WEEK 8 (Cell signalling) Flashcards

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1
Q

With respect to their surrounding membrane system, which is the odd one out?
a) Nucleus
b) Endoplasmic reticulum
c) Mitochondria
d) Chloroplasts

A

Endoplasmic Reticulum

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2
Q

Which of the following proteins is a transmembrane protein responsible for anchoring the extracellular matrix (ECM)?
a) Laminin
b) Fibronectin
c) Integrins
d) Collagen

A

Integrins

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3
Q

What is the key role of fibroblasts?

A

Producing extracellular matrix

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4
Q

Which type of endomembrane secretion occurs in nerve cells?
a) constitutive
b) regulatory
c) non-continuous
d) intermittent

A

Regulatory

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5
Q

Which of the following biomolecules are contained in the lysosomes?
a) nucleic acids
b) ribonucleic acids
c) proteins
d) polysaccharides

A

Proteins

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6
Q

What happens in anaphase 1?

A

Each homolog reaches the opposite pole

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7
Q

There exists attraction between the homologs in Metaphase 1? (TRUE/FALSE)

A

FALSE

EXPLANATION: The homolog’s centromeres repel each other which assist separation to opposite pole

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8
Q

What is the function of axonemal dynein?

A

Responsible for the beating of flagella and cilia

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9
Q

What can Ehlers-Danlos Syndrome affect?

A

The production or organisation of collagen which is a critical component of connective tissue

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10
Q

What applies to both eukaryotic cell walls and animal cell extracellular matrices?

A
  • They are built to a common overall structure that can be described as ‘fibres in a matrix’
  • Their protein components are synthesised by ribosomes of the rough endoplasmic reticulum
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11
Q

Bacterial and eukaryotic cell walls have the same general function (TRUE/FALSE)

A

TRUE

EXPLANATION: The cell walls of bacteria and eukaryotic cells have the same general function of preventing cell lysis in hypotonic environments

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12
Q

What applies to fibronectins?

A
  • They are disulphide linked dimers with each polypeptide composed of a number of binding domains joined together by short flexible segments
  • They have an essential role in linking the extracellular matrix to its underlying cells
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13
Q

Glycosaminoglycans contribute to two of the tissue properties: withstand mechanical pressures and favour the movement of cells and molecules through tissues (TRUE/FALSE)

A

TRUE

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14
Q

The Elasticity of bones is partially provided by collagen fibers (TRUE/FALSE)

A

TRUE

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15
Q

Chronic pain is usually localised to the hyper mobile joints is a symptom of which disease?

A

Ehlers Danlos Syndrome (EDS)

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16
Q

What does cell signalling allow?

A

Cells to perceive and respond to extracellular environment allowing development, growth and immunity

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17
Q

What are the three stages of cell signalling?

A

1) RECEPTION = signal molecule binds the receptor
2) SIGNAL TRANSDUCTION = chemical signal results in a series of enzyme activations
3) RESPONSE = resulting cellular responses

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18
Q

How do cells usually communicate with each other?

A

Through extracellular messenger molecules

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19
Q

How do cells usually communicate with each other?

A

Through extracellular messenger molecules

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20
Q

How do extracellular messengers travel?

A
  • SHORT DISTANCE and stimulate cells that are in close proximity to the origin of the message
  • LONG DISTANCE stimulating cells that are far away from the source
21
Q

What are the four types of chemical signalling?

A
  • Endocrine signalling
  • Paracrine signalling
  • Neuronal signalling
  • Contact-dependent signalling
22
Q

What happens in Endocrine/Hormonal/Long-distance signalling?

A

Specialised cells release hormone molecules which travel to target cells elsewhere in the organism

23
Q

What happens in Paracrine/Short-distance signalling?

A

Rather than entering the bloodstream, the signal molecules diffuse locally through the extracellular fluid, remaining in the neighborhood of the cell that secretes them.

24
Q

What happens in Autocrine signalling?

A

The cell that is producing the messenger expresses receptors on its surface that can respond to the messenger that it itself produces -> Cells releasing the message stimulate or inhibit themselves

25
Q

What happens in neuronal signalling?

A

A message is delivered quickly and specifically to individual target cells -> A neuron is activated by signals from the environment or from other nerve cells -> A neuron sends electrical impulses along its axon -> Once reaching the exon terminal, the electrical signal are converted into a chemical form

26
Q

What happens in neuronal signalling?

A

A message is delivered quickly and specifically to individual target cells -> A neuron is activated by signals from the environment or from other nerve cells -> A neuron sends electrical impulses along its axon -> Once reaching the exon terminal, the electrical signal are converted into a chemical form

27
Q

What happens in Contact-dependent signalling?

