Mcat Biology Lecture 9

Front 1

First filial

Back 1

F1 generation

first generation after crossing

Front 2

Dominant

Back 2

trait present in F1 generation

Front 3

Recessive

Back 3

trait not present in F1 generation

Front 4

F2 generation

Back 4

second generation after F1 crossed with F1

expressed both dominant and recessive traits (3 to 1 ratio)

Front 5

Mendelian ratio

Back 5

3 to 1 ratio of dominant to recessive traits expressed after F1 self-pollination

Front 6

Phenotype

Back 6

expression of a trait

Front 7

Genotype

Back 7

individual's genetic make up

Front 8

complete dominance

Back 8

dominant phenotype still expressed even if heterozygous genotype

Front 9

Locus

Back 9

position on respective chromosomes

Front 10

Allele

Back 10

each gene contributes an allele to the genotype, however only one allele (dominant) is expressed

Front 11

homozygous

Back 11

2 dominant or 2 recessive alleles

Front 12

heterozygous

Back 12

1 dominant and 1 recessive allele

hybrid

Front 13

law of segregation

Back 13

Mendel's 1st law of heredity

alleles segregate independently of each other when forming gametes

any gamete is equally likely to posses any allele

phenotypic expression of alleles is not a blend of 2, but an expression of the dominant allele (principle of complete dominance)

Front 14

inbreeding

Back 14

mating relatives

doesn't change frequency of alleles, but does increase number of homozygous individuals within a population

Front 15

outbreeding

Back 15

outcrossing

mating of nonrelative which produces hybrids or heterozygotes

Front 16

Punnet square

Back 16

used for predicting genotypic ratios of offspring

genotypes of all possible gametes of each parent are displayed in 1st column and 1st row respectively

alleles are combined in corresponding boxes to show possible genotypes of offspring

Front 17

Law of independent assortment

Back 17

Mendel's 2nd law of heredity

genes located on different chromosomes assort independently of each other

if 2 genes are on same chromosomes, likelihood that they will remain together during gamete formation is indirectly proportional to distance separating them (closer on chromosome, more likely they will remain together)

Front 18

Dihybrid cross

Back 18

more than 1 allele being investigated

make assumption that genes are on separate chromosomes and will assort independently of each other

phenotypic ratio: 9:3:3:1

Front 19

Sex chromosome

Back 19

23rd pair of chromosomes that establishes sex of individual

Front 20

Karyotype

Back 20

map of chromosomes

Front 21

sex-linked

Back 21

when gene is found on sex chromosome

Y chromosome doesn't carry allele for sex-linked traits, thus allele carried by X chromosome in male is expressed whether dominant or recessive

Front 22

Barr body

Back 22

in most somatic cells, one of the X chromosomes (females) with condence and most of its genes will become inactive forming a tiny dark object

formed at random, therefore active allele is split about evenly among cells

in most cases, recessive phenotype is only displayed in homozygous recessive individuals

Front 23

carrier

Back 23

female may carry recessive trait on her 23rd pair of chromosomes without expressing it

she is a carrier for the trait

recessive trait has a strong chance of being expressed in her male offspring regardless of genotype of mate

Front 24

gene pool

Back 24

total of all alleles in a population

Front 25

evolution

Back 25

change in the gene pool

Front 26

Classification system of animals

Back 26

Kingdom
Phylum
Class
Order
Family
Genus
Species

Front 27

Vertebrata

Back 27

subphylum, in the phylum Chordata

Front 28

Mammalia

Back 28

class to which all animals belong

Front 29

Chordata

Back 29

phylum to which all animals belong

Front 30

Aves

Back 30

phylum chordata
class aves

ex: birds

Front 31

domains

Back 31

new superkingdoms

1. bacteria
2. archae
3. eukarya

Front 32

Ontogeny reapitulates phylogeny

Back 32

course of development of an organism from embryo to adult reflects its evolutionary history

ex: human fetus has pharyngeal pouches reflecting gilled ancestor

Front 33

species

Back 33

all organisms that can reproduce fertile offspring with each other

all organisms which normally reproduce selectively fit offspring in the wild

Front 34

niche

Back 34

way in which a species exploits its environment

no two species can occupy the same niche indefinitely

Front 35

survival of the fittest

Back 35

predicts one species will exploit the environment more efficiently, eventually leading to extinction of the other with the same niche

