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General Biology 1 > Genetics > Flashcards

Genetics Flashcards

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1
Q

Give an exemple of a character and a trait that applies.

A

Character: eye color, skin color, height, etc.
Traits (eye color):blue, green, brown, etc.
traits (skin color): brown, tanned, white, etc.
traits (height): tall, short, average, etc.

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2
Q

What does true-breeding mean?

A

Individuals that have 2 copies of the same allele, meaning homozygous

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3
Q

What is the name of the original generation?

A

Parental generation

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4
Q

For the Mendel experiment the parental generation have to be pure. What is another word for pure?

A

True-breeding

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5
Q

Why does the parental generation need to be true-breeding?

A

Because we want a first filial generation that completely has both recessive and dominant allele for the experiment to prove useful

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6
Q

What is the name of the generations that come after the parental generation?

A

(First, second, third, etc.) Filial generation

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7
Q

What is a monohybrid cross?

A

involves the dominant and recessive trait from the same character crossing together

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8
Q

What is the genotype ratio of the F2 generation in Mendel’s experiment?

A

3:1

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9
Q

What is the particulate theory?

A

It is the process in which the discrete particles that are responsible for inheritance (existing in pairs) seperate during gamete formation

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10
Q

What is a gene?

A

It is Mendel’s unit of inheritance (a characteristic)

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11
Q

What are alleles?

A

They characterize the gene. An alternative form/a variation of the gene.

Ex.: Gene: the color of the eyes
Allele: blue, brown, green, etc.

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12
Q

What does homozygous mean?

A

Having two copies of the same allele

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13
Q

What does heterozygous mean?

A

Combination of two different alleles

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14
Q

What is a genotype?

A

Composition of the organisms’ alleles for a gene (combination of allele ex.:SS)

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15
Q

What is a phenotype?

A

The physical appearance of the organism

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16
Q

What is Mendel’s first law? Explain.

A

The law of segregation: 2 alleles separate when an individual makes gametes

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17
Q

What is the specific location of a gene?

A

The locus

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18
Q

What is the meiotic interphase?

A

The homologous chromosomes duplicate

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19
Q

What is meiosis I?

A

2 chromosomes are separated into 2 daughter cells

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20
Q

What happens in meiosis II?

A

The 2 daughter cells each divide in two (meaning 4 gametes at the end). Each gamete is haploid

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21
Q

What is Mendel’s second law?

A

The law of independent assortment: alleles of different genes (ex.: Ss and Yy) assort into gametes independently from each other

22
Q

How do you calculate the probabilities of the outcome of dihybrid crosses (ex. SSYy)?

A

Multiply the outcomes from each of the individual monohybrid components. Do a Punnet scare to find the possible allelic combination.

An F1 (dihybrid) cross of SsYy generates
1/4 SS, 1/Ss, 1/4 ss, and 1/4 YY, 1/2 Yy, 1/4 yy.

The probability of the SSYy genotype is the probability of SS genotype (1/4), times the probability of the Yy genotype (1/2), which is 1/8 (1/4 x 1/2 = 1/8)

23
Q

How is human genetics studied?

A

By using pedigrees (not very accurate)

24
Q

What is autosomal dominant inheritance?

A

It is a pedigree analysis of the dominant allele for a given phenotype that:

  • Every affected person has an affected parent
  • About half of the offspring of an affected person are also affected (assuming only one parent is affected
  • The phenotype occurs equally in both sexes
25
Q

What is autosomal recessive inheritance?

A

It is a pedigree analysis of the dominant allele for a given phenotype that:

  • If neither parent has a given phenotype, but it shows up in their progeny, the trait is recessive and the parents are heterozygous
    -Half of the children from such a cross will be carriers (heterozygous for the trait)
  • The chance of any one child’s getting the trait is 1/4
26
Q

What is the most common type of allele in a population?

A

The wild type (seen more often than mutant allele)

27
Q

What is incomplete dominance?

A

When heterozygotes show intermediate phenotype, which might seem to support the blending theory

Ex.:
RR (red) and rr (white) are the parents
F1: are all pink (Rr) because the red (RR), the dominant allele is incompletely dominant
When the F1 generation interbreeds
F2: 1/2 pink, 1/4 red, 1/4 white

28
Q

What is codominance?

