Genetics Flashcards

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1
Q

Hereditary

A

the passing of traits from parent to offspring

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2
Q

Genetics

A

branch of biology that studies the ways in which hereditary info is passed from parents to offspring

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3
Q

Gregor Mendel

A

monk who began the study of hereditary by carrying out experiments using pea plants

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4
Q

Why were peas useful to study?

A

Several traits of the peas only existed in two forms, mating can be easily controlled, and peas grow easily/mature fast/produce many offspring

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5
Q

Why can pea mating be easily controlled?

A

The female and male parts are enclosed within the same flower

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6
Q

How do flowers (peas) fertilize?

A

Either self fertilize or cross pollination

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7
Q

what is cross pollination?

A

transferring the pollen from one plant to another flower on a different plant

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8
Q

monohybrid cross

A

studies inheritance of only one pair of contrasting traits

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9
Q

What did Mendel begin his experiments by using?

A

a monohybrid cross

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10
Q

True breeding plant

A

Only produces offspring of the same type

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11
Q

What did Mendel do to ensure that each plant was true breeding?

A

He allowed each plant to self pollinate for several generations

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12
Q

What is the P generation?

A

The parental generation, or the true breeding plants that produce more of themselves

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13
Q

What was the F1 generation?

A

The first filial generation

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14
Q

What did the F1 generation result from?

A

Cross pollination of the two, different, P generation plants (by Mendel)

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15
Q

What happened to the F1 generation?

A

They were allowed to self pollinate, resulting in the F2 generation

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16
Q

What were Mendel’s results with the F1 generation?

A

They all had only one trait. In this example, all the flowers were purple-the white trait had disappeared.

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17
Q

What were Mendel’s results with the F2 generation?

A

The missing trait had reappeared. (705 purple:224 white) (3.15:1)

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18
Q

What did Mendel’s experiment prove instead?

A

Peas (and humans) have separate heritable factors for each trait, one from each parent.

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19
Q

What did Mendel disprove with his experiments?

A

Scientific belief that an offspring’s traits were a blend of the parents.

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20
Q

What are the separate heritable factors for each trait called?

A

Genes.

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21
Q

How many copies of a gene does an individual have, and where do they get them according to Mendel’s Hypotheses?

A

An individual has two copies of every gene, one from each parent

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22
Q

What are alleles?

A

Alternative versions/copies of the same gene

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23
Q

What is the example of an allele in relation to Mendel’s experiment?

A

Purple vs white flowers

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24
Q

What happens when there are two different alleles in an organism?

A

Only one will be expressed

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25
Q

What is a dominant allele?

A

Observable/expressed

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26
Q

What is a recessive allele?

A

Trait that isn’t expressed in presence of dominant

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27
Q

Which alleles (dominant v. recessive) were present in Mendel’s experiments?

A

One dominant, one recessive

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28
Q

Did Mendel’s hypotheses include alleles and dominance?

A

Yes

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29
Q

Gametes formed by meiosis have how many alleles for each trait? Was this mentioned in Mendel’s experiments?

A

Only one, and yes

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30
Q

What happens to the alleles when gametes unite in fertilization?

A

Each gamete contributes one allele, their allele

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31
Q

How are dominant alleles represented?

A

Write the first letter of trait as capital

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32
Q

How are recessive alleles represented?

A

First letter of dominant trait, but lowercase

33
Q

Homozygous

A

Individuals that have two alleles for the same trait

34
Q

Heterozygous

A

Individuals that have two different alleles

35
Q

Which allele is expressed in heterozygous individuals?

A

Dominant

36
Q

Phenotype

A

Appearance

37
Q

Genotype

A

Alleles an individual has

38
Q

What is the law of segregation?

A

Two alleles separate from one another when gametes are formed

39
Q

What does the law of segregation explain?

A

the behavior of chromosomes during meiosis

40
Q

What are the laws of heredity?

A

The law of segregation, law of independent assortment

41
Q

What did Mendel do after studying monohybrid crosses

A

He investigated whether the inheritance of one trait (like flower color) affected inheritance of a different trait (like plant height)

42
Q

How did Mendel investigate whether inheritance of certain traits were linked?

A

He experimented with dihybrid crosses

43
Q

What are dihybrid crosses?

A

Crosses that consider 2 pairs of contrasting traits

44
Q

What is the law of independent assortment?

A

The inheritance of one trait does not influence others bc the alleles of different genes separate independently from one another during gamete formation

45
Q

Test cross

A

an individual whose phenotype is dominant but genotype is unknown is crossed w/ a homozygous recessive individual

46
Q

Why would one use a test cross?

A

To know whether an organism w/ a dominant phenotype is heterozygous or homozygous for a trait

47
Q

How do the results of a test cross exemplify the answer?

A

If all offspring exhibit this dominant phenotype, the genotype must be homozygous for that allele. If half offspring exhibit both phenotypes, it must be heterozygous.

48
Q

Incomplete dominance

A

The inheritance of a dominant trait and a recessive trait results in a blending of traits that isn’t exactly like either parent

49
Q

Codominance

A

two dominant traits, both visible

50
Q

How is codominance often represented?

A

Capital letters w/ superscripts

51
Q

How is codominance found in humans?

A

Blood type-AB

52
Q

Multiple Alleles

A

more than 2 possible alleles for a certain trait (individual only inherits two possibilities)

53
Q

Multiple Alleles-blood type

A

3 different alleles for blood, a, b, and o, but you can only have 2

54
Q

What do the A and B alleles code for?

A

the presence of certain markers on the surface of red blood cells

55
Q

What does the O allele code for?

A

No markers

56
Q

Which blood type alleles are dominant?

A

A, B

57
Q

Which blood type alleles are recessive?

A

O

58
Q

How does AB phenotype occur?

A

If both A and B alleles are present, since they’re codominant

59
Q

Setting up Punnett Square-dihybrid crosses

A
  1. determine genotype of parents
  2. determine possible gametes
  3. write these gametes on the top and left of a 16sq punnett square
  4. complete the punnett square
60
Q

What is an autosome?

A

A non-sex chromosome

61
Q

Autosomal trait

A

A trait located on an autosome

62
Q

Sex-linked/X-linked trait

A

trait whose allele is located on the X chromosome

63
Q

Will a male who carries the recessive allele on his X chromosome exhibit the condition?

A

Yes, bc he only has one X

64
Q

Will a female who carries the recessive allele on one of her chromosome exhibit the condition?

A

No, only if it is on both X chromosomes. Otherwise, she will just carry it.

65
Q

How can you learn about the chances of passing down a trait within your own family?

A

A pedigree

66
Q

Pedigree

A

family history constructed by geneticists that shows how a trait is inherited over several generations

67
Q

In what case might a pedigree be helpful?

A

If the trait is a genetic disorder and the family members want to know if they are carriers, or if their children can get the disorder

68
Q

How to tell by a pedigree if a trait is autosomal or sex linked?

A

Sex linked usually appears in more males

69
Q

How to tell by a pedigree if a trait is dominant or recessive?

A

Dominance will appear in every generation (usually) while recessive can appear in one, then skip a generation, then appear in a later generation

70
Q

How to tell by a pedigree if a trait is homozygous or heterozygous?

A

If the phenotype shows the dominant allele, genotype must be homozygous dominant or heterozygous. If phenotype is recessive, genotype must be homozygous recessive.

71
Q

Blood type O

A

ii

72
Q

Blood type A

A

IAi or IAIA

73
Q

Blood type B

A

IBi or IBIB

74
Q

What is blood type AB

A

IAIB

75
Q

What is dominance in blood type?

A

A and B over O, codominance together

76
Q

Polygenic trait

A

Trait influenced by several genes

77
Q

Where can polygenic traits be located?

A

Same chromosome or different chromosomes

78
Q

Why do many different polygenic combinations occur in offspring?

A

Independent assortment, crossing over

79
Q

What can an individual’s phenotype also depend on?

A

Environmental conditions