Lecture 18 Flashcards
Where in the cell does photosynthesis occur?
The chloroplasts
What happens in light-dependent reactions? Where do they occur?
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
What happens in light-independent reactions? Where do they occur?
Occur in the stroma of chloroplasts
Dark reactions/ Calvin cycle
Oxidation: produces water
Reduction: carbon dioxide to form carbs
What is programmed cell death/ apoptosis?
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
How is apoptosis characterized?
Shrinkage of the cell
Fragmentation of DNA and nucleus
Blebbing of the plasma membrane
Loss of attachment to other cells
Engulfment by phagocytosis
Describe the intrinsic pathway of apoptosis
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
How is apoptosis related to disease
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)
What is the function of the cytosol?
Protein synthesis
many metabolic pathways
What is the function of the endoplasmic reticulum (ER)
Synthesis of lipids and proteins
What is the function of the Golgi apparatus
protein modification, packaging of proteins and lipids
What is the functions of lysosomes
Degradation of cellular material
What is the function of endosomes
sorting and recycling
What is contained within the endomembrane system
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
What is the origin of cytoplasmic membrane systems
The infolding of plasma membrane
What is GFP and why is it useful?
Green Fluorescent Protein
Fuses to other cellular proteins so they can be seen under a microscope
Provides information on the endogenous protein
Describe vesicular transport/trafficking
(3 points)
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)
What are the key elements of vesicle trafficking to a compartment
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
How are transmembrane proteins oriented in the cytoplasm and ER
End of the protein sticks out into the cytosol
End of protein sticks into the ER lumen
Can the orientation of the transmembrane proteins be tracked
Yes with GFP
What is exocytosis?
Secretion of a neurotransmitter
From organelle to the plasma membrane
