Module #1

In the following cross, what proportion of individuals will have the Bombay phenotype? AB Hh x AB Hh a. 3/4 b. 0 c. 1/4 d. 1/2

1/4

One form of hemophilia is caused by a sex-linked recessive gene. Assume that a man with hemophilia marries a phenotypically normal woman whose father had hemophilia. What is the probability that they will have a daughter with hemophilia? (Note: In this problem you must include the probability of having a daughter in your computation of the final probability.)

1/4

What conclusions did Mendel make from his monohybrid crosses?

(1) Progeny inherit genetic factors from both parents. (2) Each individual possesses two factors (alleles) that control the appearance of each phenotypic trait. (3) The two alleles in each individual separate (segregate) during gametogenesis and are randomly distributed with equal probability of being distributed into the gametes. (4) From a cross between two true-breeding (homozygous) parents expressing different phenotypes for a given trait, traits that appeared unchanged in the F 1 heterozygous offspring were dominant, and traits that disappeared in F 1 heterozygous offspring were recessive.

Glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as an X-linked recessive gene in humans. A woman whose father suffered from G6PD marries a normal man. (a) What proportion of their sons is expected to be G6PD? (b) If the husband were not normal, but were G6PD deficient, would you change your answer in part (a)?

(a) 1/2 (b) no

In mice, there is a set of multiple alleles of a gene for coat color. Four of those alleles are as follows: C = full color (wild) cch = chinchilla cd = dilution c = albino the gene locus is not sex-linked and that each allele is dominant to those lower in the list, give the phenotypic ratios expected from each. (a) wild (heterozygous for dilution) X chinchilla (heterozygous for albino) (b) chinchilla (heterozygous for albino) X albino Clearly label (a) and (b), and enter the phenotype and number in ratio format. (ie, 1pink:2yellow:1white)

(a) Ccd × cchc ⇒ 2 full color:1 chinchilla:1 dilution (b) cchc × cc ⇒ 1 chinchilla:1 albino

A cross was made between homozygous wild-type female Drosophila and yellow-bodied male Drosophila. All of the resulting offspring were phenotypically wild type. Offspring of the F2 generation had the following phenotypes: Sex Phenotype Number male wild 96 male yellow 99 female wild 197 Based on this information, fill in each of the blanks below. Is the mutant gene for yellow body behaving as a recessive or dominant? Is the yellow locus on an autosome or on the X-chromosome?

(a) recessive (b) X-linked

Other than genes, name three other regions of chromosomes? What are their functions? Which of them represent euchromatin? Heterochromatin?

-Centromere - the attachment point for spindle microtubules (heterochromatic) -Telomeres - natural ends, the tips of linear chromosomes that serve to stabilize the chromosome (Heterochromatic) -Origin of replication - where DNA synthesis begins (euchromatic)

Describe three different sex determination systems.

-Chromosomal sex-determining -Genic sex-determining -Environmental sex-determining

What would the expected phenotypic ratios be when an F2 individual that is homozygous dominant in a dihybrid cross is testcrossed and why would you expect this ratio.

...they would all be dominant

Assuming independent assortment, what proportion of the offspring of the cross AaBbCcDd X AabbCCdd will have the aabbccdd genotype?

0

If a couple with Sickle cell disease genotypes Ss and Ss mate and have one child with the disease, what is the chance the next child has the disease as well? 0.25 1 0 0.5

0.25

What is the probability of obtaining 3 heads in four flips of a fair coin? a. 0.50 b. 0.0625 c. 0.75 d. 0.25

0.25

Dentinogenesis imperfecta is a rare, autosomal, dominantly inherited disease of the teeth that occurs in about one in 8000 people (Witkop, 1957). The teeth are somewhat brown in color, and the crowns wear down rapidly. Assume that a male with dentinogenesis imperfecta and no family history of the disease marries a woman with normal teeth. What is the probability that: their first child will be a girl with dentinogenesis imperfecta?

1/4

What are three of the characteristics of an autosomal recessive trait that are observed in a pedigree analysis?

1. effects males and females equally 2. Affected individuals all have an affected parent 3. If either one of the parents are homozygous dominant, all of the children will be affected 4. If one parent is not affected and the other is heterozygous, the child will have 1/2 probability of being affected

In the following tetrahybrid cross AaBbCcDd x AaBbCcDd what proportion of the F2 offspring would be expected to be genotypically AaBbCcDd ? a. 1/16 b. 8/256 c. 4/256 d. 81/256 e. 1/256

1/16

Ability to roll the tongue is caused by a dominant allele. A woman is a "roller," but one of her parents is not. Reference: Ref 6-2 The woman is expecting a child with a man who is a "nonroller." What is the probability that their child will be a "roller"? a. 1/2 b. 3/4 c. 1/4 d. 1/3 e. 2/3

1/2

One form of hemophilia is caused by a sex-linked recessive gene. Assume that a man with hemophilia marries a phenotypically normal woman whose father had hemophilia. What is the probability that their first son will have hemophilia? a. 3/4 b. 1/16 c. 1/4 d. 1/8 e. 1/2

1/2

Polydactyly is expressed when an individual has extra fingers and/or toes. Assume that a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. Having extra digits is caused by a dominant allele. The couple has a son with normal hands and feet, but the couple's second child has extra digits. What is the probability that their next child will have polydactyly? a. 7/16 b. 3/4 c. 1/2 d. 1/32 e. 1/8

1/2

Two organisms, AABBCCDDEE and aabbccddee, are mated to produce an F1 that is self-fertilized. If the capital letters represent dominant, independently assorting alleles, what proportion of the F2 genotypes will be recessive for all five loci? Enter your answer as a fraction in the box below.

1/243 of the distinct genotypes, or 1/(1,024) of all independently-occurring genotypes.

In the following tetrahybrid cross AaBbCcDd x AaBbCcDd what proportion of the F2 offspring would be expected to be genotypically AABBCCdd ? 1/256 9/256 81/256 1/2 3/4

1/256

In the following tetrahybrid cross AaBbCcDd x AaBbCcDd what proportion of the F2 offspring would be expected to be phenotypically recessive? a. 1/256 b. 4/256 c. 81/256 d. 2/256

1/256

A cross is made between a female calico cat and a male cat having the gene for black fur on his X chromosome. What fraction of the offspring would one expect to be calico?

1/4 Female Calico: Xb Xy (display mix colors) Male: Xb Y (black fur) _____|___Xb___|__Xy__ _Xb_|_XbXb _|_XbXy_ __Y__|__XbY__|__XyY XbXy = Calico Xb = Black Xy = Yellow

Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a). Two parents with normal pigmentation have an albino child. What is the probability that their next three children will be albino?

1/4X1/4 X1/4=1/64

Albinism, lack of pigmentation in humans, results from an autosomal recessive gene (a). Two parents with normal pigmentation have an albino child. What is the probability that their next child will be an albino girl?

1/8

What is the probability of obtaining 3 heads in three flips of a fair coin? 1/4 1/2 1 1/8

1/8

If they live long enough, the penetrance of individuals carrying the Huntington's Disease allele will be what? 50% 100% 0% 25%

100%

In snapdragons, heterozygotes for one of the genes have pink flowers, whereas homozygotes have red or white flowers. When plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers? a. 75% b. 100% c. 50% d. 25%

100%

Many of the color varieties of summer squash are determined by several interacting loci: AA or Aa gives white, aaBB or aaBb gives yellow, and aabb produces green. Assume that two fully heterozygous plants are crossed. Give the phenotypes (with frequencies) of the offspring

12 (white):3 (yellow):1 (green)

Assume that, regarding a particular gene, one scored 30 second-division ascospore arrangements and 70 first-division arrangements in Neurospora. What would be the map distance between the gene and the centromere? a. 15 b. insufficient information provided to answer this question c. 70 d. 60 e. 30

15

If a typical somatic cell has 32 chromosomes, how many chromosomes are expected in each gamete of that organism? a. 46 b. 32 c. 0 d. 64 e. 16

16

In a healthy male, how many sperm cells would be expected to be formed from (a) 400 primary spermatocytes? (b) 400 secondary spermatocytes? a) 400, b) 400 a) 1600, b) 800 a) 100, b) 800 a) 800, b) 800 a) 1600, b) 1600

1600, 800

With incomplete dominance, a likely ratio resulting from a monohybrid cross would be a. 1:2:2:4 b. 3:1 c. 3:3 d. 1:2:1 e. 9:3:3:1

1:2:1

What types of phenotypic ratios are likely to occur in crosses when dealing with a single gene pair where all the genotypic combinations are of equal viability? a. 1:2:1, 3:1 b. 1:4:6:4:1, 1:1:1:1 c. 12:3:1, 9:7 d. 9:3:3:1, 27:9:9:9:3:3:3:1 e. 2:3, 1:2

1:2:1, 3:1

Assume that a cross is made between two organisms, both heterozygous for a gene that shows incomplete dominance. What phenotypic and genotypic ratios are expected in the offspring? phenotypic ratio? genotypic ratio?

