changes in the genetic makeup of a population

Question 1

gene

Answer 1

a sequence of DNA nucleotides that codes for a particular trait.

Question 2

allele

Answer 2

a variation of a gene.

Question 3

genotype

Answer 3

a combination of alleles.

Question 4

phenotype

Answer 4

observable traits that are caused by the genotype and environment.

Question 5

traits can be monogenic or polygenic. what does that mean?

Answer 5

Traits can be monogenic- discontinuous (discrete) variation

Traits can be polygenic- continuous

Question 6

gene pool?

Answer 6

all the alleles possessed by an entire population, which may potentially be passed on to the next generation.

Question 7

allele frequency definition and equation

Answer 7

relative proportion of an allele in a population. Percentage or decimal

Allele frequency: 2(homozygotes) + (heterozygotes)/
2(total individuals) x 100

Question 8

how do new alleles arise? how does allele frequency change?

Answer 8

New alleles arise with mutations

Allele frequency changes with changes to environmental pressures

Question 9

define mutation

Answer 9

a change to DNA.

Question 10

what cab mutations be?

Answer 10

neutral, beneficial, harmful

Question 11

what is a mutagen?

Answer 11

neutral, beneficial, harmful

Question 12

how are most mutations dealt with?

Answer 12

Most mutations are detected and repaired by enzymes

Question 13

somatic mutations

Answer 13

in body cells. Only affects individual.

Question 14

germline mutations

Answer 14

affect gametes. Passed to offspring.

Question 15

what are the types of point mutation?

Answer 15

substitution and frameshift

Question 16

what is a point mutation?

Answer 16

alters, adds or removes a nucleotide. Affect a single gene.

Question 17

types of substitution mutations?

Answer 17

Silent
Missense
Nonsense

Question 18

what is a silent mutation?

Answer 18

New codon that still codes for the same amino acid

Question 19

what is a missense mutation?

Answer 19

The amino acid changes

The protein may be able to function depending on the amino acid changed

Question 20

what is a nonsense mutation?

Answer 20

Creates a stop codon

No more amino acids can be coded for

Question 21

what is a frameshift mutation?

Answer 21

one or two nucleotides are added or removed from the nucleotide sequence, altering every codon.

Question 22

types of frameshift mutations?

Answer 22

Nucleotide insertion

Nucleotide deletion

Question 23

what are block mutations? when does it occur? how is it caused? what are the affects?

Answer 23

affect large sections of a chromosome.

Usually occur during meiosis
Can be caused by mutagens
Serious or lethal

Question 24

types of block mutations?

Answer 24

Duplication
Deletion
Inversion
Insertion
Translocation

Question 25

what is duplication?

Answer 25

Multiple copies of the same gene

Question 26

what is deletion?

Answer 26

Section removed | Often fatal

Question 27

what is inversion?

Answer 27

Upside down

Question 28

what is insertion?

Answer 28

Section of one chromosome breaks off and attached to another

Question 29

what is translocation?

Answer 29

A whole chromosome or segment attaches to another chromosome or segment

Question 30

what are the types of chromosomal abnormalities?

Answer 30

polyploidy | aneuploidy

Question 31

what is chromosomal abnormality?

Answer 31

mutations involving whole chromosomes.

Question 32

what is aneuploidy?what is it caused by?

Answer 32

presence of an abnormal number of a chromosome; an extra or one missing Often caused by non-disjunction: two homologous chromosomes do not desperate in meiosis

Question 33

what is polyploidy? who survives? what can it lead to?

Answer 33

more than two full sets of chromosome in every chromosome set. Some animals and plants may survive Humans do not survive Can lead to speciation

Question 34

how does variation occur?

Answer 34

Variation occurs due to different combinations of alleles- independent assortment, recombination, mutations, random mating

Question 35

what are selection pressure?

Answer 35

conditions that influence allele frequency. Can be natural or artificial such as selective breeding.

Question 36

what drives evolution?

Answer 36

Mutations and selection pressures drive evolution.

Question 37

what is natural selection?

Answer 37

influence of environment pressures on allele frequency in a population that affect survival and reproduction. Individuals with advantageous phenotypes more likely survive.

Question 38

what are environmental selection pressures?

Answer 38

Climate Competition Mates availability predators

Question 39

what are the environmental pressures influence on allele frequencies?

Answer 39

Variation- genetic differences in pop Reproduction- alleles are heritable Survival- not all survive to reproduce Environmental selection pressures- some phenotypes are better suited

Question 40

high adaptive value

Answer 40

High adaptive value phenotypes- survival of fittest

Question 41

what is gene flow?

Answer 41

migration of individuals leading to a change in gene pool. When not possible, populations are isolated

Question 42

what is genetic drift? what ways can it occur?

Answer 42

Genetic drift: chance events that change the allele frequencies in a gene pool. Small pop- death of an individual, loss of genetic diversity Can occur when population decreases over time (bottleneck) or in a small founding pop (founder effect)

Question 43

what is the bottleneck effect?

