Genetics Exam 1
Mendel's Law of Segregation
the two copies of a gene segregate from each other during transmission from parent to offspring
an unspecified characteristic controlled by a single gene is examined in pea plants. only two phenotypic states exist for this trait. one phenotypic state is completely dominant over the other. a heterozygous plant is self crossed. what proportion of the progeny of plants exhibiting the dominant phenotype is homozygous?
1/3
A hypothetical human trait is controlled by a single gene. Four alleles of this gene have been identified: a, b, c, and d. Alleles a, b, and c are all codominant; allele d is recessive to all other alleles. a. How many phenotypes are possible? b. How many genotypes are possible?
Seven phenotypes are possible: A, B, C, D, AB, AC, BC.b. Ten genotypes are possible: a/a, b/b, c/c, d/d, a/d, b/d, c/d, a/b, a/c, b/c.
In the experiments of Avery, MacLeod, and McCarty, what was the purpose of treating the transforming extract with enzymes?
Protease destroyed any small amounts of protein contaminants in the transforming extract. Similarly, treatment with RNAse destroyed any RNA present in the mixture. Most importantly, treatment with DNAse destroyed any DNA in the mixture and was the only enzyme treatment to abolish transforming ability in the extract.
List the pyrimidine bases, the purine bases, and the base-pairing rules for DNA.
Purines (2 rings): adenine and guanine Pyrimidine (1 ring): cytosine and thymine Base pairing for DNA: A-T C-G
Until 1944, which cellular component was thought to carry genetic information?
protein
Adenine is a: a. nucleoside b. purine c. pyrimidine d. nucleotide e. base
purine base
Gene
sequence of DNA that codes for a protein and thus determines a trait
Determine the possible genotypes of the following parents by analyzing the phenotypes of their children. In this case, we will assume that brown eyes (B) is dominant to blue (b) and that right-handedness (R) is dominant to left-handedness (r).Parents: brown eyes, right-handed × brown eyes, right-handedOffspring: 3/4 brown eyes, right-handed1/4 blue eyes, right-handed
BbHH X BbHH or BbHH X BbHh
Determine the possible genotypes of the following parents by analyzing the phenotypes of their children. In this case, we will assume that brown eyes (B) is dominant to blue (b) and that right-handedness (R) is dominant to left-handedness (r).Parents: brown eyes, right-handed × blue eyes, right-handedOffspring: 6/16 blue eyes, right-handed2/16 blue eyes, left-handed6/16 brown eyes, right-handed2/16 brown eyes, left-handed
BbHh X bbHh
Determine the possible genotypes of the following parents by analyzing the phenotypes of their children. In this case, we will assume that brown eyes (B) is dominant to blue (b) and that right-handedness (R) is dominant to left-handedness (r).Parents: brown eyes, right-handed × blue eyes, left-handedOffspring: 1/4 brown eyes, right-handed1/4 brown eyes, left-handed1/4 blue eyes, right-handed1/4 blue eyes, left-handed
BbHh X bbhh or Bbhh X bbHh
Define genetic variance.
"heritability" Pheno variance observed in a population that is attributed to genotypic differences
If the genetic code used four bases at a time, how many amino acids could be encoded?
4^4=256
How does DNA replication occur in a precise manner to ensure that identical genetic information is put into the new chromatid? See Figures 8.12 and 8.13.
A replicated DNA molecule contains one new strand and one old strand. This mechanism is called semiconservative replication.
Allele
An alternative form of a gene.
What are the unique features of mitochondria that are not present in other cellular organelles in human cells?
DNA
Huntington disease is a rare, fatal disease that usually develops in the fourth or fifth decade of life. It is caused by a single autosomal dominant allele. A phenotypically normal man in his twenties who has a 2-year-old son of his own learns that his father has developed Huntington disease. What is the probability that he himself will develop the disease? What is the chance that his young son will eventually develop the disease?
He will get it prop: 50% Prop his young son will have it: 25%1/2 times 1/2 =1/4
locus
Location of a gene on a chromosome
Is an entire chromosome made into an mRNA during transcription?
No only the exons are made into an mRNA. No, because of mechanisms such as splicing.
Can conjoined (Siamese) twins be dizygotic twins in light of the theory that conjoined twins result from incomplete division of the embryo?