1:3 1:2:1

Mitosis ends with _____, while meiosis ends with _____. 2 diploid cells; 4 haploid cells 4 haploid cells; 2 diploid cells 4 diploid cells, 2 haploid cells 2 haploid cells; 4 diploid cells

2 diploid cells; 4 haploid cells

The trait for medium-sized leaves in iris is determined by the genetic condition PP'. Plants with large leaves are PP, while plants with small leaves are P'P'. The trait for red flowers is controlled by the genes RR, pink by RR', and white by R'R'. A cross is made between two plants each with medium-sized leaves and pink flowers. If they produce 320 seedlings, what would be the expected numbers of the phenotypes below? Assume no linkage. large, red? medium, red? small, red? large, pink? medium, pink? small, pink?

20 large, red 40 medium, red 20 small, red 40 large, pink 80 medium, pink 40 small, pink 20 large, white 40 medium, white 20 small, white

A diploid somatic cell from a rat has a total of 42 chromosomes (2n = 42). As in humans, sex chromosomes determine sex: XX in females and XY in males. Reference: Ref 2-1 What is the total number of chromosomes in a polar body cell from a rat? 21 84 42 40 41

21

If a typical somatic cell has 44 chromosomes, how many chromosomes are expected in each gamete of that organism? 88 22 44 72 18

22

The house fly, Musca domestica, has a haploid chromosome number of 6. How many chromatids should be present in a diploid, somatic, metaphase cell? Enter a number in the box below.

24 chromatids

Myrmecia pilosula actually consists of several virtually identical, closely related species of ants, with females having chromosome numbers of 18, 20, 32, 48, 60, 62, and 64. The males are haploid, and each gamete contains the n complement. Assume one crossed a female of species (A) with 32 chromosomes and a male species (B) with 9 chromosomes. How many chromosomes would one expect in the body (somatic) cells of the female offspring? a. 32 b. 41 c. 25 d. 4.5 e. 9

25

A recessive gene for red-green color blindness is located on the X chromosome in humans. Assume that a woman with normal vision (her father is color-blind) marries a color-blind male. What is the likelihood (give a percentage) that this couple's first son will be color-blind? 25% 100% 50% 75% 0%

25%

A trihybrid cross is a cross between two individuals who are heterozygous for three genes. For example: AaBbCc x AaBbCc. Assuming these three genes are unlinked and assorting independently, what segregation ratio would be observed? 16:9:9:3:3:1 12:9:3:1 27:9:9:9:3:3:3:1 1:1:1:1 9:3:3:1

27:9:9:9:3:3:3:1

How many haploid sets of chromosomes are present in a diploid individual cell with a chromosome number of: 46? 32?

2;2

You may have heard through various media of an animal alleged to be the hybrid of a rabbit and a cat. Given that the cat (Felis domesticus) has a diploid chromosome number of 38 and a rabbit (Oryctolagus cuniculus) has a diploid chromosome number of 44, what would be the expected chromosome number in the somatic tissues of this alleged hybrid? Why?

2n = 41 chromosomes Explanation: Cat (2n=38) produces haploid gametes with 19 chromosomes (n-19). Rabbit (2n=44) produces haploid gametes with 22 chromosomes(n=22) 19+22= 41 chromosomes in the alleges hybrid

The following F2 results occur from a typical dihybrid cross: purple: A_B_ 9/16 white: aaB_ 3/16 white: A_bb 3/16 white: aabb 1/16 If a double heterozygote (AaBb) is crossed with a fully recessive organism (aabb), what phenotypic ratio is expected in the offspring? Enter the phenotype and number in ratio format (ie, 1pink:2yellow:1white)

3 (white):1 (purple)

In one strand of DNA, the nucleotide sequence is 5'-ATGC-3'. The complementary sequence in the other strand must be: 5'-CGTA-3' 3'-ATGC-5' 5'-TACG-3' 5'-ATCG-3' 3'-TACG-5'

3'-TACG-5'

How many different F2 genotypes would you expect in a cross with four heterozygous gene pairs? a. 81 b. 162 c. 27 d. 243 e. 9

3^4= 81

How many haploid sets of chromosomes are present in an individual cell that is tetraploid (4n)?

4

There is about as much nuclear DNA in a primary spermatocyte as in ________ (how many) spermatids?

4

The ant, Myrmecia pilosula, is particularly interesting because it carries all its genetic information in a single pair of chromosomes. In other words, 2n = 2. (Males are haploid and have just one chromosome.) For the purposes of this question, assume that a G1 somatic cell nucleus in a female Myrmecia pilosula contains 2 picograms of DNA. How much DNA would be expected in a Metaphase I cell of a female? a. 4 picograms b. 8 picograms c. 16 picograms d. 32 picograms e. not enough information to answer this question

4 picograms

Human gametogeneis from one oogonium and one spermatagonium results in how many mature gametes of each?

4 sperm, 1 egg

A diploid somatic cell from a rat has a total of 42 chromosomes (2n = 42). As in humans, sex chromosomes determine sex: XX in females and XY in males. Reference: Ref 2-1 What is the total number of chromosomes present in the cell during metaphase I of meiosis? 168 42 21 84 126

42

Assume that there are 12 map units between two loci in the mouse and that you are able to microscopically observe meiotic chromosomes in this organism. If you examined 200 primary oocytes, in how many would you expect to see a chiasma between the two loci mentioned above? 46 48 24 0 32

48 primary oocytes

When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? a. 50% b. 25% c. 0% d. 75%

50%

The horse (Equus caballus) has 32 pairs of chromosomes, whereas the donkey (Equus asinus) has 31 pairs of chromosomes. How many chromosomes would be expected in the somatic tissue of a mule? a. 31.5 b. 33 c. 63 d. 126

63

An organism has a haploid number of 6. How many possible assortments of chromosomes are possible based on the independent assortement of the chromosomes? 256 32 128 not possible to determine based on this information 64

64

A recessive allele in tigers causes the white tiger. If two normally pigmented tigers are mated and produce a white offspring, what percentage of their remaining offspring would be expected to have normal pigmentation? 50% 25% 75% about 90% about 66%

75%

How many different kinds of gametes will an individual with the genotype PpCcTTRr produce (assume all genes assort independently)?

8

In a three-point mapping experiment, how many different genotypic classes are expected? a. 2 b. 4 c. 6 d. 8 e. 10

8

Drosophila melanogaster, the fruit fly, has a 2n chromosome number of 8. Assuming that a somatic G2 nucleus contains about 8.0 picograms of DNA, how many picograms of nuclear DNA would you expect in: a) Mitotic metaphase b) a primary oocyte (metaphase) c) a secondary oocyte (metaphae) d) a first polar body (metaphase) a. a-d: 4, 4, 8, 8 b. a-d: 8, 4, 2, 2 c. a-d: 8, 4, 4, 4 d. a-d: 8, 8, 4, 4

8, 8, 4, 4

In the following tetrahybrid cross AaBbCcDd x AaBbCcDd what proportion of the F2 offspring would be expected to be phenotypically ABCD ? 81/256 1/2 9/256 1/256

81/256

Assume that a dihybrid cross is made in which the genes' loci are autosomal, independently assorting, and incompletely dominant. How many different phenotypes are expected in the offspring? a. 4 b. 3 c. 9 d. 7 e. 6

9

Assume that a dihybrid cross (AaBb X AaBb) is made in which the gene loci are autosomal, independently assorting, and incompletely dominant. What phenotypic ratio would you expect from such a cross? Just provide the ratio, not the phenotypes.

