancestor and therefore have genetic similarities although in most cases there are also similarities in morphology, physiology, etc. However, two organisms might have similarities in morphology and physiology without genetic similarities. Due to this, if you need to determine whether two species are related or not the best method is a genetic analysis as only those organisms that share a common ancestor (phylogenetic relationship) are genetically similar.
The unit of genetic material not divisible by recombination or mutation is the:
a. coding region of DNA
b. intron
c. exon
d. single nucleotide pair
e. codon
Answer:
Single nucleotide pair.
Explanation:
DNA is present as genetic material in all the living organism except some viruses. DNA is made of nitrogenous base, pentose sugar and the phosphate group.
DNA can be hydrolyzed further into the single sub units of the nucleotide. The single nucleotide pair unit of the DNA consists of a single nucleotide that can not be broken down further. Mutation or even recombination is not enough for the division of single nucleotide pair.
Thus, the correct answer is option (d).
Which of the following is not a characteristic that distinguishes gymnosperms and angiosperms from other plants?
a. dependent gametophytes
b. ovules
c. pollen
d. alternation of generations
Answer:
d. alternation of generations
Explanation:
The alternation of generations is when an organisms lives a part of its life cycle being diploid and other part being haploid in a multicellular state. Plants such us as ferns (Pteridophyte) also have alternation of generations.
Alternation of generations is not a characteristic that distinguishes gymnosperms and angiosperms from other plants, because it is a feature common to all land plants. The other options listed, dependent gametophytes, ovules, and pollen, are unique to gymnosperms and angiosperms.
Explanation:All of the options listed are characteristics that generally distinguish gymnosperms and angiosperms from other plants, but one of them is also characteristic for most plants: the alternation of generations.
Dependent gametophytes, ovules, and pollen are unique to gymnosperms and angiosperms, serve as distinguishing features. The gymnosperms and angiosperms have a distinctive reproductive strategy involving dependent gametophytes, which are reduced in size and rely on the parental sporophyte, enclosed ovules, and pollen as a transport mechanism for male gametes.
Alternation of generations refers to a life cycle that includes both a multicellular diploid phase (the sporophyte) and a multicellular haploid phase (the gametophyte). This cycle is not unique to gymnosperms and angiosperms and is, in fact, a characteristic of all land plants.
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Unusual nucleosides that are found in mature tRNA molecules are added during:
a. transcription initiation
b. transcription elongation
c. transcription termination
d. post transcriptional modification
e. it is not currently known when the unusual nucleosides are added
Answer:
The correct answer will be option-D.
Explanation:
tRNA or transfer RNA is an adaptor molecule used during the translation process to add specific amino acids to the polypeptide.
The tRNA structure contains modified bases like inosine which is the first nucleotide of the anticodon loop and has the ability to form a hydrogen bond with more than one base of the codon. Inosine is derived from the adenine base during post-transcriptional modification of mRNA by methylation.
Thus, option-D is the correct answer.
Which statements is true of all atoms that are anions?
a. The atom has more electrons than protons.
b. The atom has more protons than electrons.
c. The atom has fewer protons than does a neutral atom of the same element.
d. The atom has more neutrons than protons.
Answer:
The atom has more electrons than protons.
Explanation:
Ions may be defined as the element that contains either positive or negative charge over it. Two types of ions are cations and the anions. The charge on the species is obtained by the loss or gain of electron.
Anions carry negative charge over them. Negative charge occurs by gaining of the electrons from its neighboring atoms. The number of protons and electrons are equal in neutral atom. Since, the ions gain the electron and hence it carries more protons.
Thus, the correct answer is option (a).
An anion is an atom that has gained electrons and has more electrons than protons.
Explanation:The correct statement among the options is a. The atom has more electrons than protons.
An anion is a negatively charged ion, which means it has gained one or more electrons. This results in the atom having more electrons than protons, giving it a net negative charge.
For example, consider the chloride ion (Cl-) in table salt. It has 17 protons and 18 electrons, so it has one extra electron, making it a negatively charged anion.
