Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Human Biosciences > Genetics part 2 > Flashcards

Genetics part 2 Flashcards

1
Q

Overall basic timeline of meiosis?

A

Pre-meiotic S-phase (DNA is doubled), so each now each chromosome has 2 sister chromatids attached at centromere

Recombination (crossing over)

Meiosis I homolog segregation (homologous pairs are seperated)

Meiosis II, sister chromatid separation (seperates the pairs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What occurs in prophase I?

A

Chromosomes condense

Homologous pairs form

Forming a synaptonemal complex

Recombination occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What occurs in metaphase I?

A

Each pair of homologues (tetrad) line up at equator

Centromers don’t divide (unlike in mitosis)

Orientation of pairs is random with respect to one another (so can end up on either side of the equator)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What occurs in anaphase I?

A

Chromosomes, each with 2 chromatids move to separate poles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What occurs telophase I?

A

2 new daughter cells will each contain one of each chromosome, however the chromosomes still consist of 2 chromatids

So products are haploid, as there is only one of each chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What occurs in Metaphase II, then anphase II, then telophase II?

A

Individual chromosomes line up at metaphase plate

Centromers split, chromatids separate to opposite poles

Each daughter cell contains one chromosome of each type, so 4 daughter haploid cells are produced from the 2 haploid cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the genotype?

A

The combination of specific alleles that they carry

The alleles at the locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is phenotype?

A

Observable characteristics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is an allele?

A

Alternate forms of a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What’s a homozygote?

A

Identical, eg YY, or yy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What’s a heterozygote?

A

Different, eg. Yy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What’s a gene?

A

Basic unit of biological information, specific segment of DNA that encodes a protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What’s it called if we look at 2 genes instead of 1?

A

Dihybrid cross

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do you find the gametes in a dihybrid cross?

A

If parents are Aa, and Bb

Gametes will be, AB, Ab, aB, ab

Due to independent assortment during metaphase I, they line up on potentially different sides of the equator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What ratio does a dihybrid cross produce, when both parents are heterozygous (F1)?

A

9:3:3:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In diploids wild type alleles are normally?

A

Dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

In diploids mutant alleles are normally?

A

Recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What’s incomplete dominance?

A

When heterozygoes shown an intermediate phenotype, eg red x white = pink

Genotypic ratio = phenotypic ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is Co-dominance?

A

Where heterozygoes show phenotype of both alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are multiple alleles?

A

When there are more than 2 alleles for a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is pleiotropy?

A

Where one gene contributes to more than one trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What’s an example of the complications of dominance and pleiotropy?

A

Sickle-cell syndrome

Normal - no symptoms

Carrier - Some symptoms, not affected by malaria

Diseased - all symptoms, not affected by malaria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What can gene combinations cause?

A

Novel phenotypes, a new unique apperance the parents didn’t have

Alleles of one gene can mask effects of alleles at another gene (epistasis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How to see of mutants are mutants in the same gene?

A

If breed them together and all offspring show mutant trait, then they are

If they aren’y won’t get the mutant trait = complementation, genes have helped each other as one set is recessive in each

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is penetrance?

A

Measures the percent of individuals with a given genotype who exhibit the phenotype associated with the genotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is expressivity?

A

Measures the extent to which a given genotype is expressed at the phenotypic level

(large variety of possible phenotypes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What’s linkage?

A

When have both genes on same chromosome so when you segregate will only get 2 gametes

Unless recombination occurs between the genes during meiosis 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What’s a testcross?

A

When you cross the F1 with a double recessive to find out the gametes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does a greater number of parental offspring suggest?

A

Linkage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Describe an example of a testcross

A

So will have 2 genes eg. Pl pl (on the same chromosome) crossed with a testcross pp ll

On the Pl pl, there will be occassional crossing over meaning instead of just getting the parental genotypes (PL and pl), can get the recombinant genotypes (Pl and pL)

The recombinant ones will occur a lot less frequently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What’s a linkage map?