9:3:3:1

Assuming Mendel's Second Law is correct, what is the expected segregation ratio for traits in a dihybrid cross? 9:3:3:1 3:1 1:1 None of the above. 1:1:1:1

9:3:3:1

What phenotypic ratios are likely to occur in crosses when dealing with two completely dominant, independently segregating gene pairs, when both parents are fully heterozygous?

9:3:3:1

Typical ratios resulting from epistatic interactions in dihybrid crosses would be ________. a. 3:1, 1:1 b. 1:2:2:4:1:2:1:2:1 c. 1:1:1:1, 1:4:6:1 d. 9:3:3:1, 1:2:1 e. 9:3:4, 9:7

9:3:4, 9:7

The following is a map of four genes on a chromosome: A W E G |___5____|__3__|_______12___| Between which two genes would you expect the highest frequency of recombination? A and E W and E A and G E and G

A and G

Assume that the somatic cells of a male contain one pair of homologous chromosomes (e.g., A1 and A2), and an additional chromosome without a homolog (e.g., W). What chromosomal combinations would be expected in the meiotic products (spermatids) of a single primary spermatocyte? (There may be more than one answer.) a. A1 A1 A2 A2 b. A1,W A1,W A2,W A2,W c. A1,W A1,W A2 A2 d. A1 A1 A2,W A2,W

A1 A1 A2,W A2,W A1,W A1,W A2 A2

Which of the following parental genotypes will produce only heterozygous F1 offspring? a. AA x Aa b. Aa x aa c. aa x aa d. Aa x Aa e. AA x aa

AA x aa

Given that loci A and B in Drosophila are sex-linked and 20 map units apart, what phenotypic frequencies would you expect in 100 offspring resulting from the following cross? (Assume A and B are dominant to a and b, respectively.) AaBb (trans) female X ab/Y male Ab = aB = AB = ab =

AB = 40; ab = 40; Ab = 10; aB = 10 (sexes have the same phenotypes)

Given that loci A and B in Drosophila are sex-linked and 20 map units apart, what phenotypic frequencies would you expect in 100 offspring resulting from the following cross? (Assume A and B are dominant to a and b, respectively.) AaBb (cis) female X ab/Y male AB = ab = Ab = aB =

AB=10 ab=10 Ab=40 aB=40

Which of the following are examples of monohybrid crosses? a. AaBB x AaBB b. Aa x aa c. AaBb x AaBb d. Aa x Aa e. AaBb x aabb

Aa*aa Aa*Aa

Assume that a man who carries an X-linked gene has children. Assuming normal meiosis and random combination of gametes, the man would pass this gene to all of his sons. half of his sons. half of his daughters. all of his daughters. all of his children.

All of his daughters

Which of the following human genotypes is associated with Klinefelter syndrome? a. none of the above b. XXY c. XXXY d. all of the above e. XXYY

All of the above

Genes come in different versions called: a. loci b. alleles c. genotypes d. genomes e. chromosomes

Alleles

Scientists use the pink bread mold Neurospora to study meiosis. What are the features of this organism that lend itself for this line of study?

Asexual colonies are easily and inexpensively maintained in the lab. The haploid state of Neurospora makes it ideal for mutational analyses as mutant alleles are always expressed directly in the phenotype.

Assume that a cross is made between AaBb and aabb plants and that the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with a cis or trans arrangement of genes in the AaBb parent?

Assume that a cross is made between AaBb plants and aabb plants and the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with the following circumstance: A. Sex-linked inheritance with 30% crossing over B. Linkage with 50% crossing over C. Linkage with approximately 33 map units between the two gene loci D. Independent assortment E. 100% recombination = 48 + 52/ 300 = 33% = 33 map units

At what stage of the meiotic cell cycle and during what chromosomal configuration does crossing over occur? Mark all that apply. a. during prophase II b. after synapsis of homologous chromosomes c. during anaphase I d. at the four strand stage of meiosis e. before the end of prophase I

At the four-strand stage of meiosis, after synapsis of homologous chromosomes, and before the end of prophase I.

Two mice of the same species have different ear shapes. You find that one mouse, having normal shaped ears, was caught in a field in Kenya. The other mouse, with curled ears, was caught in the frozen tundra of Greenland. You have determined that both mice have identical genotypes at the gene loci controlling ear shape. How would you explain the differences in ear shape? Describe an experiment by which you could test your hypothesis. More (correct) detail will increase your likelihood of getting full credit.

Because both mice have the same genotype at the relevant loci controlling ear shape, there is most likely an effect of environment on phenotype. Because Kenya and Greenland have quite different climates (but also different food sources, humidity, sunlight intensities, etc.), it is possible that the very different temperature ranges within each region resulted in differential expression of identical genotypes for ear shape in each mouse—for example, differential expression of temperature-sensitive allele(s) involved in ear development. However, the phenotypic differences could also be a result of differences in diet, light conditions, exposure to chemicals, nutrition, or a range of other non-genetic factors.

What is hemophilia and why can females, but not males, be carriers of hemophilia and other X-linked recessive characteristics?

Blood clotting factor sex X-linked recessive

Polygenic traits ______________________ Both A and B may be measured quantitatively and have continuous variation are influenced by both genes and the environment fall into discrete classes of phenotypes are not affected by the environment

Both A and B

If a typical somatic cell has 64 chromosomes, how many chromosomes are expected in each gamete of that organism? a. 64 b. 16 c. 32 d. 8 e. 128

C. 32

The following coat colors are known to be determined by alleles at one locus in horses: palomino = golden coat with lighter mane and tail cremello = almost white chestnut = brown Cross Parents Offspring 1 cremello x cremello all cremello 2 chestnut x chestnut all chestnut 3 cremello x chestnut all palomino 4 palomino x palomino 1/4 = chestnut 1/2 = palomino 1/4 = cremello Using the gene symbols C1 and C2, diagram the mating for cross #4.

C1C1 = cremello, C2C2 = chestnut, C1C2 = palomino (3) C1C1 X C2C2 (4) C1C2 X C1C2

Within cells, DNA and genes are organized into structures called ________.

Chromosomes

Yellow leaves on a plant can be caused by genetic mutations, viruses, or unfavorable environmental conditions. Suppose you find a plant that has yellow leaves and want to determine if the cause of the phenotype is a genetic mutation or an environmental stress. Design an experiment to differentiate between the different possibilities.

Cross the yellow plant with a normal plant. Self the resulting F 1 and look for a consistent, predictable segregation pattern. For example, the presence of a 3 green :1 yellow segregation ratio would suggest that the yellow phenotype was caused by a recessive mutation

The ability to curl one's tongue into a U-shape is a genetic trait that is inherited in a standard Mendelian fashion. Curlers always have at least one curler parent but noncurlers can have one or both parents who are curlers. Using C and c to symbolize this trait, what is the genotype of a noncurler?

Curler: C_ Noncurler: cc

During interphase of the cell cycle, a. DNA content essentially doubles. b. sister chromatids move to opposite poles. c. the nuclear membrane disappears. d. DNA recombines. e. RNA replicates.

DNA content essentially doubles

Explain dominance and codominance with respect to the ABO blood groups. Which blood types are dominant, which are recessive, and which are codominant? What does it mean to say that two blood types are codominant?

Dominant: a relationship between alleles of a single gene, in which one allele masks the phenotypic expression of a second allele at the same gene locus Co-dominance occurs when the contributions of both alleles are visible in the phenotype. For example, in the ABO blood group system, chemical modifications on the surfaces of blood cells are controlled by three alleles (IA, IB and IO) at the ABO locus. The IA and IB alleles produce different modifications, and the non-functional IO allele produces no modification. Thus IA and IB alleles are each dominant toIO (IA IA and IA IO individuals both have type A blood, and IB IB and IB IO individuals both have type B blood. But IA IB individuals have both modifications on their blood cells and thus have type AB blood, so the IA and IB alleles are said to be co-dominant.)

Which are abnormalities involving numbers of X chromosomes? Mark all that apply. a. Huntington's disease b. Down syndrome c. XXXX syndrome d. Klinefelter syndrome e. Turner syndrome

Down Syndrome XXXX Syndrome Turner Syndrome

Genetic information can be carried in which of the following biomolecules? a. Either DNA or RNA b. RNA and not DNA c. DNA and not RNA d. proteins

Either DNA or RNA

If an X-linked disorder is lethal to the affected individual prior to the age at which one reaches reproductive maturation, the lethality will be expressed only in males. Why?

