Cell Biology

Question 1

What is the bilayer of a membrane composed of?

Answer 1

Phospholipids, sphingolipids, cholesterol

Question 2

What is the structure of microfilaments?

Answer 2

Double strands of actin.

Question 3

What is the function of microfilaments?

Answer 3

Provide support to the cell and allow the cell to fix its shape.

Question 4

What is the structure of microtubules?

Answer 4

Alpha and beta tubulin polymerise into protofilament.

13 protofilaments form a tube which can be enlarged.

Question 5

What is the function of microtubules?

Answer 5

Intracellular movement of organelles.

Question 6

Which motor protein is involved in anterograde transport?

Answer 6

Kinesins

Question 7

Which motor protein is involved in retrograde transport?

Answer 7

Dyneins

Question 8

What allows cilia and flagella to move?

Answer 8

Dyneins

Question 9

What are cilia and flagellum made from?

Answer 9

Mobile projections of the plasma membrane, made from microtubules.

Question 10

What is the function of intermediate filaments?

Answer 10

Providing cell strength and support.

Question 11

What are the functions of RER?

Answer 11

1. Membrane synthesis.
2. Modifying proteins.
3. Quality control (monitors misfoldings).
4. Signals stress, usually when secretion is blocked.

Question 12

How did mitochondria evolve?

Answer 12

An endosymbiotic event where a bacteria was captured by a eukaryote.

Question 13

What happens when a lysosome ruptures?

Answer 13

Cell self digests (autolysis).

Question 14

What are degradable proteins tagged with?

Answer 14

Ubiquitin.

Question 15

What is the structure of a proteasome?

Answer 15

Protein complex arranged in four rings around a central core.

Question 16

What is the function of peroxisomes?

Answer 16

1. Resemble lysosomes.
2. Break down fatty acids.
3. Synthesise specialised lipids.

Question 17

What happens if a protein has a signal recognition receptor?

Answer 17

The protein will go the ER, bind to it and be used in membrane synthesis.

Question 18

What are the four types of adhesion molecules?

Answer 18

1. Cadherins.
2. Selectins.
3. Integrins.
4. Intercellular and vascular adhesion molecules.

Question 19

What do cadherins do?

Answer 19

1. Bind to actin via catenins.

2. Contains a dimer with 4 calcium binding sites which binds to cadherin on adjacent cell.

Question 20

What do selectins do?

Answer 20

Bind to glycoproteins.

Question 21

What do integrins do?

Answer 21

1. Bind to cytoskeletal proteins in ICM.

2. Bind in laminin and fibronectin in ECM.

Question 22

What do vascular adhesion molecules do?

Answer 22

Involved in interactions between endothelial cells and leucocytes.

Question 23

What enzyme allows transfer of a phosphate group to a protein in a cell?

Answer 23

Tyrosine kinase.

Question 24

What is the difference between ligand gated, receptor-operated and voltage gated channels?

Answer 24

1. Ligand gated open directly to chemicals.
2. Receptor-operated open indirectly to chemicals.
3. Voltage-gated open by change in electrical potential.

Question 25

What is secondary active transport?

Answer 25

Exploitation of the Na+/K+ pump by allowing Na+ to diffuse back into the cell, releasing energy which is used to pump other substances in or out.

Question 26

What is a symport?

Answer 26

Na+ and substance travel in same direction.

Question 27

What are the three types of endocytosis?

Answer 27

1. Phagocytosis. 2. Pinocytosis. 3. Receptor-mediated endocytosis.

Question 28

What is receptor mediated endocytosis?

Answer 28

1. Receptor is covered in clathrin. 2. Cathrin coated intracellular vesicle fuses with an endosome of low pH. 3. Complex dissociates. 4. Ligand goes to lysosome or transported in cytoplasm. 5. Membrane returns to cell surface.

Question 29

What is transcytosis?

Answer 29

Mechanism to move substances across cells. 1. Substance enters through receptor mediated endocytosis into an endosome. 2. Endosome fuses with opposing plasma membrane

Question 30

What are GAGs?

Answer 30

1. Long chain of repeating disaccharide. | 2. Highly charged.

Question 31

Three examples of GAGs.

Answer 31

1. Hyaluronan 2. Keratin sulphate. 3. Chondroitin sulphate.

Question 32

What type of vesicle is used to transport proteins from the RER to Golgi?

Answer 32

COPII.

Question 33

What is collagen produced in?

Answer 33

A fibropositor (membrane tube).

Question 34

What do proteoglycans do?

Answer 34

1. Link proteins in ECM. | 2. Link ECM and cell surface.

Question 35

What cells make up connective tissue?

Answer 35

1. Fibroblasts 2. Myofibroblasts. 3. Chondroblasts. 4. Osteoblasts. 5. Adipocytes. 6. Blood cells.

Question 36

What protein does myofibroblasts secrete

Answer 36

Collagen.

Question 37

What proteins do myofibroblasts synthesise?

Answer 37

1. Actin. 2. Myosin. 3. Desmin.

Question 38

What cadherins are used in desmosomes?

Answer 38

1. Desmocollins. | 2. Desmogleins.

Question 39

What proteins are contained in the plaque of desmosomes?

Answer 39

1. Desmoplakin. | 2. Plakoglobin.

Question 40

What three junctions make up an intercalated disc?

Answer 40

1. Gap junction. 2. Desmosome. 3. Fascia adherens.

Question 41

Explain the general principle of a junction?

Answer 41

ICM links to plaque which contains an adaptor which binds to transmembrane protein which binds to ECM.

Question 42

What happens in DMD?

Answer 42

Gene mutation causing absence of the adaptor protein dystrophin.

Question 43

How can DMD be treated?

Answer 43

Using Ataluren (PTC 124).

Question 44

Explain the basics of a micro invasion of a carcinoma.

Answer 44

1. Expression of cadherins is reduced. 2. Production of metalloproteases. 3. Expression of interns. 4. Autocine motility factors. 5. Angiogenesis factors i.e. VEGFs promote vascularisation.