No. Dizygotic twins arise from two separate fertilized eggs. Only monozygotic twins can be Siamese, because they originate from the same fertilized egg and are genetically identical.Dizygotic twins are also known as fraternal twins. They are the result of two separate sperms fertilizing two separate eggs in the mother. They develop separately in separate placentas, it will be unlikely that siamese twins are a result of dizygotic twins, in order to conjoin they would have to be in the same placenta.
Do you think Frederick William's experiment would have worked better if he had ordered brother-sister marriages within tall families instead of just choosing the tallest individuals from throughout the country?
Tallest guards had AABBCC genotypes and shorter individuals were AaBBCC. If we were to force brother marriage, he would need to select both brother sisters having AABBCC genotypes. If a sister had recessive allele, it will result in shorter offspring. They have to be homozygous
a.) Aabb b.) AABb c.) AaBb
a- 1/2 Ab 1/2 ab b- 1/2 AB 1/2 Ab c- 1/4 all
List and describe two other diseases inherited in the following fashion: a. autosomal dominant b. autosomal recessive
a. autosomal dominant Huntington's disease: 1 copy of abnormal HTT gene is passed on. affects nerve cells in brain. Individuals with HTT mutated gene produce abnormal HTT protein = nerve cells malfunction and don't work = part of the brain to atrophy b. autosomal recessive Albinism- 2 mutations needed, effects skin, eyes, and hair. no pigment or ability to produce melanin
Nucleosomes are complexes of:
histones and DNA
a.) AABb X Aabb b.) AaBb X aabb c.) AaBb X AaBb
a.) 1/2 AB 1/2 Ab b.) 1/4 AB 1/4 Abb 1/4 aaB 1/4 aabb c.) 9:3:3:1
What are the following genotypes for the following blood types A B O AB
a: lai, lala b: lbi, lblb d: lalb c: ii
Sunflowers with flowers 10 cm in diameter are crossed with a plant that has 20 cm flowers. The F1 plants have flowers 15 cm in diameter. In the F2 generation, 4 flowers are 10 cm in diameter and 4 are 20 cm in diameter. Between these are 5 phenotypic classes with diameters intermediate to those at the extremes.a. Assuming that the alleles that contribute to flower diameter act additively, how many genes control flower size in this strain of sunflowers? b. How much does each additive allele contribute to flower diameter? c. What size flower makes up the largest phenotypic class?
10 cm to 22 cm with 5 intermediate diameters. Thus, there are 7 phenotypes. 10 cm flower is recessive and each dominant allele adds diameter to the flower. The first intermediate with have one dominant allele, the second has 2, and the 5th has 5. 22 cm flower has 6 dominant alleles. Two alleles code for one gene so there are 3 genes coding for diameter. Each contributes 2 cm/allele because (22-10)/6= 2 cm. 15 cm would be largest phenotypic class
At the age of 9 years, your genetics instructor was able to perform the mental tasks of an 11-year-old. According to Wilhelm Stern's method, calculate his or her IQ.
11/7x100=157
In peas, straight stems (S) are dominant to gnarled (s), and round peas (R) are dominant to wrinkled (r). The following cross (a test cross) is performed: SsRr × ssrr. Determine the expected phenotypes of the progeny and what fraction of the progeny should exhibit each phenotype.
2/4 straight2/4 gnarled2/4 round2/4wrinkled
P1: AABBCCDDEE x aabbccddee F1: AaBbCcDdEe x AaBbCcDdEe What is the chance of getting AaBBccDdee in F2
2/4: Aa 1/4: BB 1/4: cc 2/4: Dd 1/4: ee multiply 4/1024 (reduce by 4)= 1/256
in the following trihybrid cross determine the chance that an individual could be phenotypically A,b,C in the F1 generation P1: AaBbCc X AabbCC
3/4 A X 1/2 b X 1C = 3/8 A,b,C
sickle cell anemia is a human genetic disorder caused by a recessive allele. a couple plan to marry and want to know the probability that there child will be affected. What can you tell them if each has one affected parent and a parent with no family history of SCA? If the man is affected by the disorder but the women has no family history of SCA?
50% chance 0% chance
Codominance
A condition in which both alleles for a gene are fully expressed
incomplete dominance
A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.
if diseases such as cardiovascular disease (hypertension and atherosclerosis) are familial, is this an indication that there is a genetic contribution to these traits? What would you do to confirm that genetics is involved in this condition?