A

Measure the frequency of recombination between 2 genes on the same chromosome will represent the distance between them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is one genetic map unit?

A

The distance between genes per 1% of recombinance = centimorgans (cM)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Are genetic maps linear and additive (can work distances out from other ones?)

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How to map chromosomes?

A

Count the parental types and recombinant types Between 2 of the genes that you want to find out distance and see if they are linked or not

Work out frequency of recombinants (add them all together), and found out the map units by dividing this by the total amount of offspring (only of the 2 genes you are looking at), if it’s bellow 50 by a lot then they are linked, if it’s around 50 they will be unlinked

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What do getting the 3 classes of offspring tell you from a triple cross (common, uncommon and rare)?

A

All 3 genes are linked

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Sometimes gene map units don’t add up to equal distances how come?

A

Most common is parental type

Least common is double recombinant type

Double recombinants need to be counted in twice as crossing over has occurred twice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Feature of independent segregation of alleles on DIFFERENT chromosomes?

A

Equally likely to get the 4 gametes

eg. Ac, aC, AC, ac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Organisms with multiples of the basic chromosome set, are referred to as?

A

Euploid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What does haploid mean?

A

Only has one chromosome set, but is part of a life cycle phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What’s a diploid organism?

A

Has 2 chromosome sets, one from each parent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What does monoploid mean?

A

Only has one chromosome set, but isn’t a part of the life cycle, and the rest of the species are diploid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

How do cells end up with more or less chromosomes?

A

Non-disjunction

During meoisis 1, if the chromosomes don’t segregate correctly (too many go to one pole)

All offspring will be abnormal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Why does having extra chromosomes affect the phenotype?

A

Gene balance - genes have evolved to function in a diploid genetic background and disrupting that background disrupts their function.

Expression of deleterious alleles on monosomic autosomes, because now we only have one allele it can’t be hidden by the dominant allele

Normally leads to death, but can be tolerated in sex chromosomes to a certain degree

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What are autosomes?

A

Non sex chromosomes (not X or Y)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What sex chromosomes do males have, and what do females have?

A 
Males = XY (heterogametic)
Females = XX
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Features of the Y chromosome?

A

It pairs with X chromosome, and determines maleness (SRY gene)

Very few genes, a mostly repeated series, and very small compared to X

Inheritance father to son

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Features of the X chromosome?

A

Has many genes unrelated to ses-determination or sex function

Males are hemizygous for X linked genes (effectively dominant as single copy, nothing to cancel it out)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What prevents X-chromosome gene dosage differences having significant effect (the amount of X chromosomes, eg. XXY, XY, XX, XO, XXX

A

In female mammals all but one X chromosome is epigenetically inactive in early development = lyonisation

They are condensed so much, they form a “Barr” body

Inactivation is random, maternal or paternal can be inactivated

Therefore the female body is mosaic for genes on X chromosome ( as each cell randomly has the the maternal or paternal X chromosome)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What’s the ZW system?

A

Males are ZZ

Females are ZW

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What are forward genetics approaches?

A

Seek to find the genes encoded by DNA that are responsible for a phenotype of interest

So phenotype to genotype

it’s a classical strategy as starts with phenotype

Enables the wild-type genes for this pathway to be identified and studied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What are CDKs?

A

Found in all eukaryotes
Control the cell cycle

If mutated can result in cancer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What is BLAST?

A

Basic Local Alignment Search Tool

Used for analysis of genes

53
Q

What is phylogenetics?

A

Estimating relatedness between species based on sequence data

54
Q

What are homologous genes?

A

Genes related by evolutionary descent

55
Q

What are paralogous genes?

A

Homologous genes in the same species

56
Q

What are orthologous genes?

A

Homologous genes but in different species

57
Q

What is reverse genetics approach?

A

Seek to find the phenotypes linked to specific sequences of DNA (including genes)

Genotype to phenotype

58
Q

What can you use for gene targeting?

