Answer:
It has a lot of functions, but its mainly to protect the spinal cord
It surrounds the spinal cord.
Explanation: it said it on my quiz
Desquamation occurs in which layer
Answer:
Desquamation occurs in the outermost layer of the skin.
Explanation:
Desquamation is also known as skin peeling and it occurs in the outermost layer or membrane of a tissue such as the skin .
Mr. A.H., age 44, had a generalized tonic-clonic seizure unexpectedly at work_ He had no history of seizures, trauma, infection, or other illness. Investigation revealed a tumor in the right parietal lobe. This was removed surgically, although the diffuse nature of the malignant mass prevented its complete elimination. Follow-up radiation treatment was recommended. After surgery, Mr. A.H. demonstrated considerable weakness and sensory loss on his left side. A few days after surgery, Mr. A.H. developed a bacterial infection at the operative site. The infection was eradicated quickly with treatment, but the tumor did not respond to radiation and chemotherapy. As a result, several tumors in the brain grew relatively large during the next 2 months.
Mr. A.H. developed severe headaches and diplopia and became increasingly lethargic, and his seizures increased in frequency despite anticonvulsant medication. He was given medication to reduce the frequency of vomiting.
Explain the specific rationale for each of his manifestations.
Answer:
a tumor is a growth of abnormal cells in the brain tissue, in this case they are malignant cancer cells since their growth is very fast, some are primary that start directly in the brain and other metastatic that start in another part of the body, in the case of Mister AH always had primary symptoms.
Tumors in the brain can show various symptoms. These are some of the most common:
Headaches, usually in the morning
Nausea and vomiting
Changes in the ability to speak, hear or see
Balance or walking problems
Problems with thinking or memory
Weakness or longing to sleep
Changes in mood or behavior
Seizures
tumors can destroy brain cells which can cause inflammation and damage to parts of the body depending on where in the brain this is exerted, this also aggravates the symptoms.
Radiation therapy used to treat brain cancers increases the risk of brain tumors up to 20 to 30 years later.
In this case, he was causing this same reaction to Mr. AH, which may also have another type of tumor such as
Meningiomas and schwanomas are two other types of brain tumor. These tumors:
They occur in most cases between the ages of 40 and 70.
They are not usually cancerous, but they can still cause serious complications and death due to their size or location. Some are cancerous and aggressive.
Mr. A.H.'s seizures and left-side weakness are due to a right parietal lobe tumor affecting brain function. Post-surgery infection, tumor growth, and severe headaches result from increased intracranial pressure. Lethargy and vomiting are linked to the tumor's impact and anticonvulsant medication side effects.
The specific rationale for each of Mr. A.H.'s manifestations can be explained as follows:
1. Generalized tonic-clonic seizure: This was likely caused by the presence of the tumor in the right parietal lobe. Seizures can occur as a result of abnormal electrical activity in the brain, which can be triggered by the presence of a tumor.
2. Considerable weakness and sensory loss on his left side: These symptoms are consistent with the location of the tumor in the right parietal lobe, which could have caused damage or compression of the motor and sensory areas of the brain responsible for controlling the left side of the body.
3. Bacterial infection at the operative site: This could have occurred due to the surgical procedure, as invasive procedures carry a risk of introducing bacteria into the body. The weakened state of Mr. A.H.'s immune system post-surgery may have contributed to the development of the infection.
4. Tumor growth despite radiation and chemotherapy: The malignant nature of the tumor likely contributed to its resistance to treatment. Additionally, the diffuse nature of the tumor made complete elimination difficult, allowing it to continue growing.
5. Severe headaches and diplopia (double vision): These symptoms could be attributed to the increased size of the tumors in the brain, causing pressure on surrounding structures and interfering with normal brain function. Increased intracranial pressure from the growing tumors can lead to headaches, while pressure on the nerves controlling eye movements can result in diplopia.
6. Increasing lethargy: Lethargy can result from the effects of the brain tumors on cognitive function and overall brain function. Additionally, the presence of seizures and frequent vomiting can contribute to feelings of lethargy and fatigue.
