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Flashcards in Mendellian Genetics Deck (88)
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1
Q

formula for determining # of unique gametes

A

2^# of heterozygotes

2
Q

linkage

A

the tendency of alleles of particular genes to be inherited togehter

3
Q

when is linkage seen?

A

when genes are on the same chromosome

4
Q

difference between linkage and sex-linkage

A

linkage refers to two or more genes that are located on the same chromosome

sex-linkage refers to a single gene that is located on a sex chromosome

5
Q

does sex-linkage indicate anything about location on a chromosome?

A

no

6
Q

recombinant

A

alleles on chromosome are different tan the parent combinations because of crossing over

7
Q

when does crossing over occur?

A

during prophase of meiosis I

8
Q

what happens when genes are located far apart on the same chromosome?

A

it is more likely that crossing over will occur someplace between these genes

9
Q

genetic map

A

a diagram showing the relative positions of genes along a particular chromosome

10
Q

when are linked genes not inherited together?

A

when crossing over occurs

11
Q

what is linkage an exception to?

A

Mendel’s principle of independent assortment

12
Q

multiple allelism

A

more than two alleles of the same gene

13
Q

example of multiple allelism

A

blood type

there are three alleles for blood type: A, B, i

14
Q

codominance

A

simultaneous expression of the phenotype associated with each of the alleles in a heterozygote

15
Q

example of codominance

A

the A and B alleles for blood type are codominant when together to form blood type AB

16
Q

incomplete dominance

A

hetereozyotes show a blend of the two alleles

17
Q

pleiotropic

A

a gene that influences many traits

18
Q

are dominant traits more common?

A

not necessarily

19
Q

is the wild type always dominant?

A

no

20
Q

Are genes the only thing that control traits?

A

no

the environment plays an important role in the development of certain phenotypes

21
Q

gene-gene interaction

A

two or more genes work together to determine a single trait

22
Q

discrete traits

A

traits that are clearly different from each other

this is what Mendel worked with

23
Q

quantitative traits

A

continuously varying traits

24
Q

example of quantitative trait

A

human height and intelligence

25
Q

how are quantitative traits produced?

A

the independent actions of MANY genes

26
Q

polygenic inheritance

A

each of many different genes adds a small amount to the value of the trait

this is how quantitative traits are produced

27
Q

central dogma

A

DNA - RNA - Protein

28
Q

wild type

A

an individual that does not have mutations under study

not always the dominant genotype

29
Q

the particle theory of inheritance

A

states that hereditary traits act like particles or units that are passed down from generation to generation

30
Q

Law of Segregation

A

hereditary factors do not blend, but keep distinct identity during breeding

maintain two distinct alleles that can be passed down. recessive alleles do not dissapear

31
Q

how is the law of segregation seen?

A

the separation of homologous chromosomes

1 allele from mom and 1 allele from dad separate

32
Q

when do homologous chromosomes split?

A

anaphase of meiosis I

33
Q

what is a real demonstation of the law of segregation?

A

true breeding

34
Q

Law of Independent Assortment

A

character traits are not connected but are inherited independently of one another (excludes linkage)

35
Q

how did Mendel determine the law of independent assortment?

A

performed a dihybrid cross of two traits

each trait was not dependent on other traits

36
Q

true breeding

A

two homozygotes for different alleles are crossed

37
Q

locus

A

particular site of chromosomal DNA where a gene resides

38
Q

what is the symbol for a female in a Punnett square?

A

circle

39
Q

mode of transmission

A

describes a trait as autosomal or sex-linked and the type of dominance of the allele

40
Q

pedigree characteristics of an autosomal recessive trait?

A

if the parents of an affected individual do not have the trait, than both of the parents must be carriers for the trait

41
Q

pedigree characteristics of an autosomal dominant trait?

A

any child with the trait must have a parent with the trait

this is because heterozygotes display the trait

42
Q

identifying sex-linked recessive traits

A

males express the trait in question more often than females

often skips a generation because an affected male passes his X-linked trait, but they get a WT from their mother. However, these daughters have 50% chance of passing an affected X to their son

43
Q

x-linked dominant trait example

A

rickets

44
Q

identifying x-linked dominant traits

A

an affected male passes the trait to all his daughters and none of his sons

he gives his X to the daughters and does not give it to the sons because they only have the Y

45
Q

What is baby superman an example of?

A

Incomplete dominance

his mother was a heterozygote who showed abnormal strength

46
Q

Baby superman disease

A

lacked myostatin protein

this is a protein that regulates / controls muscle growth through negative feedback

47
Q

Wild-type

A

an individual that does not have mutations in the allele under study

often the most common phenotypes observed in nature

48
Q

The Particle Theory of Inheritance

A

states that hereditary traits act like particles, units, or factors and they are passed from generation to generation

49
Q

law of segregation

A

hereditary factors do not blend, but stay distinct during breeding

keep a copy of the recessive allele that does not get blended with the dominant allele

50
Q

when does the law of segregation take place?

