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CELS191 > The rest of module 2 > Flashcards

The rest of module 2 Flashcards

1
Q

What is a gene

A

A defined region (sequence) of DNA that produces a type of RNA molecule that has some function

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2
Q

Gene expression definition

A

The process by which information from a gene is used in the synthesis of a functional gene product

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3
Q

How does RNA polymerase synthesise mRNA

A

Catalyses formation of phosphodiester bonds between ribonucleotides

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4
Q

What are the three stages of transcription

A

Initiation, elongation, termination

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5
Q

What occurs in the initiation stage of transcription

A

Transcription factors bind to promoter region (TATA box), RNA polymerase II binds forming a transcriptional initiation complex together with transcription factors. 2 DNA strands separate and RNA pol II starts synthesis without the need of a primer

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6
Q

What occurs in the elongation stage of transcription

A

RNA polymerase II uses the template strand which runs in the 3’->5’ direction as a template and inserts complementary RNA nucleotides in the 5’ -> 3’ direction

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7
Q

What parts of the gene are transcribed

A

5’ UTR, coding sequence, 3’ UTR

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8
Q

What parts of the gene are translated

A

Exons

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9
Q

What is splicing

A

Removal of introns from mRNA strand to make continuous coding sequence

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10
Q

What is pre mRNA

A

mRNA stored while still containing introns, so that proteins can be made quickly when required

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11
Q

Purpose of promoter region

A

DNA segment recognised by RNA polymerase to initiate transcription

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12
Q

5’UTR purpose

A

Contain regulatory elements, facilitates addition of 5’ G cap

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13
Q

3’UTR purpose

A

Contain regulatory elements, facilitates addition of poly-A tail

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14
Q

5’G cap

A

Prevents mRNA degradation, promotes intron excision and provides a binding site for the small ribosomal subunit

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15
Q

Poly-A tail

A

Prevents mRNA degradation, promotes intron excision and facilitates export of mRNA from the nucleus to the cytoplasm

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16
Q

Where does transcription occur in eukaryotes

A

In the nucleus

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17
Q

Where does translation occur

A

In the endoplasmic reticulum or cytoplasm

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18
Q

Where does transcription occur in prokaryotes

A

In the cytoplasm

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19
Q

What is a functional gene product

A

Protein or non-coding RNA (doesn’t give rise to a protein but has some other function, e.g tRNA, rRNA)

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20
Q

What is a monohybrid cross

A

Crossing two heterozygotes for one gene

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21
Q

What is the expected phenotype ratio of a monohybrid cross

A

3:1

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22
Q

What is a test cross

A

Crossing an unknown genotype but dominant phenotype with a known genotype, recessive phenotype

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23
Q

What are Mendel’s two laws

A

Law of segregation, law of independent assortment

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24
Q

What is a dihybrid cross

A

Crossing two heterozygotes for two genes

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25
Q

What is the expected phenotype ratio of a dihybrid cross

A

9:3:3:1

26
Q

Product rule

A

Multiply independent events (e.g unlinked genes)

27
Q

Sum rule

A

Add mutually exclusive events

28
Q

What is a polymorphic trait

A

A monogenic trait but with many alleles

29
Q

What is incomplete dominance

A

When a heterozygote has a blend of the two phenotypes

30
Q

What is co dominance

A

When a heterozygote expresses both traits

31
Q

What is a polygenic trait

A

A phenotype controlled by the additive effects of many genes (groups of genes). Characters appear continuous or quantitative (non discrete)

32
Q

What are examples of apparent exceptions to Mendel’s laws

A

Co dominance, incomplete dominance, polymorphism

33
Q

How does the environment affect phenotype

A

Smooths differences between phenotypes (continuous traits can have a simple genetic basis)

34
Q

Polygenic vs polymorphic

A

Polygenic: trait which has many genes causing it
Polymorphic: gene which has many alleles

35
Q

What is a sex linked trait

A

Involving genes on sex chromosomes

36
Q

Around how many linked genes are there per chromosome

A

1000

37
Q

What is the recombinant frequency

A

The proportion of recombinant gametes

38
Q

How do you calculate the recombinant frequency

A

Recombinant phenotypes/ total phenotypes

39
Q

What is the approximate recombinant frequency for distant (unlinked) genes

A

~50%

40
Q

What is the recombinant frequency for linked genes

A

0-50%

41
Q

What type of relationship is there between distance between linked genes and recombination frequency

A

Linear

42
Q

What is the centimorgan

A

Arbitrary unit used for measuring distance between linked genes. cM = 100 x recombination frequency

43
Q

What is a map unit and how long is a chromosome

A

Same as a centimorgan, a chromosome is about 50 map units

44
Q

Population definition

A

Localised group of individuals of the same species

45
Q

Gene pool definition

A

Total aggregate of genes (and their alleles) in the population at one time

46
Q

Hardy-Weinberg Equation

A

p^2 + 2pq + q^2

47
Q

Allele frequency Hardy-Weinberg Equation

A

p+q = 1

48
Q

What is p Hardy-Weinberg Equation

A

Frequency of dominant allele

49
Q

What is q Hardy-Weinberg Equation

A

Frequency of recessive allele

50
Q

How can allele frequencies change

A

Non- random mating (assortative mating, in breeding), random genetic drift, bottleneck effect, founder effect, natural selection, gene flow, migration, mutation

51
Q

Random genetic drift

A

A random change in allele frequencies due to sampling error over generations

52
Q

Bottleneck effect

A

Catastrophic event results in the death of a random part of the population. Consequential population may not be representative of original

53
Q

Founder effect

A

Random event results in the relocation of part of population. Resulting populations may not be representative of original

54
Q

Stabilising selection

A

Reduces variation but does not change the mean

55
Q

Directional selection

A

Changes the mean value toward one extreme

56
Q

Disruptive selection

A

Favours the two extremes producing two peaks

57
Q

Frequency dependent selection

A

Natural selection maintains an equal proportion of phenotypes (e.g left and right mouthed perissodus microlepis)

58
Q

Cline

A

The gradual geographic change in genetic/phenotypic composition

59
Q

Migration features

A

Brings new alleles, changes proportions of existing alleles, changes population size, makes two populations more similar

60
Q

Centimorgan = (in terms of recombinant frequency)

A

Centimorgan = 100x recombinant frequency

61
Q

What are the human examples of sex linked traits

A

red-green colour blindness (recessive), haemophilia

CELS191 (7 decks)

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