cell and molec exam 3

wee 1

protein kinase responsible in phosphorylation

cdc 25

dephosphorylate the sites through phosphatase function

cyclin protein also directs the CDK to specific target proteins

How do different cyclin-CDK complexes trigger different cell-cycle events?

CDK inhibitor proteins (CKIs)

-responsible for inhibitory phosphorylation
- protects from DNA damage for generations
- rise and fall of cyclin cycles is the primary control

anaphase promoting complex or cyclosome (APC/C)

- allows for occurrence of anaphase
- key regulator of metaphase to anaphase transition
- member of ubiquitin family of enzymes

CDC 20

what activates APC?

ubiquitin

usually a signal for degradation

APC polyubiquitylate

targets proteins for destruction via proteasome

securin

holds sister chromatid pairs together

destroys the securin so that sister chromatids can separate

what happens when polyubiquitylate binds to securin?

SCF

-ubiquitin ligase
-ubiquitinates (break down) CK 1 proteins late in G1, and G1/S, cyclins in early of S phase

CDC6 and CDT1

what proteins collaborate with ORC to load inactive DNA helicase around the DNA next to the origin

s-Cdk

what triggers origin activations by phosphorylating initiator proteins

CDC 6

what is needed to prevent the assembly of new preRC until the end of mitosis

increase the production of histone proteins

what happens during S phase to provide raw material needed for packaging?

cohesin

-facilitates the attachment of 2 sister chromatids
- deposited at many locations along the length of each sister chromatid
- forms ring like structure around the two sister chromatids

ring-like

what structure does cohesin form around the two sister chromatids?

sister chromatids

what helps organize DNA until it is time to separate?

chromosome condensation

large scale reorganization of the intertwined sister chromatids into compact rod-like structures

M-cyclin and M-Cdk

what accumulates prior to Mphase

CDC activation kinase (CAK)

what tries to activate Cdk1 but is not able to because of Wee1

Wee 1

inhibits Cdk1 through inhibitory phosphorylation sites

Cdc 25

phosphatase removes the inhibitory phosphates on M-Cdk1-cyclin

Wee 1

inhibits positive feedback loop that allows for M-Cdk1-cyclin activity to increase

positive feedback

does not shut itself down unless there is nothing left (forest fire for example)

negative feedback

something in pathway that stops it (inhibition)

-positive feedbaclk loop that uses M-cdk-cyclin to activate Cdc25
- S-Cdk also activates Cdc25

what activated Cdc 25?

M-Cdk-Cyclin

enough of what will inhibit inhibition by activation of Cdc25?

condensin

sister chromatid resolution depends on this 5 subunit protein complex

phosphorylation by M-Cdk

what is condensin stimulated by?

chromosome

what is easier to separate? chromosomes or chromatin?

green

are the microtubules green or orange?

orange

are the chromosomes orange or green?

prophase

what phase condenses into chromosomes and have the mitotic spindle formation at the centrosomes?

prometaphase

What phase causes a sudden nuclear envelope breakdown, and have the chromosomes attach to the spindle microtubules by their kinetochore?

metaphase

What phase causes the chromosomes to align at the equator at the spindle where the microtubules attached at the kinetochores at the sister chromatids to opposite poles of the spindle?

anaphase

What phase causes the sister chromatids to synchronously separate to form two daughter chromosomes, and pull them towards the spindle poles to have chromosome segregation?

contractile ring

What separates 2 cells with the use of actin and myosin to form a cleavage furrow during telophase?

telophase

What phase has the two sets of daughter chromosomes that arrive at the poles of the spindle and decondense, a new nuclear envelope reassembles, and uses the contractile ring to help begin the contraction of the cell and cytoplasm?

cytokinesis

what phase of the cell cycle has the cytoplasm divide in two by the contractile ring with the actin and myosin filaments to pink the cell in two to form two new cells with their separate nucleus?

negative

What charge are the ends of the microtubules?

interpolar microtubule

what overlaps with plus ends of other microtubules?

kinetochore microtubule

what has the positive ends that attach to sister chromatid pairs?

astral microtubule

what radiates outward from the poles helping to position the mitotic spindle?

centrosome

What is it when the spindle pole is focused at protein organelle?

centrioles

what do centrosomes contain a pair of?