Heterozygous females are carriers and do not express the disorder

In deer mice, red eyes (r) is recessive to normal black eyes (R). Two mice with black eyes are crossed. They produce two offspring, one with red eyes and one with black eyes. Give the genotypes of parents and offspring of this cross.

For red eyes (recessive) to be expressed in the progeny (i.e., to segregate in the progeny), both parents must be heterozygotes ( Rr ). Rr × Rr 1 ( RR ), 2 ( Rr ), 1 ( rr ) = 3:1 (black eyes:red eyes). Note that even with only two progeny produced, you have determined the genotypes of the parents because you observe segregation of the recessive allele (red eyes)

When cells withdraw from the continuous cell cycle and enter a "quiescent" phase, they are said to be in what stage? a. M b. G2 c. S d. G0 e. G1

G0

The complete genetic makeup of any organism is its

Genome

Name the single individual whose work in the mid-1800s contributed to our understanding of the particulate nature of inheritance as well as the basic genetic transmission patterns. With what organism did this person work? Calvin Bridges, Drosophila (fruit fly) Gregor Mendel, Pisum sativum George Beadle, Neurospora Thomas Hunt Morgan, Drosophila (fruit fly) Boris Ephrussi, Ephestia

Gregor Mendel, Pisum sativum

Because of the mechanism of sex determination, males of many species can be neither homozygous nor heterozygous. Such males are said to be: a. dominant b. recessive c. complementary d. none of these answers e. hemizygous

Hemizygous

Red-green color-blindness is an X-linked recessive condition. Juliet has a bit of difficulty passing the red-green color distinction test when she tries to get her driver's license. She has two children with a man who is not color blind. Neither Juliet's son (Henry) nor daughter (Roxanne) is color blind. Henry and Roxanne have normal karyotypes. Roxanne has a son who is color blind. Reference: Ref 4-8 Why aren't Henry and Roxanne color blind?

Henry is not color blind because he inherited the X with the normal red-green color vision allele from Juliet. Roxanne is not color blind because she is heterozygous like her mother, and does not have appreciable mosaicism for X-inactivation in her eye tissues

A woman who has blood type A has a daughter who is type O and a son who is type B. Which of the following is a possible genotype for the son? a. IBIB b. IBIA c. IBi d. ii

IBi

Explain, at a molecular level, why some traits display X-linked inheritance while others display sex-influenced inheritance. What is the determining factor in whether a trait will display one or the other?

In X-linked inheritance, the gene in question is on the X chromosome, while in sex-influenced inheritance, the gene is autosomal

What is one feature of meiosis that produces genetic variability in gametes? In two or three sentences, explain how this feature causes genetic uniqueness.

In meiosis, there is the ability for chromosomes to experience crossing over, where genes switch chromosomes. Crossing over produces genetic variability. It creates chromosomes that are not identical.

In a Chi-square test, as the value of the (chi)2 increases, the likelihood of rejecting the null hypothesis ________.

Increases

During the cell cycle, chromosomal replication occurs in Telophase Prophase Interphase Metaphase

Interphase

The following are features and characteristics of the DNA molecule except _________________ a. is used as genetic material by all organisms b. is capable of being replicated c. can be mutated d. composed of four nitrogenous bases e. all of the above

Is used as genetic material by all organisms

What is the relationship between the degree of crossing over and the distance between two genes?

It is direct, as the distance increases, the frequency of recombination increases

Where on the chromatid are the microtubules attached? Telomere Centriole Kinetochore Centromere

Kinetochore

Individuals with Klinefelter and Turner syndromes have how many chromosomes, respectively? Klinefelter? Turner?

Klinefelter: 47 Turner: 45

a. Meiosis I anaphase b. Meiosis I prophase c. Meiosis II prophase d. Meiosis II anaphase e. Mitosis prophase f. Mitosis prophase Reference: Ref 2-2 The first stage after which a dividing cell that started as a diploid would be haploid Enter only the letter of your choice.

Meiosis I anaphase

a. Meiosis I anaphase b. Meiosis I prophase c. Meiosis II anaphase d. Meiosis II prophase e. Mitosis telophase f. Mitosis prophase Reference: Ref 2-2 Crossing over (genetic recombination) occurs in...

Meiosis I prophase

a. Meiosis I anaphase b. Meiosis I prophase c. Meiosis II anaphase d. Meiosis II prophase e. Mitosis telophase f. Mitosis prophase Reference: Ref 2-2 Chromosomes are in unseparated, sister-chromatid form, at the end of which phase(s)? Separate multiple answers with commas, and enter only the letter of your choice(s)

Meiosis I prophase Meiosis I anaphase Meiosis II prophase Mitosis Prophase

These two terms generally refer to meiosis I or II. Enter the correct stage of meiosis in the box below each term. Equational? (I or II) Reductional? (I or II)

Meiosis I: Reductional Meiosis II: Equational

List four terms used to describe the normal morphologies, with respect to arm ratio, of eukaryotic chromosomes.

Metacentric, submetacentric, acrocentric, telocentric

The cellular organelles with inheritance independent of the nucleus are the _____________ and the ____________ .

Mitochondria and Chloroplast

Explain why mitosis does not produce genetic variation and how meiosis leads to the production of tremendous genetic variation.

Mitosis produces cells that are genetically identical to the parent cell. Meiosis includes two distinct processes that contribute to the generation of genetic variation: crossing over shuffles alleles on the same chromosome into new combinations, whereas the random distribution of maternal and paternal chromosomes shuffles alleles on different chromosomes into new combinations.

The stage at which "sister chromatids go to opposite poles" immediately follows which stage listed below? a. Telophase of Meiosis II b. Mitotic anaphase c. Telophase of Meiosis I d. Mitotic metaphase

Mitotic metaphase

Male mammals inherit an X chromosome from which of their parents? Their _____________.

Mother

Assuming a normal number of autosomes, what would be the sex of the following: XXY mouse? XXY Drosophila?

Mouse. XXY is male Normally XY is male, due to nondisjunction at first meiosis, an additional X chromosome is added. Drosophila. According Bridge's balance theory, XXY is female.

For an individual with the XXY chromosomal composition, the expected number of Barr bodies in interphase cells is a. zero b. three c. variable d. one e. two

One

One form of deafness is caused by a rare autosomal recessive gene. In a mating involving a deaf man and a deaf woman, would you expect some of the children to have normal hearing? Explain your answer.

Since the gene in question is recessive, both of the parents are homozygous and one would not expect normal hearing in the offspring.

Among dogs, short hair is dominant to long hair and dark coat color is dominant to white (albino) coat color. Assume that these two coat traits are caused by independently segregating gene pairs. For each of the crosses given below, write the most probable genotype (or genotypes if more than one answer is possible) for the parents. It is important that you select a realistic symbol set and define each symbol below. Parental Phenotypes Phenotypes of Offspring Short, Dark Long, Dark Short, Albino Long, Albino (a) dark, short X dark, long 26 24 0 0 (b) albino, short X albino, short 0 0 102 33 (c) dark, short X albino, short 16 0 16 0 (d) dark, short X dark, short 175 67 61 21

Parental Phenotypes: albino, short X albino, short Albino - Recessive cc Short - Dominant Ll or LL Dark - Dominant Cc or CC Long - Recessive ll Most probable genotype for parent are Llcc X Llcc. Because: (135 Dogs/4 varied features) = 33.75 33.75 Dogs for each feature if equal: however, we know that they are not. Because two feature = 0 & 1 feature = 33.... It translates that 1 feature = (33.75 X 3) = 102 So, we have a 3:1 Ratio Meaning that the probable genotype for the dogs is Heterozygous X Heterozygous ????

How does epistasis differ from Mendel's principle of dominance?

Phenotypic expression is often the result of products produced by multi-step metabolic pathways involving several different genes; each gene encodes an enzyme that regulates a specific biochemical step or event. Epistasis refers to the interaction among two or more genes that control a common pathway. For example, a mutation in any single gene contributing to a metabolic pathway can affect the expression of other genes in the pathway, and, of course, the final phenotype, depending on which biochemical step that gene controls. Epistasis thus involves interaction among alleles located at different gene loci. This is in contrast to dominance, which involves interaction between alleles located at the same gene locus.