All genes code for a protein. Proteins are responsible for normal (or abnormal) body functions. People who have cardiovascular diseases (CVD) such as atherosclerosis may have a protein that leads a build up plaque in the blood vessels. Finding of an abnormal protein that lead to this increase plaque build up will link the disease to an abnormal gene. However, as CVD is a multifactorial trait this doesn't mean the abnormal gene alone will cause the disease, factors such a diet and exercise must be considered.
The X and Y chromosomes are structurally and genetically distinct. However, they do pair during meiosis at a small region near the tips of their short arms, indicating that the chromosomes are homologous in this region. If a gene lies in this region, will its pattern of transmission be more like that of a sex-linked gene or an autosomal gene? Why?
Autosomal because 2 copies an individual
Why do you think nucleic acids were originally not considered to be carriers of genetic information?
Chromosomes contain both proteins and DNA, but the organization of DNA, involving only 4 different nucleotides, seemed too simple to carry genetic information. Cells contain hundreds or thousands of different proteins; only 2 main types of nucleic acids.
n analyzing the base composition of a DNA sample, a student loses the information on pyrimidine content. The purine content is A = 27% and G = 23%. Using Chargaff's rule, reconstruct the missing data and list the base composition of the DNA sample.
Based on Chargaff's rule there should be an equal amount of the corresponding base pair T=27% C=23%Base composition: A = 27% T = 27% C = 23% G = 23% 100%`
Why are monozygotic twins who are reared apart so useful in the calculation of heritability?
Bc it will tell us how much the environment impacted their phenotype. A researcher analyzing the heritability of height can use MZ twins reared apart to find out how much environmental factors contribute to height differences. They would not need to control for genetic differences, as MZ twins have 100% identical genes.
Describe why continuous variation is common in humans and provide examples of such traits.
Bc there are many more genes and variations that go into humans vs pea plants that impact the variety of phenotype expressed. Ex) of cont variation is tobacco plants, their height is cont and follows a bell-shaped curve
A plant geneticist is examining the mode of inheritance of flower color in two closely related species of exotic plants. One species may have two pure-breeding lines—one produces a distinct red flower, and the other produces flowers with no color at all, or very pale yellow flowers—however, she cannot be sure. A cross of these varieties produces all pink-flowered progeny. The second species exhibits similar pure-breeding varieties; that is, one variety produces red flowers, and the other produces an albino or very pale yellow flower. A cross of these two varieties, however, produces orange-flowered progeny exclusively. Analyze the mode of inheritance of flower color in these two plant species.
Because neither species produces progeny resembling a parent, simple dominance is ruled out. The species producing pink-flowered progeny from red and white (or very pale yellow) suggests incomplete dominance as a mode of inheritance. However, in the second species, the production of orange-colored progeny cannot be explained in this fashion—because orange would result from an equal production of red and yellow pigments. Instead, in this case, codominant inheritance is suggested, with one parent producing bright red flowers and the other producing pale yellow flowers.
Discuss the pertinent features of meiosis that provide a physical correlate to menders abstract genetic laws of random segregation and independent assortment
During meiotic prophase I, the replicated chromosomes synapse, or pair, with their homologues. These paired chromosomes align themselves at the equator of the cell during metaphase I. During anaphase I, it is the homologues (each containing two chromatids) that separate from each other. There is no preordained orientation for this process—it is equally likely that a maternal or a paternal homologue will migrate to a given pole. This provides the basis for the law of random segregation. Independent assortment results from the fact that the polarity of one set of homologues has absolutely no influence on the orientation of a second set of homologues. For example, if the maternal homologue of chromosome 1 migrated to a certain pole, it would have no bearing on whether the maternal or paternal homologue of chromosome 2 migrated to that same pole.
A women is heterozygous for two genes. How many different types of gametes can she produce, and in what proportions
Four in equal proportions AB Ab aB ab
What role might environment have played in causing Frederick William's problems, especially at a time when nutrition varied greatly from town to town and from family to family?
Environment does factor into human height as well as genetics. When even a kid that is predicted to be tall, because his genetics favor tall- without the proper environment like nutrition the body is not supplied with enough nutrients to allow growth
The genetic material has to store information and be able to express it. What is the relationship among DNA, RNA, proteins, and phenotype?