Front 36

definition of the "fittest" organism

Back 36

organism which can best survive to reproduce offspring with will, in turn, reproduce offspring and so on generation after generation

Front 37

R-selection

Back 37

reproduction strategy

involves producing large numbers of offspring that mature rapidly with little or no parental care

high brood mortality rate

exponential population growth curves

found in unpredictable, rapidly changing environments affected by density independent factors such as floods or drastic temperature changes

Front 38

K-selection

Back 38

reproduction strategy

involves small brood size with slow maturing offspring and strong parental care

sigmoidal growth curve which levels off at carrying capacity (max number of organisms that an environment can maintain; density dependent factor)

Front 39

speciation

Back 39

process by which new species are formed

when gene flow ceases between 2 sections of a population, speciation begins

factors include:
geographic, seasonal and behavioral isolation

Front 40

adaptive radiation

Back 40

several separate species arise from a single ancestral species

ex: 14 species of galapagos finches that evolved from one ancestor

Front 41

evolutionary bottleneck

Back 41

species faces crisis so severe as to cause shift in allelic frequencies of survivors of crisis

Front 42

divergent evolution

Back 42

when 2 or more species evolving from same group maintain a similar structure from common ancestor (homologous structure)

Front 43

convergent evolution

Back 43

when 2 species independently evolve similar structures (analogous or homoplastic)

ex: wings of bats and birds; 2 do not share a common ancestor from which they received wings

Front 44

polymorphism

Back 44

occurence of distinct forms

ex: chicken plumage is either barred or non-barred

Front 45

symbiosis

Back 45

relationship between 2 species

Front 46

mutualism

Back 46

relationship between 2 species which is beneficial for both

Front 47

commensalism

Back 47

relationship between 2 species which is beneficial for 1 and doesn't affect the other

Front 48

parasitism

Back 48

relationship between 2 species which is beneficial for 1 and detrimental for the other

Front 49

Hardy-Weinberg Equilibrium

Back 49

No change in gene pool of sexually reproducing population possessing 5 conditions:
1. large population
2. mutational equilibrium (rate of forward mutations equals rate of back mutations)
3. immigration or emigration must not change the gene pool
4. random mating
5. no selection for the fittest organism

Front 50

genetic drift

Back 50

one allele may be permanently lost due to death of all members having that allele (factor in small populations)

not caused by selective pressure (random)

Front 51

binomial theorem

Back 51

p^2 + 2pq + q^2

predicts genotype frequency of a gene with only 2 alleles in a population in Hardy-Weinberg equilibrium

p + q = 1

p: dominant allele
q: recessive allele
2pq = frequency of heterozygotes
p^2 = frequency of dominant homozygotes
q^2 = frequency of recessive homozygotes

Front 52

Urey-Miller experiment

Back 52

early experiments attempting to recreated the atmosphere of early earth, which resulted in autosynthesis of molecules such as urea, amino acids and adenine

Front 53

coacervates

Back 53

what first cells evolved from

lipid or protein bilayer bubbles

spontaneously form and grow from fat molecules suspended in water

assimilated carbon from methane and carbon dioxide in early atmosphere

Front 54

earliest fossils

Back 54

organisms date at 3.6 billion years old

Front 55

photosynthetic bacteria

Back 55

2.3 billion years ago

ancestors of cyanobacteria

able to use sunlight and water to reduce carbon dioxide

first oxygen producing organisms

Front 56

Chordata

Back 56

phylum containing humans

chordates have bilateral symmetry (doesn't mean backbone)

they are deuterostomes

possess a coelom, a notochord at some stage in development, pharyngeal slits, a dorsal hollow nerve cord and a tail

Front 57

deuterostomes

Back 57

anus develops from or near blastopore

Front 58

notochord

Back 58

embryonic axial support

not a backbone

Front 59

Vertebrata

Back 59

subphylum


notochord replaced by a segmented cartilage or bone structure

distinct brain enclosed in a skull

most chordates are vertebrates