GMC > Env. Perception > Flashcards

Env. Perception Flashcards

(84 cards)

Study These Flashcards
1
Q

What is autocrine signalling

A

Cell detects a signal that it produced itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is Juxtracrine signalling?

A

Adjacent cell initiates a response by direct contact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is paracrine signalling?

A

Cell detects a local signal from neighbouring cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is endocrine signalling?

A

Cell detects signal secreted by distant cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

State the range of stimuli that cells/ organisms can respond to.

A

Physical stimuli, adjacent cells, external chemicals, internal metabolites or hormones, small molecules, peptides or gases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How can cells and organisms respond to stimuli?

A

Physical movement, physiological and behavioural responses, differential gene expression.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the name of the structure than can activate a receptor by binding to it?

A

Ligand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Receptors are designed to perceive information with:

A

Specificity and sensitivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What effect do cells having different types of receptors create?

A

Differences in capacity for response.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Various signal transduction processes couple receptors to d__________ r_______________.

A

downstream responses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Signaling mechanisms often amplify the level of response relative to the ___________ of the initial stimulus.

A

Magnitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is signal desensitization?

A

Negative feedback upon receptor activation to switch off/ remove receptor, used to curtail a response if stimulus persists.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is signalling cross-talk?

A

When activation of one receptor might inhibit signalling from another receptor. Used to prioritize incoming information in order to give appropriate responses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Applications of understanding reception/signalling mechanisms

A

Drug design, synthetic biology: optogenetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is channelrhodopsin?

A

Simple light-activated ion channel that functions in phototaxis of unicellular green algae.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is channelrhodopsins structure?

A

7-transmembrane protein, forms a LIGHT-GATED ion channel in the plasma membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What channelrhodopsins does Chlamydomonas have?

A

ChR1 and ChR2, non-specific cation channels.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the cofactor bound by channelrhodopsin protein that is the chromophore for light absorption called?

A

Retinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How does light absorption open up the channel? (channelrhodopsin)

A

Light absorption causes isomerization of retinal which in turn causes conformational change in the protein, opening up the ion channel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the nicotonic acetylcholine receptor?

A

Ligand gated ion channel that functions in transmission of an electrical signal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the ligand for the nicotinic acetylcholine receptor?

A

The neurotransmitter acetylcholine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How many subunits does the nicotonic acetylcholine receptor have?

A

5, arranged around a central channel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does binding of the ligand do to nicotonic acetylcholine receptor?

A

Causes conformational change to receptor, which opens ion channel to Na+ and Ca2+ ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do bacteria respond to factors?

