Brainscape's Knowledge GenomeTM

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


See full index

Animal kingdom > Molecular 1-6 > Flashcards

Molecular 1-6 Flashcards

1
Q

What general processes and population characteristics determine the fate of new mutations?

A

Selection: Whether the new mutation has a negative fitness effect (selection against), is neutral or has a positive fitness effect.
Drift and effective population size: if small population drift has a strong effect and loss of any variant is likely, whether it is neutral or selected.
Mutation rate: more mutations more chance of a new variant arising and becoming fixed.

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

What is a ‘transspecies polymorphism’ and in what situation is it most likely to occur?

A

Transspecies polymorphism is where two species derived from a common ancestor have both maintained the same polymorphism. Most likely with balancing selection

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

Give an example of transspecies polymorphism.

A

Blood group in humans and apes.

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

What is meant by the term ‘wobble’ ?

A

The 3rd anticodon of a tRNA molecule can have some non-specificity allowing the tRNA to bind to different mRNA codons

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

Describe what types of noncoding DNA there are in eukaryote genomes and what functions they may have.

A

Introns: noncoding DNA that is in between the exons, and spliced out before mature mRNA is generated.

Tandem repeats:
Telomeres: short tandem repeats: protection chromosome ends
Centromere: short tandem repeats for attachment of the spindle fibers
rDNA: long tandem repeats

Dispersed repeats:
Can be generated through transposition
Mostly non-functional but can have detrimental effect if jumping to a location that interferes with gene function. Can be a very large proportion of genome, eg. LINEs and SINEs

Pseudogenes: when genes are duplicated one of the two copies may become non-functional and mutations are accumulating.

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

What are tandem repeats and dispersed repeats ?

A

Dispersed repeats are segments of DNA that occur multiple times at more or less random positions in the genome.

Tandem repeats occur in DNA when a pattern of one or more nucleotides is repeated and the repetitions are directly adjacent to each other.

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

What use do introns have ?

A

Carry out some regulatory control

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

Why are non protein coding genes conserved ?

A

The are conserved due to failure of having the molecules is fatal.

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

What are the parts of genes that are non transcribed called ?

A

Flanking regions- Control initiation and tissue specificity eg TATA box

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

What is necessary for alignment and editing of protein-coding DNA sequences ?

A

Translate the DNA sequence into its amino acid sequence, via standard or specific codon translation tables.

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

What 5 factors make sequence data more suitable for phylogenetic reconstruction than morphological characteristics ?

A
  1. Sequence data is strictly heritable and not effect by the environment
  2. Sequence data is unambiguous
  3. Molecular characteristics evolve at a regular rate and thus show relationships between taxa.
  4. The nature of sequence data is more open to quantitive analysis.
  5. Molecular data such as rRNA are measures of long term evolutionary divergence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the main vehicles for reverse transcriptase ?

A

Retrotransposons- Allows re-insertion of DNA into genome

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

How do RNA viruses replicate RNA ?

A

RNA dependent RNA polymerase

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

What is a point mutation ?

A

A single base change in a DNA sequence. They occur by mispairing during DNA replication.

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

Name the 2 types on point mutations ?

A

Synonymous: No change in amino acid sequence

Non synonymous : Causes a change in amino acid sequence

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

What are the 2 types of synonymous mutations ?

A

Silent-Produces same amino acid, occurs due to wobble

Noisy-Occurs due to coding sequence being used as attachment site for regulatory control

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

What are the 3 types of non-synonymous ?

A

Missense -Same length protein with a different amino acid
Non-sense-Changes amino acid to stop codon
Sense - Stop codon changed to amino acid

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

What are point mutations useful markers for ? And what are they known as ?

A

Variations

SNPs

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

What are the 3 types of segmental mutations ?

A

Recombination
Insertion/ deletion
Inversion

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

What does a segmental mutation cause ?

A

Gene duplication

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

When does the segmental mutation recombination occur ?

A

During chromosomal cross over

During the insertion of retroviral sequences

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

why are insertion/deletion mutations known as indels and why are they fatal ?

A

Often don’t know which was the ancestral state (and whether an insertion or deletion occurred)
Cause a frameshift two thirds of the time

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

When do indels occur ?

A

During unequal crossing over resulting in the deletion of one sequence and the insertion of another.

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

Why do inversions occur ?

A

Intrachromosomal crossing over

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

What is the haplotype ?

A

Alleles set in adjacent or linked loci

-Genotype in non-recombining set of genes

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

What does monomorphic mean ?

A

All individuals in a population are identical for a locus

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

What does polymorphic mean ?

A

2 or more alleles present in a population for a locus

28
Q

What are 2 forces that determine the fate of alleles ?

A

Random genetic drift

Selection

29
Q

If alleles are codominant what is the expected fitness of hetrozygotes ?

A

Average of the two homoztgotes

30
Q

What happens when heterozygotes are over dominant ?

A

Both alleles are maintained
Balancing selection
Example sickle cell anemia

31
Q

What happens with heterozygotes are under dominant ?

A

Lose one allele

32
Q

What is the over riding force in large populations ?

A

Selection

33
Q

What is the deterministic approach in terms of allele frequency ?

A

Changes in allele frequencies can be predicted from knowledge of conditions.
Assumes populations are infinite size and selection is constant

34
Q

What is the Stochastic approach in terms of allele frequency ?

A

changes in allele frequencies occur in a probabilistic manner

35
Q

What is the effective population (Ne) ?

A

Imaginary population with no migration, distinct generations with equal offspring. No selection.
Often smaller than census population (N)

36
Q

What causes Ne to decrease ?

A

Sex ratios becoming biased

37
Q

What does coalescence allow ?

A

Estimate past population sizes

38
Q

What is coalescence ?

A

is when two alleles that trace back to a common ancestral allele in past generation

39
Q

What is gene genealogy ?

A

Relationship of all alleles

40
Q

What does coalescence assume ?

A

Mutations are all unique

Genetic variation is a balance between mutations and a loss of alleles due to genetic drift

41
Q

What does allele fixation depend on ?

A

Ne
Current frequency
Selective pressures

42
Q

What effect on polymorphism does an advantageous and a neutral substitution have ?

A

Little polymorphism= Advantageous substitution quickly fixed
Transient polymorphism= Substitution change slowly over time

43
Q

What does mendels law of inheritance assume ?

A

Law of segregation- Alleles in diploid cells are passed on equally
Law of independent assortment- Alleles at separate loci are passed on independently from one another

44
Q

What violates the law of segregation ?

A

Transmission ratio distortion (alleles not passed on 50:50)

45
Q

What causes Transmission ratio distortion ?

A

Meiotic drivers
Autonomous replication elements
Genomic elements

46
Q

What is intergenomic conflict ?

A

When the chloroplast or mitochondria have different evolutionary interests nucleus.

47
Q

What is genetic hitchhiking ?

A

When an alleles frequency increases due to it being positioned near a gene that is undergoing selective sweep

48
Q

What is selective sweep ?

A

The reduction of variation among nucleotides near a mutation in DNA.
Results from a beneficial allele being fixed.

49
Q

What does selective sweep cause ?

A

Increases differentiation between populations
Eliminates diversity in region of genome that is close to selected gene.
Creates linkage disequilibrium

50
Q

What is linkage disequilibrium ?

A

Non-random association between 2 or more loci.

This can cause allele frequency to be higher or lower than it would be if the allele was independent

51
Q

Briefly describe 5 methods for detecting natural selection.

A

See notes

52
Q

What is the opposite of selective sweep ?

A

Background selection describes the loss of genetic diversity at a non-deleterious locus due to negative selection against linked deleterious alleles.
Doesnt cause linkage disequilibrium

53
Q

What is epistasis ?

A

Interaction amongst alleles at different loci

It is a major contributer to long term molecular evolution

54
Q

What happens if there is no epistasis ?

A

Amino acid substitutions in one species would be accepted in another

55
Q

What is purifying selection ?

A

Gene variants are removed due to being linked to a mutation on another gene

56
Q

what does the neutralist hypothesis think are the driving forces in evolution ?

A

Mutation
Drift
Purifying selection

57
Q

What is an example of the selectionist view ?

A

Sickle cell anemia- Evidence for balancing selection

58
Q

What does the neutral theory expect to be the same in terms of mutations ?

A

Ratio of synonymous and non-synonymous is the same

59
Q

What is P distance ?

A

The minimum degree of divergence

Max value =0.75

60
Q

What is wrong with assuming evolutionary distance between two sequences is equal to the number of difference ?

A

Likely to be an under estimate as mismatched sequence does not equal substitutions

61
Q

What does the jukes cantor model assume ?

A

Equal base frequencies

Equal substitution rate for all mutations

62
Q

What does Kimura 2 parameter model assume ?

A

Assumes different rates of substitutions for transitions and transversions (Purine-Pyrimide)

63
Q

How can you calculate variation between sequences ?

A

Gamma distribution

64
Q

What are invariant sites and how can they be used ?

A

Some codons do not vary.

The proportion of invariant sites in a set of sequences to be compared can be used to adjust the model.

65
Q

What does time till coalescence depend on ?

A

Ne

Number of allelic lineages

Animal kingdom (13 decks)

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