Cellular Mechanisms

Question 1

Kinase Linked Receptors Outline

Answer 1

Large single chain protein. Single membrane spanning helical region. Extracellular = binding domain, intracellular = variable function.

Question 2

Kinase Linked Receptors Function

Answer 2

Immune response, cell division and cell differentiation

Question 3

3 Kinase Receptor types

Answer 3

tyrosine kinases (eg nerve growth), serin/theroine kinase (eg growth factor) and cytosolic kinases (interacts with cytokine receptors with no enzyme activity eg interferons)

Question 4

Growth Factor (serine receptor) Pathway steps

Answer 4

Agonist binding, (polymerization +) dimerisation, autophosphorylation and gene transcription

Question 5

Autophosphorylation Def

Answer 5

Phosphate attaches to receptor from cytosol. Receptor doesn’t need phosphate applied from other receptors

Question 6

Dimerisation Outline

Answer 6

Allosteric binding to receptor inducing confirmational change for more effective action

Question 7

Cytokine Receptors Pathways Step

Answer 7

Receptor binding, dimerization, phosphorylation and gene transcription

Question 8

Purpose of medicine

Answer 8

Pharmacological intervention. Maintain physiological functions (homeostasis).

Question 9

Cell Types

Answer 9

Blood, muscle, bone, fat, nervous and sex

Question 10

Cell Functions

Answer 10

Structure, growth, reproduction, apoptosis, metabolism, temp regulation, communication and material transport

Question 11

Differences between juxtracrine and paracrine

Answer 11

Juxtracrine stimulate cells in contact with them. Paracrine cells stimulate cells close to them (but not necessarily in contact with eachother)

Question 12

Apoptosis Def

Answer 12

Regulated cell death

Question 13

Rapidly acting cell mechanisms (milliseconds to hours)

Answer 13

Excitation (changes in membrane potential), contraction (smooth and skeletal muscles) and secretion (chemical mediators - cytokines)

Question 14

Slower acting cell mechanisms (days+)

Answer 14

Cell proliferation and apoptosis

Question 15

Host Defence Response Acting Cell Mechanisms

Answer 15

Anti-inflammatories and immuno-therapeutics

Question 16

How is short term cell mechanisms regulated

Answer 16

Stores and release of intracellular Ca^2+. Dependent regulation of functional proteins (enzymes, contractile and vesicle proteins)

Question 17

Where Calcium is stored in cells

Answer 17

Sarcoplasmic Reticulum (muscle cells), Endoplasmic Reticulum, mitochondria, free Ca, extracellularly (1/50 the amount Ca free)

Question 18

4 main routes that Ca enters cell

Answer 18

Voltage gated channels, ligand gated Ca channels, store operated Ca channels and Na+ - Ca^2+ exchange channels

Question 19

Voltage Gated Ca Channels Outline

Answer 19

Ca^2+ enters cell when membrane depolarises. 5 types: L, T, N, P/Q and R

Question 20

Ligand Gated Ca Channels Outline

Answer 20

Activated by excitatory neurotransmitters (eg GABA). Non-selective transports Ca^2+ and other cations

Question 21

Store Operated Ca Channels Outline

Answer 21

Channels that open within the cell membrane when ER Ca levels are low. Not sensitive to cytosolic free Ca

Question 22

Na+ and Ca^2+ exchange

Answer 22

Controlled Ca^2+-ATPases. Ca^2+ is pushed out so 3 Na+ ions can be pushed in

Question 23

2 types of Ca channels in endoplasmic and sarcoplasmic reticulum

Answer 23

Inositol trisphosphate receptors (Ca influx) and Ryanodine receptors (Ca efflux)

Question 24

Ionisotal Trisphosphate Receptor Outline

Answer 24

Gq-coupled receptors stimulated Ionisotal Trisphosphate. Results in increased Ca in ER and SR

Question 25

Ryanodine Receptor Coupling

Answer 25

Excitation-contraction coupling in cardiac and skeletal muscles

Question 26

2 ways in which Ca Mediates

Answer 26

Direct Binding or Binding to Intermediate Proteins

Question 27

Examples of an intermediate protein

Answer 27

Calmodulin. This undergoes further protein interactions to effect gene interactions

Question 28

Relationship between voltage required for channels and concentration gradient

Answer 28

The steeper the push up the con gradient = more voltage required

Question 29

Excitability Def

Answer 29

Cell's ability to regenerate an electrical response due to the depolarisation of it's membrane as an action potential

Question 30

Cells that respond to action potentials

Answer 30

Neurons, muscle, skeletal, cardiac, smooth and endocrine

Question 31

Why might fluctuations of free Calcium differ from cell to cell

Answer 31

Due to different action potentials firing due to different resting membrane potentials

Question 32

3 subcategories of muscle cells

Answer 32

Skeletal (sarcomeres, voluntary movement), cardiac (sarcomeres, involuntary heart beat) and smooth (no sarcomeres, involuntary airways, GIT, ect)

Question 33

Association between Ca movement and contraction of muscle cells

Answer 33

Contraction is a result of increased Ca^2+ in all cells by stimulation of IP3

Question 34

What process does cardiac and skeletal muscle have that smooth cells doesn't

Answer 34

The binding of Ca to troponin when forming cross bridges. In smooth cells the troponin and tropomysoin molecules aren't present so Ca converts myosin to myosin P

Question 35

How does subutamol act in the treatment of asthma

Answer 35

Beta 2 (protein-kinase A) receptor antagonist. Binding results in a decrease in free cell Ca

Question 36

Examples of endogenous (natural) chemical mediators

Answer 36

Neurotransmitters, hormones and inflammatory mediators

Question 37

Relationship between Ca and Exocytosis

Answer 37

Vesicles only fuse to cell membrane, releasing contents when Ca influx has occurred at end of depolarisation

Question 38

2 ways in which Ca influences diffusion of chemical mediators into synapse

Answer 38

Voltage gated Ca channels (rapid acting) and Intraceellular stores (slow acting (endocrine and exocrine glands)