Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Advanced Higher Biology > Unit 1 - Communication and Signalling > Flashcards

Unit 1 - Communication and Signalling Flashcards

1
Q

What are extracellular signalling molecules?

A

Cues ( growth factors, hormones, neurotransmitters etc) designed to transmit specific information to target cells

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

What are hydrophobic signalling molecules?

A

Signalling molecules that can diffuse through membranes, so their receptor molecules can be within the nucleus

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

What are transcription factors?

A

Proteins that when bound to DNA can either stimulate or inhibit initiation of transcription.
They can enhance or block binding of RNA polymerase to specific genes, therefore controlling whether a gene is transcribed and expressed

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

When is the hormone-receptor complex formed?

A

When steroid hormones bind to specific receptors in the cytosol or the nucleus; they bind to specific sites on DNA and affect gene expression

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

What is a hormone response element?

A

A short sequence of DNA within the promoter of a gene that is able to bind to a specific hormone-receptor complex and therefore regulate transcription

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

What are hydrophilic signalling molecules?

A

Signalling molecules which are not able to pass through the membrane

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

What is signal transduction?

A

The conversion of extracellular signals into an intracellular response

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

What is a gene protein?

A

A family of proteins that act as molecular switches inside cells, they are involved in transmitting signals from a variety of stimuli outside a cell to its interior

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

What is a phosphorylation cascade?

A

A series in which one kinase activates the next one in a sequence, can result in the phosphorylation of many proteins as a result of the original signalling event

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

What is GLUT-4?

A

An insulin-regulated glucose transporter

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

What is the resting membrane potential?

A

The difference in ion concentration between the inside and outside the cell

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

What is an action potential?

A

A wave of electrical excitation along a neuron’s plasma membrane

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

What is depolarisation?

A

An electrical state in an excitable cell whereby the inside if the cell is made less negative relative to the outside than it is at the resting membrane potential.

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

What is the threshold value?

A

When the depolarisation reaches about -55mV

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

What is ion concentration gradient created by?

A

It is created by ion pump enzyme that transport ionic solutes across the membrane; energy is required to produce a gradient, so the gradient is a form of stored energy.

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

What is repolarisation?

A

The restoration of a membrane potential following depolarisation

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

What is a photon?

A

The basic unit of light

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

What are photoreceptor cells?

A

Cell found in the retina that are capable of phototransduction

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

What are rod cells?

A

Photoreceptor cells in the retina that function in dim light and respond to low light intensities; don’t allow colour perception

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

What are cone cells?

A

Photoreceptor cells responsible for colour vision, they only function in bright light

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

What is opsin?

A

A light-sensitive protein molecule

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

What is retinal?

A

A light-sensitive molecule within the eye that binds with opsin to form photoreceptors in the eye

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

What is rhodopsin?

A

The retinal-opsin complex in rod cells

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

What is transducin?

A

A protein naturally expressed in vertebrate retina rods and cones; important in vertebrate phototransduction

25
Q

What is cGMP?

A

A second messenger for visual transduction; it is present in high concentrations in photoreceptor cells

26
Q

What is phosphodiesterase?

A

The enzyme that catalyses the hydrolysis of cGMP

27
Q

How do multicellular organisms signal between cells?

A

Extracellular signal molecules

28
Q

What are example of extracellular signalling molecules?

A

Steroid hormones, peptide hormones, neurotransmitters

29
Q

What does communication occur through in animals?

A

Nerve transmission and hormone secretion

30
Q

What are receptor molecules?

A

Proteins with a binding site for a specific signal molecules

31
Q

When a receptor binds to a signal molecule, what happens?

A

The receptor changes conformation which initiates a response

32
Q

Why can hydrophobic signals bind to intracellular receptors?

A

Since they can diffuse directly through the phospholipid bilayer of membranes since the tails of phospholipid bilayers are also hydrophobic and allow molecules to pass across

33
Q

What are the receptors for hydrophobic signalling molecules?

A

Transcription factors

34
Q

Action of steroid hormones (hydrophobic signalling molecules) ?

A
  • Steroid hormones bind to specific receptors in cytosol or nucleus, forms hormone-receptor complex
  • Complex moves to nucleus, binds to specific sites on DNA called hormone response elements (HRE).
  • Binding at these sites influences rate of transcription
35
Q

What do hydrophilic signalling molecules do?