Crossing over occurs during anaphase. metaphase. prophase. interphase. telophase.

Prophase

In eukaryotes, chromosomes do not contain: a. chromatin b. histones c. DNA d. proteases e. proteins

Proteases

Provide simple definitions that distinguish segregation and independent assortment.

Segregation is the separation of alleles during meiosis, while independent assortment states that a member of one gene pair has an equal and independent opportunity of segregating with either member of another gene pair.

Homologous chromosomes are those that can be matched by virtue of their similar structure and function within a nucleus. What chromosomes making up the human genome do not follow the same characteristics of homology?

Sex chromosomes

In a three-point mapping experiment, what three general classes of offspring are expected (assuming crossovers occur)? Select all those that apply. Noncrossovers Subcrossovers Triple crossovers Single crossovers Double crossovers

Single crossovers Double crossovers Noncrossovers

Human blood types are an example of codominance because: a. The A and B alleles both express equally in individuals with both alleles. b. The only individuals with O type blood are homozygous recessive c. Individuals with both A and B alleles produce a blended blood type with neither allele expressing fully d. An individual with genotype AO will have A type blood

The A and B alleles both express equally in individuals with both alleles.

A color-blind, chromatin-positive male child (one Barr body) has a maternal grandfather who was color-blind. The boy's mother and father are phenotypically normal. Construct and support a rationale whereby the chromosomal and genetic attributes of the chromatin-positive male are fully explained.

The boy has Kleinfelters syndrome. He received 2 X chromosomes and one Y chromosome. Since he is color-blind, we can assume he received 2 X chromosomes from his mother. One of the X chromosomes was inactivated and turned into a Barr body. One of his mothers gametes experienced nondisjunction, resulting in 2 X chromosomes. One of the X chromosomes contained the color-blind gene his mother inherited from her father (the maternal grandfather). The other, "normal", X chromosome was turned into a Barr body.

You are conducting a cross using Drosophila melanogaster. The results of your cross indicate that the recombination frequency is very high. How do you feel about the accuracy of your map unit calculations based on this cross?

The calculations are not very accurate. The distance would be underestimated because double crossovers are not observed.

How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle? a. The daughter cells have half the amoung of cytoplasm and half the amount of DNA b. The daughter cells have half the number of chromosomes and half the amount of DNA c. The daughter cells have the same number of chromosomes and twice the amount of DNA d. The daughter cells have the same number of chromosomes and half the amount of DNA e. The daughter cells have the same number of chromosomes and the same amount of DNA

The daughter cells have the same number of chromosomes and the same amount of DNA.

When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result? a. Other male-specific factors influence eye color inflies b. The gene involved is on an autosome c. The gene involved is on the Y chromosome d. The gene involved is on the X chromosome

The gene involved is on the X chromosome

A yeast geneticist isolates two different haploid mutant yeast strains, Strain A and Strain B, which cannot grow unless the amino acid leucine is added to the growth media. Wild-type yeast strains can make their own leucine, so do not require that it be added to the growth media. The geneticist discovers that each mutant yeast strain contains a single recessive mutation that leads to the observed leucine-requiring phenotype. When she crosses the two mutant strains together, she observes that the resulting diploid can grow without leucine added to the growth media. Explain the allelic relationship between the mutations in these two strains.

The mutations in strains A and B are NOT allelic because complementation was observed. Strain A contains a mutation at gene A, which is recessive (a), and strain B contains a mutation at a separate genetic locus, gene B, which is also recessive. Strain A contains a wild-type B gene and strain B contains a wild-type A gene. These wild-type genes complement the corresponding mutant alleles in the diploid.

Assume that a dihybrid F2 ratio, resulting from epistasis, was 15:1. If a double heterozygote was crossed with the fully recessive type, what phenotypic ratio is expected among the offspring?

The phenotypic ratio expected among the offspring is 3:1. This can be better explained by considering an example below Epistasis - the interaction between two or more genes to control a single phenotype. Epistasis can be best explained by an example as follows 1. If a pure line wheat plant with a colored kernel (genotype = AABB) is crossed to plant with white kernels (genotype = aabb) and the resulting F1 plants are selfed, a modification of the dihybrid 9:3:3:1 ratio will be produced. The following table provides a biochemical explanation for the 15:1 ratio. Genotype Kernel type 9 A_B_ Colored kernels 3A_bb Colored kernels 3aaB_ Colored kernel 1aabb colorless kernel If we combine all the genotypes that exhibit the property of colored kernel, then the ratio of colored kernels with colorless kernel is to be 15:1. Because either of the genes can provide the wild type of phenotype.

Under what conditions does one expect a 1:1:1:1 phenotypic ratio among the offspring of a cross? What must be true about the parents? What must be true about the genes in question?

This occurs in a cross involving doubly heterozygous individuals crossed to fully recessive individuals. The genes involved assort independently of each other.

For a particular plant, red flowers (A) are dominant over yellow flowers (a). An initial cross was made between a plant that was true-breeding for red flowers, and another plant true-breeding for yellow flowers. F1 progeny, all having red flowers, were allowed to form seeds (through self-fertilization), which were then planted to generate F2 progeny. Pollen from all the resulting F2 plants was pooled and used to fertilize true-breeding yellow plants. What proportion of the progeny resulting from this cross would be expected to have yellow flowers?

The proportion of the progeny resulting from this cross that is expected to have yellow flowers is ½ of the flowers.

The expected ratio of phenotypes among the progeny of a test cross is 1:1:1:1. Out of 200 total resulting progeny, 48 occur in one of the four phenotypic classes. Given this information, which of the following must also be true? The value of observed - expected for this cell = -2. All of the other classes have observed values of 48 The progeny of this cross do not conform to a 1:1:1:1ratio. Since 48 is so close to the expected value, there is no need to calculate chi square before drawing a conclusion about the ratio. At least one additional cell must also contain a count of 48.

The value of observed - expected for this cell = -2.

Which of the following species is considered a genetic model organism? The worm, Caenorhabditis elegans The frog, Hyla chrysoscelis The deer mouse, Peromyscus maniculatus The chimpanzee, Pan troglodytes The plant, Linaria vulgaris

The worm, Caenorhabditis elegans

If a cyclin protein was produced at a constant level (instead of variably) througout the cell cycle what effect would you predict?

There are several different cyclin proteins, each responsible for a particular phase of cell cycle. Depending on which cyclin and at what time during the cell cycle, introduction of constant rate in a particular cyclin would either bring about an inappropriate cell cycle stage or turn off a stage prematurely or fail to come out of a stage. All of these would likely lead to apoptosis of the cell.

Which of the following statements about homologous chromosomes are true? They occur together in haploid cells. They always contain the same alleles. They are always genetically identical. They occur together in diploid cells.

They occur together in diploid cells.

Between which stages of the cell cycle is G0 located?

Within G1

Which modes of inheritance are influenced by the sex of individuals. Select all that apply. Y-linked autosomal dominant X-linked sex-limited autosomal recessive

X-linked, sex-limited, Y-linked

Extensive pedigree analysis on a characteristic shows all of the following: •only males are affected. •affected fathers always pass the trait to sons. What does this pedigree indicate:

Y-linked inheritance

During an experiment you come across a RF of 50%. What can you conclude about the two loci you are looking at?

You wont know if the two loci are either far apart on the same chromosome or located on different chromosomes.

In a mating between individuals with the genotypes IAIB X IOIO, what percentage of the offspring are expected to have the O blood type?