7. Frequency of vomiting: Vomiting can be a side effect of increased intracranial pressure due to the growing tumors. It can also be a side effect of anticonvulsant medication, which Mr. A.H. was likely taking to manage his seizures. Medication to reduce vomiting frequency was given to alleviate this symptom.
You are counseling a young Greek couple because both parents and their first-born son have been tested and found to be carriers of Beta thalassemia, an autosomal recessive severe hemoglobinopathy. They wish to know whether a current pregnancy is likely affected. Explain
Answer&Explanation:An individual with an autosomal dominant disorder, has a single mutant gene unless when their both parents are affected.
A person will have an autosomal dominant disorder if only a single parent is affected and if parent have autosomal dominant disorder only there is a 50% of inheriting a mutant gene.
In autosomal recessive disorders a person will get Ill if they inherit both mutant genes from both parents who are carriers . This person will be homozygous for the gene and will be affected by the disorder and this is highly likely to happen in their baby since they are both the carriers of this disorder.
Answer:
Beta thalassemia is an autosomal recessive disorder. It is usually inherited by children if both parents are carriers. It is a blood disorder that is characterized by decreased production of hemoglobin. Hemoglobin is an important protein in red blood cells that binds oxygen to be transported to other cells in the body.
Pregnant women with beta thalassemia can develop anemia due to the stress and other underlying factors. This can increase the chances of premature delivery. She may need more frequent blood transfusions during the pregnancy period for her health and the health of the baby.
The Z disc is the: Group of answer choices separation between sarcomeres. electrical voltage at which a muscle cell fires an action potential. area of a sarcomere where only thick myofilaments are found. point where the axon and the sarcolemma meet. place where two cardiac muscle cells meet.
Answer:
Separation between sarcomeres.
Explanation:
The structure of the muscle fibre is composed of many functional units called sarcomere which is interrupted by the discs called Z-discs.
These Z-discs are made of the alpha-actin homodimers which allow the actin filament allows to bind to it along with other proteins. The Z-discs since present at regular intervals in a muscle appears to separate the sarcomere and defines the boundaries of the sarcomere.
Thus, the selected option is correct.
Omega-3 and omega-6 essential fatty acids are readily available in leafy green plants. What is one way to ensure that animals raised for commercial purposes have enough of these fatty acids in their diets such that fatty acid supplementation is not needed
Answer:
Omega-3 and omega-6 essential fatty acids are readily available in leafy green plants. One way to ensure that animals raised for commercial purposes have enough of these fatty acids in their diets such that fatty acid supplementation is not needed is to allow the livestock adequate environment for natural grazing.
Explanation:
Animals raised on pasture are generally healthier and under less stress than those raised in confinement, making them hace omega-3 and omega-6 readily available in leafy graan plants. Pasture-based livestock farming reintegrates the cycle, putting livestock on grass or in another natural environment. These types of systems are also climate friendly.
To ensure that animals raised for commercial purposes get enough omega-3 and omega-6 essential fatty acids, natural grazing is encouraged. This practice enables the animals to obtain these vital nutrients from their diet directly, eliminating the need for supplements. Grass-fed animals typically have higher quantities of these fatty acids.
Explanation:One way to ensure that animals raised for commercial purposes have enough omega-3 and omega-6 fatty acids in their diets without requiring fatty acid supplementation is by facilitating natural grazing. Leafy green plants are rich sources of these essential fatty acids. If commercial animals are allowed to graze naturally, they can obtain these essential nutrients directly from their diet.
By facilitating natural grazing, animals can get a balanced amount of essential fatty acids from their diets.Grass-fed animals have generally been shown to have higher amounts of omega-3 and omega-6 fatty acids in their meat as compared to animals fed with commercially prepared feed.This approach also supports the sustainability of farming practices and respects the animals' natural dietary needs.Learn more about Essential Fatty Acids here:https://brainly.com/question/12771870
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Muscle is an example of which level of organization?
A plant cell is an example of which level of organization?
Our skeleton is an example of which level of organization?
