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Worcester Sixth Biology 101 > Inheritance > Flashcards

Inheritance Flashcards

1
Q

What is a Genome?

A

complete set of chromosomes of an organism. usually a copy of each cell

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2
Q

What is an allele?

A

A variant nucleotide sequence for a particular gene at a given locus which codes for a different phenotype, same gene - different types

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3
Q

What is the locus?

A

specific location of a gene on a chromosome

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4
Q

What is a gene?

A

sequence of DNA which codes for a protein

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5
Q

What is a genotype?

A

All the alleles an individual has

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6
Q

What does homozygous mean?

A

both alleles are the same for a particular gene from both parents

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7
Q

What does heterozygous mean?

A

different alleles for a particular gene from each parent

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8
Q

what is a phenotype?

A

visible characteristics, gene/allele that codes for the outward expression of a genotype in a specific environment

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9
Q

what does dominant mean (genetics)?

A

allele always expressed when present

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10
Q

What does recessive mean (genetics)?

A

allele only expressed when homozygous, not expressed in presence of dominant allele

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11
Q

What are the properties of continuous variation?

A

Is a measurement, has a scale

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12
Q

What are the properties of discontinuous variation?

A

is categorical

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13
Q

What are some examples of continuous variation?

A

height, weight etc.

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14
Q

What are some examples of discontinuous variation?

A

Hair colour, blood type etc.

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15
Q

How can continuous variation be represented?

A

on a line graph

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16
Q

How can discontinuous variation be represented?

A

Bar graph

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17
Q

What is continuous variation controlled by?

A

lots of genes and environment - range of phenotypes between 2 extremes, like height in humans

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18
Q

what is discontinuous variation controlled by?

A

a few genes - limited number of phenotypes with no intermediates. like A, B, AB, O blood groups in humans

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19
Q

If both parents are heterozygous for brown eyes (Bb) what would the offspring look like?

A

25% homozygous brown (BB), 50% heterozygous brown (Bb). 25% homozygous blue (bb)

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20
Q

How could you check to see if an organism is heterozygous or homozygous for a dominant characteristic?

A

test cross/ back cross

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21
Q

What is test crossing? + results?

A

crossing of an unknown individual representing dominant trait with individual representing recessive phenotype. If any of the offspring express the recessive trait then the dominant parent must be a heterozygous dominant allele.

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22
Q

What is co-dominance?

A

in heterozygous - some cells express dominant allele other cells express recessive allele e.g. holstein friesian cattle (black and white patched cows)

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23
Q

What is incomplete dominance?

A

in heterozygous - intermediate between the recessive and dominant allele e.g. Palamino horses (linked with chestnut (brown) and cremello (white) horses)

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24
Q

What is monohybrid inheritance?

A

the inheritance of the alleles of a single gene, 2 different alleles, dominant one represents characteristic

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25
Q

What is a genetic diagram?

A

shows how characteristics are inherited, phenotype and genotype of parents, gametes, and ratio of offspring

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26
Q

What does F1 mean?

A

First Filial Generation (filial is the offspring of a cross)

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27
Q

What is dihybrid inheritance?

A

simultaneous inheritance of 2 unlinked genes

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28
Q

What did Mendel explore to do with dihybrid inheritance?

A

relationship of peas, as to whether they were round or wrinkled, yellow or green

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29
Q

What ratios did Mendel discover between round(R) yellow(Y) wrinkled(r) and green(y)?

A

RY:Ry:rY:ry 9:3:3:1

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30
Q

What is Mendel’s law of segregation?

A

the characteristics of an organism are determined by factors (alelles) which occur in pairs, only one of the pair is present in each gamete.
Each member of a pair of alleles may combine randomly with either of a another pair on a different chromosome

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31
Q

What is Mendel’s law of independent assortment?

A

the alleles of two (or more) different genes get sorted into gametes independently of one another
segregation of alleles for one gene into different gametes is independent to any other gene

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32
Q

What is Mendel’s law of dominance?

A

recessive alleles will be masked by dominant alleles (not so for co-dominance or incomplete dominance

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33
Q

What is independent assortment?

A

Genes which are unliked can combine with any alleles in gametes. genes for different traits are inherited independently of each other. e.g. eye colour and eye shape

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34
Q

What is a dihybrid test cross?

A

test for genotype of parent for 2 different features by crossing with recessive organism for both features (it will outwardly express this characteristic)

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35
Q

What is the purpose of the Chi-sqaured test?

A

test for statistical difference in the numbers of offspring expressing specific characteristics

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36
Q

What is the null hypothesis?

A

‘there is no significant difference between the observed and expected values’

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37
Q

What is a pedigree diagram?

A

‘family trees’ way of graphically illustrating inheritance patterns over a number of generations (commonly used to study inheritance of genetic disorders)

38
Q

what is linkage?

A

genes on same chromosome are inherited together

39
Q

what can crossing over do?

A

may separate genes and produce new combination of alleles (it is rare)

40
Q

What is the parental genotype?

A

no crossing over, only copy of one parents genotype, alleles on the chromosome.

41
Q

What is the recombinant genotype?

A

only happens if crossing over occurs, contains alleles from both parents, is a new genotype

42
Q

What are angiosperms? what is there determination of sex?

A

flowering plants, they are hermaphrodites so have both sexual organs

43
Q

How do plants prevent self fertilisation?

A

stigma is hidden or less accessible by chance, stigma and anthers mature at different times

44
Q

What are some examples of lower phylum hermaphrodites?

