Lec 9-10

Question 1

Cell theory

Answer 1

All cells come from other cells

Question 2

Prokaryote cells

Answer 2

Contains ribosomes
Small
No nucleus, mitochondria, membrane bound organelles
DNA is circular, one chromosome

Question 3

Eukaryote cells

Answer 3

Contains membrane bound organelles, nucleus, mitochondria/chloroplasts
Large
DNA is linear, multiple chromosomes

Question 4

True or false?

1. Prokaryotic cells are not capable of protein synthesis.
2. Prokaryotic cells have DNA.
3. Eukaryotic cells can attach to other cells.
4. Eukaryotic cells are divided into compartments.

Answer 4

1. False
2. True
3. True
4. True

Question 5

The theory of endosymbiosis

Answer 5

Original mechanism: Archaeon engulfed bacterium by folding inward to form eukaryotes

New mechanism: Archaeon had protrusions that surround the bacterium to form eukaryotes

Shows how new technology can challenge accepted theories

Question 6

How do mitochondria and chloroplasts behave like bacteria?

Answer 6

-reproduce by pinching in half
-have circular DNA
-their DNA replicates when they reproduce
-proteins that function in them are often made by ribosomes in them

Question 7

Eukaryotic cells are compartmentalized. Compartmentalization causes? Choose ALL
a) Chemical reactions more efficient
b) Chemical reactions less efficient
c) Substrates sequestered together
d) Substrates all spread out in the cell
e) Enzymes all spread out in the cell.
f) Incompatible chemical reactions
separated.

Answer 7

A, C, F

Question 8

Extracellular matrix

Answer 8

Surrounds cell membrane

Composed of:
~Proteoglycans-proteins with lots of carbs attached. Protects cell
~Collagen-rope-like protein. Provides strength and form
~Integrins-span the cell membrane. Connects the inside of the cell to the ECM

Question 9

When cancer cells invade other parts of the body, their ECMs become detached. What would you expect to see?

a) Excessive, robust proteoglycans.
b) Few, deformed proteoglycans.
c) Excessive, robust integrins.
d) Few, deformed integrins.

Answer 9

D

Integrins connect the ECM to cells, so if they become detached, they have few, deformed integrins

Question 10

Communication between cells

Answer 10

Signals (hormone or neurotransmitter) can be proteins or other
molecules.

Receptors are proteins that are on or inside the cell membrane of receiving cells.

The signal will fit perfectly into the receptor.

Question 11

Signal types

Answer 11

Neurotransmitter-travel through nerve cells in the nervous system to reach their destination (FAST)

Hormone-travel in blood to reach their destination (SLOW)

Question 12

When does signal binding activate proteins?

Answer 12

Receptor is embedded within the cell membrane

For lipid insoluble molecules

Interacts with already existing proteins

SIGNAL TRANSDUCTION

Question 13

When does signal binding interact with DNA?

Answer 13

Receptor is in the cell

For lipid soluble proteins

Causes a new protein to be made

Question 14

Signal transduction via G-protein receptors

Answer 14

1. G protein is inactive, signal binds to receptor
2. Signal binds, receptor changes shape, GDP gets kicked off protein, GTP binds, G protein changes shape, splits off
3. G protein binds to enzyme, induces second messenger, triggers response

Question 15

Signal transduction via RTK receptors

Answer 15

1. Signal binds to RTK receptor causing them to dimerize
2. RTK phosphorylates itself
3. Bridging proteins bind to RTK and activate Ras by causing it to exchange GDP for GTP
4. Ras triggers phosphorylation and activation of a protein kinase
5. Phosphorylation cascade

Question 16

Imagine that in a liver cell, Ras is defective and can not interact with GTP. Insulin approaches the liver cell. What will occur?

a) Insulin will bind.
b) Phosphorylation cascade.
c) Glucose transporter activated.
d) Glucose brought in from the bloodstream

Answer 16

A

Question 17

In patients with Grave’s disease, antibodies bind to the TSH receptor (G-protein receptor), so that it becomes activated in the absence of TSH. Which of the following occurs in patients with Grave’s disease?

I. TSH binds to TSH receptor
II. GTP-bound G protein subunit splits off receptor
III. GTP-bound G protein subunit binds to enzyme
IV. Second messenger is produced
V. Cytoplasm enzymes release
T3 from storage vacuoles

a) None
b) I
c) II, III, IV
d) II, III, IV, V
e) I, II, III, IV, V

Answer 17

D

The receptor becomes activated by the antibodies so the entire process happens, but without the proper signal