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Bacterial transformation and bacteriophage labeling experiments proved that DNA was the hereditary material in bacteria and in DNA-containing viruses. Some viruses do not contain DNA but have RNA inside the phage particle. An example is the tobacco mosaic virus (TMV) that infects tobacco plants, causing lesions in the leaves. Two different variants of T MV exist that have different forms of a particular protein in the virus particle that can be distinguished. It is possible to reconstitute T MV in vitro (in the test tube) by mixing purified proteins and RNA. The reconstituted virus can then be used to infect the host plant cells and produce a new generation of viruses. Design an experiment to show that RNA acts as the hereditary material in TMV.
Answer:
Mix RNA from virus type I with the protein from virus type II to reconstitute a hybrid virus. In a parallel experiment, mix protein from virus type I with the RNA from virus type II. After that infect the cells with each of these reconstituted hybrid viruses distinctly, and assess the protein in the progeny viruses, which originates from each of the infections.
One will see that the progeny viruses in each case exhibit the protein, which matches the type of RNA in the parent hybrid virus. The protein in the progeny did not match with the protein in the parent hybrid virus.
Final answer:
To demonstrate RNA's role as hereditary material in TMV, an experiment involving modifying and tracking RNA in recombinant viruses, which are then used to infect plants, could be conducted. Progeny exhibiting the modified RNA's characteristics would confirm RNA as the hereditary material.
Explanation:
Experiment to Show RNA as Hereditary Material in TMV
To design an experiment proving that RNA is the hereditary material in Tobacco Mosaic Virus (TMV), a researcher could follow the precedent set by the Hershey and Chase experiments. First, one would need to acquire two strains of TMV with distinct protein coats but identical RNA. The RNA of one TMV strain should be modified with a mutagenic agent to introduce a detectable change, while keeping the protein coat unaltered. Next, the modified RNA and protein coats from both strains should be reconstituted to form new TMV particles. These recombinant viruses would be used to infect tobacco plants. If RNA is indeed the hereditary material, the progeny viruses isolated from the plants should exhibit the introduced change from the modified RNA irrespective of the protein coat it was packaged with.
Additionally, one could label the RNA with a radioactive or fluorescent marker to track its inclusion into the host cells and the manufacturing of new virus particles. If the marker is found in the progeny viruses, it would provide further evidence that RNA is passed onto the next generation, confirming it as the hereditary material of TMV.
Bowman’s capsule is part of the nephron where filtration happens.
a. True
b. False
Answer: True
Explanation:
The kidneys are the two blood purifying and excretory organs. These discharge excess water, waste metabolites, excess sugars and salts from the body. The nephron is the unit which performs the filtration process in each kidney. The bowman's capsule is the cup like structure inside the tubular part of the nephron. It performs the process of filtration of blood so as to form urine.
Assume that genes A and B are 50 map units apart on the same chromosome. An animal heterozygous at both loci is crossed with one that is homozygous recessive at both loci. What percentage of the offspring will show recombinant phenotypes? Without knowing that these genes are on the same chromosome, how would you interpret the results of this cross?
Answer:
Explanation:
The homozygous recessive individual can only produce 1 type of gamete (aabb).
The heterozygous individual can produce 8 types of gametes, of which 2 are parental and the rest are recombinant.
Genetic distance (m.u.) = Frequency of Recombination (%)
If the distance between genes A and B is 50 m.u., 50% of the gametes produced by the heterozygous individual, and therefore the offspring, will have recombinant phenotypes.
Without knowing that the genes are located on the same chromosomes, I'd think they are on different chromosomes, because you would get the same result: 50% recombinant offspring.
Whenever the genes on the same chromosome are separated by at least 50 m.u., or they are in different chromosomes, crossing over between them can happen with no restrictions and they will behave as independent of one another.
Given a genetic distance of 50 map units (centimorgans, cM), we would expect to see approximately 50% of offspring expressing recombinant phenotypes due to recombination or crossover events. This rate corresponds to a 50% recombination frequency. If we didn't know the genes resided on the same chromosome, we'd expect a Mendelian ratio assuming independent assortment.
