Unit 5 AP Bio

mitosis

creates two identical daughter cells, asexual reproduction, division of replicated chromosomes

meiosis

creates four unique daughter cells

checkpoint

a critical control point in the cell cycle, gives a “go-ahead” signal before going on to the next phase

g1 checkpoint

“restriction point”, places cells in a non-dividing phase (g0)

g2 checkpoint

uses protein kinases to signal “go-ahead” for the g2 phase, activated by a protein complex

MPF

CDK and cyclin, protein complex required for a cell to progress to g2 to mitosis, triggers a chain of protein kinases activations

CDK

a protein kinase, inactive without cyclin, remains constant throughout the cycle

cyclin

protein whose concentration builds during interphase; when enough is present, active MPF is formed

active MPF

triggers mitosis

cytokinesis

division of the cell’s cytoplasm

chromosome movement

chromosomes move via a motor protein at the kinetochore, they walk themselves down the spindles to separate

PDGF

platelet-derived growth factor, stimulates cell division to heal injuries

density dependent inhibition

high density=no cell division, low density= cell division

anchorage dependent

inhibition of cell division unless the cell is attached to a substratum, prevents cells from dividing and floating off in the body

uncontrolled cell division

errors in mitosis (making new cells) and apoptosis (cell death), causes cancer

meiosis results

four cells produced, chromosome number halved, gametes or sex cells made, genetic variaiton increased

asexual reproduction

parents passes all genes to offspring, uses mitosis

sexual reproduction

two parents contribute dna to an offspring

meiosis purpose

to reduce the number of the chromosomes by half, prevents doubling of chromosome numbers during sexual

karyotype

an ordered display of the pairs of chromosomes from a cell

homologous pairs

two chromosomes in a pair

crossing over

in prophase 1, homologous pairs share genetic info

law of dominance

the dominant allele is expressed and the recessive alleles is hidden (until the dominant allele is absent)

law of segregation

the two alleles for each trait separate during gamete formation and end up in different cells

law of independent assortment

the inheritance of one trait does not affect the inheritance of another (eg. hair color does not impact height)

probability

the chance that an event will occur out of the total number of possible events

incomplete dominance

blending of traits (ex. red x white = pink offspring)

codominance

both alleles are expressed in the phenotype (ex. spots or stripes)

multiple alleles

when there are more than 2 alleles for a trait

polygenetic inheritance

factors that expressed as continuous variation

mitochondrial inheritance

mitochondria pass from mother to offspring through egg; no mitochondria from sperm are present in a fertilized egg

epistatic inheritance

one gene overrides others

recessive pedigree

a trait is skipped in a generation

sex-linked traits

genetic traits whose expression are dependent on the sex of the individual

x-linked gene

mostly present in males

not x-linked genes

mostly present in females

barr bodies

seeing partial expression or expression only in certain areas