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Genetics - BI 312 > Ch. 4: Extensions and Modifications of Basics Principles > Flashcards

Ch. 4: Extensions and Modifications of Basics Principles Flashcards

1
Q

Define sex

A

Referring to sexual phenotype (Male/Female/Intersex)

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2
Q

Define sex determination

A

The mechanism by which biological sex is established

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3
Q

Define gender

A

A category assigned by the individual or others based on behavior and cultural practices

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4
Q

Define sex chromosomes

A

Chromosomes that determine the sex of an organisms

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5
Q

Define autosomes

A

Non-sex chromosomes in an organisms

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6
Q

Define heterogametic sex

A

When two different types of gametes regarding sex chromosomes are produced (Male; XY)

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7
Q

Define psuedoautosomal regions

A

Chromosomes that are homologous in small regions

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8
Q

Define genetic sex determination

A

genotypes at one or more loci determine the sex of an individual

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9
Q

Define turner syndrome

A

Females who often have underdeveloped secondary sex characteristics

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10
Q

Characteristics of turner syndrome

A
  • 1 in 3,000 female births
  • Short in height
  • Low hairline
  • Relatively broad chest
  • Folds of skin on neck
  • Average intelligence
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11
Q

Define Klinefleter syndrome

A

Cells with one or more Y chromsomes and multiple X chromosomes

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12
Q

Characteristics of Klinefelter syndrome

A
  • 1 in 1,000 male births
  • Cells with one or more Y chromsomes and multiple X chromosomes
    Usually XXY
    Can also be
    XXXy
    XXXXY
    XXYY
  • Small testes
  • Reduced facial and pubic hair
  • Taller than normal
  • Sterile
  • Normal level of intelligence
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13
Q

Characteristics of Triple-X syndrome

A
  • 1-1,000 female births
  • 3 x chromones (XXX)
  • Tall and thin
    Few are sterile
  • Most have average level of intelligence though some are struggle more
  • The more X chromosomes present, the more disabilities
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14
Q

Define sex-determining region Y (SRY) gene

A

The male-determining gene in humans

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15
Q

Define sex-linked characteristics

A

Characteristics determined by genes located in the sex chromosomes

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16
Q

Define X-linked characteristics

A

Genes on the X chromosome that determine the characteristics of the organism

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17
Q

Define Y-linked characteristics

A

Gene on the Y chromosome that determine the characteristics of the organism

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18
Q

Define hemizygous

A

The condition of a gene where only one set of chromosomes from a chromosomal pair is observed

(Ex: male drosophila only have one sex chromosome that affects eye color)

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19
Q

Define dosage compensation

A

Mechanisms evolved to equalize the amount of protein produced by the single X and two autosomes in the heterogametic sex

Ex: In fruit flies, dosage compensation is achieved by a doubling of the activity of the genes on the X chromosome of males but not that of females

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20
Q

Define Barr bodies

A

Condensed, darkly staining bodies in the nuclei of cells

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21
Q

Define Lyon hypothesis

A

Within each female cell, one of the two X chromosomes is inactivated; which X chromosome is inactivated is random

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22
Q

Define complete dominance

A

When on phenotype is completely dominant over another (Ex: A = red, a = white and Aa makes red while aa makes white. Then “A” in this case expresses complete dominance)

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23
Q

Define incomplete dominance

A

When the phenotype of the heterozygote falls in between the phenotypes of two homozygotes

(Ex: A = red, aa = white. A flower with Aa is pink.)

Doesn’t always need to be in-between, can just be a lighter shade of red

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24
Q

Define codominance

A

The phenotype of the heterozygote is not intermediate between the phenotypes of the homozygotes; rather, the heterozygote simultaneal expresses the phenotype of both homozygotes.