Explanation:Given the genetic distance of 50 map units or centimorgans (cM) apart, genes A and B indicate that they are far apart on the same chromosome. Thus, the likelihood of recombination or crossover events between these genes resulting in recombinant phenotypes is high. Specifically, the recombination frequency corresponds to the genetic distance, meaning that with a distance of 50 cM, we expect about 50% of the offspring to express recombinant phenotypes.
Since you asked how one might interpret this information without knowledge of these genes being on the same chromosome, it is important to mention that if we didn't know this, we would expect to see Mendelian ratios assuming independent assortment of the genes. That is, the appearance of recombinant and parental types would be approximately equal, again indicative of a 50% recombination frequency.
This is due to the random segregation during the formation of gametes, where it's equally likely that either allele from one parent will be passed on to the offspring. This recombination frequency therefore, indicates that every type of allele combination is represented with equal frequency or 50 percent of offspring are recombinants. The other 50 percent retain the original, parental combinations of traits.
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Skeletal muscles are arranged in antagonistic pairs. What does this mean and what is an example?
A. There are always paired tendons and ligaments; the hip joint.
B. When one sarcomere contracts, the neighboring one relaxes; triceps and biceps.
C. One is under conscious control and one is not; the diaphragm and ribs.
D. There is always paired cartilage and muscle tissue; the knee joint.
E. When one contracts, the other relaxes and this allows the bones to move; triceps and biceps.
Answer: E. When one contracts, the other relaxes and this allows the bones to move; triceps and biceps.
Explanation:
Antagonistic action occurs between the two pairs of muscles. In this action one muscle while contracts other muscle relaxes. The example of antagonistic pair is of biceps and triceps. The triceps remain in the relax phase while the biceps contracts so as to lift the arm.
In humans, a dimple in the chin is a dominant characteristic. a. A man who does not have a chin dimple has children with a woman with a chin dimple whose mother lacked the dimple. What proportion of their children would be expected to have a chin dimple? b. A man with a chin dimple and a woman who lacks the dimple produce a child who lacks a dimple. What is the man's genotype? c. A man with a chin dimple and a non-dimpled woman produce eight children, all having the chin dimple. Can you be certain of the man's genotype? Why or why not? What genotype is more likely, and why?
A.
Answer:
Let's assign the dominant allele for dimples as - D - and the recessive as – d.
Based on the description, the woman must be heterozygous (Dd) for the dimple allele while the man is homozygous recessive (dd).
For the woman, her mother never had dimples meaning she was homozygous recessive (dd). This means the woman got a dominant allele from his father’s side and one recessive from the mother.
The man and the woman will, therefore, have the chances of bearing offspring as shown in the punnet square below;
50% will have dimples while 50% will not.
B.
Answer:
The same as above (and punnet square attached) because there is merely a switch of genotypes between the sexes as per the description.
C.
Answer:
Yes because in such case, the man is homozygous dominant (DD) for dimple allele. This way all offspring will be heterozygous dominant meaning they'll all have dimples. See the next punnet square (attached)
Dimple in chin is a dominant trait controlled by genes. The children produced by mixed genotypes parents have certain percentages for expressing either trait typically. However, probability may not always translate into real world results due to luck.
Explanation:In genetics, traits like a chin dimple are controlled by genes. The term genotype refers to the genes of an individual that determine traits. The dominant trait (like a chin dimple in this case) can be denoted by 'B', while the recessive trait (like a smooth chin) is denoted by 'b'. Dominant traits only require one gene (either from the father or mother) to be expressed, while recessive traits require both parent genes to be expressed.
(a) A woman with a chin dimple (B) paired with a man without a chin dimple (b) would result in children who have a 50% chance of having a dimple (Bb), given that the woman would be carrying the recessive trait from her mother.
(b) If a man with a chin dimple (B) and a woman without one (b) produce a child without a chin dimple, it means that the man must have been heterozygous for the trait (Bb), otherwise all the children would have had chin dimples.