Explanation:
muscle is an example ofthe tissue level of organization
a plant cell is an example of the cell level of organization
our skeleton is an example of the system level of organization☺
The diagram shows a bean plant growing in soil.
Which labels best complete the diagram?
X: Positive gravitropism
Y: Negative gravitropism
X: Negative gravitropism
Y: Positive gravitropism
X: Thigmotropism
Y: Hydrotropism
X: Hydrotropism
Y: Thigmotropism
Answer:
A i think
Explanation:
Answer:
The answer is A)
X: Positive gravitropism
Y: Negative gravitropism
Explanation:
If you need any help with this question please ask me! :)
Explain the cellular functions that occur when antibiotics attack a bacteria cell?
Thank you!
Tasting involves many different cell-signaling processes that ultimately generate nerve signals transduced by membrane depolarization. Sweet tastes result in PIP2 hydrolysis, while salty tastes allow sodium ions to directly alter the membrane potential. What can you deduce about the signaling mechanisms for sweet and salty?
Choose one or more:
A. Sweet ligands bind to and close sodium channels, which starts a membrane potential.
B. Sodium ions directly enter the cells, indicating the signal is transduced by an ion channel.
C. Sweet and salty signaling pathways use the same taste receptor molecule, but with different efficacy on the sweet and salty taste center in the brain.
D. Sweet utilizes the GPCR signaling pathway, activating phospholipase C.
Answer:
B. Sodium ions directly enter the cells, indicating the signal is transduced by an ion channel.
D. Sweet utilizes the GPCR signaling pathway, activating phospholipase C.
Explanation:
The taste received by the taste buds is processed through different channels
a) The Sweet, bitter, and umami tastes are transduced by the GPCR (G-protein-coupled receptors) signaling pathway
b) Sour taste reaches the taste bud through the acidification of acid-sensitive membrane proteins with in the taste cell
c) The epithelial sodium channels in the renal tissues directly takes up the salty taste
Hence, option B and D are correct
List two reasons why food is important.
Answer:
gives you energy, and for some animals helps them survive winter (bears)
Explanation:hope this helps god bless
1. Vitality.
A healthy diet has you glowing with vitality outside and in. Healthy food leaves you feeling energetic and raring to go!
2. Preserving youthful looks.
Healthy eating keeps your skin supple and radiant, your eyes bright and your hair in good condition.
Sperm tails in the fruit fly Drosophila bifurca can reach up to 6cm long, which is over 20 times the length of the organism itself. Because the tails are so long, they aren’t able to provide the swimming force that other sperm tails are used for. Please provide a hypothesis as to why the fruit fly sperm has evolved to be so long.?
Explanation:
The length of the sperm in a few species is much larger or giant than the size of the animal-like observed in the Drosophila bifurca.
In this fruit-fly, the tails of the sperm are too long which could be accounted for many reasons:
1. The sexual selection prefers the long tails over the small tail.
2. The large sperms can displace the small sperms in the female reproductive organ.
3. The female reproductive organ increases the promiscuity of the large sperms that is favour the large sperms over the small sperms.
During which stage of mitosis do the chromosomes attach to the spindle fibers and line up in the center of the cell
Anaphase
Interphase
Metaphase
Telophase
Answer:
The answer is
Explanation:
Metaphase
Answer:
the answer is c!!!! i took the test so i know its c
Explanation:
The diagram shows what enters and exits a plant during photosynthesis. Which labels belong in the areas marked X and Y? X: Glucose Y: Chlorophyll X: Chlorophyll Y: Glucose X: Carbon dioxide Y: Oxygen X: Oxygen Y: Carbon dioxide
Answer:
X: Carbon Dioxide
Y: Oxygen
Explanation:
Answer:
X: carbon dioxide
Y: oxygen
Which is the answer for it? I will appreciate the help
true or false: natural resources can be man made
Answer:
False
Explanation:
Natural resources are made by nature
Answer:
False
Explanation:
Natural resources are resources that aren't made with any human action. If a resource is made by man, they would be called man-made resources of human-made resources.
