BIO101 Chapter 11 Unit 3

binary fission

form of asexual reproduction and cell division where a single organism or cell copies its genetic material and splits into two identical daughter cells.

(eukaryotic) cell cycle

two distinct phases, interphase and m phase

interphase

preparatory phase of cell cycle, g0, g1, S phase, g2

g0 phase

when a cell is not actively dividing

g1 phase

involves cell growth and expression of regulatory protiens

s phase

involves the synthesis of DNA

g2 phase

involves prep for mitosis

semiconservative model

said that after DNA replication, the new DNA duplex consisted of one old strand and one new strand

conservative model

said that after DNA replication the new DNA duplex consisted of two new strands and the old strands stayed intact

DNA polymerase

adds nucleotides to the growing strand of DNA

RNA primase

synthesizes a short RNA primer complimentary to the parental strand

helicase

unwinds DNA at the replication fork

single stranded binding proteins

bind ssDNA so they to not rebind

topoisomerase

cuts the DNA backbone to prevent stress from unwinding

leading strand

replication is continuous, 1 rna primer needed

lagging strand

replication is discontinuous, made of okazaki fragments, multiple RNA primers needed, DNA ligase stitches it all

okazaki fragments

short sections that make up lagging strand b/c of directionality issues

RNA primers

provides a starting point for DNA polymerase in DNA replication

DNA ligase

joins fragments of DNA together once synthesis is complete

proofreading

DNA polymerase goes through this and when a nuelceotide is incorrect, its removed and replaced with the right one

prokaryote replication of circular dna

replication starts at the origin and move around the circular chromosome in both directions

eukaryote replication of linear dna

long line of replication, multiple origins of replication, end replication problems where DNA polymerase cant replicate ends of linear chromosomes

telomeres

ends of linear chromosomes, 5’- TTAGGG-3’ repeated thousands of times, extends ends of chromosomes

telomerase

allows the shortend 3’ end of the template strand to be restored by teh addition of more telomere repeats

mitosis

cell division

prophase

chromosomes condense into X shape, centrosomes radiate microtubules and migrate to opposite poles

prometaphase

mictroubules of the miotic spindle attach to chromosomes, nuclear envelope begins to break down

kinetochores

a protein complex the associates with the centromere and serves as an attachment site for microtubules

metaphase

chromosomes align in center of cell

anaphase

sister chromatids seperate and travel to opposite poles

telophase

nuclear enevlope reforms and chromosomes decondense

cytokinesis: animal cells

pinch in two via cleavage furrow

cytokinesis: plant cells

build a cell plate down the middle

cyclins

proteins that appear and disappear throughout the cell cycle and activate cyclin dependent kinases (CDKs)

cyclin d and e -CDK

prepare cell for DNA synthesis

cyclin A CDK

initiates DNA synthesis and prevents DNA from replicating more than once per cycle

cyclin B CDK

prepares cell for mitosis

DNA damage checkpoint

in G1 before entering S phase checkpoint, checks if DNA is damaged

DNA replication checkpoint

at end of G2, checks if all DNA is replicated

Spindle assembly checkpoint

before anaphase in mitosis, in M stage of cell cycle, are all chromosomes attached to the spindle?

p53 regulation

found in nucleus, gets phosphorylated when cell is damaged, then activates genes that inhibit cell cycle which gives cell time to repair

apoptosis

regulated cell death

oncogene

cancer causing gene

protooncogene

normal genes that is important in cell division and has the potential to become cancerous if mutated

tumor supressor genes

encode proteins whose normal activities inhibit cell division