Cell and DNA Replication

This took so long to understand ;-;

why is cell replication so important for single celled organisms?

only way for them to grow

why is cell replican so important for multicelled organisms

need it to grow and replace bad cells

what does cell dividing do

produces 2 identical daughter cells

what is cell differentiation

cells stop dividing to work as structure and function

what is apoptosis

cell death

what are cell cycle regulators

molecular signals that control the cells cycle

what happens if the cell cycle regulators fail

cancer

what are the two different types of cell cycle regulators

stimulating proteins, and inhibitory proteins

What do stimulate proteins encoded by

proto-oncogenes

what happens if there are mutations in the oncogenes

more stimulating/protein production and cancer

how many allels are required to mutateoncogenes

1

is mutated oncogenese dominant or recessive

dominant

does mutation of oncogenes cause an increase or decrease in the function

increase

What do stimulate proteins do

moves the cell to the checkpoint to see if it’ correct

whats an example of a stimulating protien

CDK-cyclin, APC/C

What do inhibitory proteins do?

stop cell from going through checkpoints

what are inhibitory proteins encoded by

tumor suppression genes

what happens if theres a mutation in tumor suppression genes

loss of inhibition of the cycle

how many alleles need to be mutated for tumor suppression genes

2

is mutated tumor suppression genes considered dominant or recessive

recessive

does this result in a loss or gain of function

loss

whats an example of a inhibitory protein

P53 (G1 checkpoint), Rb

what causes cancer

improperly regulated cell cycle

What are checkpoints

sees if its replicating properly

What is the first step of interphase

G1 (Gap 1)

What does G1 do

cell increases in size preps to replicate, does function

When can the cell enter G0 phase

when exiting the G1 phase

What is G0

when a cell exits the cell cycle

what is the 2nd step of interphase

S (Synthesis)

What does S do

replicates its DNA, ends with 2 sets of chromosomes

what is the third stage of interphase

G2 (Gap 2)

what does G2 do

Grows and preps

What does mitosis used for

growth, repair, asexual reproduction

How many cells does mitosis produce in the end

how many chromosomes does each cell have when produced by mitosis

46

how many times does a cell divide in mitosis

1

Whats the first phase of mitosis

prophase

What happpens during prophase

forms +condenses chromosomes, spindles for and attach

what are spindles attached to

centrioles

whats the second phase of mitosis

metaphase

what happens during metaphase

chromosomes line up in middle of cell

Whats the third stage of mitosis

anaphase

wwhat happens during anaphase

sister chromatids are pulled apart 

whats the foruth stage of mitosis

telophase

what happens during telophase

spindles delete, chromosomes lose shape, undos all changes from prophase

Whats the fifth stage of mitosis

cytokinesis

what happens during cytokinesis

splits cytoplasm down middle

what forms during cytokinesis in plant cells

cell plate

what forms during cytokinesis in animal cells

cleavage furrow forms

What is the purpose of meiosis

produces gametes, needed for sexual reproductions and genetic diversity

how many cells are produced by meiosis

4

how many chromosomes are in mieosis each cell

23

why is there only 23 chromosomes in gamates

so when they merge with other gamete there’s 46 total instead of however many

how many times does meiosis divide

twice

What are the phases like of meiosis

Goes through all the phases of mitosis, but twice, with the addition of crossing over and skipping the 2nd interphase

what makes up chromosomes

DNA twisted around histones

what are the different types of chromosomes

haploid and diploid

how many chromatids does haploids have?

1

how many chromatids does diploids have?

2

Where in the cell cycle does DNA replication take place?

S

Where does DNA replication begin

origin of replication

What creates the replication fork

Enzyme Helicase

What is a replication fork

where the double helix seperates

What is a replication bubble

bubble formed by replication fork

how many bubbles do prokaryotes have

1

how bubbles doe eukaryote have

a lot

What keeps the replication fork open

single strand binding (SSB)

What helps relieve stress on dna through bubble after SSB

topoisomerase

What creates attachment points for DNA polymerase through RNA primers

Primase

what adds nucleotides

DNA polymerase

where are nucleotides added to

3’ end

why are nucleotides only added to 3’ end

makes correct anti-parallel pattern

What are leading stands

1 long strand built on 3’ making it a 5’

Whats a lagging strand

groups of Okazaki fragments that forced to go away, then jump backwards, since they can only follow anti-parallel structure (check study guide, makes more sense)

What are Okazaki Fragments

little segements joined together by ligase that make up the lagging strand

How does proofreading work during DNA replication?

DNA polymerase checks if Chargaff’s rule is being obeyed

What type of replication is DNA replication

Semiconservative

What makes DNA replication a semiconservatuve model

fork is opend with two seperate old stand, which each gets a new new strand

Why do you have to do DNA repair

chemicals and UV rays

How does DNA repair work

bad stuff gets cut out, DNA polymerase puts DNA in and Ligase glues it all together