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LIFE103 > Daimark Bennett Genetics In Evolution > Flashcards

Daimark Bennett Genetics In Evolution Flashcards

(61 cards)

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1
Q

What is evolution

A

Change over time
Within a species - gene pool - microevolution
Type and number of species - macro evolution

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2
Q

Microevolution

A

Evolution within a species

Differences between related species

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3
Q

Microevolution

A

Longer periods of time

How and when all forms of life came to be

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4
Q

Organic evolution
Lamarck
Pre Darwinian

A

Most primitive forms of life were produced by spontaneous generation
Acquire traits by use disuse
Slowly evolved to be more complex (progressive development )
Eg a horse grows muscle mass therefore it’s offspring are larger and have more muscle

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5
Q

Darwin and Wallace

A

Origin of species
Variation in living forms in nature and domestication
Similarity between species

Descent by modification 
Too many individuals to survive 
Differential survival between individuals 
Gradual change in traits in population 
New species
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6
Q

Geographic variation

A

Genetic differences increase with distance

Isolated populations evolve down separate pathways

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7
Q

Spatial variation and forming species

A

Races - variation across space , interbreeding possible

Sub-species - geographic isolation, limited genetic differentiation

Ring species - variation , interbreeding from some populations possible

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8
Q

Islands

A

Show importance of isolation in endemicity

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9
Q

Artificial selection

A

Give a species different phenotypes by breeding select individuals of 1 character type over another

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10
Q

Malthus

A

Found the human population increasing
Humans reproducing too quickly faster than the environment can sustain - overproduction
Have to limit family size or fall victim to famine and disease

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11
Q

Malthus applied to Darwin

A

Organisms overproduce
Population is limited by predation, food, climate
Creates competition

Some individuals have advantageous traits and are better competitors
They survive and these traits are passed to offspring
Over time the species has a higher reproductive success

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12
Q

Conditions of Natural Selection

A

IF
individuals vary in character
Some of that variation is heritable
Variation differs in mean number of offspring produced

THEN
Next gem will be biased to variants that give a greater mean of offspring

Gradual accumulation of change

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13
Q

Hutton and Lyell

A

Geological processes seen today are the same as in the past

Small yearly changes over a large amount of time produce dramatic changes in geological features

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14
Q

Hutton applied to Darwin

A

Small differences in fitness between individuals create large morphological differences over time

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15
Q

Phenotype

A

Observed characteristics appearance

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16
Q

Genotype

A

Particular set of alleles that determine the genetic constitution of an organism

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17
Q

Allele

A

One of two or more forms of a particular gene

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18
Q

Gene

A

The unit of inheritance which specifies a polypeptide contributing to cell function

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19
Q

What determines phenotype

A

Genotype establishes a fixed potential and the environment decides to what potential it is reached

Enviro - language and religion
Interactional - height behaviour and weight
Mostly genetic - bloody type and eye colour

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20
Q

5-HTT

A

Gene environment interaction
5HTT is involved in the release of serotonin, if there is a mutation then too little serotonin will be released and mag cause depression
Prozac can be taken to increase serotonin release

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21
Q

What is the ‘normal’ phenotype

A

There isn’t one

In genetics we talk about the ‘wild-type’ alleles and ‘mutant’ alleles

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22
Q

Polymorphism

A

Different alleles for many genes giving natural variation

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23
Q

Discontinuous characters

A

Discrete
Eg eye colour
You either have one or the other

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24
Q

Continuous characters

A

Not discrete types eg height as many genes effect it

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25
Where does genetic variation come from ?
Pre existing Mutations in previous gremlins Recombination in meiosis
26
Types of mutation
Substitution - transition or trans version Duplication Deletion
27
Effects of mutations
Deleterious - protein is changed meaning a loss of function Advantageous - Increased activity of enzyme Neutral - no observable change
28
Synonymous changes
Still codes for the same amino acids producing the same protein
29
Non synonymous change
Missense - substitute an amino acid Nonsense - truncate the protein Frameshift - alter every subsequent amino acid
30
How is variation maintained in a population
Heterozygote advantage | Each meiosis creates new mutations
31
Homeotic genes
Master control genes Mutants transform one tissue type into another Very dangerous can be lethal
32
Mechanisms of change
Mutation - change in dna bases Migration - some individuals in a population join a new population and they become more present in the new population Genetic drift - random passing of certain genes to the next generation Natural selection - advantageous alleles
33
Genetic variation occurs through
Mutations - changes in dna , a single mutation can have a large effect or even no effect in most cases it is the accumulation of small changes overtime Gene flow - any movement of genes from one population to another Sex - can introduce new gene combinations into a population
34
Somatic mutations
Occur in non reproductive cells and cannot be passed into offspring
35
Causes of mutations
DNA fails to copy accurately and so naturally occur through mistakes in dna replication External influences such as chemicals or radiation in the environment
36
Genetic drift
In each generation some individuals may by chance leave behind a few more descendants than other individuals The genes of the next genes of lucky individuals not better individuals
37
Conserved sequences
Selection limits the amount of genetic variation in coding sequences Essential sequences tend to be invariable through generations The lack of variability is a sign that specific sequences are highly selected for
38
Duplicated genes
A duplicated gene can accumulate changes without being selected against Duplication can lead to formation of multi gene families Individual members are sufficiently different for the gene products to have distinctive properties
39
Role of DNA duplication
Gene duplication is evolutionary May be facilitated by the presence of introns Creation of new genes
40
Types of repeated DNA sequence
``` Repeated genes and pseudo genes Mostly non coding DNA Structural DNA such as telomeres and centromeres Junk DNA Parasitic DNA DNA with no specific function ```
41
Micro satellites
Short simple tandem repeats Dinucleotides Trinucleotides Tetranucletides
42
Diploid cells
Two sets of every chromosome | Somatic cells
43
Haploid cells
One set of every chromosome | Gamete
44
Prophase
In mitosis homologous chromosomes do not pair up however in meiosis they do allowing genetic recombination
45
Crossing over at prophase 1
Genetic recombination between non sister chromatids at the chiasmata Allows homologues to exchange chromosomal material
46
Independent assortment at metaphase 1
Homologues held together by chaismata from crossing over Microtubules attach to each homologues Not each sister chromatid Pulling them to random poles
47
Sex is counter productive
Two fold cost of sex | Only 1 sex reproduces and gives birth and males give little parental care
48
Advantages of sex
Removing deleterious mutations Spreading beneficial mutations Variance
49
Mullers ratchet
Under asexual reproduction mutations can not be lost from a strain If a population is small lose ‘zero mutation’ class Sex can restore this
50
Transposable elements
LINEs Encore reverse transcriptase Self mobile SINEs Not encode reverse transcriptase is Not self mobile but can move when LINEs move
51
How transposable elements effect genes
Insertion mutagenesis - can disrupt splicing Alter gene expression Frameshift Has no effect if in an intron Exon shuffling can insert copy a gene and shuffle taking the exon with it
52
Chromosome mutations
``` Deletion Duplication Inversion Centric fusion Translocation Reciprocal translocation ```
53
Inversions during meiosis
Followed by crossing over Can be lethal as same alleles so not switch with one another and can mean homologous chromosomes cannot pair and inviable offspring is produced Could also be advantageous and frequency would increase
54
Chromosomal polymorphism
Varying chromosome counts or shapes of chromosomes Common in insects Cline - regular chnage in allele or inversion frequencies over geographical areas
55
Supergenes
Inversions protect groups of alleles within them reducing the frequency of crossing over Alleles are Locked tightly together and inherited as a single unit
56
Karyotype
Number size and shape of a set of chromosomes
57
Synteny
Changes in chromosome organisation during evolution can be traced by synteny and can contribute to speciation Island mice separated by mountains Became isolated it seemed no phenotypic change but hybrids were infertile
58
Ploidy
Variations in chromosome number Euploid - changes in whole sets of chromosomes Aneuploid - changes in numbers of single chromosomes
59
Polyploids
Polyploids tend to be larger due a larger cell size Auto polyploids - all chromosomes derived from a single species Allopolyploids - chromosomes come from more than one species
60
Autotetraploids
Chromosome doubling | A 2x genome becomes 4x
61
Allotetraploids
Made by hybridation Accidental doubling Lyger zonkey etc

LIFE103 (3 decks)

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