Cells

Question 1

What features do both Prokaryotes AND Eukaryotes have?

Answer 1

Plasma membrane, DNA, ribosomes

Question 2

What are Eukaryote specific features?

Answer 2

DNA wrapped in histones,
Nucleus contained by nuclear envelope
Contains complex membranous cytoplasmic organelles
Specialised cytoplasmic organelles for aerobic respiration
Endocytosis and Exocytosis
Gene diploidy

Question 3

What is Euchromatin and Heterochromatin

Answer 3

Euchromatin is ‘activated chromatin’, Heterochromatin is ‘inactivated’

Question 4

What mutations lead to cancer?

Answer 4

sON divide signals
sOFF don’t divide signals
loss of correction mechanism on DNA replication
loss of escape mechanism from cell division
loss of limit on number of times a cell can divide
loss of control keeping within tissue boundaries
ability to evade body defence mechanisms
ability to recruit blood vessels t growing tumour
ability to migrate into blood stream or lymph tissue
ability to establish tumours in the wrong tissue (metastasis)

Question 5

What are the main functions of blood?

Answer 5

Transport
Connective tissue
Heat distribution
Haemostats
Homeostasis

Question 6

What is the difference between plasma and serum?

Answer 6

Plasma is the fluid component of blood

Serum is plasma without the proteins

Question 7

How do erythrocytes transport O2?

Answer 7

Oxyhaemoglobin

Question 8

Describe the negative feedback mechanism that seeks to rectify low blood O2

Answer 8

Low O2 > kidney releases erythropoietin > bone marrow produces more erythrocytes > increase in blood Hb > Increase in O2

Question 9

What are reticulocytes, and what are they indicative of?

Answer 9

They are precursors to erythrocytes and high levels are diagnostic of anaemia or chemotherapy

Question 10

What is the lifespan of an erythrocyte? How are they removed?

Answer 10

120 days by the reticulo-endothelial system (phagocytic macrophages in the spleen)

Question 11

What are normal [Hb] parameters?

Answer 11

135-165(M) 115-145(F)

Question 12

What are normal [RBC] parameters?

Answer 12

5. 4x10^-12/L(M)

4. 8x10^-12/L(F)

Question 13

What are normal haematocrit parameters?

Answer 13

0. 4-0.54(M)

0. 35-0.47(F)

Question 14

Define anaemia

Answer 14

Low blood haemoglobin concentration

Question 15

What are the three types of anaemia and why are they caused?

Answer 15

Microcytic (small MCV): iron deficiency due to slow bleeds, cancer, infection, parasite
Normocytic (normal MCV): acute blood loss
Macrocytic (large MCV): fewer RBC caused by folic acid deficiency (Vitamin B12 prevent folic acid actions as well)

Question 16

What are the different types of leukocyte (and their relative percentages) ?

Answer 16

Neutrophils (40-75%)
Lymphocytes (20-45%)
Monocytes (2-10%)
Eosinophils (1-6%)
Basophils (<1%)

Question 17

What is raised/low levels of leukocytes called? What does it show?

Answer 17

Leukocytosis = Raised; Infection, cancer
Leukopenia = Low; HIV, chemotherapy

Question 18

What cells are platelets derived from?

Answer 18

Megakaryocytes

Question 19

What do platelets form when activated?

Answer 19

Filopodia

Question 20

How are platelets activated?

Answer 20

• Collagen normally found in vessel walls

- Thrombin-coagulation cascade

Question 21

What do phospholipids form when suspended in water?

Answer 21

Micelles

Question 22

Why can phospholipids be described as amphiphilic?

Answer 22

They contain both polar and non-polar groups

Question 23

What are the components of a phospholipid?

Answer 23

Glycerol attached to a phosphate group and two fatty acid tails. There is also an anionic or cationic group. The phospholipid must be net anionic or neutral.

Question 24

How are membranes asymmetrical?

Answer 24

Extracellular side populated with neutral phospholipids and glycolipids.
Membrane facing cytosol tend to have phospholipids with a negative charge, giving that side a net negative charge.

Question 25

How is membrane protein movement contained?

Answer 25

Intracellular actin cytoskeleton fences

Question 26

What are lipid bilayers permeable to?

Answer 26

• Small uncharged molecules
• Water molecules
• Lipid soluble molecules

Question 27

What are lipid bilayers NOT permeable to?

Answer 27

• Ions
• Small hydrophobic molecules
• Macromolecules

Question 28

What is the lipid/protein composition percentages of the following membranes:

• Myelin sheath
• Plasma membrane
• Inner mitochondrial membrane

Answer 28

Myelin sheath - 80% lipid, 20% protein
Plasma membrane - 50/50
Inner mitochondrial - 25% lipid, 75% protein

Question 29

What are the two types of membrane protein couple transporters?

Answer 29

Symporters: both molecules move in same direction (mainly with Na+ moving IN cell)
Antiporters: both molecules moving in opposite direction

Question 30

What is the structure of the sodium-potassium pump?

Answer 30

Two polypeptide chains:

• alpha chain with 1000 aa, spanning the membrane 10 times, forming a hydrophilic pore
• beta chain with 300 aa forming a controller

Question 31

What does the sodium-potassium pump transport?

Answer 31

2K+ inside the cell for every 3Na+ out.

Question 32

How does the sodium-potassium pump work?

Answer 32

1) 3NA+ ions bind to protein
2) ATP phosphorylases an aspartyl residue
3) Change in conformation allows 3Na+ to dissociate from protein into extracellular fluid
4) 2K+ binds to protein
5) This causes a change in conformation leading to the hydrolysis of the aspartyl phosphate, releasing phosphate into cytoplasm
6) Channel has original shape and 2K+ forced out

Question 33

What are viruses?

Answer 33

Obligate intracellular parasites

Question 34

What are Helminth parasites?

Answer 34

Multicellular eukaryotes including tapeworms, flatworms and roundworms

Question 35

What is the diameter of a platelet cell?

Answer 35

2-3 um