Genes produce phenotypes through the action of proteins. DNA is the genetic code that stores the instructions to make a protein. mRNA is involved in reading DNA, in a process known as transcription. This mRNA is then processed b ribosomes to make proteins. Ribosomes read mRNA by attaching a complementary tRNA containing an amino acid, this process is known as translation. After the mRNA has been read there will be a chain of amino acids that can be a functional protein. Proteins are responsible for the phenotype.
DNA contains many hydrogen bonds. Are hydrogen bonds stronger or weaker than covalent bonds? What are the consequences of this difference in strength?
H2 bonds are weaker than covalent bonds. Nucleotides are joined by covalent bonds to form polynucleotide chains. 2 polynucleotide strands are held together by H2 binding between the bases.
Monozygotic (MZ) twins have a concordance value of 44% for a specific trait, whereas dizygotic twins have a concordance value of less than 5% for the same trait. What could explain why the value for MZ twins is significantly less than 100%?
Heritability is the amount a trait can be explained by genes, with 1,0 being 100% explained by genes, 0% by environmental conditions, and 0.7 70% explained by genes, 30% by environmental conditions etc. Concordance is the probability that a pari of people will have the same trait. Due to heritability and environmental factors a pair of people such as monozygotic twins who have the same genes may not both display the same trait. This makes concordance less than 100% because a twin who lives in an environmentally favor condition will display the trait whereas the twin who doesn't won't display it.
How is heritability related to genetic and environmental variance?
Heritability measures the amount a phenotype is caused strictly by gene than environmental factors. For example, if heritability of a trait is 0.7 than 70% of the phenotype can be explained by genes and 30% by environment.If hereditability is 1.0 = genetic, if it is 0.0= environmental Again, its the phenotypic variation that is being observed when asked about heritability. The genotypic diff or environmental diff affect the pheno variation
If monozygotic twins show complete concordance for a trait, whether they are reared together or apart, what does this suggest about the heritability of the trait?
If concordance is 100% and they were reared apart with different environmental conditions, it suggests that heritability is closer to 1.0. However, they were reared together, the heritability would be much lowers than being reared apart because of similar environmental conditions.
What is the importance of the comparison of traits between adopted and natural children in determining heritability?
It is important to compare traits between adopted (non similar genes) and natural children (similar genes) in heritability bc natural children will have a higher heritability than adopted as compared to parents and each other. But has similar environmental factors, such as going to the same schools, eating similar meals. This is a way controlling for environment factors while varying genetics.
Describe the phenotype and primary gene or protein defect of the X-linked recessive disease muscular dystrophy.
MD: x-linked recessive disease Phenotype is movement issues Dystrophin gene connects proteins to actin filaments which aid in movement, but in MD there is a full or partial gene defect on dystrophin
If you are informed that tune deafness is a heritable trait, and that a tune deaf couple is expecting a child, can you conclude that the child will be tune deaf?
No conclusion can be made because we do not know the inheritance.
. Describe why there is a fundamental difference between the expression of a trait that is determined by polygenes and the expression of a trait that is determined monogenetically.
Monogenic traits are controlled by 1 gene and polygenic traits are controlled by many, therefore, fundamentally they express different phenotypes bc one is always going to be 1 or another ie pea plants and one will be continuous dependent on the genes involved. In the case of traits controlled by several genes, expression of the trait depends on the interactions of many genes, each of which contributes a small amount to the phenotype. Thus, the differences between genotypes are often not clearly distinguishable. In the case of monogenic determination of a trait, the alleles of a single locus have major effects on the expression of the trait, and the differences between genotypes are usually easy to discern.
Clubfoot is a common congenital birth defect. This defect is caused by a number of genes but appears to be phenotypically distributed in a noncontinuous fashion. Geneticists use the multifactorial threshold model to explain the occurrence of this defect. Explain this model. Explain predisposition to the defect in an individual who has a genotypic liability above the threshold versus an individual who has a liability below the threshold.
Multifactorial threshold model explains the likelihood of an individual displaying a trait based on their genetic predisposition for the trait and favorable environmental conditions for trait display. Not all individuals with genetic predisposition will develop the trait. The threshold is a genetic predisposition which makes an individual more likely to develop the trait if they are above the threshold and less likely to develop the trait below the threshold. The likelihood of developing the trait also depends on favorable environmental to develop it, if the environment conditions are met the individual will more likely develop it.In the multifactorial threshold model, liability is caused by a number of genes acting to produce the defect. If exposed to certain environmental conditions, the person above the threshold will most likely develop the disorder. The person below the threshold is not predisposed to the disorder and will most likely not develop the disorder.