A

Homologous recombination

Disruption or deletion

So Make sure trans gene is homlogous to DNA

59
Q

What’s a knockout mouse?

A

Had one or more genes knocked out

Careful to not knockout essential genes or will die

60
Q

What is CRISPR (Clustered Regulary Interspaced Short Palindromic Repeats) in Bacteria? And what do they do?

A
  1. Short viral DNA sequence is intergrated into CRISPR locus
  2. RNA is transcribed from CRISPR locus, processed and bound to Cas protein forming crRNAs
  3. small crRNA in complex with Cas seeks out and destroys viral sequences
61
Q

How can CRISPR be used for gene editing?

A

Make CRISPR target your DNA sequence instead of viral DNA

Have to have guide RNA and Cas9 protein

62
Q

Modes of inheritance?

A

Dominant
Vertical patterns

Recessive
Horizontal patterns

Autosomal recessive
Consanguinity (related) often present between parents

Autosomal
Males and females affected with equal probability

X linked recessive
Males affected, female carriers

X linked dominant
All daughters of affected males are affected

Mitochondrial
Non-mendelian (don’t go by normal laws)
Maternal inheritance

63
Q

Features of autosomal recessive?

A

Makes and females equally likely to be affected

25% chance of each child of an effected parent

Trait found in siblings not parents

Parents of effected children are likely to be related

Trait may appear as an isolated event

64
Q

Features of x linked recessive?

A

Males far more likely to have disease

Trait never passed father to son

All affected males in a family are related though their mothers (carriers)

65
Q

Features of mitochondrial inheritance?

A

Non Mendelian

Everyone inherits the condition through the maternal line

66
Q

What can affect interpretations of pedigrees?

A

New mutations
Penetrance ( either the carrier does express gene or not in phenotype)
Expressivity (all carriers express phenotype, but severity varies)
Delayed onset (takes time for disease to develop)
Anticipation (as you have more generations, the onset of the disease)
Imprinting (genes that are only affected by one of the parents as the other one can’t cancel them out)

Google all definitions

67
Q

What’s lod score?

A

lod score = log10 (odds loci are linked / odds loci are unlinked)

statistical estimate of whether two genes, or a gene and a disease gene, are likely to be located near each other on a chromosome and are therefore likely to be inherited.

68
Q

What are discontinuous traits?

A

Eg. Tongue roll or no tongue roll

Not many genes

No environmental factors

69
Q

Quadratics traits?

A

Eh, height or weight

Effected by multiple genes and alleles

Strongly influenced by envirnonemnets

70
Q

What are the 3 types of poly genetic traits?

A

Metric

Meristic

Threshold

All rely on normal distribution

71
Q

Feature of metric trait?

A

Mean is centre of distribution

Has a variance to measure spread

72
Q

Features of meristic traits?

A

Eg. Amount of hairs on nuckle

73
Q

Features of threshold traits?

A

Discrete phenotypes that are multifactorial

Have to tick over threshold to be classified

74
Q

How are quantitive traits different to Mendelian laws?

A

Now have to consider environment

Patterns of inheritance are the same

75
Q

Word equation for phenotypic variation?

A

= genetic variance + environmental variance + genetic and environmental interaction variance

76
Q

What does VG (genetic variance£?

A

Alleles present + dominance interactions + epistaxis interactions

All of these are variances

77
Q

What does the heritability of a trait describe?

A

How much variation is genetic

Broad sense- tells you how much is related to genetics and how much to the environment

Narrow sense - tells you how much is allleles and how much is environmental

Add equations

H^2 represents how heritable it is will be between 0 and 1

78
Q

How to predict genotype frequencies?

A

Put the allele frequencies into ur punnet square and multiply them to find genotype frequencies

79
Q

Hardy Weinberg equation for a 2 allele locus?

A

p + q = 1

p = dominant allele

q = recessive allele

Therefore

p^2 + 2pq + q^2 = 1

RR + Rr + rr = 1

80
Q

H-W equilibrium only applies when?

