Biology Unit 3- chapter 11 (part 2) Flashcards
1
Q
what do cells use to communicate with each other?
A
hormones
2
Q
what are the four steps for signal pathways?
A
- signal recognition
- signal processing
- signal response
- signal deactivation
3
Q
true or false: different molecules can serve as hormones.
A
true, amino acids, proteins, and fatty acids
4
Q
what happens when the hormone binds to its receptor?
A
the receptor changes shape, which initiates something else to happen
5
Q
where do hydrophobic/ lipid soluble have their receptors?
A
inside of the cell, in the intracellular fluid
6
Q
where do hydrophilic/ not lipid soluble have their receptors?
A
on cell membrane
7
Q
what is signal reception?
A
A cell detects a signaling molecule from the outside of the cell
8
Q
lipid soluble/ hydrophobic steps to enter nucleus.
A
- arrival of signal
- signal entry (no transporter)
- signal reception (binding to receptor exposes NLS)
- direct signal response (signal with the receptor reach the target DNA)
9
Q
amplification
A
single bonding to a receptor makes a big change in the cell
10
Q
intracellular hormone receptors change what
A
DNA transcription and expression
11
Q
signal transduction leads to _____
A
signal amplification
12
Q
signal transduction definition
A
converting something from one form to another
13
Q
steps for cell surface receptors
A
- signal reception (hormone binds, changes shape of receptor)
- signal transduction
- signal response (specific proteins are activated, inducing change in gene expression)
14
Q
three types of cell-surface receptors
A
- ion-channel coupled receptors
- G - protein coupled receptors
- enzyme linked receptors
15
Q
ion-channel coupled receptors
A
signal binds and opens up an ion channel through the plasma membrane
16
Q
G protein coupled receptors
A
Binding causes G proteins to activate and exchange a GDP for a GTP
17
Q
GTP on/off
GDP on/off
A
GTP- on
GDP- off
18
Q
enzyme linked receptors
A
receptor has catalytic properties but only when binded to a specific hormone
19
Q
steps for G protein
A
- G protein is inactive (GDP), signal arrives
- receptor changes shape, causes G protein to bind to GTP and splits into two parts
- G protein binds to an enzyme which causes a second messenger to trigger a response
20
Q
second messenger
A
chemical produced in a cell in response to an extracellular signal on the cel surface
21
Q
what secondary messenger are we focusing on?
A
cyclic adenosine monophosphate
22
Q
what does epinephrine (adrenalin) do for G-protein coupled receptors?
A
increases phosphorylase activity
23
Q
what does glycogen do?
A
storage of glucose in animals
24
Q
what releases the glucose from glycogen?
A
glycogen phosphorylase
25
what does the enzyme phosphorylase look and function like?
it has an active site for glycogen and a regulatory site where phosphate binds to. glycogen will only bind if regulatory site is phosphorylated
26
kinase definition
enzyme that adds a phosphate to something
27
examples of kinase from G- protein receptors pathway
PKA and active phosphorylase kinase
28
what is the receptor used in enzyme- linked receptors
tyrosine kinases
29
how do enzyme-linked receptors work?
1. signal arrives causing monomers to dimerize
2. dimerization activates energy which phosphorylates RTK (receptor tyrosine kinase)
3. activates Ras by causing it to exchange GDP for GTP
4. activated Ras triggers phosphorylation and activation of protein kinase
5. this results in a kinase cascade.
30
what is the molecule celled in intracellular receptors?
hormones
31
what does dimerize mean?
two of the same things brought together
32
kinase cascase
phosphorylation cascade where each step triggers another response in the cell
33
crosstalk
different signaling pathways can (and do) intersect
34
quorum sensing
a way for single-celled organisms to tell if their population has reached a certain density.
35
Which statement about hormones is FALSE?
1. Some hormones are largely hydrophilic.
2. All hormones work by binding to an integral membrane protein on the cell surface.
3. Some hormones are largely hydrophobic.
4. Various kinds of small molecules (proteins, steroids, lipids, gases, etc.) can be used as hormones.
All hormones work by binding to an integral membrane protein on the cell surface.
36
What happens when a hormone binds to its receptor?
1. The binding event changes the shape of the receptor, allowing the receptor to do something new/different.
2. The binding event causes the receptor to activate a channel that in turn lets the hormone diffuse into the cytosol.
3. The binding event causes the receptor to make more copies of itself, so there is a stronger response.
4. The binding event allows the receptor to deliver the hormone to different protein in the cell, which in turn passes the hormone to yet another protein, etc. until finally the hormone is eventually delivered to its final target.
The binding event changes the shape of the receptor, allowing the receptor to do something new/different.
37
Steroid hormones, like testosterone or estrogen, _______.
1. bind to cell-surface receptors that in turn bind to DNA and regulate gene expression.
2. bind to intracellular receptors that initiate the production of second messengers inside the cell.
3. bind to cell-surface receptors that initiate the production of second messengers inside the cell.
4. bind to intracellular receptors that in turn bind to DNA and regulate gene expression.
bind to intracellular receptors that in turn bind to DNA and regulate gene expression.
38
Which statement about G-protein coupled receptors (GPCRs) is TRUE?
1. Hormone binding to a GPCR causes the receptor to dimerize and initiate a kinase cascade.
2. Hormone binding to a GPCR causes the receptor to enter the nucleus and bind DNA.
3. Hormone binding to a GPCR causes the G-protein to replace GDP with GTP and then trigger the next step in the pathway.
4. Hormone binding to a GPCR causes the G-protein to hydrolyze GTP into GDP and then trigger the next step in the pathway.