(A = red, a= white, Aa = red and white, but not pink)

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25
Q

Define incomplete penetrance

A

A phenomenon when the genotype does not always produce the expected phenotype

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26
Q

Define penetrance

A

The percentage of individual organisms having a peculiar genotype that express the expected phenotype

Ex: 42 people have an allele for polydactyly and found that only 38 of them were polydactylies, the penetrance would be 38/42 = 0.90 * 100 = 90% penetrance

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27
Q

Define expressivity

A

The degree to which a trait is expressed

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28
Q

Define lethal allele

A

Causes death at an early stage of development- often before birth- so that some genotypes od not appear among the progeny

29
Q

Define Multiple alleles (allelic series)

A

When more than two alleles are present within a locus

30
Q

Define compound heterozygote

A

An individual who carries two different alleles at a locus that result in a recessive phenotype

31
Q

Define gene interaction

A

An interaction between the effects of genes at different loci (genes that are not allelic)

32
Q

Define epistasis

A

A phenomenon where the effect of a gene interaction is that one gene masks (hides) the effect of another gene at a different locus

33
Q

Define epistatic gene

A

The gene that does the masking in epistasis

34
Q

Define hypostatic gene

A

The gene who’s effect is masked (hidden) in epistasis

35
Q

Define complementation test

A

A test used to determine whether different mutations that affect a characteristic occur at the same locus (are allelic) or at different loci.

36
Q

Define complementation

A

When an individual organism possessing two recessive mutations had a wild-type phenotype, indicating that the mutations are nonallelic.

37
Q

Define sex-influenced characteristics

A

Characteristics determined by autosomal genes and are inherited according Mendel’s principles but are expressed differently in males and females

38
Q

Define Sex-limited characteristic

A

A characteristic encoded by autosomal genes that are expressed in only one sex; the trait has zero penetrance in the other sex

39
Q

Define cytoplasmic inheritance

A

Characteristics are encoded by genes located in the cytoplasm

40
Q

Define genetic maternal effect

A

A genetic phenomenon where the phenotype of the offspring is determined by the genotype of the mother

41
Q

Define genomic imprinting

A

A differential expression of genetic material depending n whether it is inherited from the male or female parent

42
Q

Define epigenetics

A

Changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself

43
Q

Define temperature-sensitive allele

A

An allele who product is functional only at certain temperatures

44
Q

Define phenocopy

A

A phenotype that is produced by environmental factors rather than by a genotype

45
Q

Define discontinuous characteristic

A

Characteristics with few easily distinguishable phenotypes

46
Q

Define continuous characteristics

A

Characteristics that exhibit a continuous distribution of phenotypes

47
Q

Define quantitative characteristics

A

Characteristics with many possible phenotypes and must be described in quantitative terms (interchangeable with continuous characteristics)

48
Q

Define polygenic characteristics

A

Characteristics encoded by genes at many loci

49
Q

Define multifactorial characteristics

A

When many factors help determine the phenotype (Ex: Continuous characteristics which are both polygenic and influenced by environmental factors)

50
Q

What process causes the genetic variation seen in offspring produced by sexual reproduction?

A

Meiosis

51
Q

How do chromosomal, genic, and environmental sex-determining systems differ?

A

In chromosomal sex determination, males and females have chromosomes that are distinguishable. In genic sex determination, sex is determined by genes, but the chromosomes of males and females are indistinguishable. In environmental sex determination, sex is determined fully or in part by environmental effects.

52
Q

What is the phenotype of a person who has XXXY

A) Klinefelter syndrome
B) Turner syndrome
C) Poly-X female

A

A) Klinefelter syndrome

53
Q

Hemophilia (reduced blood clotting) is an X-linked recessive disease in humans. A woman with hemophilia mates with a man who exhibits normal blood clotting. What is the probability that their child with have hemophilia?

A

All of their male offspring will have hemophilia, and none of their female offspring will have hemophilia, so the overall probability of hemophilia in their offspring is 1/2.

54
Q

How many Barr bodies will a male with XXXYY chromosomes have in each of his cells? What are those Barr bodies?

A

Two barr bodies; each barr body is an inactive X chromosome

55
Q

How do complete dominance, incomplete dominance, and codominance differ?

A

With complete dominance, the heterozygote expresses the same phenotype as one of the homozygote’s.