In snapdragon plants, they can be red (dominant) or white (recessive). However, when you have a heterozygous plant, the flower is actually pink (incomplete dominance).
Two pink flowers are crossed.
Genotype possibilities:
RR:
Rr:
rr:
Phenotype possibilities:
Red:
Pink:
White:
Please help
It would be easier to put an image instead of explaining it. Here you are!
R = Red
r = white
RR = 25% - 25% chance of red
Rr = 50% - 50% chance of pink
rr = 25% - 25% chance of white
The seed color of the garden pea was used to derive Mendel's two laws: segregation and independent assortment. Now, we know that the Y allele codes for the enzyme converting green to yellow chlorophyll. The mutant allele, y, is caused by a loss-of-function mutation on this gene. Let's assume that this mutation manifests its phenotype through the haploinsufficiency mode. Answer the following questions.
P YY (Yellow) x yy (Green)
F1 Yy (?) x Yy (?)
F2 1YY (?) : 2Yy (?): 1yy (?)
1. Which color would be recognized as a dominant trait, and what would be ratio of F2 between Yellow and Green seeds? (You need to explain why)
2. In this situation, which breeding scheme should be the proper testcross and what will be the outcome of this testcross? (You also need to explain why)
Answer:1.Yellow color will be dominant and the ratio is Yellow to green allele is 3:1
2.A recessive test cross should be appropriate.The result will be all yellow colored pea plants.
Explanation:
Since Yy x Yy produces
1YY,2Yy and 1yy then it shows that YY and Yy are 3 yellow pea plants and 1yy green pea plant.
A recessive test cross should be used because a recessive genotype being homozygous can be noticed by its physical appearance
Which symbolizes a molecule of a compound
He
Be
N2
NaCl
Answer:
NaCl
Explanation:
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Red-green color blindness is a human X-linked recessive disorder. A young man with a 47,XXY karyotype (klinefelter syndrome) is color blind. His 46,XY brother also is color blind. Both parents have normal color vision. Where did the nondisjunction occur that gave rise to the young man with Klinefelter syndrome?
Answer:
Mother, meiosis II
Explanation:
Red-green color blindness is a human X-linked recessive disorder. A young man with a 47,XXY karyotype (klinefelter syndrome) is color blind. His 46,XY brother also is color blind. Both parents have normal color vision.The nondisjunction occured in mother during meiosis II that gave rise to the young man with Klinefelter syndrome.
Etiology:
Meiotic Non-disjunction of the chromosome pairs during the First or second division of gametogenesis. Because of the extra chromosome, individuals with the condition are usually referred to as 47XXY. As in the above mentioned scenario, meiotic nondisjunction during meiosis II in the mother resulting in the failure of the sister chromatids to separate during meiosis II thus resulting in too many chromosomes.
Answer:
The non-dis-junction occur with Klinefelter syndrome is occurred at "Meiosis II;Mother"
Explanation:
Thus, the more likely than not acquired the Y chromosome from his dad who has typical shading vision, there is no chance for a nondisjunction occasion to have occurred from the fatherly heredity. His mom must be heterozygous [tex]X^{+} X^{c}[/tex] in light of the fact that she has typical shading vision. This implies she more likely than not acquired a visually challenged X chromosome from her partially blind dad.
For him to acquire two partially blind X chromosomes from his mom, the egg more likely than not been the result of a non-dis-junction in meiosis II.
In meiosis I, the homologous X chromosomes independent, so one cell has the [tex]X^{+}[/tex] and different has [tex]X^{c}[/tex]. Disappointment of sister chromatids to isolate inmeiosis II would then bring about an egg with two duplicates of [tex]X^{c}[/tex]Xc.
The loss of an organism at the bottom of a food chain negatively impacts all organisms in the chain.
Please select the best answer from the choices provided
От
OF
Answer:
True
Explanation:
It would break the natural order each row dying or having to adjust messing up another food chain
A trait is a characteristic. Think about your physical traits (eye color, skin tone, height, hair, face, allergies, etc.) What traits do you think you inherited or received from your parents?