A

By swimming towards/ away from them using their flagellae and through regulating gene expression.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What comprises a 2-component system?
Receptor histidine kinase that detects stimulus and a response regulator that initiates the response.
26
What is a beta-turn?
Allow polypeptide chains to turn abruptly and go in the opposite direction, allowing proteins to attain a globular shape.
27
Proline and Glycine are often found in beta turns. Why?
Proline - cyclic structure Glycine - small size makes it flexible
28
Proteins fold to the ___________ free energy conformation.
Lowest
29
As folding proceeds, what happens to free energy and entropy?
They decrease to a minimum.
30
Where are hydrophobic residues found in a protein?
In the interior core.
31
What is a molten globule?
Partially folded protein state : conserves a native-like secondary structure content but without the tightly packed protein interior.
32
What does natural selection favour (protein wise)?
Protein sequences that have a single conformation that form easily and seldom makes mistakes.
33
What is the hydrophobic effect?
The observed tendency of non-polar molecules to aggregate in water.
34
What is TGF beta
Transforming growth factor - type of cytokine (small regulatory protein)
35
What are the functions of TGF betas superfamily?
Regulating growth, regulating cell division, immunosuppression, cell differentiation, dorso-ventral specification.
36
How many TGF isoforms so humans have?
3
37
What type of signalling does TGF take part in?
Paracrine
38
How is TGF synthesised?
With a signal peptide that targets it to the endoplasmic reticulum, and is removed by proteolytic cleavage during translation and translocation into the ER.
39
What is TGF secreted as?
A proprotein (propeptide domain blocks ligand activity)
40
What must happen to the proprotein in order to release the mature TGF ligand?
Propeptide is cleaved by proteolytic cleavage.
41
What type of protein is the TGF receptor and where is it located?
Transmembrane protein - plasma membrane
42
There are 2 types of TGF receptors. How do they work together?
Binding of an extracellular dimeric TGF ligand to type II receptor causes it to bind to and phosphorylate type I, causing it to become activated
43
What happens once TGF receptor type I is phosphorylated?
SMAD2 or SMAD3 proteins are phosphorylated. These are signalling proteins and transcription factors for TGF signalling.
44
What happens when SMAD2 or SMAD3 is phosphorylated?
Dissociates from the receptor and binds to SMAD4
45
What does the SMAD2/3-SMAD4 complex activate?
Transcription of target genes in the nucleus.
46
What do tumours contain that cause excessive growth?
Inactivating mutations in TGF receptors or SMAD proteins, making them resistant to growth inhibition by TGF.
47
What is the JAK/STAT signalling mechanism involved in?
Regulation of transcription by regulatory cytokines.
48
What is erythropoitein (EPO)?
Cytokine protein that stimulates formation of erythrocytes in bone marrow.
49
When and where is EPO secreted?
In response to hypoxia, secreted by the kidney
50
What happens to the receptor once EPO binds?
The receptor dimerises. Is now able to bind the soluble protein kinase JAK
51
What happens once JAK binds to its receptor?
JAK is activated and it phosphorylates tyrosine amino acids on the cytoplasmic domain of the receptor.
52
What does STAT stand for?
Signal transducer and activator of transcription.
53
What do STAT transcription factors bind to?
phospho-tyrosines on the receptor via the SH2 domain.
54
What does STAT being bound to phospho-tyrosines enable?
Phosphorylation of STAT by JAK kinase
55
What happens once STAT is phosphorylated?
STAT released from receptor, forms dimers and translocates to nucleus.
56
What does STAT do in the nucleus?
Binds to DNA regulatory sequences to stimulate transcription of genes required for erythrocyte maturation.
57
What is estradiol?
An oestrogen steroid hormone, regulates the reproductive cycle and development
58
Where is estradiol produced?
Mainly in ovarian follicles, but also in other tissues.
59
How do estradiol levels change during the menstrual cycle and menopause?
Fluctuate during menstrual cycle and decrease to low levels during menopause.
60
What molecule is estradiol synthesised from?
Cholesterol
61
Estradiol is a small, _____ soluble molecule
Lipid
62
What is the pathway of estradiol binding?
Estradiol binds to oestrogen receptor in the cytosol, forms a dimer and translocates to the nucleus.
63
Biological timing is enable by the :
Circadian Clock
64
How is distance measured for a GPS?
Differences in times transmitted by satellites
65
What are some human daily rythms?
Sleep/wake cycle, melatonin level in blood, blood pressure and body temperature
66
What do interactions between internal clock and external environment enable?
Time-dependent patterns of behaviour
67
What is a way of easily monitoring rhythm?
Use of promotor:reporter fusions to generate transgenic organisms.
68
What are some ways of identifying clock components?
Mutagenesis, cloning of the relevant genes.
69
What does crepuscular mean?
Most active near dawn and dusk.
70
How does the circadian clock control expression of genes?
Promotors - DNA sequence upstream of gene that controls its expression
71
How does bioluminescence imaging work?
Transgenic expression of firefly LUCIFERASE induces bioluminescence in the presence of luciferin substrate
72
What are some qualities required for circadian clocks to keep time?
Oscillate once every 24 hours, show temperature compensation, reset to environmental conditions
73
What is circadian gating?
Differential responses at different times of day to identical inputs
74
What are the components of circadian control systems?
Input pathways, central oscillator, output pathways.
75
Most circadian clocks are:
Transcription-translation feedback loops
76
What is the effect of FASP syndrome?
Fast circadian clocks, short circadian period leads to a phase advance. early onset of sleep.
77
What can clock mutations cause?
Prevent species from correctly responding to environmental cues, impairs survival of organisms
78
Where is the mammal 'master clock' located?
Brain suprachiasmatic nuclei (SCN)
79
The ER is an efficient Ca store, Ca is pumped in from the cytosol by another (related) ATPase:
SERCA
80
What is the name of the storage protein Ca binds to so high Ca2+ can be achieved
Calsequestrin
81
IP3 binds to a binding site on a Ca channel in the ER. What does this induce?
Conformational change, which opens the channel. Allows rapid movement of Ca into the cytosol.
82
Ca2+ and DAG bind to protein kinase C superfamily and induce...
Conformational changes, activates kinase domain (results in signal transmission)
83
How do Ca channel blockers lower blood pressure?
Reduce constriction of arteries. dilated arteries lower the blood pressure.
84
GMC
flashcards
Decks in class (3)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions