Brainscape's Knowledge GenomeTM

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


See full index

Module 6 > Patterns of Inheritance > Flashcards

Patterns of Inheritance Flashcards

1
Q

Causes of phenotype variation

A

The appearance of a living organism (phenotype) is influenced both by its genotype (genetic makeup) and environment

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

What is a mutation

A

Change in the genetic material
-Structure of DNA
-Change to structure/ gross number of chromosomes

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

What is a mutagen

A

Certain physical/ chemical agents that cause mutations

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

Physical mutagen agents e.g.

A

-X-rays
-Gamma rays
-UV light

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

Chemical mutagen agents e.g.

A

-Benzopyrene (in tobacco smoke)
-Mustard gas
- Nitrous acid

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

Biological mutagen agents e.g.

A
  • Some viruses
    -Transposons - jumping genes, remnants of viral nucleic acid that have become incorporated into our genome
    -Food contaminants i.e. mycotoxins from fungi
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mutations that occur during gamete formation

A

Can be advantageous/ neutral/ harmful
-Persistent: Can be transmitted through many generations without change
-Random: Not directed by a need on the part of the organism in which they occur

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

When do chromosome mutations occur

A

Meiosis

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

Types of chromosome mutations

A

-Deletion
-Inversion
-Translocation
-Duplication
-Non-disjunction

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

Deletion (Chromosome mutation)

A

Part of a chromosome (containing genes and regulatory sequences) is lost

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

Inversion (Chromosome mutation)

A

Section of the chromosome may break off and turn 180 degrees and then join again

=Although all genes are still present, some may now be too far away from their regulatory nucleotide sequence to be expressed

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

Translocation (Chromosome mutation)

A

A piece of one chromosome breaks off and attaches to another chromosome
-May also interfere with the regulation of genes on the translocated chromosome

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

Duplication (Chromosome mutation)

A

A piece of the chromosome may be duplicated
-Overexpression of genes can be harmful, as too many of certain proteins/ gene regulating nucleic acids, may disrupt metabolism

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

Non-disjunction (Chromosome mutation)

A

One pair of chromosomes/chromatids fails to separate, leaving one gamete with an extra chromosome

=When fertilized by a normal haploid gamete, the resulting zygote has one extra chromosome

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

What diseases are caused by Non-disjunction

A

Down syndrome / trisomy 21

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

Two types of Non-disjunction

A

-Aneuploidy
-Polyploidy

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

Aneuploidy

A

The chromosome number is not an exact number of the haploid number for that organism
-Sometimes chromosomes/chromatids fails to separate during meiosis

All in pairs but one set has an extra chromosome i.e. chromosome 21 has an extra chromosome which results in the disease trisomy

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

Polyploidy

A

Polyploidy- more than two copies of chromosomes

Diploid - meiosis error = instead of producing haploid egg and sperm it produces diploid egg and sperm
2n+ 2n = tetraploid plant

When diploid+ tetraploid fertilise
n+ 2n = 3n it will produce a triploid plant (non-viable and infertile)

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

Species

A

Interbreed; produce fertile offspring

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

How does sexual reproduction increase genetic variation

A
  • Allele shuffling: P1
    -Independent assortment: M1+A1/M2/A2

-Ransom fusing of gametes

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

Environmental factors that cause variation

A

-Speaking with a particular regional dialect
-A scar

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

Genetic factors that cause variation

A

-Blood group
-Tongue rolling

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

Genetic and Environmental factors that cause variation

A

-Skin colour
-Intelligence
-Sporting mass
-Body mass
-Height

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

How is variation caused by the environment interacting with genes

A

If plants are kept in dim light after germination/ soil contains insufficient nutrients then leaves do not develop enough chlorophyll
-Plant described as chlorotic + cannot photosynthesise

=Chlorotic plants have the genotype to make chlorophyll but environmental factors prevent them from expressing this gene

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

Dominant/ Recessive

A

Dominant: D
Recessive: d

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

Pure breeding

A

BB/ bb not Bb

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

TT
tt
Tt

A

Homozygous dominant
Homozygous recessive
Heterozygous

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

F1 generation

A

Parent phenotypes: Tall Short
Parent genotypes: TT tt
Gametes: T t
T
t = Tt

so F1 generation 100% chance of being tall

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

F2 generation

A

Parent phenotypes: Tall Short
Parent genotypes: Tt Tt
Gametes: T or t T or t
T t
T TT Tt
t Tt tt 3: 1 ratio and 75% chance of being tall