Zero

Red-green color blindness is X-linked recessive. A woman with normal color vision has a father who is color blind. The woman has a child with a man with normal color vision. Which phenotype is NOT expected? a noncolor-blind female a color-blind male a noncolor-blind male a color-blind female

a color-blind female

The primary structure of a protein is: A chain of genes A linear chain of amino acids An active site A folded up ball of cells A long coil

a linear chain of amino acids

In humans, the genetic basis for determining the sex "male" is accomplished by the presence of ________. a. one X chromosome b. high levels of estrogen c. a portion of the Y chromosome d. a balance between the number of X chromosomes and e. the number of haploid sets of autosomes multiple alleles scattered throughout the autosomes

a portion of the Y chromosome

What is the probability of rolling two six-sided dice and obtaining the following numbers: a) 2 and 3? (enter answer in box 1) b) 6 and 6? (enter answer in box 2) c) at least one 6? (enter answer in box 3) d) Two of the same number (two 1s, or two 2s, or two 3s, or two 4s etc.)? (enter answer in box 4) e) An even number on both dice? (enter answer in box 5) f) An even number on at least one dice? (enter answer in box 6) Enter all answers as fraction (e.g. 1/3 ). When possible use the simpliest form (e.g. simplify 2/6 to 1/3)

a) 1/18 b) 1/36 c) 11/36 d) 1/6 e) 1/4 f) 1/4

a) In a healthy female, how many secondary oocytes would be expected to form from 100 primary oocytes? b) How many first polar bodies would be expected from 100 primary oocytes? a) 100, b) 50 a) 200, b) 300 a) 50, b) 50 a) 200, b) 50 a) 100, b) 100

a) 100, b) 100

Listed below are blood types for several children and their mothers. Give all possible genotypes and blood types for the father of each child. Child's blood type Mother's blood type a. A A b. O B c. AB A d. B AB

a) The child's genotypes would be AO, AA The Mother's genotype would be AO, AA so that means the father can have blood types B, O, A or AB the genotypes of the father would be BO, OO, AO, AA, AB b)The child's genotypes would be OO The Mother's genotype would be only BO, because if it is BB then no matter what the father's blood type is the child will automatically possess a B blood gene within him. so that means the father can have blood types B, O or A the genotypes of the father would be BO, OO or AO. The father can only BO for blood type B and only AO for blood type A, since both parents must have O present in their blood genes in order to reproduce a child with OO c) The child's genotypes would be AB The Mother's genotype would be AO, AA so that means the father can have blood types B or A the genotypes of the father would be BO, BB,AO or AA d)The child's genotypes would be BB,BO The Mother's genotype would be AB so that means the father can have blood types B or A the genotypes of the father would be BO,BB or AO

You are doing lab work with a new species of beetle. You have isolated lines that breed true for either blue shells and long antenna, or green shells and short antenna. Crossing these lines yields F1 progeny with blue shells and long antenna. Crossing F1 progeny with beetles that have green shells and short antenna yield the following progeny: blue shell, long antenna: 82 green shell, short antenna: 78 blue shell, short antenna: 37 green shell, long antenna: 43 total: 240 a. Which shell color and antenna length alleles are dominant? b. Are the shell color locus and antenna length locus linked? c. Check your answer to the previous question with the chi-square test. d. If the genes are linked, calculate the recombination frequency between them.

a) blue shell, and long antenna is dominant because it says that when isolated lines that breed true for either blue shells and long antenna or green shells and short antenna were crossed the F1 progeny all had blue shells and long antenna. b) The progeny should have exhibited 1:1:1:1 ratio but were more like 2:2:1:1. The progeny numbers do not exhibit roughly equal amounts of all 4 different phenotypes, which does indicate that the two genes are linked. The most common phenotypes have one dominant trait and one recessive trait (blue short = 82 and green long = 78). This means that the F1 heterozygote must be in the trans configuration, since it gave one dominant allele and one recessive allele together. Recombinant offspring (blue long and green short ) were created when crossing over rearranged the alleles. c) [(82-60)^2+(78-60)^2+(37-60)^2+(43-60)^2]/60 = 27.1 d)Recombination frequency = (37 + 43)/(82 + 78 + 37 + 43) = 80/240 = 33.3%

Two gene loci, A and B, are unlinked (and thus assort independently), and alleles A and B are dominant over alleles a and b. Indicate the probabilities of producing the following. a. An AB gamete from an AaBb individual? b. An AB gamete from an AABb individual? c. An AABB zygote from a cross AaBb × AaBb? d. An AaBb zygote from a cross AaBb × AABB? e. An Aabb zygote from a cross AaBb × AAbb? f. An AB phenotype from a cross AaBb × AaBb? g. An AB phenotype from a cross aabb × AABB? h. An aB phenotype from a cross AaBb × AaBB?

a. 1/4 b. 1/2 c. 1/16 d. 1/4 e. 1/4 f. 9/16 g. 1 h. 1/4

Genetically speaking, brown eyes (B-) are dominant to blue eyes (bb). However, an individual can wear colored contacts in order to change his or her eye phenotype. Suppose a man with blue eyes (bb) marries a woman who appears to have blue eyes and together they have five children. Listed below are three possible outcomes. For each of the outcomes, predict the woman's genotype. a. All 5 children have brown eyes b. Three have blue eyes and 2 have brown eyes c. All 5 chldren have blue eyes The woman naturally has blue eyes (bb). The woman naturally has brown eyes and is heterozygous for the trait (Bb). The woman naturally has brown eyes and is homozygous for the trait (BB).

a. All 5 children have brown eyes=. The woman naturally has brown eyes and is homozygous for the trait (BB). b. Three have blue eyes and 2 have brown eyes= The woman naturally has brown eyes and is heterozygous for the trait (Bb). c. All 5 chldren have blue eyes= The woman naturally has blue eyes (bb)

Prokaryotic chromosomes do not have telomeres because: they are circular. they do not go through DNA replication. they are in the cytoplasm. they have no centromeres. they do not go through mitosis.

are circular

You just bought two black guinea pigs from the pet store that are known to be heterozygous (Bb). You also know that black fur (BB) is dominant over white fur (bb), and that a lethal recessive allele is located only one cM away from the recessive b allele. You decide to start raising your own guinea pigs, but after mating these animals several times, you discover they produce only black progeny. a) How would you explain this result? b) If the original black guinea pigs produce an average of 10 offspring per mating, how many matings would you have to make with these same parents before you'd expect to see a white guinea pig? c) Indicate the most likely genotype of the white offspring.

a. The recessive allele is b, we can say that white fur (which was homozygous recessive, bb) alleles slowly mutated to lethal allele. This resulted in black fur since it could be BB or Bb. The 1/4 prgeny carrying bb died while the heterozygotes which were Bb survived and produces black progeny due to the recessive nature of lethal allele. Since the distance given is only one cM it can be implied that all the b changed to lethal alleles. b. Originally the cross would have produced 75% black and 25% white fur progeny. So in the first mating 25% of 10 offsprings would be expected to be white offsprings. c. Since the white phenotype is produced in the absence of dominant B, hence, it is bound to be homozygous recessive. Therefore, the most likely genotype for white fur would be bb. (bb, {lethal allele}{lethal allele})

An allele is a. another term for epistasis. b. an alternate form of a gene. c. one of the bases in DNA. d. found in mitochondria but not in nuclei. e. present only in males and is responsible for sex determination.

an alternate form of a gene

Genetic distances within a given linkage group cannot be determined. are measured in centiMorgans. B and C A, B, and C B, C, and D are dependent upon crossover frequencies between paired, non-sister chromatids. cannot exceed 100 cM.

are dependent upon crossover frequencies between paired, non-sister chromatids. are measured in centiMorgans.

What inheritance pattern is suggested by the following observations of a particular pedigree? Reference: Ref 6-5 Extensive pedigree analysis on a characteristic shows all of the following: •the characteristic affects males and females equally. •two unaffected parents can have an affected child. •in families in which the parents are unaffected but the children are affected, 1/4 of the children are affected.

autosomal recessive

Two- and three-factor testcrosses can both be used to _____________ and _____________. a. screen recessive mutants b. map gene loci c. determine parental origin d. determine genotype e. identify double-crossover events

b. map gene loci d. determine genotype

The "distance" between two linked gene pairs can be expressed as a percentage. Name the unit based on percent recombination that was created in honour of the scientist who pioneered the use of fruit flies for genetic research.

centimorgan

The attachment point on the chromosome for spindle microtubules is the

centromere

Provide an example of sex-influenced inheritance.

certain genes are dominant over the other in one sex and recessive in the other

In anaphase a. chromosomes replicate b. chromosomes move to opposite poles c. homologous chromosomes are paired d. the nuclear membrane is dissolved

chromosomes move to opposite poles

Interactions among the human ABO blood group alleles involve _______ and ________. a. expressivity b. continuous variation c. complete dominance d. incomplete dominance e. co-dominance

co-dominance; complete dominance

Linked genes ____________. a. co-segregate b. can crossover and recombine c. are allelic d. will segregate independently e. assort randomly

co-segregate

In order to determine if mutations from different organisms that exhibit the same phenotype are allelic, which test would you perform? a. allelic series test b. test cross c. complementation test d. biochemical test e. epistasis test

complementation test

Assume that a cross is made between AaBb and aabb plants and that all the offspring are either AaBb or aabb. These results are consistent with the following circumstance: a. codominance b. incomplete dominance c. alternation of generations d. hemizygosity e. complete linkage

complete linkage because there are no recombinants only parentals

What events during sexual reproduction are significant in contributing to genetic diversity?

crossing over random segregation independent assortment

Why would it make sense for cyclin proteins to vary in concentration throughout the cell cycle?

cyclins are proteins that kinases bind to in order to be activated (Cdk or cyclin dependent kinase) Cyclin levels vary during cell cycle which vary levels of activated kinases result in variable phosphorylation by kinases and different results/effects depending on point in cell cycle

__________________ refers to the splitting of the cytoplasm, separating one cell into two.

cytokinesis

Phenotypic mosaicism for X-linked genes in female mammals can be caused by what?

dosage compensation involving the X chromosome formed from only one chromosome. A tortoiseshell cat is a good example, where the Xblack is deactivated fur is ginger, where Xorange is deleted fur is black.