What does OMIM stand for? what kinds of information is in the database
Online Mendelian Inheritance in Man All known human genetic traits
Make the complementary strand for the following DNA template and label both strands as 5′ to 3′ or 3′ to 5′ (P = phosphate in the diagram). Draw an arrow showing the direction of synthesis of the new strand. How many hydrogen bonds are in this double strand of DNA? template: P—AGGCTCG—OH
P- 5 primeOH- 3 prime
Define environmental variance.
Phenotypic variance observed in a population that is attributed to differences in the environment
Chemical analysis shows that a nucleic acid sample contains A, U, C, and G. Is this DNA or RNA? Why?
RNA, because uracil is present.
Define replication, transcription, and translation. In what part of the cell does each process occur?
Replication is the process of making DNA from a DNA template. transcription makes RNA from a DNA template, and translation makes an amino acid chain (a polypeptide) from an mRNA template. Replication and transcription happen in the nucleus, and translation occurs in the cytoplasm.
yellow is dominant to green and smooth is dominant to wrinkled. smooth yellow is crossed with wrinkled green. 1/4 smooth yellow, 1/4 smooth green, 1/4 wrinkled yellow, 1/4 wrinkled green what is genotype of smooth yellow what are the genotypes of the 4 offspring
S= smooth s= wrinkled Y=yellow y=green smooth yellow parent is SsYy SsYy, Ssyy, ssYy, ssyy
Consider the following cross in pea plants, in which smooth pea shape is dominant to wrinkled, and yellow pea color is dominant to green. A plant with smooth yellow peas is crossed to a plant with wrinkled green peas. The offspring produced peas that were all smooth and yellow. What are the genotypes of the parents? What are the genotypes of the offspring?
Smooth, yellow parent is SSYY; wrinkled, green parent is ssyy; all offspring are SsYy.
What is the start codon? What are the stop codons? Do any of them code for amino acids?
Start codons: AUG. Yes, methionine. Stop codons: UAA, UAG, and UGA. No.
Recently, scientists discovered that a rare disorder called polkadotism is caused by a bacterial strain, polkadotiae. Mice injected with this strain (P) develop polka dots on their skin. Heat-killed P bacteria and live D bacteria, a nonvirulent strain, do not produce polka dots when injected separately into mice. However, when a mixture of heat-killed P cells and live D cells were injected together, the mice developed polka dots. What process explains this result? Describe what is happening in the mouse to cause this outcome.
The P Bacteria DNA is infiltrating the D DNA thus affecting mice. The process is transformation, discovered by Frederick Griffith. The P bacteria contain genetic information that is still functional even though the cell has been heat killed. However, it needs a live recipient host cell to accept its genetic information. When heat-killed P and live D bacteria are injected together, genetic information from the dead P bacteria can be transferred to the live D bacteria. As a result, the D bacteria are transformed into P bacteria and can now cause polka dots.
A characteristic of snapdragons amenable to genetic analysis is flower color. Imagine that a true-breeding red-flowered variety is crossed to a pure line having white flowers. The progeny are exclusively pink-flowered. Diagram this cross, including genotypes for all P1 and F1 phenotypes. What is the mode of inheritance? Let F = red and f = white.
The P1 generation is FF × ff. The F1 generation is Ff. The mode of inheritance is incomplete dominance.
Think about this one carefully. Albinism and hair color are governed by different genes. A recessively inherited form of albinism causes affected individuals to lack pigment in their skin, hair, and eyes. In hair color, red hair is inherited as a recessive trait and brown hair is inherited as a dominant trait relative to red hair. An albino woman whose parents both have red hair has two children with a man who is normally pigmented and has brown hair. The brown-haired partner has one parent who has red hair. The first child is normally pigmented and has brown hair. The second child is albino.A- What is the hair color (phenotype) of the albino parent?B- What is the genotype of the albino parent for hair color?C- What is the genotype of the brown-haired parent with respect to hair color? Skin pigmentation?D- What is the genotype of the first child with respect to hair color and skin pigmentation?E- What are the possible genotypes of the second child for hair color? What is the phenotype of the second child for hair color? Can you explain this?