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

Monogenic

A

Determined by a single gene

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

The test cross

A

When you want to find the tall plants original genotype is tall/ short you need to cross-breed it with a plant with the recessive gene (the small plant)

Tall Plant = TT Tt
Short plant = tt

 T                       T     t   t   Tt                   t  Tt  tt

all tall 50% chance

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

Co-dominance

A

Where both alleles present in the genotype of a heterozygous individual are being expressed

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

Cow coat colour e.g. of co-dominance

A

C(R) - red cows
C(W) - white cows

Red White
C(R) C(R) C(W) C(W)

           C(R)    C(W)    C(R) C(W)    = F1 generation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Cow coat colour e.g. of co-dominance (F2 generation)

A

Roan Roan
C(R) C(W) C(R) C(W)

       C(R)  C(W)   C(R)   C(W)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Multiple alleles

A

Characteristic where there are three or more alleles in the population gene pool

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

Multiple alleles - human blood

A

3 Blood groups: A;B;O
- A/B dominant over O

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

Multiple alleles - human blood combinationS

A

I(B) I(B) = B
I(O) I(O) = O
I (A) I(B) = AB
I(B) I(O) = B

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

Multiple alleles - human blood e.g.

A

Female Male
I(B) I(O) I(A) I(O)

            I(B) I(O)                    I(A)  I(O)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Sex- linkage

A

Gene present on (one of) the sex hormones

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

Autosomes

A

The first 22 chromosomes
-Fully homologous
-Match for length and contain the same genes at the same loci

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

23rd chromosome onwards

A

Sex chromosomes
Female: XX
Males: XY

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

Male 23rd chromosome

A

Not fully homologous but a small part of one matches a small part of the other so that the chromosomes can pair before meiosis

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

Why do males often suffer from genetic diseases via sex hormones and females do not

A

If a female has an abnormal allele on her X chromosome she probably has a functioning gene on the other X chromosome

If a male inherits from his mother the X chromosome with the abnormality he will suffer from a genetic disease as he won’t have another functioning allele for that gene

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

Men and X linked genes

A

Haploid/ hemizygous

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

Haemophilia A

A

Unable to clot blood fast enough; injuries may cause an internal haemorrhage

  • on the h = recessive allele
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How is Haemophilia A caused

A

Female (carrier) Male
X(H) X(h) X(H) Y

                X(H)            X(h)

X(H) X(H) X(H) X(H) X(h)

Y X(H) Y X(h) y

47
Q

Why can males not pass sex-linked diseases to their sons

A

Gene for the X-linked disease is nearly always on the X -chromosome and males pass their copy of the X chromosome to their daughters and pass their Y chromosomes to their sons

48
Q

Can haemophilia males pass the disease to their grandsons

A

Yes. The X with the mutated allele that they pass to their daughters could then pass to their daughters sons

49
Q

Female Haemophiliacs

A

Very rare and fatal
Genotype: x(h) x(h)
Phenotype: X(H) X(h) - mum
x(h) y - dad

50
Q

Sex linkage in cats

A

C(O) = Orange
C(B) = Black

if it was X(CO) X (CB) = Tortoiseshell
-mainly only females as need 2x X chromosomes

51
Q

How do females have the same amount of X-linked genes expressed as men and not 2x as many

A

In every female nucleus, one X chromosome is inactivated
-Determination of which pair will become inactivated is random and happens during early embryonic development

52
Q

Dihybrid Inheritance

A

The different genes are inherited independently of each other. They are on different chromosomes

53
Q

Dihybrid Inheritance e.g.

