Cell physiology

Question 1

4 categories of cells

Answer 1

Epithelial, Connective tissue, Nerve, Muscle

Question 2

Central Dogma of Molecular Biology

Answer 2

Genetic information only flows in one direction (DNA&raquo_space; RNA&raquo_space; Protein)

Question 3

Free ribosomes synthesize:

Answer 3

Cytosolic proteins

Question 4

Membrane-bound ribosomes (attached to the rough ER) synthesize:

Answer 4

Membrane-bound proteins

Question 5

Smooth ER function

Answer 5

Lipid synthesis (fatty acids, phospholipids, steroids) and detoxification of harmful substances (especially in the liver)

Question 6

Rough ER function

Answer 6

Protein synthesis and distribution of proteins to the Golgi apparatus/other organelles

Question 7

Chronic ER stress can lead to

Answer 7

Cell death

Question 8

Mitochondrial myopathy

Answer 8

Mitochondrial diseases that cause muscle problems (limb weakness, muscle fatigue)

Question 9

Lysosomes break down:

Answer 9

Damaged/worn out organelles, Engulfed (harmful) bacteria & debris of dead cells

Question 10

Peroxisomes break down:

Answer 10

Long chain fatty acids, toxins (such as alcohol)

Question 11

Fluid Mosaic Model

Answer 11

The plasma membrane is a ‘mosaic’ of phospholipids, proteins, and cholesterol

Question 12

Zellweger syndrome

Answer 12

Most severe peroxisome biogenesis disorder - fatal

Question 13

Function of cell membranes (4 points)

Answer 13

1. Link adjacent cells together
2. Regulate passage of substances into and out of cell
3. Detect chemical messengers arriving at the cell surface
4. Anchor cells to extracellular matrix

Question 14

Junction space between cells from least to most

Answer 14

Tight junctions < Gap junctions < Desmosomes

Question 15

4 Types of membrane transport

Answer 15

Diffusion, Protein-mediated transport, Vesicular transport, Epithelial transport

Question 16

What is the relationship between the surface area of a membrane (A) and the net flux

Answer 16

Diffusion can occur at a faster rate with a larger surface area, therefore the net flux will increase

Question 17

What is the relationship between the concentration difference (Co-Ci) and the net flux

Answer 17

A larger concentration difference drives greater diffusion, increasing the net flux

Question 18

Electrochemical gradient (only for ions)

Answer 18

An electrical gradient (difference in charge across a membrane) and a chemical gradient (ion concentration gradient)

Question 19

What does ion channel selectivity depend on? (3 points)

Answer 19

1) Ion channel diameter
2) Charge of the polypeptides that make up the channel
3) Number of water molecules associated with each ion

Question 20

Ligand-gating

Answer 20

Binding of specific ligands change the conformation of the ion channel

Question 21

Voltage-gating

Answer 21

A change in membrane potential causes a conformational change

Question 22

Mechanical-gating

Answer 22

A conformational change that results from mechanical stress (a physical change) to the membrane (eg. stretching)

Question 23

What does the magnitude of flux through a passive transporter depend on? (4 points)

Answer 23

1) Solute concentration
2) Affinity of transporter for solute
3) Number of transporters in the membrane
4) Rate at which the transporter goes through conformational change

Question 24

Potocytosis

Answer 24

A form of RME in which small molecules are transported (eg. vitamins) via. caveolae (small vesicles) into the cytosol, rather than lysosomes

Question 25

Fate of the vesicle in pinocytosis, phagocytosis, and RME

Answer 25

Pino and Phago: The vesicle fuses with a lysosome where the contents are hydrolyzed RME: The vesicle can have multiple fates (nucleus, endosome, lysosome) but the receptors are usually recycled to the cell membrane

Question 26

Is the paracellular/transcellular pathway of epithelial transport between cells or through cells

Answer 26

Paracellular pathway is between cells, Transcellular pathway is through cells

Question 27

3 ways that cells communicate with each other

Answer 27

Lipids Lipid soluble messengers Water soluble messengers

Question 28

Cell signalling depends on what 4 ligand-receptor interactions?

Answer 28

Specificity - a specific receptor will bind a specific ligand Affinity - strength of ligand binding to receptor Saturation - extent to which receptors are bound by ligand Competition - presence of other ligands 'competing' for binding sites

Question 29

Agonist

Answer 29

A ligand that produces the same effect as the endogenous ligand when bound to a receptor

Question 30

Antagonist

Answer 30

A ligand that inhibits the action of an agonist or endogenous ligand by binding to the binding site

Question 31

5 cellular responses from signal transduction

Answer 31

1) Change in membrane properties 2) Cellular metabolism 3) Secretory activity 4) Rate of proliferation/differentiation 5) Contractility or other activity

Question 32

Janus kinase

Answer 32

Cytoplasmic kinases that may be activated by receptors

Question 33

The 4 major second messengers

Answer 33

cyclicAMP (cAMP) Inositol triphosphate (IP3) Diacylglycerol (DAG) Calcium

Question 34

The 3 classes of G-proteins and their function

Answer 34

Gi proteins - inhibit adenylyl cyclase and production of cAMP Gs proteins - activates adenylyl cyclase and production of cAMP Gq proteins - activate phospholipase C and production of IP3 and DAG