A

garden snail
worms

45
Q

What is sexual dimorphism?

A

a distinct difference in size or appearance between sexes in addition to sexual organs themselves

46
Q

How is human sex determined?

A

by chromosomes
XX and XY

47
Q

What is sequential hermaphroditism?

A

limpets in pile, fertilise the female at bottom of chain, they move away, then next limpet becomes female to be fertilised

48
Q

How is sex determined within bees?

A

by their ploidy level
unfertilised eggs are haploid and become male drones
fertilised eggs are diploid and become female workers

49
Q

How is sex determined in turtles?

A

temperature of eggs can turn on and off genes for sex

50
Q

How is siamese cat affected by temperature?

A

if in colder place the extremeties will have gene for melanin turned on, so will result in black paws, tail, ears and face. if it is warmer it will be turned off and result in more white cat.

51
Q

How is sex determined in clown fish?

A

Dominant Female and Dominant Male supress breeding of others in the group. If dominant female dies or leaves, dominant male with take over this place. becoming a female.
eggs produce male or female offspring

52
Q

What gene controls inheritance of Y chromosome?

A

SRY gene

53
Q

What is klinefelter syndrome?

A

1/500 males are XXY 1/18000 males are XXYY

54
Q

What can happen to Y chromosome in men? why?

A

they can lose Y chromosome with increasing age
other factors that increase it:
smoking
alcohol consumption

55
Q

SRY gene on Y chromosome codes for what?

A

everything male, (testes male genitalia in embryo

56
Q

What can a mutation in SRY lead to in XY genotype?

A

female genitalia despite XY genotype

57
Q

What is the difference between X chromosome on males and females regarding inheritance?

A

alleles on X chromosome in female can either be dominant or recessive depending on expression
alleles on X chromosome in males will be expressed regardless of dominance

58
Q

What is haemophilia?

A

An inherited disorder in which the blood does not clot due to insufficient clotting factors

59
Q

What chromosome is haemophilia carried on?

A

X

60
Q

What represents a normal allele in haemophilia?

A

X^H

61
Q

What represents a mutated allele in haemophilia?

A

X^h

62
Q

How many possible genotypes are there in males? what are they? for haemophilia

A

2
X^HY
X^hY

63
Q

What does the genotype X^HY mean?

A

Male with blood that clots normally

64
Q

What does the genotype X^h mean?

A

Male with haemophilia

65
Q

How many different genotypes are the of haemophilia in females? what are they?

A

3
X^HX^H
X^HX^h
X^hX^h

66
Q

What does the genotype X^HX^H mean?

A

homozygous dominant blood clots normally

67
Q

What does the genotype X^HX^h mean?

A

heterozygous blood clots normally, this person is a carrier of haemophilia (but is not affected)

68
Q

What does genotype X^hX^h mean?

A

homozygous recessive, person has haemophilia

69
Q

Is haemophilia more prevalent in males or females? why?

A

males
as only needs one mutant allele to be affected

70
Q

What are is Duchenne Muscular Dystrophy (DMD)?

A

An inherited disorder characterised by progressive muscular weakness

71
Q

What are the affects on a child with DMD ages 5-7 years?

A

motor delay
enlarged calves
toe walking
standing from supine, climbing stairs more difficult

72
Q

What are the affects on a child with DMD ages 8-11 years?

A

increasing loss of walking ability
part time wheelchair use

73
Q

What are the affects on early teens with DMD?

A

loss of ambulation
full-time wheelchair use
increasing loss of upper limb function

74
Q

What are the affects on teens with DMD?

A

increasing respiratory impairment
ventilation support often required
unable to perform activities of daily living

75
Q

What are the affects of DMD on teens to twenties?

A

increasing cardiac dysfunction
heart failure
death

76
Q

How is DMD inherited compared with haemophilia?

A

in the same way

77
Q

What 3 things are gene expression influenced by?

A

physiological effects of the environment
differences in DNA nucleotide sequences
Epigenetic modifications

78
Q

Give 2 examples of a physiological effect of the environment and what it affects?

A

light intensity affects plant growth
temperature dependent albinos - melanin produced when cold from enzyme tyrosenase e.g. Siamese cat, can give extremities black fur like ears, face, paws

79
Q

What is an epigenetic modification?

A

environment altering expression of genes by affecting how they are transcribed, without changing sequence

80
Q

How do epigenetics work?

A

they are heritable changes in the gene function
do not change DNA sequence

81
Q

What are the 2 types of epigenetics?

A

Post-replication methylation
Histone modification

82
Q

What is DNA methylation?

A

the addition of methyl groups to DNA sequence

83
Q

What happens if there are many methyl groups on a DNA strand?

A

there will be less transcription

84
Q

Application: If tumour suppressor gene was heavily methylated what would happen?

A

It would be less likely to be transcribed, less proteins coding for tumour suppressor gene, leading to a higher chance of tumour growth

85
Q

What are histones?

A

proteins that provide structural support for a chromosome

86
Q

where are histones found?

A

nucleus

87
Q

What are the functions of histones?

A

Histones bind to DNA, help give chromosomes their shape, help control the activity of genes

88
Q

What are some examples of histone modification?

A

acetyl group to lysine
methyl group to lysine to argnine

89
Q

In Histone modification what does unmodified mean?

A

nucleosomes pack tightly = transcription reduced

90
Q

In Histone modification what does modified mean?

A

nucleosomes uncoil = transcription increased

Worcester Sixth Biology 101 (31 decks)

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