Answer:
Explanation:
Genetic inheritance occurs due to genetic material in the form of DNA being passed from parents to their offspring, we inherit physical traits from our parents when parents pass copies of their genes to their children and such traits are observable characteristics that children inherit from their parents which can be dominant or recessive inheritance of a single gene.
For example chrildren can inherite : Free or attached ear lobes ,
Eye Colour. Dominant and recessive genes play a role in determining eye colour of the child,brown eyes,blue eye color,green and hazel.
Hair color
Height
Dimples
Handedness
Fingerprints
Hair color
Teeth structure
Freckles
Final answer:
Physical traits like eye color and skin tone are often inherited from our parents, while traits like intelligence and disease susceptibility are influenced by both genetic and environmental factors. Examples of inherited traits include curly hair and tall stature, but personality characteristics can also have a genetic component and be shaped by the environment.
Explanation:
Understanding Inherited Traits
Genetics is the study of how traits are inherited from one generation to the next. Many physical traits, such as eye color, skin tone, and height, are inherited from our parents due to genetic factors. These traits, defined by our genes, make up our genotype, which manifests externally as our phenotype, the observable characteristics.
However, traits are not solely determined by genetics. The environment also plays a significant role in shaping who we are, which is why even traits with a genetic component, such as intelligence or susceptibility to certain diseases, can be influenced by environmental factors. For instance, while a parent might pass down genes that predispose a child to high intellectual capacity, the child's environment, such as access to education, can greatly affect how this potential is realized.
As an example of inherited traits, one might have inherited curly hair and a tall stature from their parents. Conversely, personality characteristics could be influenced not only by genetic predisposition but also by modeling from parents, social interactions, and cultural context. Thus, understanding that a trait can be a feature like bipedalism or a specific genetic sequence, it's clear that traits encompass a wide range of inherited and environmentally influenced characteristics.
Inherited Traits and the Environment
When considering traits we have inherited from our parents, examples might include physical attributes like hair color or facial features. Personality characteristics often have a genetic component, with research suggesting that attributes such as extraversion or introversion can be inherited. Yet, these same traits are also shaped by environmental factors, or modeling, as we grow and interact with the world around us. An individual's tendency towards kindness, for instance, may be influenced by being raised in a nurturing environment, regardless of their genetic predispositions
Recall that in the Hardy-Weinberg lab we did earlier in the semester, the clams in some of the populations we studied were exposed to saxitoxin. Some of these clams were sensitive to the toxin. Saxitoxin affected the sensitive clams by blocking their voltage-gated sodium channels, ultimately killing the clams. Now that you know more about the role of voltage-gated sodium channels from completing this lab, explain why the saxitoxin killed those clams.
Answer:
Due to failure of vital organ system and body functions
Explanation:
Saxitoxin is a toxin that acts as a blocker to the voltage-gated sodium channels. It binds to voltage-gated sodium channels within the muscle and the nerve fibers and causes Paralytic Shellfish Poisoning following bioaccumulation and ingestion. It binds to the receptor at the voltage gate and causes inward Na+ flow thereby substituting cation. Its high exposure could lead to muscle paralysis and respiratory failure leading to death of clams
Saxitoxin killed the clams by blocking their voltage-gated sodium channels, disrupting neural communication and essential cellular functions, which ultimately led to their death.
Recall that in the Hardy-Weinberg lab, we studied clams exposed to saxitoxin. Saxitoxin affected the sensitive clams by blocking their voltage-gated sodium channels. This blockage prevented the clams' sodium channels from opening, thereby stopping the flow of sodium ions into their cells. Because sodium channels are essential for the generation and propagation of action potentials in excitable cells, the inhibition by saxitoxin disrupted neural communication and other vital cellular processes. As a result, the clams could not sustain necessary biological functions, leading to their death.
The citric acid cycle is a stage of catabolism that oxidizes acetate into carbon dioxide and generates energy. There are eight enzymes involved in the citric acid cycle.
