12 - CELL CYCLE & KARYOTYPE

diploid

2 sets of chromosomes (2n) or 46

haploid

one set of chromosomes (n) or 23

homologous chromosomes

Chromosomes that have the same sequence of genes and the same structure

nonhomologous chromosomes

chromosomes that do not match because they have different sets of genes (chromosome 1, chromosome 2)

paternal chromosome

a chromosome inherited from the father

autosomal chromosomes

22 chromosome pairs that control traits NOT related to gender--same in females and males.

maternal chromosome

chromosome inherited from the mother.

sex chromosome

Chromosomes that determine the sex of an individual

gamete

specialized cell involved in sexual reproduction (i.e., sperm, egg)

somatic

body cells (liver, skin, blood)

Rb protein (retinoblastoma)

This tumor suppressor gene protein controls progression past G1 checkpoint, before S and is a gatekeeper protein

binary fission (prokaryotic replication)

prokaryotes

- reproductive signals (nutrients, pH, osmolarity)

- replication of DNA (dsDNA [circular] chromosome, ORI moving bidirectionally, ends at TER site, cell grows in size)

- segregation: replicate at center, ORI regions move to opposite poles

- cytokinesis: begins immediately after replication, FtsZ protein disassembles to fibers & Z-ring

Aneuploidy

Abnormal number of chromosomes.

replisome

large, coordinated multiprotein complex that carries out DNA replication. It acts at the replication fork to unwind parental double-stranded DNA and synthesize two new complementary strands simultaneously

eukaryotic replication

- reproductive signals: unicellular (similar to bacteria - respond to

environmental signals); multicellular - signals come for the external &

internal environments (organs & tissues)

- replication of dna: many dsDNA (linear) chromosomes; replication starts

at multiple ORI sites within each chromosome

- segregation of DNA molecules (mitosis): complex process for separation of

sister chromatids; each new cell has the same amount of DNA

- cytokinesis: different mechanisms in plants and animals

cell plate

plant cell - double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis

cleavage furrow

animal cell - the area of the cell membrane that pinches in and eventually separates the dividing cell

interphase

pd. of preparation for mitosis

G0

non-dividing state (neurons, heart cells)

G1

unreplicated chromosomes (single chromatid)

production of organelles

cell growth and regular functioning

-

adequate cell size, nutrients, social signals

S

DNA replication

chromosomes "X" - two sister chromatids attached at centromeres

-

dna completely replicated undamaged

G2

prep. for mitosis

cell growth, replication of organelles

synthesis of spindle apparatus

-

chromosomes replicated, dna undamaged, activated MPF

M

mitosis and cytokinesis

-

chromosomes attached to spindle apparatus, properly segregated, MPF absent

cyclin protein

regulates cell cycle, increases or decreases in density depending on cell cycle phase

can actually turn on cell division and also turn it off also

MPF (M-phase promoting factor)

A protein complex required for a cell to progress from late interphase to mitosis; the active form consists of cyclin and cdc2, a protein kinase. (CDK catalyzes phosphorylation of other proteins, starts mitosis)

cdk + cyclin

conformational change

allosteric regulation

process where regulatory molecule binds to protein at a site other than active site -> shape change

activation of MPF

- cyclin binds to CDK -> both cdk sittes phosphorylated

- late G2 -> phosphotase removes inhibitory phosphate, activating MPF

- MPF (kinase) activates M-phase effector proteins

deactivation of MPF

- late M-phase (anaphase)

- ubiquitin attached to cyclin from enzyme complex degraded in proteosome

phosphatase

removes phosphate

negative feedback inhibition

active MPF activates APC, which eventually destroys own cyclin

restriction point (R)

G1 -> S-phase

tumor suppressors

regulatory proteins that halt cycle / trigger apoptosis (p21-p53-RB)

cell cycle arrest

1. DNA damage detected during G1

2. p53 activated by phosphorylation

3. activated p53 binds to DNA and initiates

transcription of p21 gene; p21 protein is made

4. p21 protein binds to C1/S cyclin-Cdk, inhibiting its

ability to phosphorylate RB

5. unphosphorylated RB binds with E2F1 and DP,

inhibiting transcription of many cell cycle genes

6. inducing cell cycle arrest

7. when DNA is repaired, p21 breaks down allowing

cell cycle to proceed

platelet derived growth factor

site of a cut and bleed;

stimulation of cell division to heal the wound

Erythropoietin

glycoprotein secreted by kidneys; stimulate red blood cell production in bone marrow

interleukins

secreted by white blood cells; primary function in activation and differentiation of immune cells during inflammatory and immune responses

ploidy

# of chromosomal sets in cell