Lecture 18

Question 1

Where in the cell does photosynthesis occur?

Answer 1

The chloroplasts

Question 2

What happens in light-dependent reactions? Where do they occur?

Answer 2

Occurs in the thylakoid membrane

Chlorophyll in produced in the light harvesting complex

electrons enter the ETC (in the thylakoid membrane)

Protons are pumped into the thylakoid lumen

ATP and NADPH are used to create CH2O in light-independent reactions

Question 3

What happens in light-independent reactions? Where do they occur?

Answer 3

Occur in the stroma of chloroplasts

Dark reactions/ Calvin cycle

Oxidation: produces water
Reduction: carbon dioxide to form carbs

Question 4

What is programmed cell death/ apoptosis?

Answer 4

A normal process that involves the death of cells in a coordinated sequence of events

Very organized process, protects cell from damage, no inflammation occurs

Ex. Cell death leads to regression of soft tissue between embryonic digits in many vertebrates

Question 5

How is apoptosis characterized?

Answer 5

Shrinkage of the cell
Fragmentation of DNA and nucleus
Blebbing of the plasma membrane
Loss of attachment to other cells
Engulfment by phagocytosis

Question 6

Describe the intrinsic pathway of apoptosis

Answer 6

initiated by intracellular stimuli (genetic damage, hypoxia, or virus infection)

Killer protein Bax interacts/ causes changes in the mitochondria membrane and it leaks cytochrome c (and nuclear fragmentation)

apoptotic mitochondrial proteins are released and commit cell to apoptosis

Question 7

How is apoptosis related to disease

Answer 7

Too little apoptosis: related to cancer (creation of malignant cells that don’t die)

Too much apoptosis: can cause degenerative diseases like Alzheimer’s disease (too much of the brain degenerates)

Question 8

What is the function of the cytosol?

Answer 8

Protein synthesis
many metabolic pathways

Question 9

What is the function of the endoplasmic reticulum (ER)

Answer 9

Synthesis of lipids and proteins

Question 10

What is the function of the Golgi apparatus

Answer 10

protein modification, packaging of proteins and lipids

Question 11

What is the functions of lysosomes

Answer 11

Degradation of cellular material

Question 12

What is the function of endosomes

Answer 12

sorting and recycling

Question 13

What is contained within the endomembrane system

Answer 13

the cytoplasm revealed membrane-bound organelles and vesicles
An extensive network of canals and sacks of sacs (cisternae)

Examples: ER, endosomal transport vesicles, golgi complex, lysosomes, vacuoles

Question 14

What is the origin of cytoplasmic membrane systems

Answer 14

The infolding of plasma membrane

Question 15

What is GFP and why is it useful?

Answer 15

Green Fluorescent Protein

Fuses to other cellular proteins so they can be seen under a microscope
Provides information on the endogenous protein

Question 16

Describe vesicular transport/trafficking
(3 points)

Answer 16

Transport between compartments:
organelle to the plasma membrane (in other direction too)
organelle to organelle

Uses transport vesicles: organelles the bud off the donor compartment and fuse with the acceptor or recipient compartment

Targeted movement: uses cytoskeleton and motor proteins, sorting signals are recognized by receptors (signals make a proteins specific function)

Question 17

What are the key elements of vesicle trafficking to a compartment

Answer 17

1) movement of the vesicle - use of cytoskeleton and motor proteins (anterograde or retrograde)

2) tethering vesicle to target compartment - proteins from rab family and others

3) docking of vesicle to target compartment - SNARE proteins provide energy for fusion and assembly (pulls vesicle to membrane)

4) Fusion of vesicle and target membrane

Question 18

How are transmembrane proteins oriented in the cytoplasm and ER

Answer 18

End of the protein sticks out into the cytosol

End of protein sticks into the ER lumen

Question 19

Can the orientation of the transmembrane proteins be tracked

Answer 19

Yes with GFP

Question 20

What is exocytosis?

Answer 20

Secretion of a neurotransmitter
From organelle to the plasma membrane