Which enzymes have an α‑keto acid substrate?
A. fumarase
B. α‑ketoglutarate dehydrogenase
C. malate dehydrogenase
D. citrate synthase
Answer:D
Explanation:
Use the following information to answer the following question below. Moss invades and establishes itself on bare rock, accumulating the beginnings of soil. After several years, enough soil has become established that grasses begin to grow where there was once bare rock. Without the moss building up soil, the grasses would have had no chance. The establishment of the mosses on bare rock and eventual addition of grasses represents intermediate succession. secondary succession. a climax ecosystem. primary succession.
Answer:
Primary succession.
Explanation:
Ecological succession refers to the changes involved in the species structure of a community that is established in a particular habitat over time. The succession is of two types: the primary succession and secondary succession.
When the succession takes place on the barren land then succession is considered primary succession.
In the given question, the moss invades and colonizes the rocks and breaks them into the soil. Here the moss species is known as the pioneer species and since the moss grows on the barren rock, therefore, is considered the primary succession.
Thus, primary succession is correct.
Can you tell the difference between female and male bacteria?
Answer:yes and no
Explanation:with the right tests but from eye only no
Phototaxis is movement in response to which stimulus?
Answer:
Phototaxis is a movement in response to light
Answer:
Light
Explanation:
Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves towards or away from a stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive light for photosynthesis.
Berkowitz and LePage (1967) found that frustrated men delivered more shocks when Group of answer choices
A) they were initially depressed.
B) badminton racquets happened to be in the room.
C) they had just received a shot that lowered their serotonin levels.
D) guns happened to be in the room.
Answer: D. Guns happened to be in the room.
Explanation: In studying different concepts of aggression, Berkowitz and Lapage(1967) found out that in their experiment, frustrated men delivered more shocks to their partners when guns rather than badminton racquets happened to be in the room.
In which of these ways might an ectotherm respond to changes in environmental temperature?
fight or flight
Answer: move elsewhere b
Explanation:
Answer: b
Explanation:
a. Bacteriophage MS2 carries its genetic information in RNA. Its chromosome is analogous to a polygenic molecule of mRNA in organisms that store their genetic information in DNA. The MS2 mini-chromosome encodes four polypeptides (i.e., it has four genes). One of these four genes encodes the MS2 coat protein, a polypeptide 129 amino acids long. The entire nucleotide sequence in the RNA of MS2 is known. Codon 112 of the coat protein gene is CUA, which specifies the amino acid leucine. If you were to treat a replicating population of bacteriophage MS2 with the mutagen 5-bromouracil, what amino acid substitutions would you expect to be induced at position 112 of the MS2 coat protein (i.e., Leu —> other amino acid)? (Note: Bacteriophage MS2 RNA replicates using a complementary strand of RNA and base-pairing like DNA.)
b.Would such mutations occur if a non-replicating suspension of MS2 phage was treated with 5-bromouracil?
Final answer:
Amino acid substitutions at codon 112 in MS2 phage could occur due to mispairing caused by the mutagen 5-bromouracil during replication, potentially resulting in a different amino acid being coded. However, mutations would not occur in a non-replicating suspension of MS2 since 5-bromouracil incorporation requires active replication.
Explanation:
If you were to treat a replicating population of bacteriophage MS2 with the mutagen 5-bromouracil, you might expect amino acid substitutions at codon 112 of the MS2 coat protein, which commonly specifies the amino acid leucine (Leu). Given that 5-bromouracil can substitute for thymine in DNA replication, and considering RNA's analogous base uracil, during RNA replication, this mutagen could potentially cause uracil to mispair, leading to a substitution mutation. Specifically for codon 112 (CUA), a possible mutation could turn it into UUA which would likely also code for leucine, or into CUG, which also encodes for leucine due to the degeneracy of the genetic code. A more significant change, such as substituting cytosine with uracil, creating UUA or UUG, could result in a phenylalanine being placed instead of leucine, since these codons specify phenylalanine.