A

Yellow-rounded Green-wrinkled
YYRR yyrr
YR yr

YyRr = Yellow-rounded

54
Q

Dihybrid Inheritance - what to remember about the pairing

A

Always pair the letters together
Yy Rr

55
Q

What can you deduce from the results of dihybrid crosses

A

-The alleles of the two genes are inherited independently of each other, so each gamete has one allele for each gene locus
-During fertilisation, any one of an allele pair can combine with any other allele pair

56
Q

Autosomal linkage

A

Gene loci present on the same autosome (non sex chromosomes) that are often inherited together

57
Q

If linked genes are not affected by crossing over of non-sister chromatids in P1of meiosis

A

They are always inherited as one unit

58
Q

Recombinant genes

A

Chromosomes affected by crossing over

59
Q

What is epistasis

A

When one gene masks or suppresses the expression of another gene

60
Q

How does epistasis reduce genetic variation

A

Reduces number of crosses in F2 generation

61
Q

Recessive epistasis

A

The homozygous presence of a recessive allele at the first locus prevents the expression of another allele at another locus

First locus = epistatic to those at the second locus
Second locus = hypostatic to those at the first locus

62
Q

Dominant epistasis

A

Dominant allele at the first locus masks anything at the second locus

63
Q

Complimentary gene action

A

The genes working to code for two enzymes that work in succession, catalysing sequential steps of a metabolic pathway

64
Q

Epistasis vs Dihybrid

A

Epistasis = one characteristic
Dihybrid = Two characteristics

64
Q

Epistasis vs Dihybrid

A

Epistasis = one characteristic
Dihybrid = Two characteristics

65
Q

Recessive epistasis ratio

A

9:3:4

66
Q

Dominant epistasis ratio

A

12:3:1 / 13:3

67
Q

Complimentary gene action ratio

A

9:7 / 9:3:4 / 9:3:3:1

68
Q

What is the Chi-squared test

A

Statistical test designed to find out if the difference between observed and expected data is down to chance

69
Q

What do you need to do before you carry out the Chi-squared test

A

State a null hypothesis
“There is no statically significant difference between the observed and expected data. Any difference is down to chance”

70
Q

How do you work out the degrees of freedom

A

(number of categories -1)

71
Q

How do you work out whether you should reject/accept the null hypothesis

A

Read critical values at 95% certainty

If (x)2 is smaller the value in the table we can accept the null hypothesis / if bigger we can reject

72
Q

Discontinuous variation

A

Phenotype classes are distinct and discrete, each clearly discernible in a qualitative way’
-No/ few intermediaries
-Monogenic

73
Q

Discontinuous variation examples

A

epistasis ; gender ; blood group

74
Q

How is epistasis an example of Discontinuous variation

A

Genes at different gene loci may interact to influence one characteristic and produce discontinuous variation

75
Q

Continuous variation

A

Where the genetic variation between individuals shows a range with a small gradation between many intermediaries

=Variation that produces phenotypic variation where the quantitative traits vary in small amounts from one group to the next

76
Q

Continuous variation examples

A

Foot size; height ; leaf length; hair colour

77
Q

Continuous variation key features

A

-Polygenic: many genes involved in determining characteristics
-Alleles have an additive effect: alleles of each gene may contribute a small amount to the phenotype
=As a result the phenotypic categories vary in a quantitative way

78
Q

How is there more continuous variation

A

Greater no. of gene loci contributing to the determination of a characteristic

79
Q

Qualitative vs quantitative

A

Qualitative research generates non-numerical data
Quantitative research generates numerical data or information that can be converted into numbers

80
Q

Quantitative genetics

A

The study of genetics of inherited characteristics
i.e. many characteristics of crop plants are polygenic so plant breeders may need to apply knowledge of quantitative genetics

81
Q

When does quantitative genetics become more complicated

A

When gene loci increases to above 2
=trihybrid cross

81
Q

When does quantitative genetics become more complicated

A

When gene loci increases to above 2
=trihybrid cross

82
Q

Does the environment have a greater affect on polygenic/ monogenic characteristics

A

Polygenic

=Each person has the genetic potential for intelligence/ height but without mental stimulation/ nutrition these potentials will nit be reached

83
Q

Multiple alleles vs polygenic

A

Multiple alleles: versions of the same gene
Polygenic: Many gene loci

84
Q

What can change allele frequencies over time

A

Natural selection and genetic drift

85
Q

Natural selection

A

Individuals, which have mutations, which make them better suited to the environment are more likely to survive a selection pressure than the individuals without the mutation
-Individuals with mutation that survive will pass off advantageous alleles to offspring