(c) If a man with a chin dimple and a woman without one produce all children with chin dimples, the man's genotype is most likely BB. This is because, if it were Bb, there would have been a 25% chance at least one child being without a chin dimple (bb), but if all children have chin dimples, it's more likely that the man is BB.
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Science depends on ___________________.
A. practice
B. beliefs
C. reasoning
D. evidence
E. luck
Answer:
The correct answer is option D. Evidence.
Explanation:
Science is the quest and application of understanding and getting information of natural world and some time social world that is obtained by following a systematic procedure that is based on evidence.
Science is established by scientific method which include; observation, evidence, experiment, analysis, and conclusion. All these steps are mandatory to follow scientific method in order.
Thus, the correct answer is option D. Evidence.
RNA is translated into protein by using ______________
a. monosaccharide language
b. nucleotide language
c. fatty acid language
d. amino acid language
Diagram the forces and structures that dictate chromosomal movement during mitosis.
Answer:
Mitosis is the biological process by which cell division occurs
Explanation:
-in interphase the nucleolus and its cell membrane are differentiated, and the chromosomes are in the form of chromatin
- in prophase the chromosomes are condensed, and the chromatin is no longer visible
-in metaphase the rolled chromosomes each with their chromatids line up in the metaphase plate
in anaphase the chromatids of each chromosome separate and move towards the poles
in telophase the chromosomes are in each pole, the cell membrane forms again and the cytoplasm is divided.
Finally in cytokinesis cell division is completed
Non-coding DNA that lies between genes:
a. regulatory regions
b. exons
c. intergenic regions
d. introns
Answer:
Introns.
Explanation:
The RNA transcript consists of the both the exons and the introns region. The exons are the coding region of the RNA that codes for the particular amino acids.
The introns are the interrupted sequences between the exon. These sequences does not code for any proteins but helps in the alternative splicing. The introns are not present in case of prokaryotes.
Thus, the correct answer is option (d).
How are restriction enzymes and ligase used in biotechnology?
a. restriction enzymes cut DNA at specific locations, producing ends that can be ligated back together with ligase
b. only restriction enzymes that produce blunt ends after cutting DNA can be ligated with ligase
c. only restriction enzymes that produce sticky ends on the DNA can be ligated with ligase
d. restriction enzymes can both cut DNA at specific sites and ligate them back together
e. restriction enzymes randomly cut DNA, and the cut fragments can be ligated back together with ligase
Answer:
A. Restriction enzymes cut DNA at specific locations, producing ends that can be ligated back together with ligase.
Explanation:
Restriction enzymes are one of the endonucleases that cut the DNA at specific base sequences. The base sequences recognized and cut by the restriction enzymes are known as restriction sites.
Restriction enzymes are used in recombinant DNA technology to cut the DNA at specific sites. Restriction enzymes can produce DNA fragments with sticky ends or blunt ends. These DNA fragments are joined together by DNA ligase enzyme.
For example, the donor DNA and the vector DNA are cut at specific sites using a particular restriction enzyme. The resultant DNA fragments have complementary ends that are ligated together by the action of a DNA ligase enzyme. The result is the insertion of a gene of interest into the vector DNA.
Genetically modified food is unsafe because it contains viruses and bacteria that may cause disease.
a. True
b. False
Answer: False
Explanation:
The genetically modified crops does not contains viruses and bacteria in it. The genetically modified crops has the desired genes that produces protein according to our will.
There are many genetically modified crops that is found today, like Bt brinjal, Bt tomato, Bt cotton and many more.
These crops are rich in minerals and vitamins and has the ability to kill the insects feeding on them.
So, it does not contains any viruses and bacteria that may cause disease.
Drag each unit to the correct location.
Identify each unit as belonging to Sl units or US Customary units
gallon
mile
meter
pound
kilogram
degrees Fahrenheit
Kelvin
SI Unit
US Customary Unit
Answer:
United States (US) customary units is a system of measurement that is used in the United States of America.
International System of Units is the latest most widely used system of measurement. It is abbreviated as SI units.
Gallon (gal): It is a US customary unit used for measuring volume.
