L9 Flashcards
(120 cards)
1
Q
What is the first step in hormone signaling?
A
Hormone binds to receptor
2
Q
What happens to the receptor’s conformation upon hormone binding?
A
It changes
3
Q
What is altered in the cell due to hormone-receptor binding?
A
Intracellular signaling pathways
4
Q
What are the two possible outcomes regarding target protein?
A
Synthesis or modification
5
Q
What type of hormones require intracellular receptors?
A
Hydrophobic hormones
6
Q
What type of hormones bind to cell surface receptors?
A
Hydrophilic hormones
7
Q
Question: What is the general size of receptors?
A
Large proteins
8
Q
What organizational structure do receptors often belong to?
A
Families
9
Q
What is the range of receptor numbers in a target cell?
A
~500-100,000
10
Q
Can receptors be activated and inhibited?
A
yes
11
Q
Where can receptors be located within a cell?
A
Cell membrane, cytoplasm, nucleus
12
Q
What is a key feature of receptor-ligand interaction?
A
Can be multiple receptors for one ligand
13
Q
What is a characteristic of receptors?
A
Variable number in target cell
14
Q
What happens as you add more testosterone?
A
More is bound to receptors
15
Q
What eventually happens when adding more testosterone?
A
No more receptors to bind to
16
Q
What is the significance of receptor saturation?
A
There’s a limit to how much hormone can bind
17
Q
What are the properties of receptors?
A
- high affinity
- saturable
- specific
- reversible
18
Q
What is high affinity in the context of receptors?
A
Strong attraction between receptor and ligand
19
Q
What does it mean for receptors to be saturable?
A
Finite number of receptors, leading to saturation at high ligand concentration
20
Q
What does specificity refer to in receptor properties?
A
Receptors bind selectively to specific ligands
21
Q
Why is reversibility important in ligand binding?
A
Allows for regulation; ligand binding is not permanent
22
Q
What is the first step in hormone signaling?
A
Hormone binds to receptor
23
Q
What happens to the receptor upon hormone binding?
A
Changes conformation and activity
24
Q
What is altered by the change in receptor activity?
A
Intracellular signaling pathways
25
What are the two outcomes of altered signaling pathways?
Change in synthesis or modification of target proteins
26
Which process is slower, protein synthesis or modification?
Protein synthesis
27
What kind of signal diffuses through the plasma membrane?
Lipophilic signal
28
What triggers a response inside the cell for hydrophilic signals?
Binding to a membrane receptor
29
What does hormone binding change?
Conformation and activity of the receptor
30
What is the first main type of receptor?
Intracellular receptors
31
What kind of hormones do intracellular receptors bind?
Lipid-soluble hormones
32
Where are intracellular receptors located?
Cytosol and nucleus
33
What effect do intracellular receptors have on gene transcription?
Directly alter it
34
What is the second main type of receptor?
Plasma membrane receptors
35
Name different types of plasma membrane receptors.
- G protein-coupled receptors
- Receptor-enzyme receptors
- Receptor-Channel
- Integrin Receptor
36
Can peptide hormones penetrate the target cell?
No, they bind to surface receptors
37
How do peptide hormones activate intracellular processes?
Through second messengers
38
Where do steroid hormones bind?
Internal receptors, usually in the nucleus
39
What do steroid hormones influence?
Gene expression
40
Why do steroid hormones take longer to show effects?
Lag for protein synthesis
41
Where do peptide hormones bind?
Cell membrane
42
What type of messenger binds to intracellular receptors?
Lipophilic messengers (e.g., steroids)
43
How do lipophilic messengers enter the cell?
Diffusion
44
Where does the hormone-receptor complex translocate?
Nucleus
45
What does the hormone-receptor complex bind to in the nucleus?
Hormone response element (HRE)
46
What is the result of the hormone-receptor complex binding to the HRE?
Altered gene transcription
47
What kind of receptor is in the cytoplasm?
Cytoplasmic receptor.
48
What is the first step for lipophilic messengers?
Diffusion
49
What is the final result of intracellular receptors?
Protein synthesis
50
What are hormone response elements?
Specific DNA sequences.
51
What is an example of a hormone response element?
Estrogen response element
52
What can receptors recruit to inhibit transcription?
Co-repressors
53
What happens to genes with the specific response elements?
Activated or repressed
54
What determines if a gene will be affected?
Presence of specific HRE
55
What does ligand binding to a G protein-coupled receptor do?
Opens an ion channel or alters enzyme activity
56
What does ligand binding to a receptor-enzyme do?
Activates an intracellular enzyme
57
What is the effect of ion channels on the membrane?
Change electrical properties
58
What moves through the open channel?
Ions (Na+, K+, Cl-)
59
What is the structure of GPCRs?
