Cell structure

Question 1

Where are membrane bound ribosomes found?

Answer 1

RER (rough endoplasmic reticulum)

Question 2

What type of proteins do membrane bound ribosomes (on RER) produce?

Answer 2

Proteins that are mostly secreted from cell
- Protein hormones, digestive enzymes

Question 3

What type of proteins do free ribosomes (cytosol) produce?

Answer 3

Proteins mostly used by cell
- Metbolism, structure

Question 4

What are Nissl bodies?

Answer 4

RER in neurons
- Synthesize NTs

Question 5

RERs are abundant in what type of cells?

Answer 5

Secretory cells
- Goblet cells (mucus)
- Plasma cells (antibodies)
- Pancreatic Beta cells (insulin)

Question 6

What is the function of the golgi?

Answer 6

Modifies and transports proteins
- Proteins sorted/shipped by adding signal sequences

Question 7

What is the functions of the smooth endoplasmic reticulum?

Answer 7

• Lipid/steroid synthesis
• Detoxification of drugs and toxins

Question 8

Why is the smooth endoplasmic reticulum called ‘smooth’?

Answer 8

It is part of the endoplasmic reticulum w/o ribosomes

Question 9

What does the sarcoplasmic reticulum contain?

Answer 9

Calcium

Question 10

What is the smooth endoplastic reticulum known as in myocytes?

Answer 10

Sarcoplastic reticulum

Question 11

What tissues have lots of SER?

Answer 11

• Hepatocytes (cholesterol synthesis, detoxification, CYP450)
• Adrenal glands
• Gonads

Question 12

What face of the golgi do vesicles from the RER enter into?

Answer 12

Cis face (cis golgi network)

Question 13

Where do vesicles leave the golgi from?

Answer 13

Trans face

Question 14

What is an oligosaccharide?

Answer 14

Polymer (chain) of sugar molecules

Question 15

How can the golgi modify oligosaccharides?

Answer 15

• Attach a Nitrogen (asparagine)
• Attach an Oxygen (serine/threonine)

Question 16

What amino acids commonly have a sugar added in the golgi?

Answer 16

Serine/threonine (extra O molecule)

Question 17

What molecule can be added to proteins destined for lysosomes?

Answer 17

Mannose-6-phosphate
- Triggers packaging in trans-golgi to lysososmes

Question 18

What molecules have mannose-6-phosphate added to them to be taken to lysosomes?

Answer 18

N-linked oligosaccharides

Question 19

What disease has an abnormal or disrupted processing in golgi where mannose-6-phosphate is not found on lysosomes?

Answer 19

I-cell disease

Question 20

How is I-cell disease inherited?

Answer 20

AR

Question 21

What are the clinical features of I-cell disease?

Answer 21

Onset in 1st year of life
- Growth failure
- Coarse facial features
- Hypotonia/ motor delay

Question 22

What type of disease is I-cell (inclusion cell) disease?

Answer 22

Lysosomal stroage disease (mucolipidosis)

Question 23

What enzyme is deficient in I-cell disease?

Answer 23

N-acetylglucosaminyl-1-phsophotransferase

Question 24

What is the function of N-acetylglucosaminyl-1-phsophotransferase (deficient in I-cell disease)?

Answer 24

Adds phosphate to mannose

Question 25

What enzymes are missing from the lysosomes yet can be found in the blood/urine in I-cell disease?

Answer 25

Hydrolases

Question 26

What will the lysosomes contain in I-cell disease?

Answer 26

Inclusions of glycosaminoglycans and glycolipids

Question 27

How are endosomes formed?

Answer 27

Endocytosis - Invagination of plasma membrane to surround molecules - Pinching of membrane to form an enclosed structure

Question 28

What are the different types of endocytosis?

Answer 28

- Receptor mediated (cells take up specific molecules, ligands, that bind receptors) - Pinocytosis (droplets) - Phagocytosis

Question 29

What type of enzymes are contained inside lysosomes?

Answer 29

Acid hydrolase enzymes

Question 30

What is the pH roughly inside a lysosome?

Answer 30

~ 4.8

Question 31

How many enzymes are thought to make up lysosomes? (acid hydrolase enzymes)

Answer 31

40+

Question 32

What are perioxisomes?

Answer 32

Cellular organelles which contain oxidative enzymes (e.g. hydrogen peroxide)

Question 33

What does catalse do?

Answer 33

Oxidizes substances with H2O2 - Detoxifies many sunstances in liver cells - Can metabolize ethanol (alternative, minor pathway)

Question 34

How can perioxisomes affect fatty acids?

Answer 34

Beta oxidation of fatty acids - Preferentially oxidize longer fatty acids

Question 35

Where other than the perioxisomes can beta oxidation occur?

Answer 35

Mitochondria (majority)

Question 36

What is the function of proteosomes?

Answer 36

Destroy aberrant proteins (misshaped/misfolded) - Req

Question 37

What is the structure of proteasomes?

Answer 37

Barrel-shaped structure - Protein complex which requires multiple protein subunits

Question 38

What do proteasomes require to function?

Answer 38

ATP

Question 39

What are proteins usually marked with before being destroyed by proteasomes?

Answer 39

Ubiquitin

Question 40

What neurological disease is thought to have an association with reduced ubiquitin-proteasome activity?

Answer 40

Parkinson's disease - Toxic accumulation of proteins in neurons

Question 41

What pulls free ribosomes to ER membrane?

Answer 41

Signal sequences - Creates RER

Question 42

Where are signal sequences found?

Answer 42

Proteins undergoing synthesis (translation) - Short peptides - Found on N-terminal of protein

Question 43

What are signal sequences recognized by?

Answer 43

Signal recognition particle (SRPs) - Found in cytosol

Question 44

What is the function of Signal recognition particle (SRPs)?

Answer 44

Move proteins from cytosol to ER lumen

Question 45

What does the SRP bind to and where?

Answer 45

SRP receptor on ER membrane

Question 46

What are 3 well-characterized coats found on the surface of vesicles?

Answer 46

- Clathrin - COPI - COPII

Question 47

What are clathrin-coated vesicles found?

Answer 47

- Transport between plasma membrane and golgi - Also to/from endosomes in cytoplasm - Extraceullar uptake (endocytosis)

Question 48

What recpetors contain clathrin-coated pits?

Answer 48

- LDL-receptor - GF receptor

Question 49

What type of vesicle coats carry things from the golgi to ER (retrograde)?

Answer 49

COPI

Question 50

What type of vesicle coats carry things from the ER to the golgi (anterograde)?

Answer 50

COPII