A

Diploid

Random mating ( if not decrease heterozygous individuals)

Allele frequencies same in both sexes

Large population size

No gene flow ( immigration or emigration )

No mutation

No selection

81
Q

Genetic drift?

A

Google definition

82
Q

What is adaptive radiation?

A

Describes the spread of new species of common ancestry into different niches

83
Q

What is convergent evolution?

A

The process wherby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches

84
Q

Features of mammals?

A 
Have efficent respiratory and circulatory  traits
Larger brain than other vertebrates
Mammary glands
Hair
Fewer, but more differentiated teeth
85
Q

What are the 3 lineages of mammals?

A

Monotremes
Marsupials
Eutherians

86
Q

Features of monotremes?

A

Warm blooded high metabolic rate
Hair over bodies
Produce milk
Lay eggs

87
Q

Features of marsupials

A

Embryos develop within placenta in mothers uterus
Born very early in embryonic development
Complete development nursing in maternal pouch called a marsupium

88
Q

Features of eutherians?

A

Complete embryonic development within uterus (mother feeds via placenta)

Compared with marsupials have a longer pregnancy and also a more complicated one

89
Q

What acts on the variation within populations?

A

Natural selection

90
Q

What occurs because of changes in allele frequencies?

A

Evolution

91
Q

Divergence of populations leads to?

A

Speciation

92
Q

Evolution is considered in terms of?

A

Changes in allele and gene frequencies over time, and the average action of selection on genotypes

93
Q

What is genetic drift?

A

The chance difference in transmission of alleles, leading to fluctuations in allele frequency

Drift most strongly affects rare alleles, affects them more than selection as well

Drift is the primary mechanism for increasing rare recessives

Drift is responsible for changing frequencies of neutral mutations (have no phenotypic effect)

94
Q

What is a genetic bottleneck?

A

Bottleneckimg event occurs meaning that there is only a small surviving population

The drift in small populations can then produce biased allele frequencies = founder effect

95
Q

Describe heterozygote advantage?

A

Where the heterozygote genotype actually produces the phenotype which is most likely to survive

Will promote frequency of rare alleles

Is also balancing selection as multiple alleles are maintained in the population

96
Q

Describe frequency dependent selection?

A

Alleles have an advantage when rare, but not when they are common

Eg. New camouflage which isn’t recognised by predators

97
Q

Describe fluctuating selection?

A

Where conditions change very rapidly meaning that allele frequencies fluctuates up and down relative to what the conditions are like

98
Q

What is fitness?

A

Survivorship and fecundity

Fitness (W) = 1 - s

s = selection coefficient

99
Q

When s is high what happens?

A

Allele frequencies change rapidly

100
Q

Describe stabilising, directional and disruptive selection?

A

Stabilising = intermediate variants are selected for, reduces variance for a trait

Directional selection = individuals at one extreme are selected for, shifts the mean value of the trait. Tends to be associated with changing environments

Disruptive selection = individuals at both extremes are selected for, leading to a bimodal distribution

101
Q

What’s kin selection?

A

Refers to changes in gene frequency across generations driven by interactions between related individuals

102
Q

Equation for coefficent of relatedness?

A

r = (0.5)^n

n = connection removed from self

Children will be 50, so will parents

grandfather would be 25 and so on

103
Q

rB > C

What are the values?

A

r = the genetic relatedness to the recipient of the altrustic act as the probability that a gene picked randomly from each locus is identical by descent

B = The additional reproductive benefit gained by the recipient of the altrusitic act

C = the reproductive cost to the individual of performing the act

Basically relatedness x benefit > cost

104
Q

What is adaptation?

A

The change or process of change by which an organism or species becomes better suited to its environment

105
Q

What’s mullers ratchet?

A

Accumulation of deleterious mutations (which can be removed by sexual reproduction and recombination)

106
Q

What can make a population seem like it’s not under selection?

A

If rate of mutation or drift balances it

107
Q

What are body plans?