The hair color of the albino parent is white (lack of pigment).b. The albino parent's genotype for hair color is homozygous recessive for red hair (rr).c. The genotype of the brown-haired parent is heterozygous (Rr). The genotype of the brown-haired parent for skin color is heterozygous (Aa).d. The genotype of the first child with respect to hair color is heterozygous (Rr), and heterozygous for skin pigmentation (Aa).e. The possible genotypes of the second child for hair color are Rr or rr. The phenotype of the second child for hair color is white (lack of pigmentation). The production of hair color depends on the synthesis and deposition of pigment in the hair. Even though the second child carries the genetic information for brown or red hair, this gene is not expressed because the gene for albinism prevents pigment formation. This is a form of gene interaction.
In the following pedigree, assume that the father of the proband is homozygous for a rare trait. What pattern of inheritance is consistent with this pedigree? In particular, explain the phenotype of the proband.
The mode of inheritance cannot be detected from the information given. because the proband is unaffected the fathers trait is either autosomal recessive or homologous x-linked bc his sister is affected
complete dominance
The situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable.
Researchers set up an obesity study in which MZ and DZ twins who served in the armed forces were studied at induction into the military and 25 years later. Results indicated that obesity has a strong genetic component. a. What are some of the problems with this study? b. Design a better study to test whether obesity has a genetic component.
The study didn't have a randomized sample and had a biased sample. They only chose twins who were in the military but not twins who weren't in the military. Select twin samples randomly instead of just those in the militarya. The study included only men who were able to pass a physical exam that eliminated markedly obese individuals, so the conclusions cannot be generalized beyond the group of men inducted into the armed forces. b. To design a better study, include MZ and DZ twin men and women, maybe even children, and include a cross section of various populations (ethnic groups, socioeconomic groups, weight classifications, etc.). Control the diet so that it remains a constant. Another approach is to study MZ and DZ twins who were reared apart (and presumably in different environments), or adopted and natural children who were raised in the same household (same environment). There are other possible answers.
RNA is ribonucleic acid, and DNA is deoxyribonucleic acid. What exactly is deoxygenated about DNA?
The sugar in DNA has one less OH group.
Read the following experiment and interpret the results to form your conclusion. Experimental data: S bacteria were heat killed and cell extracts were isolated. The extracts contained cellular components, including lipids, proteins, DNA, and RNA. The extracts were mixed with live R bacteria and then injected together into mice along with various enzymes (proteases, RNAses, and DNAses). Proteases degrade proteins, RNAses degrade RNA, and DNAses degrade DNA. S extract + live R cells mouse dies S extract + live R cells + protease mouse dies S extract + live R cells + RNAase mouse dies S extract + live R cells + DNAase mouse lives Based on these results, what is the transforming principle?
When the DNA is degraded the mouse lives, so DNA is the transforming factor.
What is the chance that a color-blind male and a carrier female will produce: a. a color-blind son? b. a color-blind daughter?
a. 50% chance b. A 50% chance
Which of the following statements is not true about DNA replication? a. It occurs during the M phase of the cell cycle b. It makes a sister chromatid c. It denatures DNA strands d. It occurs semiconservatively e. It follows base-pairing rules
a
stem length in pea plants is controlled by a single gene. Consider the cross of a true breeding long stemmed variety to a true breeding short stemmed variety in which long stems are completely dominant a) if 120 F1 plants are examined how many plants are expected to be long stemmed. SHort stemmed? b) Assign genotypes to both P1 varieties and to all phenotypes listed in a c) A long stemmed F1 plant is self crossed. of 300 F2 plants how many should be long stemmed? Short stemmed? d) For the F2 plants mentioned in c what is the expected genotypic ratio.
a- All long stemmed b- long stemmed P1 genotype SS. short stemmed P1 genotype ss. long stemmed F1 genotype Ss c- 225 long 75 short d) 1SS:2Ss:1ss
State the properties of the Watson-Crick model of DNA in the following categories: a. number of polynucleotide chains b. polarity (running in same direction or opposite directions) c. bases on interior or exterior of molecule d. sugar/phosphate on interior or exterior of molecule e. which bases pair with which f. right- or left-handed helix
a. 2 b. opposite directions c. interior: ATGC d. Interior: sugar exterior: phosphate (alternating) e. A-T, G-Cf. right handed
What is the chance that a man with type AB blood and a woman with type A blood whose mother is type O can produce a child that is: a. type A b. type AB c. type O d. type B
a. 2/4 b. 1/4 c. none d. 1/4
he father of 12 children begins to show symptoms of Huntington disease. a. What is the probability that Sam, the man's second-oldest son (II-2), will suffer from the disease if he lives a normal life span? (Sam's mother and her ancestors do not have the disease.) b. Can you infer anything about the presence of the disease in Sam's paternal grandparents?
a. 2nd son is 50% will suffer b. yes, at least one of his paternal grandparents have the HD trait.