A

A cell surface bound signal molecule binds to a receptor protein on an adjacent cell

28
Q

What is contact dependent signalling important in?

A
  • Development
  • Immune responses
29
Q

What happens in Lateral inhibition?

A

Each future neuron delivers an inhibitory signal to the cells next to it deterring them from specialising as neurons too

30
Q

What are the different signalling components?

A
  • Signalling molecules
  • Receptors
  • Signalling intermediates
  • Effector proteins
31
Q

What is the difference between First messengers and Second messengers?

A
  • FIRST MESSENGERS = extracellular factors (often hormones/neurotransmitters)
  • SECOND MESSENGERS = intracellular signalling molecules released by the cell in response to exposure to extracellular signalling molecules
32
Q

What are signalling molecules?

A

Molecules that are responsible for transmitting information between cells in your body

33
Q

What are receptors?

A
  • Proteins associated with cell membrane or located within the cell
  • Recognise signalling molecules by binding to them
  • Binding of receptors by signalling molecules causes cell behaviour changes
34
Q

Describe Myasthenia Gravis

A

Myasthenia gravis is a long-term neuromuscular disorder that’s usually caused by an autoimmune problem which leads to varying degrees of skeletal muscle weakness. Most commonly affected muscles are eyes, face and swallowing.

DEFICIENCY: acetylcholine

SYMPTOMS:
- difficulty breathing
- difficulty swallowing/chewing
- facial paralysis
- problems walking up stairs/lifting objects
-droopiing of eyelids

[severity of symptoms increases over time if left untreated]

35
Q

How do signal molecules work to regulate the behaviour of the cell?

A

Every cell type displays a set of receptor proteins that enables it to respond to a specific set of extracellular signal molecules produced by other cells -> the signal molecules work I combinations to regulate the behaviour of the cell

36
Q

What are the two classes of Extracellular signal molecules?

A
  • Molecules that are TOO LARGE or TOO HYDROPHILIC to cross the plasma membrane
  • Molecules that are SMALL ENOUGH or HYDROPHOBIC ENOUGH to pass through the plasma membrane
37
Q

Some small hydrophobic hormones binds to intracellular receptors that act as ______________________________

A

Transcription regulators

38
Q

Describe how Cortisol acts

A

1) Cortisol cross the plasma membrane and a conformational change activates the receptor protein
2) Activated receptor-cortisol complex moves into the nucleus
3) Activated receptor-cortisol complex binds to regulatory region of target gene and activates transcription

39
Q

Describe how acetylcholine causes the blood vessel to dilate

A

Acetylcholine binds to receptors on the surface of endothelial cells which stimulates cells to make and release NO -> NO is synthesised from the amino acid arginine and diffuses readily from its site of synthesis into adjacent smooth muscle cells -> NO regulates the activity of specific proteins causing the muscle cells to relax

40
Q

What does NO activate in smooth muscle cells

A

GUANYLYL CYCLASE

[catalyses the production of cyclic GMP from GTP]

41
Q

What are the functions of intracellular signalling pathways?

A
  • RELAY the signal onward and spread it through the cell
  • AMPLIFY the signal received making it stronger
  • can detect signals from more than one intracellular signalling pathway and INTEGRATE them before relaying a signal onward
  • DISTRIBUTE the signal to more than one effector protein
42
Q

What are the two classes that proteins that act as molecular switches fall into?

A
  • Proteins that are activated or inactivated by phosphorylation
  • GTP-binding proteins
43
Q

What switches the GTP-binding protein on and off?

A

GUANINE NUCLEOTIDE EXCHANGE FACTORS (GEFs) promote the exchange of GDP or GTP switching the GTP-binding protein ON

GTPASE-ACTIVATING PROTEINS (GAPs) stimulate the hydrolysis of GTP to GDP switching the GTP-binding protein OFF

44
Q

What are the three different classes of cell-surface receptors which differ in the transduction mechanism?

A
  • Ion-channel-coupled receptors
  • G-protein-coupled receptors
  • Enzyme-coupled receptors
45
Q

What is the function of all cell-surface receptor proteins?

A

They bind to an extracellular signal molecule and transduce its message into one or more intracellular signalling molecules that alter the cell’s behaviour

46
Q

Describe Ion-channel-coupled receptors

A

They change the permeability of the plasma membranes to selected ions such as Na+, K+ or Ca2+ altering the membrane potential and producing an electrical current

47
Q

What are transmitter-gated ion channels?

A

Ion-channel-coupled receptor that opens in response to binding an extracellular signal molecule

48
Q

What happens when a G-protein-coupled receptor binds its extracellular signal molecule?

A

The activated receptor signals to a G protein on the opposite side of the plasma membrane which turns on or off an enzyme in the same membrane