A

Common basic body plan for different groups of organisms

Use to be a lot more of them

108
Q

What is saltation?

A

Huge major changes in body plan over one generation (just a theory)

109
Q

What are homologous structures and analogous structure?

A

Homologous structures:
Similarity by common descent
Similar form and function
Similar developmental trajectory

Analogous structures:
Different ancestry
Same function
Different developmental trajectory

110
Q

What is speciation and the 2 types?

A

Allopatric - in different environment so new species is created due to evolution

Sympatric - new species evolving even though in same environment and time

New species mean cant breed and produce fertile offspring

111
Q

Why animals can no longer breed together?

A

Pre mating isolation:

Behavioural choices
Temporal isolation (mate at different times)
Mechanical incompatilbillity

Post-zygotic isolation
Hybrid sterility

112
Q

What is Co-evolution?

A

The evolution of reciprocal adaptations of 2 or more species that have prolonged close interactions

Eg. Mutualism, benefits both, eg bees getting pollen off plants

Parasitsm, predation, driven adpaptions in each other to catch or escape

Competition drives to adapt to out compete other

113
Q

What’s mimicry in butterflies?

A

One unpalatable model butterfly which is most abundant will have a certain pattern and other butterflies will copy it to avoid predation

Batesian mimicry is when palatable butterfly just copies pattern

114
Q

What’s adaptive radiation?

A

Describes the spread of new species of common ancestry into different niches involving an excess of caldogenesis (formation of branches on evolutionary tree) over extinction

115
Q

What’s convergent evolution?

A

The process wherby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches

116
Q

What is ecological release?

A

When a species expands its niche within it’s own habitat or into a new habitat where there is little competition for resources, which remain abundant

117
Q

What’s evolutionary capacitance?

A

Living systems have the ability to accumulate genetic variation that has no phenotypic effect until the system is disturbed

This mechanism allows rapid phenotypic change in a population and rapid adaptation to new environmental conditions

118
Q

What is evolutionary relay?

A

Independent species acquiring similar characterisitcs through their evolution in similar eco-systemsbut not at the same time

119
Q

What is parallel evolution?

A

Independent species evolving together at the same time in the same ecospace and acquiring similar characteristics

120
Q

Homologous structures are evidence of?

A

Radiation

Eg. limbs of mammals

121
Q

Analogous structures are evidence of?

A

Convergent evolution

Eg. wings of birds and insects

122
Q

What are the conclusions from the paper which examined ecological oppurtubity and competition in driving genetic diversification?

A

Ecological opportunities promoto morphological diversification

Homogoenous environments do not promote adaptation

Mutation and selection alone are sufficient to promote new designs

Competition amongst niche variants maintains variation

Trade-offs in competitive ability drive adaptive radiation

123
Q

Quick desciption of paper?

A

Had cultures of bacteria shaken or unshaken

Put on lab bench

Smooth colony was found throughout

Wrinkly spreader was found at surface

Fuzzy spreader was found at bottom of broth

Had a control in a shaken beaker

After 7 days found heterogenous environment (not shaken) had produced a lot of biodiversity, Whereas the homeogenous shaken produced no biodiversity

Fuzzy spreader can’t invade wrinkly spreader

Wrinkly spreader may cut off oxygen to fuzzy spreader

124
Q

Good example of convergent evolution?

A

Marsupials vs eutherians

125
Q

2 important jaw closing muscles of mammals?

A

Temporalis and masseter

126
Q

Dentition pattern in mammals?

A 
Molars
Pre molars
Cannes
Incisors
Cannes
Premolars
Molars
127
Q

What are flightless birds known as?

A

Ratites

128
Q

How are birds adapted for flight?

A

Hollow bones
Lack urinary bladder
Small testicles, females only have one ovary

129
Q

How to know which gene is in the middle in a test cross?

A

It will be the one when it’s the only variable that is in the rare and the parental genotype

Human Biosciences (69 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions