Cell Organelles

Question 1

The endoplasmic reticulum consists of what?

Answer 1

Cisternae

Tubules

Vesicles

Question 2

What is the cytoplasm divided into by the ER.

Answer 2

The luminal or cisternae compartment

The cytoplasmic or cytoplasmic compartment

Question 3

What types of cells have a lot of rough ER?

Answer 3

Cells that secrete protein.

(eg: Pancreatic exocrine cells v Liver Hepatocytes / 60 v 35)

Question 4

Where does protein modification and assembly occur?

Where do these proteins go?

Answer 4

Rough ER

Some proteins are sorted for intracellular use and others for outside of the cell (collagen, cell membrane proteins)

Question 5

How do ribosomes attach to the RER?

Answer 5

Under the guidance of the amino acid sequence, they are synthesizing. This is called the signal sequence.

Question 6

What side of the Golgi Apparatus do proteins usually go in to?

Answer 6

The cis side.

Question 7

What does the smooth ER do?

Answer 7

Glycogen metabolism

Lipid Synthesis

Phospholipid Synthesis

Detoxification

Steroidogenesis

Calcium regulation

Question 8

What is the structure and purpose of the Golgi Apparatus?

Answer 8

Stacks of cisternae, which have a cis face facing the ER and trans face facing towards plasma membrane or nucleus

PTM of proteins and lipids, as well as trafficing

Question 9

How much Nick Cage could a Nick Cage chuck if a Nick Cage could Nick Cage Nick Cage?

Answer 9

A Nick Cage amount of Nick Cages.

Question 10

What does the smooth ER produce?

Answer 10

Polysaccharides & oligosaccharides

Sphingomyelin and glycosphingolipids

Also modifies carbs on glycoproteins and proteoglycans and provides post-translational changes.

Question 11

What are lysosomal enzymes marked with in the Golgi apparatus?

Answer 11

Mannose-6-phosphate

Question 12

In what way do materials in the Golgi Apparatus move?

Answer 12

Either way, retrograde or anterograde

Question 13

What are those products moved to the lysosome from the Golgi Apparatus or membrane coated in?

What substance from the exterior is often brought to lysosomes?

Answer 13

Clatherin

Cholesterol

Question 14

What do COP-coated vesicles direct themselves to?

COPII-coated vesicles?

Answer 14

COP I = Between Stacks and from GA to ER

COPII = From ER to GA

Question 15

Describe endocytosis

Answer 15

Clathrin surrounds the receptors and adaptin to form a clatherin coated vesicle

Dynamin surrounds the neck of the coated pit, causing the vesicle to pinch off from the membrane.

Question 16

What do lysosomes contain? How do they help the cell?

Answer 16

50-60 hydrolytic enzymes functional at acidic pH.

The monomeric subunits produced can escape into the cytoplasm through specific transporters and be reused.

Question 17

How do primary lysosomes form?

Answer 17

In the GA lysosomal enzymes are phosphoralated with mannose-6-phosphate.

These bind to M6P receptor which cause the clatherin coated transport vehicle to be lost.

The enzymes are then stored in a primary lysosome

M6P receptors are returned to GA.

Question 18

Differences in primary versus secondary lysosomes?

Answer 18

Primary - No digestive events, Homogenous, inactive enzymes

Secondary - Digestive enzymes, heterogeneous, active enzymes

Question 19

What fuses to form the lysosome?

What is the hallmark of this event?

Answer 19

Fusion of transport vehicle and endosome

Lowering of pH to 5.5

Question 20

What is the cause of Familial hypercholesterolmia?

Answer 20

Mutation in LDL receptor (incapable binding, binding at reduced capacity, incapable of internalization.)

Marked by elevation of LDL

Can cause atherosclerotic plaques

Question 21

What is the function of peroxisomes?

Answer 21

synthesis and degradation of hydrogen peroxide

ß -oxidation of long-chain fatty acids

bile acid and cholesterol synthesis

detoxify alcohol

Question 22

What are peroxisome disorders known as?

Answer 22

Zellweger spectrum disorders

The worst of which is Zellweger syndrome which is the absence or reduced number of peroxisomes in cells. Usually death within the first year of life.

Question 23

How do high energy cells pack mitochondria versus others?

Answer 23

Much more packed, such as between myofibrils in high energy cells.

Question 24

What causes the mitochondrial DNA diseases?

Answer 24

Mutations in the mt DNA that affect function (sometimes)

Also caused by mutations in the nuclear DNA which products may be imported into the mitochondria.