Answer 43

Individuals are drastically and quickly reduced by a random event eg. Natural disaster Individuals survive by chance not phenotype Allele frequency changes Bottleneck effect is the impact on remaining- inbreeding leading to reduced variation and increased homozygous Smaller pop = greater effect Lower variation makes pop more vulnerable

Question 44

what is the founder effect?

Answer 44

Small group from a population move to a new location and establish a new population. Smaller gene pool Increased inbreeding and lower variation Environmental pressures usually differ which drive evolution

Question 45

evolution?

Answer 45

change in genetic composition of a population over time.

Question 46

what are the processes of evolution?

Answer 46

``` Natural selection drives Environmental selection pressures Genetic drift Mutations Populations evolve, not individuals ```

Question 47

what is a species?

Answer 47

Species: a group of individuals that are genetically similar enough to produce fertile viable offspring when interbreeding. Gene pool is isolated from that of other species

Question 48

how does genetic isolation occur?

Answer 48

Genetic isolation occurs due to prezygotic (before reproduction) or after reproduction (postzygotic)

Question 49

what is prezygotic isolating mechanisms?

Answer 49

Prezygotic isolating mechanisms: prevent individuals from different populations interbreeding.

Question 50

what are the types of prezygotic isolating mechanisms?

Answer 50

geographical, ecological, temporal, behavioural, structural or morphological, gamete mortality, sexual selection

Question 51

geographical

Answer 51

Geographical (spatial) | Populations are separated by eg. A mountain

Question 52

ecological

Answer 52

``` Ecological isolation (niche partitioning) Occupy same ecosystem but have different niches within that ```

Question 53

temporal

Answer 53

Temporal isolation | Breeding cycles do not overlap

Question 54

behavioural

Answer 54

Behavioural isolation Mating calls and rituals are highly specific Often result of sexual selection

Question 55

structural morphological

Answer 55

Structural or morphological isolation | Reproductive organs are incompatible

Question 56

gamete mortality

Answer 56

Gamete mortality Egg and sperm fail to fuse in fertilisation Signalling molecules may not be adequate May not be able to support sperm of another species Pollen may be blocked by a chemical barrier

Question 57

define sexual selection. describe

Answer 57

Sexual selection: evolution has resulted in behaviour acting as a reproductive isolating mechanism. Select a mate based on specific traits- good health, fitness, high adaptive value Alleles of good traits are inherited Animals may compete for mates Conflicts ensure ‘fittest’ phenotypes win- creates a more favourable gene pool

Question 58

define postzygotic isolating mechanisms

Answer 58

Postzygotic isolating mechanisms: prevent as zygote of two different species from developing into a fertile adult.

Question 59

types of post zygotic isolating mechanisms?

Answer 59

hybrid inviability, reduced hybrid viability, hybrid sterility

Question 60

hybrid inviability

Answer 60

Hybrid inviability: sperm from one species does successfully fertilise the egg from another species to from a hybrid but it has unmatched chromosomes- zygote does not survive.

Question 61

reduced hybrid viability

Answer 61

Reduced hybrid viability: zygote survives but will not fully develop to reach adulthood.

Question 62

hybrid sterility

Answer 62

Hybrid sterility: hybrids that reach adulthood usually are infertile. Without homologous chromosomes, meiosis cannot occur to form gametes (at all or they are abnormal) First generation of hybrids can be semi-fertile and can sometimes mate with another hybrid Second generation is sterile and is an isolating mechanism (hybrid breakdown)

Question 63

define speciation

Answer 63

the evolution of a species form an ancestral species.

Question 64

define allopatric speciation

Answer 64

Allopatric speciation: population becomes divided by a geographical barrier. Overtime different environmental selection pressures and or genetic drift drive changes May eventually be unable to interbreed- different species

Question 65

define artificial selection/selective breeding

Answer 65

humans decide which individuals may breed.

Question 66

how does selective breeding occur? compared to GMO

Answer 66

Steps: Determine desired trait Interbreed those with trait Select offspring with best form of trait and interbreed them Continue until population reliably reproduced desired trait Genetically modified organisms is a faster and more specific approach to this

Question 67

how does selective breeding in plants work?

Answer 67

Higher quality food Seeds collected from individuals with largest yield Seeds are planted and cross pollinated with plants with similar traits May be modified for disease resistance

Question 68

selective breeding in animals?

Answer 68

Selected for physical quality, quality of produce

Question 69

what are potential detrimental effects of selective breeding?

Answer 69

Decreases genetic variation of other alleles and increases homozygosity Gene linkage means that selecting for one allele may result in the selection of other traits Selective breeding reduces resistance to environmental change Low genetic variation, all individuals similar If environment changes, selective pressures change Vulnerable Selective breeding reduces biodiversity Selectively bred replace wild varieties Food security is at risk Food arks and seed banks formed to reduce risk Selective breeding can increase genetic abnormalities Genetic diseases that are rare in wild are common in pure bred animals Many recessive conditions but interbreeding has increased the frequency of alleles- increases chance of homozygous recessive conditions