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Genetics > Exam 3 - mendel > Flashcards

Exam 3 - mendel Flashcards

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1
Q

What are true-breeding strains?

A

Homozygous

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2
Q

What is the genetic terminology for crosses?

A

P1=>F1=>F2=>F3=>etc

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3
Q

in Mendel’s pea plants, the violet allele is ________ and the white allele is __________.

A

B) Dominant; recessive

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4
Q

What were the F1 products of a Violet x White cross?

A

All of the offspring were violet

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5
Q

What were the F2 products of a F1 x F1 cross?

A

A phenotypically 3:1 (Violet: White ratio)

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6
Q

What are Mendel’s first three postulates?

A

1) Unit factors occur in pairs
2) Dominance/ Recessiveness
3) Segregation.

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7
Q

What are the phenotypic ratios of all of Mendel’s F2 generations?

A

3:1 (mendelian ratio)

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8
Q

a method that is used to predict the genotypes and phenotypes that will be present in the offspring of a genetic cross, and their relative frequencies.

A

Punnett square

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9
Q

In a standard monohybrid cross, what is the probability that an F2 individual will be heterozygous?

A

50% (1/2)

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10
Q

In a standard monohybrid cross, what is the probability that an F2 individual displaying the dominant phenotype is a heterozygote?

A

66% (2/3)

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11
Q

What is a testcross used for?

A

To distinguish between GG and Gg genotypes

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12
Q

A method to determine whether an individual displaying the dominant phenotype has a heterozygous or homozygous dominant genotype.

A

testcross

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13
Q

To carry out a testcross, the individual expressing the dominant phenotype (but having an unknown genotype) is crossed with a known ___ ___ individual.

A

homozygous recessive

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14
Q

in a testcross, if the recessive phenotype appears in the progeny, the tested individual must be a ___

A

heterozygote (carrier)

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15
Q

lines can only produce one gamete type, no matter how many genes or traits are under consideration.

A

“True-breeding”

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16
Q

an individual that is heterozygous for two genes is known as

A

dihybrid

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17
Q

used to predict the frequency with which two independent events will occur simultaneously.
3/4 x 3/4 = 9/16

A

Product law

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18
Q

a mendelian ratio, typical of the F2 generation of dihybrid cross

A

9:3:3:1

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19
Q

the expected ___ phenotypic ratio holds true for each individual trait

A

3:1

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20
Q

What is Mendel’s fourth postulate?

A

Independent assortment

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21
Q

What is the probability that an F2 plant with round yellow seeds has the genotype GgWw?

A

4/9

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22
Q

Summarize Mendel’s work:

  • Inheritance is ___, not blending
  • Inheritance is controlled by _____ ____
  • Mendel’s four postulates
A

particular; discrete factors (genes)

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23
Q

What is the Mendelian ratio for monohybrid selfcross (AaxAa)?

A

1:2:1 genotypic ratio
3:1 phenotypic ratio

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24
Q

What is the Mendelian ratio for monohybrid testcross (Aaxaa)?

A

1:1 genotypic ratio
1:1 phenotypic ratio

25
Q

What is the Mendelian ratio for dihybrid selfcross (AaBbxAaBb)?

A

9:3:3:1 phenotypic ratio

26
Q

What is the Mendelian ratio for dihybrid testcross (AaBbxaabb)?

A

1:1:1:1 genotypic ratio
1:1:1:1 phenotypic ratio

27
Q
  • The molecular nature of genes and alleles
  • The biochemical roles of gene products (RNA and protein)
  • The cytological behavior of chromosomes during meiosis
A

What created the Mendelian principles?

28
Q

monohybrids can produce ___ gamete types

A

two
Aa –> A & a

29
Q

dihybrids can produce ___ gamete types

A

four
AaBb –> AB, Ab, aB, ab

30
Q

How many different gamete types can a trihybrid (AaBbCc) individual produce?

A

8

31
Q

Gametes are morphologically indistinuisghable, but are often divided into mating types (a and alpha in yeast, + and - in Chlamydomonas)

A

isogamy

32
Q

Gametes are morphologically distinct (usually different size); the individual that produces larger gametes is “female”, the smaller gametes come from the “male”

A

anisogamy (or heterogamy)

33
Q

One of a variety of mechanisms which controls whether an embryo (or individual cell) will display male or female sexual characteristics

A

sex determination

34
Q

Sex is determined genetically, by the chromosome or gene composition of a cell or organism

A

genotypic sex determination (GSD)

35
Q

Sex is determined by environmental conditions encountered during an organism’s development (temperature, day length, proximity of conspecifics, etc)

A

environmental sex determination (ESD)

36
Q

A chromosome that exhibits sex-specific differences in individuals of the same species (eg. human X and Y chromosomes)

A

sex chromosome

37
Q

Any chromosome that is not a sex chromosome (eg. human chromosomes 1-22)

A

autosome

38
Q

In organisms with GSD, the sex in which both sex chromosomes are the same (females in humans)

A

homogametic sex

39
Q

In organisms with GSD, the sex which has two different sex chromosomes (males in humans)

A

heterogametic sex

40
Q

What is the sex determination of birds?

A

GSD
ZW = female
ZZ = male

41
Q

What is the sex determination of crocodilians?

A

ESD
low/high temp = female
intermediate temp = male

42
Q

sex determination of Drosophila?

A

GSD
XX = female
XY = male

43
Q
  • Haplodiploidy
  • No sex chromosomes
  • Females are diploid
  • Males are haploid
A

sex determination of bees

44
Q

What is the name of the group where sex is determined by the number of chromosome sets?

A

Hymenopterans (bees, ants, wasps)

45
Q

The ratio of X chromosomes to sets of autosomes determines sex.
- This is known as the “X to autosome” or “X to A” (X:A) ratio.
- X = number of X chromosomes
- A = number of haploid sets of autosomes (normally, 2)

A

sex determination in drosophila

46
Q

sex-determining region Y (___) is a gene on the Y chromosome that initiates “male” development

A

SRY

47
Q

What does SRY encode for?

A

Testis determining factor (TDF) which is a key regulator of male-specific gene expression

48
Q

________ mutations in SRY can promote female development in XY individuals

A

loss of function

49
Q

______ of SRY can promote male development in XX individuals

A

Translocation of SRY (transfer to a different chromosome)

50
Q

XXY = __
X0 = ___

A

Klinefelter syndrome (male); Turner syndrome (female)

51
Q
  • X:A chromosome ratio determines sex
  • Y-chromosome is not involved in sex determination
  • Y-chromosome is required for male fertility
A

Drosophila

52
Q

SRY gene (sex determining region Y) on the Y chromosome determines maleness

A

Human

53
Q

in flies and mammals, males and females have different numbers of copies (“doses”) of X-linked genes
- males have __ copy
- females have __ copy

A

dosage compensation

one; two

54
Q

What happens to inactivated X chromosomes?

A

They condense into Barr bodies

55
Q

What is the equation to find the number of Barr bodies?

A

Barr bodies = (X chromosomes -1) in either sex

56
Q
  • Either the maternal or paternal X chromosomes in inactivated in each cell
  • Inactivation occurs randomly in early embryos
  • X-inactivation is heritable through mitosis (the same X chromosome will be inactive in all daughter cells)
  • X-inactivation is rest (erased) during meiosis
A

the Lyon hypothesis

57
Q

intact X chromosomes which are highly condensed and transcriptionally repressed

A

Barr bodies

58
Q

if a male is hemizygous for a recessive allele, he will display the ___ phenotype

A

recessive

Genetics (17 decks)

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