7 membrane-spanning proteins
60
What is linked to the cytoplasmic tail of GPCRs?
G protein
61
What system is the G protein-coupled adenylyl cyclase-cAMP system?
Signal transduction system
62
What lipid second messengers do GPCRs use?
DAG and IP3
63
What are the two main effects when G proteins are activated?
1. Open ion channels
2. Alter enzyme activity
64
Where does the alteration of enzyme activity occur?
Cytoplasmic side of the membrane
65
What is the role of the G protein?
Transducer molecule
66
What does the alpha subunit do?
Exchanges GDP to GTP
67
What happens after GTP binds to the alpha subunit?
It travels to adenylyl cyclase
68
What does adenylyl cyclase do?
Activates cAMP
69
What activates protein kinase A?
cAMP
70
What is the role of ATP in activating adenylyl cyclase?
ATP is converted to cAMP
71
What is the final result of the Gs signaling pathway?
A response in the cell
72
What is the role of protein kinase A?
Phosphorylates proteins
73
What is the function of adenylyl cyclase?
Converts ATP to cAMP
74
What is the first step in G-protein coupled signal transduction?
A signal molecule binds to a GPCR
75
What does the G protein activate?
Adenylyl cyclase
76
What is the role of second messengers?
Amplify target cell responses
77
What activates phospholipase C?
Gq protein
78
What does phospholipase C cleave PIP2 into?
DAG and IP3.
79
What does DAG activate?
Protein kinase C (PKC)
80
What does IP3 release from the endoplasmic reticulum?
Ca2+ (calcium ions)
81
What is the role of calcium ions in G-protein coupled signal transduction?
Leads to various cellular responses
82
What type of enzyme is phospholipase C?
Amplifier enzyme
83
What type of G protein is Gai?
Inhibitory
84
What enzyme does Gai inactivate?
Adenylyl cyclase
85
What happens when a hormone binds to a receptor coupled with Gai?
Inhibition of adenylyl cyclase
86
What is the effect of Gai on cAMP levels?
Decreases cAMP
87
What is the role of the inhibitory regulative G protein (Gi)?
Inhibits adenylyl cyclase
88
What is the significance of Gai in hormone signaling?
It provides an off-switch for certain pathways
89
What are the three main types of G proteins?
Gs, Gq, and Gi
90
What does Gs stimulate?
Adenylyl cyclase
91
What does Gq stimulate?
Phospholipase C
92
What is the fight or flight response mediated by?
G-protein coupled receptors
93
What hormones trigger fight or flight responses?
Epinephrine and norepinephrine
94
What happens in the liver during fight or flight?
Glucose release
95
What is released from fat tissue?
Fatty acids
96
What happens to the heart during fight or flight?
Increased muscle contraction
97
What happens to skeletal muscle blood vessels?
Less vasoconstriction
98
What happens to blood flow in the intestine, skin, and kidney?
Vasoconstriction to redirect blood flow
99
What are the two adrenergic receptor isoforms mentioned?
Alpha and beta 2
100
What does epinephrine binding to alpha receptors cause in intestinal blood vessels?
Vasoconstriction
101
What does epinephrine binding to beta 2 receptors cause in skeletal muscle blood vessels?
Vasodilation
102
Where are alpha receptors found in the example?
Intestinal blood vessels
103
Where are beta 2 receptors found in the example?
Skeletal muscle blood vessels
104
What determines the diverse effects of epinephrine and norepinephrine?
Receptor specificity
- Beta 1 and 2 are both Gs proteins
- Alpha 1 is a Gi protein
- Alpha 2 is a Gq protein
105
How can hormone levels be reduced?
Hormone degradation
106
How can receptor sensitivity be changed?
Receptor down-regulation or up-regulation
107
What is receptor desensitization?
Receptors become less sensitive
108
How are second messengers affected?
Breakdown of second messengers
109
What else can be modified in the pathway?
Any component in the pathway
110
What provides feedback to reduce hormone secretion?
Biological effect
111
What happens if a hormone is not stable?
It can't stimulate processes
112
What does down-regulation cause?
Cell is not as sensitive to the response
113
What is the first step in turning off membrane receptor signaling?
Ligand binds to membrane receptor
114
What happens after the ligand binds?
Receptor migrates to clathrin-coated pit
115
What process internalizes the receptor?
Endocytosis
116
What happens to the vesicle after endocytosis?
Vesicle loses clathrin coat
117
What happens to the receptors and ligands inside the vesicle?
They separate
118
Where do the ligands go for processing?
Lysosomes or Golgi complex
119
What happens to the receptors?
They are recycled back to the membrane
120
How are receptors transported back to the membrane?
Through transport vesicles via exocytosis
