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IB Bio HL > C2.1 Chemical Signalling (HL) > Flashcards

C2.1 Chemical Signalling (HL) Flashcards

1
Q

What is chemical signalling?

A

A process by which cells, tissues, and organisms communicate using signalling molecules.

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2
Q

What are the two types of cell-to-cell interactions in chemical signalling?

A
  • Direct interactions
  • Indirect interactions
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3
Q

What are ligands?

A

Signalling molecules that include hormones, neurotransmitters, cytokines, and growth factors.

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4
Q

What role do receptors play in chemical signalling?

A

Receptors exhibit specificity to ligands due to the structure of their binding sites.

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5
Q

What are the main functions of chemical signalling in humans?

A
  • Maintaining homeostasis
  • Development
  • Immune response
  • Neural function
  • Metabolic regulation
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6
Q

What initiates the cascade of biochemical reactions in signal transduction?

A

Conformational change in the receptor caused by ligand binding.

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7
Q

What are some specific cellular responses that can result from activated signalling pathways?

A
  • Changes in gene expression
  • Activation or inhibition of enzymes
  • Alteration of ion channel activity
  • Modulation of cellular metabolism
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8
Q

What is quorum sensing in bacteria?

A

A process where bacteria communicate to coordinate group behaviour in response to cell density.

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9
Q

What are autoinducers?

A

Small signalling molecules released by bacteria that diffuse and accumulate in their environment.

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10
Q

What types of autoinducers do Gram-positive and Gram-negative bacteria use?

A
  • Gram-positive: processed oligopeptides
  • Gram-negative: acylated homoserine lactones (acyl-HSLs)
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11
Q

How does Vibrio fischeri utilize quorum sensing?

A

Releases N-acyl homoserine lactone to bind to regulators and induce the lux operon.

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12
Q

What is the function of the lux operon in Vibrio fischeri?

A

Regulates luminescence by encoding regulatory and luminescent proteins.

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13
Q

What chemical reaction produces light in bioluminescence?

A

The oxidation of luciferin by luciferase.

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14
Q

What hormone is produced by the pancreas in response to high blood glucose levels?

A

Insulin

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15
Q

What hormone is produced by the pancreas in response to low blood glucose levels?

A

Glucagon

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16
Q

What are hormones?

A

Chemicals secreted by endocrine glands into the extracellular fluid that act on target organs/tissues

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17
Q

What are neurotransmitters?

A

Chemical substances that carry signals from one neuron to another or from a neuron to a target cell

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18
Q

What are cytokines?

A

Small proteins important in cell signalling related to immune response

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19
Q

Which cells primarily secrete cytokines?

A

White blood cells such as macrophages and lymphocytes

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20
Q

What are the three main types of hormones?

A

Amines, peptide hormones, and steroids

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21
Q

What are amine hormones derived from?

A

Amino acids, specifically tyrosine and tryptophan

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22
Q

Give an example of an amine hormone.

A

Epinephrine (adrenaline)

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23
Q

What are peptide hormones?

A

Hormones in the form of polypeptide chains or small proteins

ex: insulin

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24
Q

What are steroid hormones derived from?

A

Cholesterol

25
What are the two ways hormones can act?
Activate second messengers or activate genes
26
Give an example of an amino acid neurotransmitter.
GABA (Gamma-aminobutyric acid)
27
What can calcium ions trigger in cellular processes?
Muscle contraction, nerve impulses, and fertilisation
28
What are the four types of signalling based on distance?
* Autocrine signalling * Paracrine signalling * Endocrine signalling * Juxtacrine signalling
29
What is autocrine signalling?
Signalling where cells secrete molecules that act on themselves
30
What is paracrine signalling?
Signalling where molecules travel a short distance to nearby target cells
31
What is endocrine signalling?
Signalling where hormones travel long distances via the bloodstream to target cells
32
What is juxtacrine signalling?
Signalling that occurs when two cells are in physical contact
33
What are cell-surface receptors?
Receptors present on the cell membrane that transmit signals from outside to inside the cell
34
What are intracellular receptors?
Receptors located inside the cell that bind to lipid-derived signalling molecules
35
What are Type I intracellular receptors?
Cytoplasmic receptors that translocate to the nucleus upon ligand binding
36
What are Type II intracellular receptors?
Nuclear receptors directly involved in gene transcription
37
Name the three categories of cell-surface receptors.
* Enzyme-linked receptors * G-protein-linked receptors * Ion channel-linked receptors
38
What does signal amplification refer to in the context of signal transduction?
A process where a small signal triggers a larger response through activation of downstream messengers/effectors ## Footnote Hormones or neurotransmitters can activate protein kinases, amplifying the signal.
39
What is a common second messenger in signal transduction?
Cyclic AMP (cAMP) ## Footnote cAMP plays a crucial role in relaying signals inside cells.
40
What is the function of protein kinases in signal transduction?
To phosphorylate proteins by adding a phosphate group ## Footnote Protein kinases remain inactive until activated by second messengers like cAMP.
41
How is the signal terminated in signal transduction?
By degradation, diffusion, reuptake, inactivation of receptors, or feedback inhibition ## Footnote For example, acetylcholinesterase degrades acetylcholine to terminate its action.
42
What are the three types of neurotransmitters based on their effects?
* Excitatory neurotransmitters * Inhibitory neurotransmitters * Modulatory neurotransmitters ## Footnote Examples of excitatory neurotransmitters include glutamate; inhibitory neurotransmitters include GABA.
43
What is the role of acetylcholine at the neuromuscular junction?
Regulates muscle contractions and other functions like heartbeat and blood pressure ## Footnote Acetylcholine is the primary neurotransmitter associated with motor neurons.
44
What are G proteins and their function in signal transduction?
Molecular switches that undergo conformational changes when GPCRs bind to ligands ## Footnote They facilitate GDP/GTP exchange within the cell.
45
How many subunits do G proteins consist of?
Three subunits: ɑ, β, and γ ## Footnote Inactive G proteins have the ɑ subunit bound to GDP.
46
What is the structure of a typical G protein-coupled receptor (GPCR)?
Has seven transmembrane ɑ helices ## Footnote GPCRs are the largest class of membrane receptors found in eukaryotes.
47
What is epinephrine also known as?
Adrenaline
48
What are the two major outcomes of protein kinase A activation by epinephrine?
* Inhibition of glycogen synthesis * Initiation of glycogen breakdown
49
What does cAMP stand for?
Cyclic AMP
50
What is the function of adenylate cyclase in the presence of epinephrine?
Converts ATP to cAMP
51
What happens to GDP when epinephrine binds to its receptor?
GDP is replaced by GTP
52
What are tyrosine kinase receptors involved in?
Cell growth, differentiation, and proliferation
53
What process does tyrosine kinase undergo upon insulin binding?
Autophosphorylation
54
What are the two critical components of feedback mechanisms in regulating signalling pathways?
* Positive feedback * Negative feedback
55
What is homeostasis?
The maintenance of a stable internal environment in living organisms
56
What is the effect of positive feedback mechanisms in cell signalling?
They result in amplification of cell signals | ex: blood clotting
57
What is the role of negative feedback in cell signalling pathways?
It inhibits upstream activation, dampening the amplification of signals | ex: insulin & glucagon
58
SIgnal tranduction cascade
1. receotor activation = ligand binds 2. signal amplification = stimuli triggers response 3. second messenger production = relay signal in cell 4. activation of protein kinases = phosphorylate proteins 5. change in gene expression 6. temrination of signal (degradation, diffusion, response, inactivation, feedback inhibition)

IB Bio HL (21 decks)

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