Mile (mi): It is a US customary unit used for measuring length.
Meter (m) : It is the SI unit used of length.
Pound (lb): It is a US customary unit used for measuring mass.
Kilogram (kg): It is the SI unit of mass.
Degrees Fahrenheit (°F) : It is a US customary unit used for measuring temperatures.
Kelvin (K): It is the SI unit of temperature.
Describe why oxygen moves from the air to the blood in the alveolar capillaries and again why oxygen moves from the blood to the interstitial fluid in the body tissues. Why is the partial pressure (concentration) of oxygen so low in the interstitial fluid?
Answer:
Higher partial pressure of oxygen in alveolar air than that of alveolar capillaries drives the diffusion of oxygen gas from air to the blood.
Higher partial pressure of oxygen in blood at tissue level as compared to the interstitial fluid drives diffusion of oxygen from blood to the tissue fluid.
Consumption of oxygen for cellular respiration in cells reduces the its concentration in the interstitial fluid.
Explanation:
Gaseous exchange in the body occurs through the process of diffusion wherein respiratory gases are exchanges down the concentration gradient.
Since the alveolar air has a higher partial pressure of oxygen than that of blood present in the surrounding blood capillaries, oxygen diffuses from the alveolar air to the blood making the blood oxygen-rich.
As the oxygen-rich blood reaches the body tissues, oxygen is diffused from the blood into the interstitial fluid since the later has lower oxygen concentration.
The supply of oxygen from the blood to the body tissues is required as the cells consume the oxygen to perform aerobic respiration and retrieve energy from the nutrients.
Oxygen moves from the air to the blood and from the blood to the interstitial fluid due to differences in partial pressure, with oxygen continuously diffusing from areas of higher to lower concentration.
Explanation:Oxygen Movement from Air to Blood and Tissues
The movement of oxygen from the air to the blood in the alveolar capillaries and from the blood to the interstitial fluid in the body tissues is driven by a gradient in partial pressure. Gases like oxygen diffuse from areas of high concentration to areas of low concentration according to Henry's Law. In the lungs, the partial pressure of oxygen is high in the alveoli (around 100 mm Hg) and low in the blood of the pulmonary capillaries (around 40 mm Hg). As a result, there is a strong gradient that drives oxygen diffusion across the respiratory membrane from the alveoli into the blood.
Once in the blood, oxygen binds to hemoglobin in red blood cells (RBCs), which transport it to the tissues. In the body tissues, the partial pressure of oxygen in the blood is higher than that in the interstitial fluid, causing oxygen to diffuse into the interstitial fluid and then into the cells of the tissues where it is used for cellular respiration. The partial pressure of oxygen is so low in the interstitial fluid because oxygen is continuously being consumed by the cells, thereby maintaining the pressure gradient necessary for diffusion.
What is normally present in urine? How does the filtration barrier function to prevent things from entering the filtrate? What does it prevent from entering?
Answer:
Generally urine comprises about 95 percent water, 2 percent electrolytes, that is, ions of salts, primarily sulphates, chlorides, potassium, bicarbonates of sodium, and others, 2.6 percent urea, 0.3 percent uric acid, and small quantities of ammonia, creatinine, hormones, some of the pigments, hippuric acid, and allantoin.
The filtration barrier comprises of the glomerular capillaries fenestrated endothelium, the filtration slits of the podocytes, and the fused basal lamina of the podocytes and the endothelial cells. The barrier allows the entry of water, small molecules, and ions from the bloodstream into the space of Bowman capsule.
The barrier restricts passing of negatively charged and/or large proteins like albumin. The basal lamina of the filtration barrier comprises three layers. Any small molecules like glucose, water, salt, urea, and amino acids can pass freely into the Bowman's space, however, the cells, large proteins, and platelets do not.
Explain how we know that DNA breaks and rejoins during recombination.
Answer:
It occurs through homologous recombination
Explanation:
GENERAL RECOMBINATION OR HOMOLOGIST
Previously we defined its general characteristics. We will now describe a molecular model of this recombination, based on the classic Meselson and Radding, modified with the latest advances. Do not forget that we are facing a model, that is, a hypothetical proposal to explain a set of experimental data. Not all points of this model are fully clarified or demonstrated:
Suppose we have an exogenote and an endogenote, both consisting of double helices. In recombination models, the exogenote is usually referred to as donor DNA, and the endogenote as recipient DNA.
1) Start of recombination: Homologous recombination begins with an endonucleotide incision in one of the donor double helix chains. Responsible for this process is the nuclease RecBCD (= nuclease V), which acts as follows: it is randomly attached to the donor's DNA, and moves along the double helix until it finds a characteristic sequence called c
Once the sequence is recognized, the RecBCD nuclease cuts to 4-6 bases to the right (3 'side) of the upper chain (as we have written above). Then, this same protein, acting now as a helicase, unrolls the cut chain, causing a zone of single-stranded DNA (c.s. DNA) to move with its 3 ’free end
2) The gap left by the displaced portion of the donor cut chain is filled by reparative DNA synthesis.
3) The displaced single chain zone of the donor DNA is coated by subunits of the RecA protein (at the rate of one RecA monomer per 5-10 bases). Thus, that simple chain adopts an extended helical configuration.
4) Assimilation or synapse: This is the key moment of action of RecA. Somehow, the DNA-bound RecA c.s. The donor facilitates the encounter of the latter with the complementary double helix part of the recipient, so that in principle a triple helix is formed. Then, with the hydrolysis of ATP, RecA facilitates that the donor chain moves to the homologous chain of the receptor, and therefore matches the complementary one of that receptor. In this process, the chain portion of the donor's homologous receptor is displaced, causing the so-called "D-structure".
It is important to highlight that this process promoted by RecA depends on the donor and the recipient having great sequence homology (from 100 to 95%), and that these homology segments are more than 100 bases in length.
Note that this synapse involves the formation of a portion of heteroduplex in the double receptor helix: there is an area where each chain comes from a DNA c.d. different parental (donor and recipient).
5) It is assumed that the newly displaced chain of the recipient DNA (D-structure) is digested by nucleases.
6) Covalent union of the ends originating in the two homologous chains. This results in a simple cross-linking whereby the two double helices are "tied." The resulting global structure is called the Holliday structure or joint.
7) Migration of the branches: a complex formed by the RuvA and RuvB proteins is attached to the crossing point of the Holliday structure, which with ATP hydrolysis achieve the displacement of the Hollyday crossing point: in this way the portion of heteroduplex in both double helices.
8) Isomerization: to easily visualize it, imagine that we rotate the two segments of one of the DNA c.d. 180o with respect to the cross-linking point, to generate a flat structure that is isomeric from the previous one ("X structure").
9) Resolution of this structure: this step is catalyzed by the RuvC protein, which cuts and splices two of the chains cross-linked at the Hollyday junction. The result of the resolution may vary depending on whether the chains that were not previously involved in the cross-linking are cut and spliced, or that they are again involved in this second cutting and sealing operation:
a) If the cuts and splices affect the DNA chains that were not previously involved in the cross-linking, the result will be two reciprocal recombinant molecules, where each of the 4 chains are recombinant (there has been an exchange of markers between donor and recipient)
b) If the cuts and splices affect the same chains that had already participated in the first cross-linking, the result will consist of two double helices that present only two portions of heteroduplex DNA.
Final answer:
DNA breaks and rejoins during recombination to exchange genetic material between chromosomes and create genetic diversity in species.
Explanation:
During recombination, DNA breaks and rejoins to exchange genetic material between homologous chromosomes. This process occurs during meiosis and involves the breakage and rejoining of parental chromosomes. It leads to the generation of novel chromosomes that share DNA from both parents, resulting in genetic diversity in species. The repair of DNA breaks during recombination is essential for accurate DNA repair and the survival of species.
In mitochondria, exergonic redox reactions
a. are the source of energy driving prokaryotic ATP synthesis.
b. provide the energy that establishes the proton gradient.
c. reduce carbon atoms to carbon dioxide.
d. are coupled via phosphorylated intermediates to endergonic processes.
