molec cell test 4 study questions

which statement about the cell cycles is false? A. once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells B. an unfavorable environment can cause cells to arrest in G1. C. A cell has more DNA during G2 than it did in G1 D. the cleavage divisions that occur in an early embryo have a modified cell cycle with essentialy no G1 or G2 phases

A is false because the cell cycle is different in normal cell cycles and the embryonic cell cycle

programmed cell death occurs ________. A. by means of an intracellular suicide program B. rarely and selectively only during animal development C. only in unhealthy or abnormal cells D. only during embryonic development

A. programmed cell death

what would happen to a mouse that expresses a mutant keratin? A. they get skin blistering B. they would be fine C. there is no way to tell what would happen D. They would die

A. they just get skin blistering

would consider formation of the outer layer of the skin cells to be due to programmed cell death? yes or no

A. yes

The retinoblastoma protein A. is a negative regulator of proliferation B. is a positive regulator of proliferation C. Drives the transition from G1 to S phase D. blocks the transition from G2 to M phase

A: because it inactivates the gene regulatory proteins that lead to proliferation *remember that the cyclin/cdk complex is what will inactivated this protein via phosphorylation

what cause M cylin to be destroyed?

APC adding ubiquitin to cyclin and it destroys cyclin reducing cdk

in DNA damage to the cell, what activates p53?

ATM and CHK2

which of the following conditions below is likely to decrease the likelihood of skeletal muscle contraction?

Addition of a drug that blocks Ca +2 binding to troponin

cytoplasmic keratins link cells together via _____ and ______.

Anchor proteins and transmembrane cadherins

what type of filament is Nuclear Lamina A. Actin filament B. intermediate filament C.microtubules

B. Intermediate filament

what affect would an overactive WNT signaling pathway have on the intestinal epithelium? A. loss of stem cells for renewal of gut lining B. formation of polyps by promoting inappropriate proliferation of gut stem cells C. formation of too many absortive cells D. formation of too few secretory cells

B. formation of polyps by promoting inappropriate proliferation of gut stem cells

you create cells with a version of cdc6 that cannot be phosphorylated and this cannot be degraded. which of the following statements describes the likely consequence of this change in cdc6? A. cells will enter s phase prematurely B. cells will be unable to complete DNA synthesis C. The origin recognition complex (ORC) will be unable to bind to DNA D. CDC6 will be produced inappropriately during the M phase.

B: because the phosphorylation and degradation of CDC6 will lead to DNA replication or synthesis. so if something stops CDC6 from being phosphorylated and destroyed then there would be no DNA synthesis/replication

how do reproductive cloning and therapeutic cloning differ? A. The DNA in the nucleus of cells produced for therapeutic clind is genetically identical to the donor genome, wheras in cells produced for reproductive cloning it is not. B. reproductive clingin requires a supply of fertilized donor egg cells , whereas therapeutic cloning it is not. C. embryos are placed into foster mothers during reproductive cloning by not during therapeutic cloning D. therapeutic cloning requires nuclear transplation, whereas reproductive cloning does not

C

levels of cdk activity change during the cell cycle because A. the cdks phosphorylate each other B. the cdks activate the cyclins C. cdk degradation precedes entry into the next phase of the cell cycle D. cyclin levels change during the cycle

D

which of these statements about microtubules is true? A. the microtubules of the mitotic spindle originate at the centromere B. because microtubules are unstable, they are used only for transient strucutures in a cell c. atp hydrolysis by a tubulin heterodimer us important for controlling the growth of a microtubule. D. motor proteins move in a directional fashion along microtubules by using the inherent structural polarity of a protofilament

D

which statement about apoptosis is true? A. cells that constitutively express BCLs will be more prone to undergo apoptosis B. the prodomain of procaspses contains the catalytic activity necessary for procaspase activation. C. Bax and Bak promote apoptosis by binding to procaspases in the apoptosome D. Apoptosis is promoted by the release of cytochrome c into the cytosol from mitochondria

D. because apoptosis is promoted by the release of cytochrome C in the cytosol

name the disease caused by a defect in keratin genes?

EBS= epidermolysis bullosa simplex

what phosphorylates everything and causes fragmentation of the Golgi apparatus, nucleus and chromatin condensation?

MCDK

where do microtubules orginate from?

MTOC - aka centrosomes

when apoptosis is caused by external signals what is the name of these signals?

TNF

what kind of apoptosis regulator is BCL-2?

antiapoptic

when is M cyclin destroyed?

at the end of mitosis

why don't embryonic cells experience growth factors until a certain point?

because maternal factors are still in the cell

what is the caspase used in apoptosis by external signals

caspase 8

what causes skin blisters to occur in mice when they have a defective keratin filament?

cell lysis after mechanical stress like rubbing, or pressure on the skin

what causes the reassembly of the nuclear envelope in daughter cells? (after mitosis)

dephosphorylation of lamins

anchor proteins and transmembrane cadherin link keratin filaments by what type of junction?

desmosome

check point: G1

determines progression to S phase

when is M cyclin at its highest point?

during Mitosis

Checkpoint: G2

ensures DNA is repaired and replicated before mitosis

Desmsosomes link cells together via integrins and anchor proteins. true/false

false

microtubules outnumber neurofilaments in the axon. true/false

false, neurofilaments outnumber microtubules in the axon

in microtubules, the positive end always grows towards the MTOC?

false, the positive end always grows away from the MTOC

neurofilaments are cross linked by integrins. true/false?

false, they are cross linked by protein cross bridges

when keratin filaments are anchored to an extracellular matrix via integrins, what is the name of this junction?

hemidesmosomes

checkpoints: M phase

make sure chromosome attachment to spindle before separation

if there is dna damage that somehow prevents atm and chk2 from activating p53, will there still be apoptosis?

no, because p53 leads to apoptosis but it will be inactive in this situation and it wont activate puma and noxa

what type of intermediate filaments provides structural support for the nucleus?

nuclear filaments

what causes the disassembly of the nuclear envelope at the beginning of mitosis?

phosphorylation of lamins

if DNA damage happens in the cell, what will p53 activate that will lead to apoptosis

puma and noxa

in the case of apoptosis caused by DNA damage what are the 2 proapoptotic proteins

puma and noxa

if the cytoskeleton of the cell has a malfunctioning intermediate filaments, what will happen to the cell when it is stretched?

the cell would rupture and break

microtubules in neuronal axons are positioned with what end towards the axon terminal?

the positive end

when TNF signals bind to TNF receptor, does it form a Dimer or a trimer?

trimer

motor proteins are energy dependent. true/false

true

when do embryonic cells experience growth factors?

when midblastula occurs

An adult hematopoietic stem cell found in the bone marrow ________. A. will occasionally produce epidermal cells when neccessary B. can produce only red blood cells C. can undergo self renewing divisions for the lifetime of a health animal D. will express all the same transcription factors as those found in an unfertilized egg

C. can undergo self renewing divisions for the lifetime of a health animal