Cell Biology Of Neurons

Question 1

In the soma (cell body), protein synthesis and packaging includes…

Answer 1

• Nucleus: genetic material
• Ribosomes: synthetic material
• Rough ER
• Golgi Apparatus: helps with packaging

Question 2

What is the process for gene expression?

Answer 2

Transcription

Question 3

What is the process for protein synthesis?

Answer 3

Translation

Question 4

Describe transcription…

Answer 4

• Occurs in nucleus
• DNA (gene) -> mRNA
• Trafficked out of nuclear pores

Question 5

Describe Translation…

Answer 5

• Occurs at ribosomes
  ~ Free ribosomes: synthesize cytosolic (free) proteins
  ~ ER ribosomes: synthesize membrane-associated proteins
• mRNA (message) + tRNA (transfers amino acids) -> peptide/protein (Amino Acid chain)
• Trafficked to final destination

Question 6

What are the three protein classes?

Answer 6

Cytosolic proteins, Nuclear & Mitochondrial proteins, Membrane-associated proteins

Question 7

Describe cytosolic proteins’ function. What are the 2 type of cytosolic proteins and what’s their function?

Answer 7

• Cytosolic Proteins are synthesized by free ribosomes
  ~ Fibrillar Proteins in cytoskeleton
  ~ Enzymes (metabolic triggers) : degrade and phosphorylate

Question 8

Describe nuclear & mitochondrial proteins.

Answer 8

• Nuclear/mitochondrial proteins are translocated to the nucleus and mitochondria
• Transcription factors

Question 9

Describe Membrane-associated proteins. What are the three types?

Answer 9

• Synthesized by ER-associated ribosomes
• 3 types:
  ~ Proteins attached to membrane
  :> Integral: amphipathic, embedded in cell membrane
  :> Peripheral: bound to integral proteins
  ~ ER Proteins
  ~ Proteins contained with vesicles and lysosomes
  Ex: secretory products, enzymes

Question 10

Describe the Golgi Apparatus.

Answer 10

• Involved in protein processing and processing
  ~ Protein glycosylation: tags that tell it where to go
  ~ Vesicle formation : lysosomes, secretory vesicles

Question 11

What structure synthesizes (translates) membrane-associated proteins in the neuron?

A. free ribosomes
B. ER-associated ribosomes
C. Rough ER
D. Golgi Apparatus

Answer 11

B. ER-associated ribosomes

Question 12

What are dendritic/axonal projections?

Answer 12

Protein transport mechanisms

Question 13

What are the 3 fibrillar proteins?

Answer 13

Microtubules: Tubulin (20nm)
Neurofilaments: Cytokeratins (10nm)
Microfilaments: Actin (5nm)

Question 14

What is anterograde axon transport?

Answer 14

• Fast active transport
• Forward toward axon terminal
• Synaptic vesicles/ secretory granules to reach terminals
• ATP-dependent
• Kinesin, a motor protein that walks along the microtubule down the axon, using ATP
  
  • Walks 400mm of microtubules per day