In mitochondria, exergonic redox reactions mainly provide the energy that establishes the proton gradient necessary for ATP synthesis. These reactions play a crucial role during cellular respiration processes.
Explanation:In mitochondria, exergonic redox reactions perform multiple roles. The statement that is most accurate is option 'b' - exergonic redox reactions provide the energy that establishes the proton gradient. During processes of cellular respiration such as the Electron Transport Chain (ETC), the energy from these reactions leads to the pumping of protons across the mitochondrial membrane. This creates a concentration gradient which is critical for ATP synthesis. Something important to note is that while these reactions are key for ATP synthesis, mitochondria are typically found in eukaryotes rather than prokaryotes (option 'a').
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The exergonic redox reactions in mitochondria [Option b] provide the energy needed to establish a proton gradient. This gradient drives ATP synthesis through oxidative phosphorylation.
In mitochondria, exergonic redox responses are a piece of oxidative phosphorylation, which includes the electron transport chain (And so on). Through a series of complexes, electrons are moved from electron donors like NADH and FADH2 to oxygen during this process. The proton motive force is an electrochemical gradient that results from this electron transfer driving the active transport of protons (H+) across the inner mitochondrial membrane. The energy put away in this slope is then used to orchestrate ATP, the principal energy money of cells, through ATP synthase.One of the side effects of anabolic steroids in girls is irregular periods.
a. True
b. False
Answer:
True.
Explanation:
Anabolic steroids may be defined as the hormones that are taken in the forms of pill or can be directly injected into the body. The muscle mass of the body can be increased by the anabolic steroids.
Anabolic steroids can have negative effects on both the male and females. The anabolic steroids effects on female causes irregular menstrual cycle, moustache and the development of broad shoulders.
Thus, the answer is true.
Which of the following metabolic processes can occur without a net influx of energy from some other process
a. ADP + P -> ATP + H2O
b. C6H12O6 + 6O2 -> 6CO2 + 6H2O
c. 6CO2 + 6H2O -> C6H12O6 + 6O2
d. Amino acids -> Protein
Answer: The correct answer is option b
Explanation:
It is the reaction of cellular respiration in which glucose is oxidized to produce energy (ATP). Carbon dioxide and water are produced as byproducts.
It is the reaction which produces energy for all other cellular functions. One molecule of glucose yields around 36-38 ATP molecules.
Rest other reactions such formation of ATP (ADP + P = ATP) gets energy from chemiosmosis produced by cellular respiration. Formation of sugars from carbon dioxide and water (option c) gets energy from solar energy (photolysis). Formation of proteins (amino acids to proteins) or translation is also an energy-driven process. It gets energy from hydrolysis of ATP.
Thus, the correct answer is option b.
The conversion of glucose (C6H12O6) and oxygen (6O2) to carbon dioxide (6CO2) and water (6H2O) can occur without a net influx of energy from some other process. This process, known as cellular respiration, is exothermic and releases energy. Other listed processes (options a, c, d), including creating ATP, photosynthesis, and protein synthesis, require the influx of energy.
Explanation:The metabolic process that can occur without a net influx of energy from some other process is option b, that is, the conversion of glucose (C6H12O6) and oxygen (6O2) into carbon dioxide (6CO2) and water (6H2O). This process is known as cellular respiration, which is an exothermic reaction that releases energy.
The other processes listed need an influx of energy from another process. For instance, the conversion of ADP + P to ATP + H2O (option a) requires energy. The process by which 6CO2 + 6H2O is converted to C6H12O6 + 6O2 (option c) is photosynthesis, which requires energy from sunlight. Lastly, the conversion of amino acids into protein (option d) is a process called protein synthesis also requires energy.
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Diferentiate between embryonic stem cells and adult stem cells. In what way are the ethical dilemmas associated with the use of embryonic stem cells different than those posed by the use of adult stem cells?
Answer:
Explanation:
Embryonic stem cellsThese stem cells come from eggs that have been fertilized in vitro during IVF procedure, and were donated for research with the consent of the donors.