kinesin and dynein

what two proteins are the microtubule dependent motor proteins?

kinesin

move toward the plus end of MT

dynein

move toward the minus end of MT

kinesin-5

-two motor domains
-interact with plus ends of antiparallel MT
- 2 motor domains will pus the 2 MT past each other toward the spindle poles

kinesin-14

-minus end directed motors, with single motor domain
- can cross-link antiparallel MT and pull the poles together

kinesin-4 and kinesin-10

-chromokinesins
- plus end directed motors that associate with chromosome arms and push the chromosome away from the pole

dynein

-minus end directed motors
- organize MT at various locations in the cell

kinesin 14 and kinesin-5

what are interpolar microtubules?

p 53

tumor suppressor that inhibits the cell cycle

ATM/ATR

-related protein kinases
- associated with the site of damage
- phosphorylate target proteins

p 21

what also helps inhibit the cell cycle with p 53?

mdm2

ubiquitin ligase

ataxia telangiectasia

caused by defect in ATM

transcription

DNA to RNA

Guanine cap

what helps the ribosome bind to mRNA?

poly A tail

what helps mRNA leave the nucleus?

Initiation, Elongation, Termination

3 steps of transcription

no

does pre-mRNA interact with ribosomes?

translation

RNA to protein

single stranded

Is RNA single stranded or double stranded?

uracil

Does RNA have uracil or thymine?

because it is single stranded

why does RNA fold on itself with H-bonds?

ribose

what sugar does RNA have?

no

does RNA require an RNA primer?

adenine

what does uracil usually bind to with 2 hydrogen bonds?

RNA polymerase

what catalyzes formation of phosphodiester bonds that link the nucleotides together to form a linear chain? It also helps with unwinding the DNA helix to help with RNA formation.

mRNA (messenger)

what RNA codes for proteins?

rRNA (ribosomal)

what RNA forms the basic structure of the ribosome and catalyze protein synthesis?

tRNA (transfer)

what RNA has central to protein synthesis as adaptors between mRNA and amino acids

snRNA (small nuclear)

what RNA functions in a variety of nuclear processes, including the splicing of pre-mRNA?

siRNA (small interfering)

what RNA turns off gene expression by directing the degradation of selective mRNAs and the establishment of compact chromatin structures

sigma factor

what helps with the promotion of bacterial transcription?

bacterial initiation

What helps the cell regulate which proteins are to be produced and at what rate in bacteria?

promoter

what special sequence of nucleotides indicates the starting point for RNA synthesis?

terminator

-chain elongation continues until polymerase hits this sequence
- polymerase halts, releases newly made RNA molecule and DNA
- Bacteria to string of AT nucleotide pairs

consensus nucleotide sequence

-common nucleotide found within a sequence
- recognized by sigma factor
- can have variation but all contain these related sequences

multiple

how many factors in eukaryotes assist with initiation?

RNA polymerase I

5,8 S, 18 S and 28 S rRNA genes

RNA polymerase II

all protein-coding genes, plus snoRNA genes, miRNA genes, siRNA genes, IncRNA genes, and most snRNA genes

RNA polymerase III

tRNA genes, 5S rRNA genes, some snRNA genes, and genes for other small RNAs

transcriptional activators

what helps RNA polymerase II by binding to specific sequences called enhancers

enhancer

What helps attract RNA polymerase?

general transcription factor

what helps position RNA polymerase at promoter?

25 nucleotides

when can the tata box during transcription?

transcription initiation complex

RNA polymerase and other transcription factors

double stranded DNA

what does the RNA polymerase need to gain access to after the Transcription Initiation Complex is formed?

TF II H

what acts ad helicase and undwinds the DNA to expose the template strand?

Cterminal domaij

when does phosphorylation of RNA polymerase occur?

RNA processing

what occurs in tandem with elongation?

CTD phosphorylation

what is it when there are covalend modifications to the ends

RNA splicing

what is it when there are removal of introns in RNA?

- capping 5' end with guanine
- poly-A tail on 3' end
-only exons

what is needed to go from pre-mRNA to mRNA?

TFIID

- recognizes TATA box
- recognizes other DNA sequences near the transcription start point

TFIIB

recognized BRE element in promoters; accurately positions RNA polymerases at the start site of transcription