For the second part of the question, mutations from 5-bromouracil would not occur in a non-replicating suspension of MS2 phage since mutations require nucleic acid replication for incorporation into the genetic material, and 5-bromouracil would not be incorporated without active replication.
In silkmoths, red eyes (re) and white-banded wings (wb) are encoded by two mutant alleles that are recessive to those that produce wild-type traits (re+ and wb+); these 2 genes are on the same chromosome. A moth homozygous for red eyes and white-banded wings is crossed with a moth homozygous for the wild-type traits. The F1 have wild-type eyes and wings. The F1 are crossed with moths that have red eyes and white banded wings in a test cross. The progeny of this test cross are:
wild-type eyes, wild-type wings 418
red eyes, wild-type wings 19
wild-type eyes, white-banded wings 16
red eyes, white-banded wings 426
a. What phenotypic proportions would be expected if the genes for red eyes and for white-banded wings were located on different chromosomes?b. What is the rate of recombination between the genes for red eyes and those for white-banded wings?
Answer:
a. The phenotypic proportions that would be expected if the genes for red eyes and for white-banded wings were located on different chromosomes is 1:1:1:1
b. The rate of recombination between the genes for red eyes and those for white-banded wings is 0.04
Explanation:
To know that two genes are linked, we must observe the progeny distribution. If individuals, whos genes assort independently, are test crossed, they produce a progeny with equal phenotypic frequencies 1:1:1:1. If we observe a different distribution, that is that phenotypes appear in different proportions, we can assume that genes are linked in the double heterozygote parent.
If the genes for red eyes and white-banded wings were located on different chromosomes, they would assort independently, and hence the expected phenotypic proportions would be 1/4:1/4:1/4:1/4
4/16=1/4 re+re wb+wb
4/16=1/4 rere wb+wb
4/16=1/4 re+re wbwb
4/16=1/4 rere wbwb
In the present example, the genotype, in linked gene format, of the double heterozygote is re+wb+/rewb.
In this way, we might verify which are the recombinant gametes produced by the di-hybrid, and we will be able to recognize them by looking at the phenotypes with lower frequencies in the progeny.
To calculate the recombination frequency we will make use of the next formula: P = Recombinant number / Total of individuals. The genetic distance will result from multiplying that frequency by 100 and expressing it in map units (MU).
The map unit is the distance between the pair of genes for which one of every 100 meiotic products results in a recombinant product.
In the present example:
Parental) re+ wb+/re wb x re wb/re wb
Gametes) re+wb+ parental type
re wb parental type
re+wb recombinant type
re wb+ recombinante type
Phenotypic class Number of offspring
wild-type eyes, wild-type wings, re+ wb+, 418red eyes, wild-type wings, re wb+, 19wild-type eyes, white-banded wings, re+ wb 16red eyes, white-banded wings, re wb, 426The recombination frequency is:
P = Recombinant number / Total of individuals
P = 19 + 16 / 418 + 19 + 16 + 426
P = 35/ 879
P = 0.0398=0.04
The genetic distance between genes is 0.04 x 100= 4 MU.
If the genes for red eyes and white-banded wings in silkmoths were on different chromosomes, a 1:1:1:1 phenotypic ratio would be expected. In the test cross given, the rate of recombination is approximately 7.7%, which suggests linkage with some degree of crossing over between the two genes.
In silkmoths, where red eyes (re) and white-banded wings (wb) are encoded by two recessive alleles located on the same chromosome, the expected outcome of a test cross can reveal the rate of recombination and indicate a linkage between the two genes.
If the genes for red eyes and white-banded wings were located on different chromosomes, we would expect to see a 1:1:1:1 phenotypic ratio due to independent assortment.Based on the given progeny of the test cross, the rate of recombination between the genes for red eyes and white-banded wings can be calculated by adding the number of recombinant offspring (19 wild-type eyes, red wings + 16 red eyes, white-banded wings) and dividing it by the total number of offspring, then multiplying by 100 to get a percentage. This calculation yields a recombination frequency of approximately 7.7%, indicating that the two genes are linked but not completely linked as crossing over does occur.