Hormone binding to a GPCR causes the G-protein to replace GDP with GTP and then trigger the next step in the pathway.
39
Enzyme-linked receptors, like receptor tyrosine kinases, ___________.
1. produce second messengers directly in response to hormone binding.
2. are found primarily in prokaryotes, not eukaryotes.
3. have an enzymatic activity that is activated by hormone binding.
4. enter the nucleus and bind to DNA in response to hormone binding.
have an enzymatic activity that is activated by hormone binding.
40
Which one of the following is true about G protein coupled receptors?
A. the hormones they bind to are typically hydrophilic and thus cannot pass through the cell membrane.
B. most GPCRs are receptors for steroid hormones.
C. the GPCR itself has enzyme activity.
D. the hormone-receptor complex travels from the plasma membrane into the nucleus.
A. the hormones they bind to are typically hydrophilic and thus cannot pass through the cell membrane.
41
which of the following is true about G proteins?
A. the G protein is active in signal transduction when it's bound to GDP.
B. the G protein stops signal transduction when it hydrolyzes GTP to GDP.
C. the enzyme adenylyl cyclase that makes cAMP is a G protein.
D. the G protein travels from the plasma membrane into the nucleus.
B. the G protein stops signal transduction when it hydrolyzes GTP to GDP.
42
which one of the following is true about steroid hormone receptors?
A. the signal molecule is lipid-soluble and thus can pass through the cell membrane.
B. typically, second messengers are involved in signal amplification.
C. the hormone-bound receptor typically remains at the plasma membrane.
D. typically, a cascade of protein kinases are involved in signal amplification.
A. the signal molecule is lipid-soluble and thus can pass through the cell membrane.
43
hydrophobic signals such as _____ hormones bind to _____ receptors then they [do/do not] bind to DNA and alter gene expression. Signal amplification usually [does/does not] occur before gene expression occurs. Amplification [usually occurs/ occurs only if it's inherent in gene expression processes.]
steriod
intracellular
do
does noot
occurs only if it's inherent in gene expression processes
44
hydrophilic signals such as _____ bind to _____ receptors that typically [do/ do not]. bind to DNA and alter gene expression. Signal transduction pathways initiated by thee receptors usually [do/do not] amplify the magnitude of the signal [before/ only once gene expression processes occur.
peptide hormones
cell surface
do not
do
before
45
INTRACELLULAR RECEPTOR AND SURFACE RECEPTOR-
receptor processed by the endomembrane system
intra- no
surface- yes
46
INTRACELLULAR RECEPTOR AND SURFACE RECEPTOR-
lipid-sulublilty of the signaling molecules
intra- lipid soluble
surface- lipid insoluble
47
INTRACELLULAR RECEPTOR AND SURFACE RECEPTOR-
examples of signaling molecules and receptors
intra- steroid hormones and their intracellular receptors
surface- peptide/polypeptide hormones; GPCR and RTK/enzyme linked receptors
48
INTRACELLULAR RECEPTOR AND SURFACE RECEPTOR-
When and how is the signal message amplified?
intra- Multiple RNA copies possible; each of those can create multiple proteins
surface- enzymes catalyze multiple steps; each step creates multiple products
49
INTRACELLULAR RECEPTOR AND SURFACE RECEPTOR-
Does the activated receptor itself bind to DNA?
intra- yes
surface- no
50
what does the acronym GPCR stand for?
G- protein- coupled- receptors
51
does the GPCR posses enzymatic activity?
no
52
why are G-proteins called G-proteins?
they bind to guanine nucleotides
53
what is a G proteins enzymatic activity?
the hydrolysis of GTP to GDP
54
how do most G proteins carry out their signaling activity?
activate second messenger molecules
55
what enzyme produces cyclic AMP?
Adenylyl cyclase
56
RTK stand for____
receptor tyrosine kinase
57
Does RTK have its own enzymatic activity?
yes
58
what happens to RTK when a signal binds to it?
Dimerization, followed by self phosphorylation because its protein kinase activity is activated.
59
How does the signal "message" get transduced and amplified within the cell?
Phosphorylated tyrosines recruit proteins such as Ras and activate it by inducing a replacement of GDP with GTP.
Active Ras phosphorylates another enzyme, starting a kinase cascade.
60
What are some advantages of having multiple steps in signal transduction?
Amplification, cross-talk (activation or inhibition of additional pathways), convergence, more opportunities for regulation
61
Liver cells respond to epinephrine by cleaving glucose from glycogen using
the enzyme _______ , which is active if phosphorylated by the enzyme ________ .That latter enzyme is active if phosphorylated by the enzyme _______ , which is activated when bound by the
second messenger ______. The second messenger is made by the enzyme ______ , which is activated by a G
protein activated when epinephrine binds to the epinephrine receptor
glycogen phosphorylase
phosphorylase kinase
protein kinase A (PKA)
cAMP
adenylyl cyclase
62
G signaling molecules activate a [GPCR / enzyme-linked receptor], which triggers a phosphorylation cascade. How does this series of events effect levels of phosphorylated ERK?
enzyme- linked receptor
The final steps in the cascade phosphorylate ERK/ decrease
63
S signaling molecules activate a [GPCR / enzyme-linked receptor], which activates adenylyl cyclase. This enzyme
increases levels of _____ , which bind to ____ and activate it. How does this series of events effect levels of phosphorylated ERK?
GPCR
cAMP
PKA
PKA inhibits ERK phosphatase, which normally dephosphorylates/deactivates ERK, so there is more active ERK
64
Given these patterns, what combination of G and S signaling would produce the highest levels of phosphorylated
ERK, and thus promote proliferation?
The presence of both G and S signals would maximize the levels of active ERK.