A

When 2 different alleles for a gene are both expressed in the heterozygotes

Ex.: In the human ABO blood group system the alleles for blood types are A, B, and O.
- AA or AO, results in type A.
- BB or BO, results in type B.
- OO results in type O.
- AB results in type AB. The alleles are called codominant.

29
Q

What is pleiotropy?

A

Single alleles that have more than one distinguishable phenotypic effect

30
Q

Pleiotropy is caused by different proteins produced by the same allele. True or False. Explain.

A

False, it is caused by the same proteins produced by the same allele

31
Q

What is episatsis?

A

When the alleles of one gene cover up or alter the expression of alleles of another gene

32
Q

What are complementary genes?

A

It is another form of epistasis in which two genes are mutually dependent; the expression of each depends on the alleles of the other.

33
Q

What is polygenic inheritance/quantitative trait loci?

A

A group of several genes that control complex inherited characteristics. Since there is constent variations in these characteristics.

34
Q

What usual factors cause variations in alleles?

A
  1. Multiple genes with multiple alleles (polygenes)
  2. Environmental influences on the expression of the genes
35
Q

What is a factor that increases or decreases the likelihood of recombination? Explain how that factor affects recombination.

A

The distance between the genes affect recombination.

  • Genes close to each other, usually stay together
  • Genes that are far from each other, more likely to separate during recombination
36
Q

What is recombinant frequency?

A

It’s the frequency that measures how often 2 genes are separated by crossing over during meiosis

37
Q

What is chiasma?

A

The physical space in which the cross-over happens

38
Q

What are genetic maps for?

A

Show the arrangement of genes along the chromosome

39
Q

How genetic maps ususally made?

A

By using recombination frequency which help to find the distance between genes on a same chromosome.

40
Q

What are the units of the distances between genes?

A

Map units
1 mu= centimorgan (cM)= 1%=0.01

41
Q

How is the map distance between 2 genes calculated?

A

Separate the parental types from the recombinants type
Find the recombinant frequency

Recombinant frequency = (nb. recombinant type A +nb. recombinant type B)/nb. total of individuals in the progeny

Then find the map distance
map distance= 100 x recombinant frequency

42
Q

What determines the sex of an offspring?

A

The sperm

43
Q

What is Turner Syndrome and its effect?

A

It is a syndrome characterised by the XO condition. It results in females who are physically abnormal but mentally normal and usually sterile.

44
Q

What is Klinefelter syndrome and its effects?

A

Is characterized by an XXY condition and results in males who are taller than average and always sterile

45
Q

What is SRY and what happens if it’s missing? What does it do?

A

The maleness-determining gene and if it’s missing the individual will be phenotypically a female.

SRY (sex determining region) gene codes for a functional protein. If this protein is present, testes develop.

46
Q

What is DAX1?

A

It is a gene on the X chromosome that produces anti-testis factor

47
Q

What is hemizygous and who are hemizygous?

A

It is when an individual has only one copy of a gene

All males are.

48
Q

Why are males hemizygous?

A

Y chromosomes carry very few genes. It doesn’t have all the genes in the X chromosome

49
Q

What are carriers?

A

Carry the X chromosome with a mutation but does not have it

50
Q

What is X-linked recessive?

A

A pedigree analysis show that:

-The phenotype appears much more often in males than in females
-A male with the mutation can pass it only to his daughters
- Daughters who receive one mutant X are heterozygous carriers
-The mutant phenotype can skip a generation if mutation is passed from male to his daughter and then to her son

51
Q

What is an X-linked dominant phenotype?

A

A pedigree analysis shows that:

  • The trait is never passed from father to son
  • All the daughters of an affected male and a normal female are affected
  • Matings of affected females and normal males produce 1/2 the sons affected and 1/2 the daughters are affected
52
Q

What is mitochondrial (maternal) inheritance?

A

Only passed down by the mother since the egg is the only gamete that can contain cytoplasm and organelles

A pedigree analysis shows that:

  • An affected mother passes the trait to all her children
  • An affected father passes the trait to none of the children

General Biology 1 (11 decks)

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