Genetics Exam 2 Review

Question 1

What are the assumptions of Hardy Weinberg equilibrium ( there are 5 )

Answer 1

• no mutations
• no genetic drift
• no migration
• no natural selection
• include random mating

Question 2

What is the Hardy Weinberg Equilibrium equation?

Question 3

Directional Selection

Answer 3

• favors the extreme phenotyoe ( unlikely ) to promote higher levels of fitness

Question 4

What is balancing selection?

Answer 4

• when a population favors the maintance of two alleles for a individal
• heterozygote advantage
  ex: sickle cell

Question 5

What is Distuptive/Diversifying Selection?

Answer 5

• when a population favors 2+ phenotyoes in an enviornment
• common in diverse enviornments (increases genetic diversity)
  ex: snail shells

Question 6

What is Stabalizing Selection?

Answer 6

• Selection against extremes (in the middle)
• leads to a decrease in genetic diversity

Question 7

What is Fitness?

Answer 7

the likelihood that a genotyoe will reproduce

Question 8

Howcan fitness be calculated?

Answer 8

1) identify the genotype with highest reproductive success, and set this value to 1
2) compare other genotypes with this one

ex:
AA= 5 WAA= 1
Aa= 4 WAa= 4/5
aa= 1 Waa= 1/5

Question 9

The Equation of Directional Selection + Hardy Weinberg

Answer 9

1) Find mean population fitness
~ w =p^2WAA + 2pqWAa + q^2Waa

2) Apply this to another set of allee freqencies
~ AA=p^2WAA/( mean population fitness )
~ Aa = 2pqWAa/(mean population fitness )

Question 10

What is genetic drift?

Answer 10

• change in genetic frequency
• random allele freqency
• common in small population

Question 11

What is the bottleneck effect (type of genetic drfit)

Answer 11

• Population collapse
• Decrease in genetic diversity

Question 12

What is the Founder Effect?

Answer 12

• When a small population migrates to a new enviornment
• New population has a lower genetic diversity

Question 13

What is migration in genetics?

Answer 13

• the transfer of alleles between populations

Question 14

What does migration causes within/between populations?

Answer 14

• Decrease in diversity within populations
• Increase in between populations

Question 15

What is assortative mating?

Answer 15

Assortative mating is non random mating

Question 16

Positive Assortative Mating

Answer 16

The probability of mating with the same phenotype

Question 17

Negative Assortative mating

Answer 17

Low probability of mating with the same phenotype

Question 18

What is inbreeding?

Answer 18

Mating between genetically relalated individuals

Question 19

What are the charateristics/effects of inbreeding?

Answer 19

• Its rare
• Consist of recessive diseases
• Causes inbreeding depression leading to a reduction of fitness.

Question 20

What are complex traits?

Answer 20

• traits determined by multiple genes and/or enviornmental factors

Question 21

What are quantative traits?

Answer 21

A gradient amount of traits that can be quantified(counted)

ex: height, speed, weight

Question 22

Charateristics of Race in Genetics

Answer 22

• race is not bounded by genetics
• race is associated traits are continious and variable within groups
• genetic variation in humans are continious and not discrete

Question 23

True or False:
There is more genetic variation within sociallt identified groups (races) than between different groups.

Answer 23

True

Question 24

What is Heritability?

Answer 24

Heritability is trait variation due to genetic variation

Question 25

How can we find heretiability?

Answer 25

Vp = VG + VE

Question 26

What does being “inbred” mean for calculating heretability?

Answer 26

1) Inbred ~ VG=0 2) Vp=VE

Question 27

How to solve for Heretiability?

Answer 27

If Given VE just place in formula and solve for VG

Question 28

What does Narrow Sense Heritability mean?

Answer 28

Nn^2 = r(obs)/r(exp)

Question 29

What does r(obs) mean?

Answer 29

r(obs) is the correlation of a trait between related individuals

Question 30

What is r(exp)?

Answer 30

r(exp) refers to expected correlations based on known ratios?

Question 31

What are the known r(exp) ratios?

Answer 31

identical twins: 1.0 siblings: 0.5 parent offspring: .5 uncle/niece: .25

Question 32

What is an example of gene and enviornmental interactions?

Answer 32

1) its the direct role of the influence of the enviornment of genes ex: minerals in soil the supplemented soil helps the heterozygote and homozygous recessive genes be as atall as the homozygous dominant gene

Question 33

What is a point mutation?

Answer 33

A mutation that results in a change in a single base pair

Question 34

What is an affect of duplication in regards to evolution?

Answer 34

The formation of new species overtime which creates paralogs and orthologs

Question 35

What is a paralog?

Answer 35

Different mutation of the same species ( different variants of the same gene) within a species

Question 36

Orthologs

Answer 36

Different mutation ( different variants of the same gene ) between species

Question 37

What is Allopatric Speciation?

Answer 37

When there is an enviornmental barrier that seperates two populations

Question 38

What is parapatric speciation?

Answer 38

When there is a partial barrier between two populations that creates a hybrid zone

Question 39

What is sympatric speciation?

Answer 39

When populations are mixed in the same area

Question 40

What is prezygotic reproductive isolation?

Answer 40

When the formation of a zyote is prevented ( mating prevention )

Question 41

What is postzygotic isolating mechanisms?

Answer 41

When the developement of a viable individual after fertilization has taken place - Genomic incompatabilities that disrupt embryonic developement or lead to steralization

Question 42

What is a phylogentic tree?

Answer 42

It is a siagram that describes the phylogeny (evolutionary developement) of a species

Question 43

What indicates that a tree is most parisominous?

Answer 43

When the tree has the fewest amount of evolutinary events ( mutations present )

Question 44

What is a molecular clock?

Answer 44

- Based on mutation rates - Rate is constant - “time calibration” - when notes are placed at specific time points

Question 45

What is the calculation for mutation rate?

Answer 45

#new mutations / generation

Question 46

What is X-inactivation?

Answer 46

Chemical modifications that turn off certain chromosomes without changing DNA sequence

Question 47

What is maternal effect?

Answer 47

When DNA/RNA is added to the eggs from the mom and directly influences phenotype outcome

Question 48

Maternal Inheritance

Question 49

What is Cytoplasmic Inheritance?

Answer 49

- Mutations from organelles (caused by mom) - Mitocondria/Chloroplast

Question 50

What is heteroplasmy?

Answer 50

- When cells have more than 1 organelle variant - Dictated by mom (mitocondria/chloroplast)

Question 51

What is epigenetics?

Answer 51

Epigenetics is a chemical modifications - occur after gene expression - can be inheritted - can be reversed

Question 52

What are some examples of epigentic-dosage compensation?

Answer 52

- gene expression regulation Placental Mammals: X-inactivation Drosphilla: X in males show double expression Cellegans: X chromosomes in females have a 50% reduction

Question 53

What is a population?

Answer 53

Individuals that interbreed in some areas

Question 54

What is x-inactivation?

Answer 54

- When only 1 x-chromosome is utilized so the remaining x-chromosomes condense into a barr body (become silent)

Question 55

What is allele frequency?

Answer 55

(# copies of an allele)/(total # alleles)

Question 56

What is genotype frequency

Answer 56

(# individuals w/ genotyoe)/(total # individuals)

Question 57

What is a molecular clock?

Answer 57

A way to measure mutations in evolution which is based on a constant mutation rate

Question 58

What describes when a tree is most parsimonious?

Answer 58

When it has the fewest mutations