86
Q

What results from Natural selection

A
  • Over time allele frequencies within a population will change
    -Can maintain constancy of species or lead to a new species
87
Q

Types of Natural selection

A

1) Stabilising
2) Directional
3) Disruptive

88
Q

Stabilising selection

A

When an organisms environment remains unchanged it favours intermediate phenotypes

89
Q

Directional selection

A

-Environment change may prefer a new phenotype and so results in a new population mean
-Individuals better suited to environment will survive under the selection pressure and pass on advantageous alleles to offspring
-Over several generations, there is a gradual shift in the optimum value for a trait

90
Q

Disruptive selection

A

Favours the extreme phenotypes and the intermediate phenotypes are selected against

91
Q

Genetic drift

A

A change in the allele frequency within a population over time
-This is caused by a chance event i.e. volcano/ earthquake

92
Q

Two things that cause a genetic drift

A

1) Genetic bottleneck
2) The Founder effect

93
Q

Genetic bottleneck

A

When an event such as a volcanic eruption greatly reduces the population and then over time the population increases again

94
Q

Effects of the genetic bottleneck

A

-Reduces genetic diversity
-Can affect fertility rates if population gets too small
-Could also improve population if surviving population has advantageous alleles to disease etc.

95
Q

Founder effect

A

A new population established by a small number of individuals, who originated from a larger parent population

96
Q

Founder effect affects

A

-Reduces genetic variation

97
Q

Important to remember for the Founder effect/ Bottlenecks

A

Do not cause mutations or the emergence of harmful alleles but they contribute to the increase of the frequency of mutations and harmful alleles within the resulting populations

98
Q

What is the Hardy Weinberg principle

A

Describes and predicts a balanced equilibrium int he frequencies of alleles and genotypes within a resulting population

99
Q

What does the Hardy Weinberg principle assume

A

1) The population is large enough to make a sampling error negligible
2) Mating within the population occurs at random
3) There is no selective advantage for any genotype and hence no selection
4) There is no mutation; migration; genetic drift

100
Q

Hardy Weinberg principle calcualtion

A

P+q=1
P(2) + 2Pq + (q)2 = 1

101
Q

Speciation

A

The process at which a new species is formed
-The two species can no longer interbreed

102
Q

How does speciation occur

A

-Species must be split into two isolated populations
-This avoids the mutations in one population affecting the other
-In each location the different selection pressures will accumulate different allele frequencies

103
Q

Sub-species

A

When during the evolutionary process the two populations are different but still able to freely interbreed

104
Q

Two types of isolating mechanisms

A

-Geographical = allopatric speciation
-Reproductive - sympatric speciation

105
Q

Geographical isolation

A

If population separated by geographical features i.e. mountains it acts as barrier to gene flow between the populations

106
Q

How does Geographical isolation work

A

1) Isolated population undergoes different selection pressures in the two different environments
2) Both undergo independent changes to different allele frequencies or/and chromosome arrangements within their gene pools
3) Genetic mutations can be a result of: Mutations; Natural Selection; genetic drift

107
Q

Allopatric isolation

A

Formation of two different species from an original species due to geographical isolation

108
Q

Reproductive isolation

A

Biological/ behavioural changes within a species may lead to reproductive isolation of one population from another

109
Q

Reproductive isolation e.g.

A

A change in the organisms foraging behaviour at the time of day may enable them to exploit a new niche and they’ll no longer mate with organisms awake at different times in the day

110
Q

How do genetic changes lead to reproductive isolation
A change in chromosome no. may

A
  • Prevent gamete fusion
    -Make zygotes less viable = fail to develop
    -Lead to infertile hybrid offspring with an odd no. of chromosomes, so that chromosome pairing during meiosis cannot occur
111
Q

What happens when members of the reproductively isolated population no longer mate with the original population due to mutations

A

Leads to changes in:
-Courtship behaviour i.e. time of year of mating
-Animal genitalia / plant flower structure

112
Q

Sympatric speciation

A

Formation of two different species from one original species, due to reproductive isolation, whilst populations inhibit the same geographical locations

Module 6 (6 decks)

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