With incomplete dominance, the heterozygote has a phenotype that is intermediate between those of the two homozygotes.

With codominance, the heterozygote has a phenotype that simultaneously expresses the phenotype of both homozygotes

56
Q

How does incomplete dominance differ from incomplete penetrance?

A. Incomplete dominance refers to alleles at the same locus; incomplete penetrance refers to alleles at different loci

B. Incomplete dominance ranges from 0% to 50%, incomplete penetrance ranges from 51% to 99%

C. In incomplete dominance, the heterozygote is intermediate between the homozygotes; in incomplete penetrance, heterozygotes express phenotypes of both homozygotes

D. In incomplete dominance, the heterozygote is intermediate between the homozygotes; in incomplete penetrance, some individuals do not express the expected phenotype

A

D. In incomplete dominance, the heterozygote is intermediate between the homozygotes; in incomplete penetrance, some individuals do not express the expected phenotype

57
Q

A number of all-white cats are crossed, and they produce the following types of progeny: 12/16 all white, 3/16 black, and 1/16 gray. What is the genotype of the black progeny?

a. Aa

b. Aa Bb

c. A_B_

d. Aa B_

A

d. Aa B_

58
Q

How do sex-influenced and sex-limited characteristics differ from sex-linked characteristics?

A

Both sex-influenced and sex-limited characteristics are encoded by autosomal genes whose expression is affect by the sex of the individual organisms processing the genes. Sex-linked characterizes are encoded by genes on the sex chromosomes

59
Q

What is the difference between polygeny and pleiotropy?

A

Polygeny refers to the influence of multiple genes on the expression of a single characteristic. Pleiotropy refers to the effect of a single gene on the expression of multiple characteristics.

60
Q

How does sex determination in the XX-XY system differ from sex determination in the ZZ-ZW system?

A

Polygeny refers to the influence of multiple genes on the expression of a single characteristic. Pleiotropy refers to the effect of a single gene on the expression of multiple characteristics.

61
Q

Match each definition to the correct genetic term

Terms (listed alphabetically):
1. Autosome
2. Chromosome
3. Genome

Definitions (listed alphabetically)
1. A complete set of genetic information for an organism
2. Genetic material that is not involved in sex determination
3. Vehicles of genetic information made of DNA and protein

A

Autosome: Genetic material that is not involved in sex determination

Chromosome: Vehicles of genetic information made of DNA and protein

Genome: A complete set of genetic information for an organism

62
Q

In Caenorhabditis elegant, the level of expression of genes on both X chromosomes of females is reduced by half. What phenomenon is this an example of?

a. Dosage compensation
b. Paternal mitochondrial leakage
c. Extranuclear inheritance
d. Genomic imprinting

A

a. Dosage compensation

63
Q

Select the definition of a Barr body

a. An active X chromosome
b. An inactive Y chromosome
c. An inactive autosome
d. An inactive X chromosomes

The first cloned car, CarbonCopy (CC), was tabby, while the cat she was cloned from, Rainbow, was calico. The surrogate mother was a tabby. Select the explanation that best explains why CC would never have been identical in pattern to rainbow.

a. Neither X chromosome is inactivated
b. The pattern of X-chromosome inactivation is established randomly in a cell linkage
c. The coat color genes are on the mitochondrial genome and inherited with the mother’s oocyte
d. the coat color genes are maternal effect genes, so CC looked like the surgate

A

d. An inactive X chromosomes

b. The pattern of X-chromosome inactivation is established randomly in a cell linkage

64
Q

Color blindness is a sex-linked recessive trait. A female is color blind in one eye, but not both.

Select the explanation for this condition
a. all x chromosomes are inactivated
b. Silencing of different X chromosomes
c. Female has XO genotype

Is it possible for a male to have different color-blindness phenotypes in each eye?
a. No, since trisomy of the sex chromosomes is lethal
b. No, since XXY males lack X-chromosome inactivation
c. Yes, in an XXY male with a different active X in each eye
d. Yes, in an XXY male where each eye had alternate Y inactivation

A

b. Silencing of different X chromosomes

c. Yes, in an XXY male with a different active X in each eye

65
Q

Which statements describe Y-linked traits? (Multiple correct answers)

a. The trait is passed down to a son by his father
b. At least 50% of the male and female offspring will inherit the trait
c. The phenotype is solely expressed in males
d. A male with the trait will pass the trait to 100% of his female offspring
e. Male offspring of a female with the phenotype will also express the phenotype

A

a. The trait is passed down to a son by his father

c. The phenotype is solely expressed in males

66
Q

Red-green color blindness is an X-linked recessive trait in humans. Polydactyly (extra fingers and toes) is an autosomal dominant trait. Martha has normal fingers and toes and normal color vision. Her mother is normal in all respects, but her father is color blind and polydactylies. Bill is color blind and polydactylies. His mother has normal color vision and normal fingers and toes.

When answering the given question, consider that the answers include the proportions of only some of the possible phenotypes; other phenotypes are also expected to occur but are not included.

If Bill and Martha marry, what proportions of children with specific phenotypes would they be expected to produce?

a. 1/8 color-blind girls with polydactyly, 1/8 boys with normal vision and normal fingers
b. 1/4 color-blind girls with normal fingers, 1/4 boys with normal vision and polydactyly
c. 1/4 girls with normal vision and polydactyly, 1/8 both with normal vision and polydactyly
d. 1/8 color-blind girls with normal fingers, 1/4 boys with normal vision and polydactyly

A

a. 1/8 color-blind girls with polydactyly, 1/8 boys with normal vision and normal fingers

67
Q

Assume that long earlobes in humans are an autosomal dominant trait that exhibits 30% penetrance. A person who is heterozygous for long earlobes mates with a person who is homozygous for normal earlobes.

What is the probability that their first child will have long earlobes? Use two decimal places for the answer

A
  1. 15

Explanation:
The penetrance of a phenotype is the percentage of individuals with a particular genotype that also expresses the associated phenotype. For example, if only 50% of individuals with a dominant allele expresses the associated phenotype, the allele has 50% penetrance.

In the case of the long earlobe allele, the dominant allele results in only 30% of the individuals having long earlobes. In other words, there is a 30% chance that being heterozygous or homozygous for the long earlobe allele will result in the long earlobe phenotype.

In order to calculate the probability of their first child having the long earlobe phenotype, multiply the penetrance (0.30) by the probability of the child inheriting the dominant allele. The probability of inheriting the dominant allele is 50% because one parent is heterozygous for the allele. Thus, 0.30 multiplied by 0.50 results in a 0.15 probability that their first child will express the long earlobe phenotype.

68
Q

Snapdragions occur in nature as either green of yellow plants. A green snapdragion is homozygous and has the genotype CC. A yellow snapdragon is heterozygous and has the genotype Cc. Suppose that a garner crosses two yellow snapdragons, and one-third of the offspring are green, and two-thirds of the offspring are yellow.

What type of allele could be responsible for the 2:1 offspring ratio seen when two yellow snapdragons are crossed?

a. Codominant allele
b. Recessive lethal allele
c. Dominant lethal allele
Polymorphic allele

A

b. Recessive lethal allele

68
Q

Suppose two independently assorting genes are involved in the pathway that determines fruit color in squash. These genes interact with each other to produce the squash color seen in the grocery store.

At the first locus, the W allele codes for a dominant white phenotype, whereas the w allele codes for a colored squash. At the second locus, the allele Y codes for a dominant yellow phenotype, and the allele y codes for a recessive green phenotype. The phenotypes from the first locus will always mask the phenotype produced by the second locus if the dominant allele (W) is present at the first locus. This masking pattern is known as dominants epistasis.

A dihybrid squash, WwYy is selfed(?) and produced 320 offspring. How many offspring are expected to have the white, yellow, and green phenotypes.

Number of white offspring:

Number of yellow offspring:

Number of green offspring:

A

Number of white offspring: 240

Number of yellow offspring: 60

Number of green offspring: 20

Genetics - BI 312 (11 decks)

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