A condition in which one gene pair masks the expression of a nonallelic gene pair is called ________. codominance recessiveness additive alleles epistasis dominance

epistasis

A man and a woman are trying to have children but are unsuccessful. As part of a series of tests, the man is karyotyped. His autosomes appear normal, but his sex chromosomes, shown in the following diagram, are not. The diagram also shows a normal male's sex chromosomes for reference. Can you tell if the mutation came from the man's mother or the man's father? Explain how you can tell.

https://osu.instructure.com/assessment_questions/1611633/files/7111382/download?verifier=6cm1grtkvO0GlCMrX3MLKuqk7gqzBDYsSoWyaADG He inherited the translocation chromosome from his father because his mother could not have carried the SRY-containing chromosome.

Codominant alleles are expressed in individuals that are __________________________. a. mutually exclusive b. penetrant c. homozygous d. polymorphic e. heterozygous

heterozygous

Regarding the ABO blood group system in humans, if an individual is genetically IBIO and yet expresses the O blood type, it is likely that they have the ________ phenotype.

hh (Bombay)

An individual has the following genotype. Gene loci (A) and (B) are 15 cM apart. Indicate all the possible gametes that this individual can produce, and the proportions of expected progeny genotypes if a testcross is performed on this individual. Your Answer: Ab = 42.5% aB = 42.5% AB = 7.5% ab = 7.5%

https://osu.instructure.com/assessment_questions/1611630/files/7111371/download?verifier=GnBIAiKz7zhZa8jRrswILMefTyycTv8L9YLorbll

A man and a woman are trying to have children but are unsuccessful. As part of a series of tests, the man is karyotyped. His autosomes appear normal, but his sex chromosomes, shown in the following diagram, are not. The diagram also shows a normal male's sex chromosomes for reference. can_you_tell_if.jpg Reference: Ref 4-6 Can you tell if the mutation came from the man's mother or the man's father? Explain how you can tell

https://osu.instructure.com/assessment_questions/1611633/files/7111382/download?verifier=6cm1grtkvO0GlCMrX3MLKuqk7gqzBDYsSoWyaADG He inherited the translocation chromosome from his father because his mother could not have carried the SRY-containing chromosome.

Two independently-assorting loci, "P/p" and "C/c" are drawn on the chromosomes above. The "P" and "p" alleles are said to be on _____________.

https://osu.instructure.com/assessment_questions/504768/files/3773364/download?verifier=BZ2YrkkqhGi3bpf1gYEKYj3gWus9iMmWvav46Jqg Different chromosomes

Assume that an organism has a diploid chromosome number of six. Two chromosomal pairs are telocentric, and the other pair is metacentric. Assume that the sex chromosomes are morphologically identical. The drawing above could represent which stage(s)? Check all that apply. Ch.2 No.15-1.jpg Secondary spermatocyte (metaphase) First polar body (metaphase) Secondary oocyte (metaphase) Primary oocyte (metaphase)

https://osu.instructure.com/assessment_questions/6216/files/200614/download?verifier=uJ3qP0dOzOEWcOfclRj5595GHkI0ypCkEjPuIj8K Secondary spermatocyte (metaphase) First polar body (metaphase) primary oocyte

Drosophila melanogaster, the fruit fly, has a 2n chromosome number of 8. Assume that you are microscopically examining the mitotic and meiotic cells of this organism. You note that in the female two chromosomal pairs are metacentric and that two pairs are acrocentric. What stage is represented in the drawing above? (Genes "P" and "C" are not relevant to this question). a. Secondary oocyte (metaphase) b. Mitotic metaphase c. Primary oocyte (metaphase) e. Ootid (G1)

https://osu.instructure.com/assessment_questions/6237/files/200637/download?verifier=REsiKghp9jVTxxjGlN91ky8L72T5PTFkTg8sCQaB Primary oocyte (metaphase)

The sketch above depicts a cell from an organism in which 2n = 2 and each chromosome is metacentric. What stage is does the sketch represent? Ch.2 No.16-1.jpg anaphase of mitosis anaphase of Meiosis I anapase of Meiosis II telophase of mitosis

https://osu.instructure.com/assessment_questions/6328/files/200640/download?verifier=PSkxcT7UGevlwgckMMmZoQdLK6fh96HMZkzIc1E0 Anaphase of Meiosis II

0.1% frequency of recombination is observed a. only in sex chromosomes b. in any two genes on different chromosomes c. on unlinked chromosomes d. in genes located very close to one another on the same chromosome

in genes located very close to one another on the same chromosome

Microscopy to look at a cell's chromosomes is often done when the cell is in mitotic metaphase. For example, karyotypes that extract chromosomes from a single cell and photograph them to look for abnormalities are done on metaphase, rather than interphase, cells. Why?

in metaphase the chromosomes are condensed and are more easily visualized

Genes contain the instructions for building proteins. Where are those instructions located? In the tRNA. In the bonds between complementary bases. In the nuclear membrane. In the sugar and phosphate groups that are part of each nucleotide. In the order of the DNA bases.

in the order of the DNA bases

A Barr body is a(n) a. extra Y chromosome in a cell that is the result of nondisjunction. b. gene on the X chromosome that is responsible for female development. c. inactivated X chromosome, visible in the nucleus of a cell that is from a female mammal. d. patch of cells that has a phenotype different from surrounding cells because of variable X inactivation. e. extra X chromosome in a cell that is the result of nondisjunction

inactivated X chromosome, visible in the nucleus of a cell that is from a female mammal.

What is the composition of a Barr body?

inactive X chromosome in a female somatic cell, rendered inactive in a process called lyonization, in those species in which sex is determined by the presence of the Y

Describe the differences between dominance, co-dominance, and incomplete dominance.

incomplete dominance= neither allele is dominant but are expressed. codominance= neither allele is dominant, but expression of alleles is observed as a distinct phenotype in heterozygous individual. Dominance= type of allele interaction in the heterozygous state, in which one allele of a gene if fully expressed and the effect of the second allele is masked

How do incomplete and co-dominance differ?

incomplete dominance= neither allele is dominant but are expressed. codominance= neither allele is dominant, but expression of alleles is observed as a distinct phenotype in heterozygous individual.

