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MD2001 > Cell Biology > Flashcards

Cell Biology Flashcards

1
Q

What is the bilayer of a membrane composed of?

A

Phospholipids, sphingolipids, cholesterol

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2
Q

What is the structure of microfilaments?

A

Double strands of actin.

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3
Q

What is the function of microfilaments?

A

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

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4
Q

What is the structure of microtubules?

A

Alpha and beta tubulin polymerise into protofilament.

13 protofilaments form a tube which can be enlarged.

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5
Q

What is the function of microtubules?

A

Intracellular movement of organelles.

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6
Q

Which motor protein is involved in anterograde transport?

A

Kinesins

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7
Q

Which motor protein is involved in retrograde transport?

A

Dyneins

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8
Q

What allows cilia and flagella to move?

A

Dyneins

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9
Q

What are cilia and flagellum made from?

A

Mobile projections of the plasma membrane, made from microtubules.

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10
Q

What is the function of intermediate filaments?

A

Providing cell strength and support.

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11
Q

What are the functions of RER?

A
  1. Membrane synthesis.
  2. Modifying proteins.
  3. Quality control (monitors misfoldings).
  4. Signals stress, usually when secretion is blocked.
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12
Q

How did mitochondria evolve?

A

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

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13
Q

What happens when a lysosome ruptures?

A

Cell self digests (autolysis).

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14
Q

What are degradable proteins tagged with?

A

Ubiquitin.

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15
Q

What is the structure of a proteasome?

A

Protein complex arranged in four rings around a central core.

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16
Q

What is the function of peroxisomes?

A
  1. Resemble lysosomes.
  2. Break down fatty acids.
  3. Synthesise specialised lipids.
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17
Q

What happens if a protein has a signal recognition receptor?

A

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

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18
Q

What are the four types of adhesion molecules?

A
  1. Cadherins.
  2. Selectins.
  3. Integrins.
  4. Intercellular and vascular adhesion molecules.
19
Q

What do cadherins do?

A
  1. Bind to actin via catenins.

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

20
Q

What do selectins do?

A

Bind to glycoproteins.

21
Q

What do integrins do?

A
  1. Bind to cytoskeletal proteins in ICM.

2. Bind in laminin and fibronectin in ECM.

22
Q

What do vascular adhesion molecules do?

A

Involved in interactions between endothelial cells and leucocytes.

23
Q

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

A

Tyrosine kinase.

24
Q

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

A
  1. Ligand gated open directly to chemicals.
  2. Receptor-operated open indirectly to chemicals.
  3. Voltage-gated open by change in electrical potential.
25
Q

What is secondary active transport?

A

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.

26
Q

What is a symport?

A

Na+ and substance travel in same direction.

27
Q

What are the three types of endocytosis?

A
  1. Phagocytosis.
  2. Pinocytosis.
  3. Receptor-mediated endocytosis.
28
Q

What is receptor mediated endocytosis?

A
  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.
29
Q

What is transcytosis?

A

Mechanism to move substances across cells.

  1. Substance enters through receptor mediated endocytosis into an endosome.
  2. Endosome fuses with opposing plasma membrane
30
Q

What are GAGs?

A
  1. Long chain of repeating disaccharide.

2. Highly charged.

31
Q

Three examples of GAGs.

A
  1. Hyaluronan
  2. Keratin sulphate.
  3. Chondroitin sulphate.
32
Q

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

A

COPII.

33
Q

What is collagen produced in?

A

A fibropositor (membrane tube).

34
Q

What do proteoglycans do?

A
  1. Link proteins in ECM.

2. Link ECM and cell surface.

35
Q

What cells make up connective tissue?

A
  1. Fibroblasts
  2. Myofibroblasts.
  3. Chondroblasts.
  4. Osteoblasts.
  5. Adipocytes.
  6. Blood cells.
36
Q

What protein does myofibroblasts secrete

A

Collagen.

37
Q

What proteins do myofibroblasts synthesise?

A
  1. Actin.
  2. Myosin.
  3. Desmin.
38
Q

What cadherins are used in desmosomes?

A
  1. Desmocollins.

2. Desmogleins.

39
Q

What proteins are contained in the plaque of desmosomes?

A
  1. Desmoplakin.

2. Plakoglobin.

40
Q

What three junctions make up an intercalated disc?

A
  1. Gap junction.
  2. Desmosome.
  3. Fascia adherens.
41
Q

Explain the general principle of a junction?

A

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

42
Q

What happens in DMD?

A

Gene mutation causing absence of the adaptor protein dystrophin.

43
Q

How can DMD be treated?

A

Using Ataluren (PTC 124).

44
Q

Explain the basics of a micro invasion of a carcinoma.

A
  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.

MD2001 (10 decks)

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