Cytoplasm & Organelles

Question 1

Cytoplasm (4)

Answer 1

1. outside nucleus
2. enclosed within plasma membrane
3. has cytosol and cellular organelles
4. medium for mechanical and chemical reactions

Question 2

RER (4)

Answer 2

1. extends from nuclear membrane
2. has ribosomes
3. synthesize proteins
4. modify newly synthesized proteins into secretory, integral membrane, soluble proteins (in ER, Golgi A, lysosomes)

Question 3

Modification (3)

Answer 3

1. oligosaccharyltransferase adds CHO
2. chaperone assists folding
3. disulfide isomerase forms disulfide bonds

Question 3

Examples of types of cells that contain extensive amount of RER

Answer 3

1. pancreas cells - produce protein insulin
2. plasma cells - secrete immune proteins
3. white blood cells - produce antibody

Question 4

SER & where it is mostly found

Answer 4

1. Interconnected tubules
2. No ribosomes
3. Synthesize lipid, phospholipids and steroids
4. endocrine cells - steroid
5. liver cells - detoxification (g6-p)
6. skeletal muscle cells - muscles contrations (regulate release of Ca2+)

Question 5

Golgi apparatus

Answer 5

1. process protein - protein trimming, amino acids modification to form membrane proteins, scretory and lysosomal proteins
2. synthesize complex polysaccharide
3. sort and pack proteins in vesicles

Question 6

cis-Golgi

Answer 6

sort out proteins - ship back to ER & futher processed in Golgi

Question 7

trans-Golgi

Answer 7

segregate proteins into different types of vesicles to be sent to proper destinations

Question 8

Lysosomes

Answer 8

1. breakdown of ingested external materials - by phagocytic cells
2. organelle turnover - autophagy
3. digested products - nutrients for reuse
4. have approx. 50 hydrolytic enzymes (acidic - pH 4.6)
5. defects - Tay-Sachs

Question 9

Mitochondrion

Answer 9

1. powerhouse of cell - produce energy
2. has double membrane system - inner (impermeable), outer (have permeable porins), intermembrane
3. abundant in liver cells, muscle cells and sperms
4. inner membrane - cristae (increase TSA), oxidative phosphorylation/aerobic respiration
5. matrix - gel, contains DNA coding & ribosomes, site for Tricarboxylic Acid cycle

Question 10

Mutation of Mitochondrion

Answer 10

1. Leber’s Hereditary Optic Neuropathy (LHON)
2. Leigh’s Syndrome
3. Kearns-Sayre Syndrome (KSS)
4. Myoclonic Epilepsy with ragged red fibres (MERRF)

Question 11

Mitochondrion’s role in Apoptosis

Answer 11

1. releases pro-apoptotic proteins - caspases

Question 12

Organelles that arise from pre-existing organelle

Answer 12

1. Mitochondria

2. Peroxisomes

Question 13

Peroxisomes

Answer 13

1. simple
2. multifunctional
3. oxidation of fatty acids
4. synthesis of plasmalogens phospholipids- myelin sheath of axon
5. synthesis and degradation of H2O2 - concentration of H202 can cause tissue damage

Question 14

How cell ensure particular proteins are targeted to the appropriate destinations?

Answer 14

by multiple signals and pathways

Question 15

Cytosolic ribosomes

Answer 15

• remain in cytosol

- synthesis proteins that are transported to nucleus, peroxisomes and mitochondria

Question 16

Cytoskeleton

Answer 16

1. Microtubules - rigid tube; protein tubulin
2. Intermediate filaments - tough, rope like fibers across cytoplasm
3. Microfilaments - solid, thin; protein actin
4. Functions;
   - structural support for cell shape
   - important in organelles’ positioning
   - as highway for intracellular movement
   - chromosome separation