They are pluripotent: they have the potential to differentiate into almost any cell in the body.
Adult stem cellsFound in most organs in an individual who has already been born, they are responsible for tissue renewal or repair of damage. They can renew themselves or differentiate into the cell types of the tissue of origin.
They are multipotent, thus limited in their ability to differentiate: they will only produce specific cell types (e.g. neural stem cells produce neurons and glia).
Ethical concernsThe research with embryonic stem cells starts with an embryo in its early stages that can't develop outside the womb. Some people consider this early embryo a human being and are against scientific research with it, while others think that it's not a human being yet and research is not harmful because it couldn't survive unless implanted. In addition, experimentation with embryos could induce unplanned genetic mutations that could cause clinical aberrations if the embryo were implanted and allowed to develop into an adult individual.
In contrast, adult stem cells are not really controversial as they are cells derived from tissues from grown individuals. The main ethical issues are related to donor consent to obtain the cells.
Embryonic stem cells are pluripotent cells derived from early-stage embryos, capable of differentiating into any type of cell. Adult stem cells are multipotent and found in mature tissues, limited to certain cell types. Ethical dilemmas differ due to the source of the cells, with embryonic stem cells being associated with concerns over embryo destruction.
Explanation:Difference Between Embryonic and Adult Stem Cells
Embryonic stem cells (ESCs) and adult stem cells (also known as somatic stem cells) are both integral to developmental biology and medical research. However, they possess distinct characteristics and capabilities.
Embryonic stem cells are derived from the inner cell mass of a blastocyst, an early-stage pre-implantation embryo. They are pluripotent, which means they have the ability to differentiate into any cell type of the body. In contrast, adult stem cells are found in various tissues of an already developed organism and are multipotent, restricted to becoming a limited range of cell types that are related to their tissue of origin.
The ethical dilemmas surrounding the use of embryonic stem cells mainly revolve around the destruction of human embryos, which raises significant concerns for many individuals and groups. In contrast, adult stem cells raise fewer ethical issues because their harvesting generally does not involve the destruction of an embryo and can sometimes be collected from the patient themselves, offering a more ethical and immune-compatible treatment option. The use of induced pluripotent stem cells (iPSCs) stands as an advancement in the field that circumvents many of these ethical concerns as they are adult cells genetically reprogrammed to behave like their embryonic counterparts.
Which (if any) of the following statements regarding chickenpox, smallpox, and syphilis is correct?
a. all can be transmitted through contact with the rash/lesion
b. all can cause congenital infection
c. all can be prevented by vaccination
d. all are caused by viruses
Answer:
a. all can be transmitted through contact with the rash/lesion
Explanation:
All the three diseases i.e. chickenpox, smallpox, and syphilis can be transmitted through contact with the rash/lesion.
Chicken pox: Chickenpox is a viral infection in which red blisters appear on the skin. It is caused by Varicella-zoster virus.
Smallpox: Smallpox was certified the global eradication by WHO in the year of 1980. Smallpox is a viral infection caused by the Variola virus. Variola viruses are of two types named Variola major and Variola minor.
Syphilis: Syphilis is a bacterial disease which is the most dangerous infection spread through sexual contact.
Some birds can detect much lower frequency sounds that humans can. These sounds are called infrasounds. What is the leading hypothesis for why they are able to detect these low frequnecy sounds?
a. to be able to make quick flight changes to avoid predators that produce infrasounds
b. to detect the orientation of the sun even at night so that they can continue to fly
c. to detect pheromones to identify intraspecific members of the opposite sex during mating
d. to orient themselves during migration by detecting waterfalls, volcanoes and thunderstorms
e. to echolocate prey by producing these infrasounds that then are reflected back to their ears
Answer:
d. To orient themselves during migration by detecting waterfalls, volcanoes and thunderstorms.
Explanation:
It's known that natural events such as earthquakes, waterfalls/ocean waves, volcanoes and severe storms generate infrasound; the primary hypothesis about why some birds can detect infrasounds is to be able to orient themselves during their migration and avoid such natural events.