Group 1

Question 1

What are the components and functions of the Extracellular matrix (ECM)?

Answer 1

Components are produced and secreted by cells and assembled into an extracellular network
Major components are proteins like collagen and glycoproteins like laminin and fibronectin.
Functions:
-cell adherence, communication between cells, cell shape, mechanical support, structural integrity
-Serves as a barrier and filters out some particles

Question 2

Active Movement across a membrane

Answer 2

Moves from a low concentration to a high one
Active transport is when the molecule that needs to pass, bind to an active transporter
-against the concentration gradient
-active transporter conforms to the compound is released on other side

Question 3

Oxidative Phosphorylation

Answer 3

step 1: generate an electrochemical gradient
-electron transports through complexes I-IV and proton pumping
-high energy electron pass from coenzymes (NADH and FADH2) in the matrix to electron carries in the IMM
-energy transfer at each complex used to pump H+ from matrix to intermembrane space
-low energy electrons are transferred to terminal electron acceptor (O2) resulting in production of water
Step 2: proton movement don electrochemical gradient to power ATP synthesis

Question 4

Key elements of vesicle trafficking to a compartment

Answer 4

1) Movement of vesicle - uses cytoskeleton and motor proteins. Can be anterograde or retrograde
2) Tethering vesicle to target compartment - via proteins from the Rab family of protein and other more specialized
3) Docking of vesicle to target compartment - uses proteins called SNARES
- SNARE assembly provides energy for fusion
4) Fusion of vesicle and target membrane

Question 5

Functions of the rough ER

Answer 5

1. Synthesis of membrane phospholipids
2. Glycosylation of proteins
   -addition of carbohydrate chains to specific proteins
3. Protein folding - quality control
   -involve the activity of molecular chaperones, a specific type of protein that assist in the folding process
4. Protein synthesis modification and transport
   -proteins targeted to the ER
   - Proteins targeted to the endomembrane and compartments
   -proteins targeted to plasma membrane (secreted and transmembrane)

Question 6

Rough ER and protein translation

Answer 6

-all protein translation begins on free ribosomes
Translation is completed in 1 of 2 ways:
-FREE or ER-bound ribosomes
1) for translation completed on free ribosomes
-cytosolic proteins
-peripheral membrane proteins
-proteins targeted to nucleus, mitochondria and chloroplasts
2) ER-bound ribosomes
-secreted proteins
-integral membrane proteins
-soluble proteins associated with inside (lumen) of endomembrane system
-proteins that function within the ER, Golgi, Lysosomes

Question 8

Co-translational protein import

Answer 8

HOW RIBOSOMES GET TO THE RER SURFACE
1. After translation of SIGNAL SEQUENCE, a Signal Recognition Particle (SRP) binds to signal sequence and STOPS the translation
2. SRP binds SRP receptor to target the whole translation complex to ER (SRP + ribosome + mRNA + new polypeptide)
3. SRP is released and ribosome binds to translocon. Once this is done, protein
synthesis resumes.
4. Polypeptide enters the ER (through the translocon) as it is translated. In the end,
the signal peptide is cleaved off and chaperone folds the protein