A

Bind to transmembrane receptors and do not enter the cytosol

36
Q

Examples of hydrophilic signalling molecules

A
  • Peptide hormones
  • Neurotransmitters
37
Q

Action of hydrophilic signalling molecules

A
  • Ligand (hydrophilic signal molecules) binds to transmembrane receptor and receptor changes conformation.
  • Signal is then transduced across the plasma membrane
  • Transmembrane receptors act as signal transducers by converting extracellular ligand-binding event into intracellular signals
  • This alters behaviour of cell
38
Q

What is transduction?

A

Process where chemicals or physical signal is transmitted through a cell by a series of molecular events resulting in a cellular response

39
Q

What do G-proteins do?

A

They relay signals from activated receptors to target proteins such as enzymes and ion channels. Enzymes then catalyse reactions within the cell, ion channels will either open or close to control ion movement

40
Q

What is a phosphorylation cascade?

A

A series of events with one kinase activating the next in the sequence. Receptor becomes phosphorylated and in turn phosphorylates cytoplasmic molecules.

41
Q

What does phosphorylation cascades allow?

A

Allows more than one intracellular signalling pathway to be activated

42
Q

What are the 2 hormones involved in blood glucose regulation?

A
  • Insulin
  • Glucagon
43
Q

Process when insulin binds to receptor

A
  • Binding of insulin to its receptor causes a conformational change that triggers phosphorylation of the receptor
  • Starts a phosphorylation cascade inside cell
  • This phosphorylation leads to GLUT-4 containing vesicles being transported to the cell membrane of fat and muscle cells
44
Q

What is type-1 diabetes caused by and how can it be treated?

A

A failure to produce insulin in the pancreas.
Treated with regular injections of insulin throughout the day

45
Q

What is type-2 diabetes caused by and how is it treated?

A

Caused by loss of insulin receptor function, associated with obesity.
Treated with medications to lower blood glucose levels along with lifestyle changes.

46
Q

What does exercise trigger?

A

Recruitment of GLUT-4 so it can improve uptake of glucose to fat and muscle cells

47
Q

When is there a resting membrane?

A

When there us no net flow of ions across the membrane

48
Q

What is nerve transmission?

A

A depolarisation of the resting potential of a neuron

49
Q

What does the transmission of a nerve impulse require?

A

Requires changes in the membrane potential of the neuron’s plasma membrane

50
Q

When may an action potential be triggered?

A

If the change in membrane potential is big enough

51
Q

What is an action potential?

A

A wave of electrical excitation along a neuron’s plasma membrane

52
Q

Process of nerve transmission

A
  • Neurotransmitters bind to receptors at synapse which triggers opening of ligand-gated ion channels at synapse
  • Positive ion movement occurs and there is depolarisation of plasma membrane
  • If sufficient ion movement occurs, and membrane is depolarised beyond threshold value, voltage-gated sodium channels open and sodium ions enter down their electrochemical gradient.
  • This leads to rapid and large change in the membrane potential
  • Shortly after, sodium channels become inactivated
  • Voltage-gated potassium channels open to allow potassium ions to move out of the cell to restore resting membrane potential
53
Q

What is a neurotransmitter receptor?

A

Ligand-gated ion channels

54
Q

What happens when action potential reaches the end of the neuron?

A

Causes vesicles containing neurotransmitters to fuse with the membrane which releases neurotransmitters which stimulates a response in a connecting cell

55
Q

What does restoration of the resting membrane potential allow?

A

Allows inactive voltage-gated sodium channels to return to a confirmation that allows them to open again in response to depolarisation of the membrane

56
Q

How are ion concentration gradients re-established?

A

By the sodium-potassium pump, which actively transports excess ions and out of cell

57
Q

What does the retina do?

A

Detects light and converts light into electrical energy

58
Q

Process of retinal response to light

A
  • Retinal absorbs a photon of light and rhodopsin changes conformation to photo excited rhodopsin
  • Activates G-protein, transducin. (1 photo excited rhodopsin activates hundreds of G-protein)
  • Transducin activates enzyme, phosphodiesterase ( 1 activated G-protein activates 1 PDE )
  • PDE catalyses hydrolysis of cGMP, PDE breaks down thousands of cGMP per second
  • This reduction in cGMP concentration affects function of ion channels in membrane of rod cells
  • Ion channels close, inward leakage of positive ions (Na+) is halted so membrane potential increases
  • Hyper-polarisation triggers nerve impulse in neurons in the retina

Advanced Higher Biology (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions