Cell Organelles

Question 1

3 pathways for cell degradation

Answer 1

1) Phagocytosis ( go to lysosome)
2) Autophagy ( damaged organelles degrade via lysosome)
3) Receptor Mediated Endocytosis- macromolecules -> early endosome(fusing vesicle from Golgi) ->late endosome-> lysosome

Question 2

3 topological categories in cell

Answer 2

1) Nucleus and cytosol (communicate through complex
2) ER, Golgi apparatus, endosome, and lysosome (secretory and endocytic pathway) (communicate through vesicles).
3) Mitochondria

Question 3

Familial hypercholesterolemia- how does it affect LDL?

Answer 3

• cholesterol uptake mechanism disrupted
  
  • main transport protein in plasma
• Causes
  1) mutation in gene encoding LDL receptor
  - LDL receptors incaplable to binding LDL
  - LDL receptors that bind at reduce capacity
  - LDL bind normally but in capable of internatzation

*high LDL => atherosclerosis plaques

Question 4

Function of Smooth ER

Answer 4

• Glycogen metabolism
• Lipid synthesis
• Phospholipid synthesis (other membranes)
• Detoxification
• Steroid genesis
• Calcium regulation

Question 5

Golgi Apparatus function

Answer 5

• Post- transcriptional modification for proteins and lipids
• Carbohydrates attached to glycoproteins and proteoglycans
• Polysaccharide/oligosaccharide synthesis
• Secretory products- mannose -6- phosphate and packing in granules

Question 6

How are lysosomes formed?

Answer 6

• Fusion of transport vesicle and late endosome ( exm cholesterol, taken up by endocytosis)
• Clathrin componenet recycle, early endosomes mature into late endosomes (Precursor to secondary lysosomes)
• to work= ph down to 5.5

Question 7

Mannose- 6- Phosphate

Answer 7

Tag on lysosomal enzyme in ER to go into lysosome

• separates it from glycoproteins in ER
• binds to M6P receptors -> transport to clarithin coated receptor-> forms primary lysosome

Question 8

Mitchondrial transfer RNA

Answer 8

• high variable
• have been linked to over 200 disease states
• mutations in:
  
  • mtDNA -> affect mitochrondrial fxn
  • nuclear DNA

Question 9

Mitochondria in high energy cells

Answer 9

• less dynamic

- much more tightly pack between myofibrils (cardiac muscle) and around flagellum of sperm cells

Question 10

Peroxisome function

Answer 10

• Catalase- enzyme broken down from h- bones
• degrade/synthesis of hydrogen peroxide
• B oxidation
• cholesterol/ bile synthesis
• detoxify alcohol

Question 11

Primary Lysosomes

Answer 11

• storage of lysomal hydrolases
  
  • no digestive event
  • homogenous
  • inactive enzymes

Question 12

Secondary Lysosomes

Answer 12

• engages in catalytic process
  
  • heterogenous
  • digestive enzymes
  • active enzyme

Question 13

Signal Sequence

Answer 13

a few AAs in the beginning of polypeptide that directs ribosome to Endoplasmic Reticulm finish protein synthesis and spit into ER
- once protein is needed, will create vesicle to transport to Golgi

Question 14

Two Types of Vesicle Transport

Answer 14

1) Clathrin-coated vesicles
- move things to break down
- transports products from Golgi or exterior of cells into LYSOSOMES (like cholesterol)
- endocytosis- dynamin pinch off of plasma membrane into cytosol
2)COP- coated proteins
COP I- move things between Golgi
COP II- move things from ER TO(2) Golgi

Question 15

Zellweger Syndrome

Answer 15

• defect in assembly of peroxisome ( no cholesterol uptake)
• 12 genes to make peroxisomes (ph 6 before closeing)
  Worst: any 12 gene will call Zellweger spectrum disorder -> none or reduced number of peroxisome cells
• congenital at birth
  no cure/treatment
  First years: death at 1year old

Question 16

Clathrin -coated vesicle protein and function

Answer 16

Dynamin- surround neck of coated pit and cause pinch off of plasma membrane

Adaptin- mediate clathrin binding to vesicle membrane