more genetics

Question 1

epistasis

Answer 1

refers to when one gene is dominant (overrides) a whole ‘nother gene

Question 2

locus

Answer 2

location on chromosome

Question 3

polyploidy

Answer 3

abnormal condition such as trisomy

Question 4

prophase I

Answer 4

nucleus dissolves; chromatin condenses into chromosomes (at this point, diploid as well as replicated )

Question 5

synapsis

Answer 5

arrangement of chromosomes during prophase I, where homologous chromosomes are paired in the center. A pair is called a BIVALENT or TETRAD

Question 6

crossing over/recombination

Answer 6

the exchange of alleles btw homologous pairs during prophase I

Question 7

synaptonemal complex

Answer 7

protein structure that mediates synapsis, forming as early as prophase. These proteins keep the neighbouring chromatids bound close so as to facilitate recombination

Question 8

nondisjunction

Answer 8

when either homologous chromosomes fail to separate, or, when sister chromatids fail. Can result in trisomy or monosomy

Question 9

law of segregation

Answer 9

two alleles in an organism are separated and passed on SINGLY to offspring

Question 10

law of independent assortment

Answer 10

alleles of one gene do not follow other alleles - not always true though

Question 11

codominance

Answer 11

heterozygous situation where two alleles are both expressed but aren’t blended; AB blood type is example

Question 12

incomplete dominance

Answer 12

heterozygous situation where phenotype is a blend (e.g. pink flowers)

Question 13

pleiotropism

Answer 13

gene that alters many seemingly unrelated parts of the phenotype

Question 14

polygenism

Answer 14

traits that are under influence of several genes, e.g. height

Question 15

penetrance

Answer 15

likelihood that a person with given genotype will express the expected phenotype (e.g. breast cancer gene doesn’t always result in cancer)

Question 16

recessive lethal alleles

Answer 16

alleles which cause death when they are homozygous recessive

Question 17

linkage

Answer 17

when genes defy law of independent assortment

Question 18

frequency of recombination

Answer 18

= number of recombinant phenotypes / total number of offspring
when genes are further apart on chromosome, recombination frequency is higher

Question 19

Hardy weinberg law

Answer 19

the frequencies of alleles in a population will NOT change over time, given
no mutation
no migration
no natural selection
random mating
population sufficiently large to prevent random drift
Where homozygotes = pp or qq; heterozygotes = 1pq
Takes 2 generations to restore equilibrium after disrupted

Question 20

artificial selection

Answer 20

e.g. humans control animal mating

Question 21

sexual selection

Answer 21

selection via mate choice

Question 22

kin selection

Answer 22

e.g. a chimpanzee protects cousins and relatives in its troupe

Question 23

prezygotic barriers

Answer 23

one of the barriers to different species reproducing

types: ecological (location), temporal, behavioral (courtship ritual), mechanical, gametic (egg and sperm can’t connect)

Question 24

postzygotic barriers

Answer 24

barriers to hybridization that occur after fertilization.
Types: hybrid inviability (may die as embryo), hybrid sterility (mules are sterile), hybrid breakdown (hybrid’s offspring sterile)

Question 25

allopatric isolation

Answer 25

speciation occuring due to geographical isolation; whereas sympatric speciation is speciation in same area

Question 26

anagenesis

Answer 26

one species simply becomes another through drift, such that it couldn’t mate with its own ancestors

Question 27

homologous structure

Answer 27

structures shared by common descendants (bat wings and monkey hands)

Question 28

analogous structure

Answer 28

similar looking structures that converged from different species (whale flipper and shark fins)

Question 29

parallel evolution

Answer 29

two species go through similar changes due to same pressures (e.g. in ice age, all animals grow to tolerate cold)

Question 30

order of taxonomy

Answer 30

domain, kingdom, phylum, order, family, genus, species

Question 31

reducing environment

Answer 31

Earth’s early atmosphere had no O2

Question 32

proteinoids

Answer 32

proteins made from abiotic synthesis

Question 33

protobionts

Answer 33

earliest forms of ‘life’
microspheres - droplets of proteinoids
liposomes - lipid layer surrounding microsphere
coacervates - have proteins, polysaccharides, nucleic acids

Question 34

back cross

Answer 34

simply the breeding of F1 generation with one of its parents
all test crosses are back crosses; they are just a specific type where you cross a suspected heterozygous F1 with a homozygous recessive parent to determine if they are indeed heterozygous

Question 35

hemizygotic

Answer 35

synonym for homozygous