A

when homologous chromosomes separate during meiosis

51
Q

what demonstrates the law of segregation?

A

true breeding shows this in the second generation of heterozygotes

52
Q

true breeding

A

crossing homozygous individuals

53
Q

law of independent assortment

A

traits are not connected but are inherited independently of one another

54
Q

SsYy x SsYy ratio

A

9: 3: 3: 1

55
Q

test cross

A

determine if an individual with a dominant phenotype is heterozgyous or homozygous dominant by crossing with a homozygous recessive

56
Q

If genes are linked what is more likely to be seen in higher ratios?

A

the parental genotypes since recombination does not occur

57
Q

map unit

A

distance between genes

one map unit corresponds to a recombination frequency of 1%

58
Q

how to calculate map units

A

total # of recombinants / total # of progeny * 100

59
Q

Do recombination frequencies of 50% indicate linkage?

A

no

50% is approaching the 1:1:1:1 ratio which would indicate that linkage did not occur and all the phenotypes are observed with the same frequency

60
Q

why does incomplete dominance not support the blending theory?

A

recessive alleles maintain their own distinct identity and can reappear in later generations

61
Q

what is hemophilia an example of?

A

x-linked recessive disorder

62
Q

SNP

A

single-nucelotide polymorphisms

are DNA markers that can show genes that are linked to certain traits

63
Q

Why are SNPs used as genetic markers?

A

they are close to the gene of interest

64
Q

Polymorphous SNPs

A

if a SNP and a gene are physically very close linkage can occur between a version of a SNP and a specific allele

the type of SNP can indicate the allele when linked

65
Q

Why is linkage between SNPs and alleles never 100%?

A

no matter how physically close and linked the SNP and the allele are there is always a possibility that recombination can occur

66
Q

An example of a SNP that is linked to an allele

A

huntingtons

67
Q

cis- alleles

A

recessive alleles that are on the same chromosome

68
Q

trans- alleles

A

recessive alleles that are on different chromosomes

69
Q

aggulitination

A

clumping of blood

can indicate the ABO type

70
Q

Why does blood clump around certain antibodies?

A

type A blood makes B antibodies, so it will clump around the A antibody

71
Q

If a person’s blood clumps around the A antibody but not the B antibody what does this indicate?

A

that they have there body produces the B antibody and they have type A blood

72
Q

What antibodies do people with type O blood produce?

A

anti-A and anti-B

their blood does not clump around A or B antibodies

73
Q

What antibodies do people with type AB blood produce?

A

neither anti-A or anti-B

their blood clumps around A and B antibodies

74
Q

Complementation

A

two mutants can breed to restore the normal phenotypes if the mutation occurs on different genes

since both parents are recessive for different genes and dominant for the other, when they make they will produce individuals with heterozygous genotype and the dominant, “normal”, phenotype will be present

75
Q

What genotype must parents have for complementation to work?

A

homozygous recessive

76
Q

What is non-complementation indicated by?

A

-

77
Q

What is complementation indicated by?

A

+

78
Q

How to count the number of genes working together to produce a trait through complementation

A

group all individuals that complementation occurred between as one and leave individuals that complementation did not occur with on their own

count the number of groups and single individuals and that is the number of genes that are working together

79
Q

Why do mutations tend to be recessive?

A

it is improbable to get a working mutated version of a gene because so many things need to happen correctly

therefore, often times the working allele will be dominant by nature because the other version of the gene simply does not function

80
Q

PKU

A

an autosomal recessive disease that cannot convert phenylalanine to tyrosine

if left untreated mental diseases can occur

BUT, if placed on a low phenylananine diet an individual can not develop mental disease

this is an example of environment influencing phenotype

81
Q

What shows the Law of Independent Assortment?

A

dihybrid cross

the genes for different traits are not inherited together

82
Q

two-point testcross

A

heterozygous x homozygous recessive

83
Q

what does a two-point testcross indicate?

A

linkage

the 1:1:1:1 ratio will not be observed

84
Q

what type of disease is cystic fibrosis?

A

autosomal recessive

85
Q

What are the effects of Huntington’s disease?

A

motor disturbances that effect both voluntary and involuntary movement

86
Q

How can Huntington’s stay dominant?

A

it affects individuals after they reproduce

87
Q

What is an example of incomplete dominance?

A

sickle-cell anemia

heterozygotes will have a mix between some normal and some sickled red blood cells

88
Q

hemizygous

A

refers to males having X and Y chromosome

makes them more suspectible to X-linked recessive diseases