According to Mendel's postulate of ________, all possible combinations of gametes will be formed in equal frequency.

independent assortment

Assume that a cross is made between AaBb and aabb plants and that the offspring fall into approximately equal numbers of the following groups: AaBb, Aabb, aaBb, aabb. These results are consistent with the following circumstance: codominance alternation of generations incomplete dominance independent assortment hemizygosity

independent assortment

What conditions are likely to apply if the progeny from the cross AaBb X AaBb appear in the 9:3:3:1 ratio? no gene interaction linked genes co-dominance independent assortment complete dominance

independent assortment complete dominance no gene interaction

Phenotypically wild F1 female Drosophila, whose mothers had light eyes (lt) and fathers had straw (stw) bristles produced the following offspring when crossed to homozygous light-straw males: Phenoytpe Number light,straw 22 wildtype 18 light 990 straw 970 Total: 2000 What is the map distance between the light and straw loci? Enter a number in the box below.

light eyes(Lt) x fathers straw(stw)-----------parental light-straw 22---- recombinant, wild 18---------- recombinant, light 990--------- -parental straw 970-------- -parental total: 2000 % of recombinant= recombinants/ total x 100= = 40/2000 x100=2 % recombination 2% recombination= 2 mu map distance between the light and straw loci.= 2 mu

Often, a mutation in a gene results in a reduction of the product of that gene. The term given for this type of mutation is: codominance loss-of-function or null (in the case of complete loss) incomplete dominance gain-of-function multiple allelism

loss-of-function or null (in the case of complete loss)

The genes for mahogany eyes and ebony body are approximately 25 map units apart on chromosome III in Drosophila. Assume that a mahogany-eyed female was mated to an ebony-bodied male and that the resulting F1 phenotypically wild-type females were mated to mahogany, ebony males. Of 1000 offspring, what would be the expected numbers of the following phenotypes: mahogany? ebony? wildtype? mahogony, ebony?

mahogany = 375; ebony = 375; wild type = 125; mahogany-ebony = 125

Homologous chromosomes move toward opposite poles of the dividing cell during a. mitosis b. meiosis I c. meiosis II d. binary fission

meiosis I

Assuming no crossing over between the gene in question and the centromere, during what phase of meiosis do alleles segregate?

meiosis I, when homologous chromosomes go to opposite poles

A situation where there are more than two alternative forms of a given gene would be called ________. a. multiple alleles b. incomplete dominance c. alternation of generations d. codominance e. hemizygosity

multiple alleles

Permanent, heritable changes in genetic information (DNA) are called

mutations

If a pair of homologous chromosomes fails to separate during anaphase of meiosis I, what will be the chromosome number of the four resulting gametes with respect to the normal haploid number (n)? a. n + 1; n + 1; n; n b. n + 1; n + 1; n - 1; n - 1 c. n + 1; n - 1; n; n d. n + 1; n - 1; n - 1; n - 1

n+ 1; n + 1; n - 1; n - 1 two of the gametes will have one extrachromosomes each and the other two gametes will have onechromosome less

The phenomenon in which one crossover increases the likelihood of crossovers in nearby regions is called: positive interference reciprocal gene exchange mitotic recombination chiasma negative interference

negative interference

In order to be functional, a chromosome requires all of the following except: centromeres telomeres nucleomeres origins of replication

nucleomeres

Genes can be located in which organelles? a. ribosome b. nucleus c. golgi d. chloroplast e. vacuole f. mitochondria

nucleus, chloroplast, mitochondria

If one is testing a goodness of fit to a 9:3:3:1 ratio, how many degrees of freedom would be associated with the Chi-square analysis?

number of classes minus 1 so, 4-1= 3

A rare dominant trait, when exhibited in men, is transmitted to half their sons and to half their daughters. The gene for this trait is carried: None of the above. on an autosome. in the mitochondria. on the X chromosome. on the Y chromosome.

on an autosome

How many Barr bodies would you expect to see in an XXY individual? 2 0 1 3

one

The F1 offspring of Mendel's classic pea cross always looked like one of the two parental varieties because a. one allele was completely dominant over another b. each allele affected phenotypic expression c. different genes interacted to produce the parental phenotype d. the traits blended together during fertilization

one allele was completely dominant over another

The DNA of a eukaryotic chromosome is: a. a pile of fibers with lots of loose ends. b. lots of double helices all jumbled together. c. two or three helices neatly arranged in the nucleus. d. attached in the middle by a centromere. e. one long double helix.

one long double helix.

The Chi-square test involves a statistical comparison between measured (observed) and predicted (expected) values. One generally determines degrees of freedom as

one more than the number of classes being compared. the number of categories being compared. ten minus the sum of the two categories. one less than the number of classes being compared. the sum of the two categories.

Choose the answer that lists--in order of appearance--all the cell types expected to be formed during oogenesis. a. oogonium, primary oocyte, ootid and second polar body, secondary oocyte and first polar body b. ootid, primary oocyte, oogonium, secondary oocyte and first polar body, second polar body c. oogonium, primary oocyte and first polar body, secondary oocyte and second polar body, ootid d. oogonium, primary oocyte, secondary oocyte and first polar body, ootid and second polar body

oogonium, primary oocyte, secondary oocyte and first polar body, ootid and second polar body

If two genes assort independently, which categories of ascospore arrangements occur in approximately equal frequencies: parental ditype, nonparental ditype, or tetratype?

parental ditype and nonparental ditype

A measurable or observable trait or characteristic is called a(n)

phenotype

Mendel's law of independent assortment has its physical basis in the: a. spindle attachment in anaphase I. b. sister chromatids separating in meiosis II. c. separation of alleles into haploid cells. d. haploid cells forming. e. random arrangement of chromosomes on the metaphase plate in meiosis I.

random arrangement of chromosomes on the metaphase plate in meiosis I.

The fundamental Mendelian process that involves the separation of contrasting genetic elements at the same locus would be called a. continuous variation. b. discontinuous variation. c. segregation. d. independent assortment. e. dominance or recessiveness.

segregation

Under what circumstance might two loci be on the same chromosome but behave as if independently assorting in crosses?

segregation of homologous chromosomes and sister chromatids ... Same Gene from Mutations in. Different ... than two alleles at a locus (because such individuals ... circumstances are identified as gene interactions; this .... function mutant alleles are usually recessive, but under certain circumstances, they may be dominant

Hemizygosity would most likely be associated with which of the following? a. sex-limited inheritance b. trihybrid crosses c. dihybrid crosses d. sex-linked inheritance e. incomplete dominance

sex-linked inheritance

What is the outcome of synapsis, a significant event in meiosis? a. monad movement to opposite poles b. side-by-side alignment of nonhomologous chromosomes c. dyad formation d. chiasma segregation e. side-by-side alignment of homologous chromosomes

side-by-side alignment of homologous chromosomes

In corn, small pollen (sp) is recessive to normal pollen (sp+) and banded necrotic tissue, called zebra necrotic (zn), is recessive to normal tissue (zn+). The genes that produce these phenotypes are closely linked on chromosome 10. If no crossing over occurs between these two loci, give the types of progeny expected from the following crosses:

sp+ zn+/sp+ zn+; sp+ zn+/sp zn; sp zn/sp zn

Choose the answer that lists--in order of appearance--all the cell types expected to be formed during spermatogenesis. a. spermatogonia, primary spermatocyte, secondary spermatocyte, spermatid, spermatozoa b. spermatozoa, primary spermatocyte, spermatogonia, secondary spermatocyte, spermatid c. spermatogonia, spermatozoa, primary spermatocyte, spermatid, secondary spermatocyte, d. spermatogonia, secondary spermatocyte, primary spermatocyte, spermatid, spermatozoa

spermatogonia, primary spermatocyte, secondary spermatocyte, spermatid, spermatozoa

Methods for determining the linkage group and genetic map in humans involve which of the following? a. tetrad analysis and bromodeoxyuridine b. twin spots and tetrad analysis c. zygotene and pachytene DNA synthesis d. chiasmatype and classical analyses e. syntenic testing and lod score determination

syntenic testing and lod score determination

In the G0 stage of the cell cycle, which of the following is true: DNA content doubles the cell exits the cell cycle RNA replicates stem cells are produced the nuclear membrane disappears

the cell exits the cell cycle

During prophase I of meiosis, crossing over is indicated by what microscopically visible structure? The ______.

the chiasmata

Cytokinesis is a. None of the above b. the formation of two new nuclei at the end of mitosis or either meiotic division c. the formation of two cells at the end of mitosis in both plants and animals d. the energy transfer process that facilitates bacterial movement

the formation of two cells at the end of mitosis in both plants and animals

Embryonic stem cells are the subject of a great deal of research. What characteristic of embryonic stems cells accounts for this scientific interest? they are potentially pluripotent they can be used to clone animals they are potentially totipotent they are not controversial they do not undergo apoptosis

they are potentially totipotent

Under what conditions does one expect a 9:3:3:1 phenotypic ratio among the offspring of a cross? What must be true about the parents? What must be true about the genes in question?

two completely dominant, independently segregating gene pairs, when both parents are fully heterozygous, dihybrid cross

In a Chi-square analysis, what condition causes one to reject (fail to accept) the null hypothesis?

usually when the probability value is less than 0.05