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44 terms

BIO (Mitosis, sensory cells, neurons)

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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