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During what phase of the cell cycle does the DNA become replicated?

S

In which mitotic phase are the sister chromatids separated and pulled to opposite poles?

Anaphase

in which mitotic phase do the chromosomes condense and the mitotic spindle begin to form?

Prophase

the division of the cytoplasm following mitosis is called ____

cytokinesis

What is the checkpoint for G2?

chromosomes have replicated successfully

Proteins that degrade cyclin are activated by events that MPF initiates. Why is this important for cell cycle regulation?

it sets up oscillation in cyclin concentration

MPF or mitosis promoting factor consists of two important cell cyle regulatory proteins called ___

cyclin and cyclin dependent kinase (CDK)

two important checkpoints that regulate the cells progression through the cells cycle are ____

G1 and G2

Why do many cancerous cells have defective forms of the Ras protein?

Ras is part of signal transduction pathway that triggers G1 cyclin production; many caner cells have defective cells forms of Ras that do not become inactivated

what two types of defects does a cancerous cell posses ?

cancerous cells possess defects that make proteins required for cell growth active and tumor suppressor genes inactive

nerve cells lose ability to undergo mitosis, instead they are permanently stuck in___

G0

Regulatory proteins that serve to prevent a cell from entering the S phase under conditions of DNA damage are also known as ___

tumor supporessors

how is phosphorylation important in a signal transduction cascade ?

phosphorylation will turn an inactive protein into an active one, which triggers another response in the cell

true or false? regulatory and basal transcription factors regulate transcription by binding to the promoter

false

what method is utilized by eukaryotes to control their gene expression that is not used in bacteria

control of both RNA splicing and chromatin remodeling

how do chromatin remodeling complexes recognize the genes they act on?

chromatin - remodeling complexes recognize specific transcription factors bound to regulatory sequences of DNA

one way to detect alternative splicing of transcripts from a given gene is to ___

compare the sequences of different mRNAs made from this gene

which of the following types of mutation would convert a pro to-oncogene into a oncogene?

a mutation that gently increases the amount of the pro to-oncogene protein

the normal function of a tumor suppressor gene is to ___

prevent progression of the cell cycle unless conditions are right for moving forward

p53 activates genes that ____

arrest the cell cycle

if you isolate a yeast mutant that contains histones resistant to acetylation, what phenotype do you predict for this mutant?

low levels of gene expression

the reason for differences in the sets of proteins expressed in a nerve and pancreatic cell of the same individual is that nerve and pancreatic cells contain different ____

sets of regulatory proteins

how do chromatin remodeling complexes recognize the genes they should act on?

chromatin remodeling complxes recognize specific transcription factors bound to regulatory sequences of DNA

regulatory transcription factors ___

influence the assembly of the basal transcription complex

if one wants to know the final amount of gene product what is the problem with measuring the level of mRNA produced from a gene?

ignores translational control possibility

what term describes the difference in electrical charge across a membrane?

membrane potential

resting neurons are most permeable to which ion?

K+

which channel is mainly responsible for the resting potential of a neuron?

potassium leak channel

what causes the release of neurotransmitter molecules ?

action potential reaching the end of the axon

neurons store neurotransmitter molecules in vesicles located in ____

synaptic terminals

if you increased the concentration of Na outside a cell which maintaing other ion concentrations the cell membrane potential would ___

increase

the depolarization phase of an action potential requires ____

opening of Na channels in membrane

if activity of the Na K pump were changed by palytoxin what would happen to the neurons membrane potential ?

slow decrease of resting potential

true or false? movement of the ions during the action potential occurs mostly through sodium pumps

false

why do Na ions enter the cells when voltage gated Na channels are opened in neurons?

Na concentration is higher outside the cell than inside and the Na ions are attracted to negatively charged interior

why do action potentials pass more rapidly along the fish's neurons than the crabs?

the fish's axons are wrapped in myelin

if you blocked voltage gated Na channels and Na K pumps, what would be the response?

loss of action potential and gradual loss of resting potential

what manipulation would reduce the release of neurotransmitter from presynaptic neuron terminal ?

reduction in extracellular calcium ion concentration at axon terminal

true or false? most synapses found so far in the mammalian CNS are classified as chemical rather than electrical

true

patients with autonomic nervous system disorders will show symptoms in all of the following except _____

contraction of skeletal muscles

what receptor would most abundant in the antennae of a moth?

chemoreceptors

deafness caused by loud sounds often results from damage to which receptor cell?

mechanoreceptors

how does an ear distinguish volumes of different sounds?

louder sounds induce a higher frequency of action potentials than softer sounds

ion channels in the hair cell membrane open when ____

membrane is distorted mechanically

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