In homozygotes, the recessive allele h prevents the A and B antigens from being placed on the surface of cells in individuals carrying either the IA or IB allele (or both alleles). The normal H allele allows these antigens to be placed on cell surfaces.Predict all possible blood-type phenotypes and their ratios in a cross between HhAB × HhAB individuals.Among those individuals with type O blood, what genotypes are present, and in what ratios?
a. 3/16: A blood type; 3/16: B blood type; 6/16 AB blood type; 1/4: O blood typeb. ½ hhIAIA ¼ hhIAIB ¼ hhIBIB
How does DNA differ from RNA with respect to the following characteristics? a. number of chains b. bases used c. sugar used d. Function
a. DNA: 2 RNA: 1 b. DNA: 4 RNA: 4 c: DNA: deoxyribose RNA: ribose d. DNA: blueprint of gen information RNA: transfer of info from nucleus to cytoplasm
As it turned out, one of the tallest Potsdam Guards had an unquenchable attraction to short women. During his tenure as guard, he had numerous clandestine affairs. In each case, children resulted. Subsequently, some of the children—who had no way of knowing that they were related—married and had children of their own. Assume that two pairs of genes determine height. The genotype of the 7-foot-tall Potsdam Guard was A′A′B′B′, and the genotype of all of his 5-foot clandestine lovers was AABB. An A′ or B′ allele in the offspring each adds 6 inches to the base height of 5 feet conferred by the AABB genotype. a. What were the genotypes and phenotypes of all the F1 children? b. Diagram the cross between the F1 offspring, and give all possible genotypes and phenotypes of the F2 progeny.
a. F1 genotype = A'AB'B, phenotype = height of 6 ft.gametes are A'B' A'B' TopAB AB Left= A'AB'B= 5 ft + 6in+6in=6ft b. . A'AB'B × A'AB'B
The text outlines some of the problems Frederick William I encountered in his attempt to breed tall Potsdam Guards. a. Why were the results he obtained so different from those obtained by Mendel with short and tall pea plants? b. Why were most of the children shorter than their tall parents?
a. Height in pea plants is determined by a single pair of genes with dominant and recessive alleles. Height in humans is a complex trait, involving a number of genes and environmental factors. b. For traits controlled by several genes, the offspring of matings between extreme phenotypes show a tendency to regress toward the mean phenotype in the population.
Describe the primary gene or protein defect and the resulting phenotype for the following diseases: a. cystic fibrosis b. Marfan syndrome
a. cystic fibrosis (AUTO RECESSIVE)CFTR gene defect bc Delta 508 AA deleted which doesn't allow chlorine to pass across the membrane as it should = mucus buildup in the lungs and pancreas b. marfan syndrome (AUTO DOM) FBN1 gene mutation = defective CT = enlarge aorta bc poor CT = cardiovascular, heart, eyes, and skeletal issues. Tall person with thin fingers
A young boy is color-blind. His one brother and five sisters are not. The boy has three maternal uncles and four maternal aunts. None of his uncles' children or grandchildren is color-blind. One of the maternal aunts married a color-blind man, and half of her children, both male and female, are color-blind. The other aunts married men who have normal color vision. All their daughters have normal vision, but half of their sons are color-blind. a. Which of the boy's four grandparents transmitted the gene for color blindness? b. Are any of the boy's aunts or uncles color-blind? c. Is either of the boy's parents color-blind?
a. maternal grandpa b. no c. no
Dizygotic twins: a. are as closely related as monozygotic twins b. are as closely related as non-twin siblings c. share 100% of their genetic material d. share 25% of their genetic material e. none of the above
are as closely related as non-twin siblings
Suppose a couple, both phenotypically normal, have two children: one unaffected daughter and one son affected with a genetic disorder. The phenotype ratio is 1 : 1, making it difficult to determine whether the trait is autosomal or X-linked. With your knowledge of genetics, what are the genotypes of the parents and children in the autosomal case? In the X-linked case?
autosomal: son/daughter affected will have aa unaffected will be Aa sex-linkedXaXa x XaY Gametes of affected are: XaXa and XaY
The basic building blocks of nucleic acids are: a. phosphate groups b. nucleotides c. ribose sugars d. amino acids e. purine bases
b
Polynucleotide chains have a 5′ and a 3′ end. Which groups are found at each of these ends? a. 5′ sugars, 3′ phosphates b. 3′ OH, 5′ phosphates c. 3′ base, 5′ phosphates d. 5′ base, 3′ OH e. 5′ phosphates, 3′ bases
b. 3′ OH, 5′ phosphates
The experiments of Avery and his coworkers led to the conclusion that: a. bacterial transformation occurs only in the laboratory. b. capsule proteins can attach to uncoated cells. c. DNA is the transforming agent and is the genetic material. d. transformation is an isolated phenomenon in E. coli. e. DNA must be complexed with protein in bacterial chromosomes.
c
Watson and Crick received the Nobel Prize for: a. generating X-ray crystallographic data of DNA structure b. establishing that DNA replication is semiconservative c. solving the structure of DNA d. proving that DNA is the genetic material e. showing that the amount of A equals the amount of T
c solving structure of DNA
Explain how camptodactyly is an example of expressivity.
camptodactyly is an autosomal dom in which immobile bent little fingers happen expressivity: 1 or both hands
What is the function of DNA polymerase? a. It degrades DNA in cells b. It adds RNA nucleotides to a new strand c. It coils DNA around histones to form chromosomes d. It adds DNA nucleotides to a replicating strand e. none of the above
d. It adds DNA nucleotides to a replicating strand
If there is no genetic variation within a population for a given trait, what is the heritability for the trait in the population?
environmentalHeritability measures the amount a trait can be explained by genetic differences. Genetic variation is the difference in genes that affect the different traits. If there is no genetic variation for a given trait, this means that the trait is not explained by genes at all.
If the genetic code uses triplets, how many different amino acids can be coded by a repeating RNA polymer composed of UA and UC (UAUCUAUCUAUC . . . )? a. one b. two c. three d. four e. five
four
The promoter and terminator regions of genes are important in: a. coding for amino acids. b. gene regulation. c. structural support for the gene. d. intron removal. e. anticodon recognition.
gene regulation
Mendel's Law of Independent Assortment
genes found on different chromosomes are sorted into sex cells independently of one another
Suppose that a team of researchers analyzes the heritability of high SAT scores and assigns a heritability of 0.75 for this ability. The team also determines that a certain ethnic group has a heritability value that is 0.12 lower compared with that of other ethnic groups. The group concludes that there must be a genetic explanation for the differences in scores. Why is this an invalid conclusion?
he heritability difference observed between the racial groups for this trait cannot be compared because heritability measures variation within one population at the time of the study. Heritability cannot be used to estimate genetic variation between populations.Comparing the heritability between different ethnic groups would be similar to comparing the heritability of the color red in apples and oranges. Heritability is measured as the percent a trait can be explained by genes within a given population. Heritability of the color red would certainly be different than heritability of the color orange because they are a different population, meaning it would be pointless to compare their heritability.
A man with blood type A and a woman with blood type B have three children: a daughter with type AB and two sons, one with type B and one with type O blood. What are the genotypes of the parents?
lai and lbi
What does the ob gene code for? How does it work? Is this a gene found only in animals, or do humans have it also?
ob gene encodes for weight-controlled hormone: lectin Leptin binds to its receptor in the hypothalamus which controls energy consumption and conversion to fatLeptin tells the brain if you are full or not, this gene is also found in mice
Define penetrance and expressivity.
penetrance: the propb that a disease pheno will be expressed when geno is present expressivity: the degree in which the pheno is expressed
Why are relatives used in the calculation of heritability?
to see how related people are and to give values to conditions Relatives are used because the proportion of genes held in common by relatives is known.Relatives are used to measure heritability because they have many genes in common. By adjusting for the common genes in relatives for some phenotype and using accurate math models researchers can get a good estimation of the heritability of a trait.
How is mitochondrial DNA transmitted?
via the cytoplasm of the egg, from the mom
