Lec 9-10 Flashcards
Cell theory
All cells come from other cells
Prokaryote cells
Contains ribosomes
Small
No nucleus, mitochondria, membrane bound organelles
DNA is circular, one chromosome
Eukaryote cells
Contains membrane bound organelles, nucleus, mitochondria/chloroplasts
Large
DNA is linear, multiple chromosomes
True or false?
- Prokaryotic cells are not capable of protein synthesis.
- Prokaryotic cells have DNA.
- Eukaryotic cells can attach to other cells.
- Eukaryotic cells are divided into compartments.
- False
- True
- True
- True
The theory of endosymbiosis
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
How do mitochondria and chloroplasts behave like bacteria?
-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
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.
A, C, F
Extracellular matrix
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
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.
D
Integrins connect the ECM to cells, so if they become detached, they have few, deformed integrins
Communication between cells
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.
Signal types
Neurotransmitter-travel through nerve cells in the nervous system to reach their destination (FAST)
Hormone-travel in blood to reach their destination (SLOW)
When does signal binding activate proteins?
Receptor is embedded within the cell membrane
For lipid insoluble molecules
Interacts with already existing proteins
SIGNAL TRANSDUCTION
When does signal binding interact with DNA?
Receptor is in the cell
For lipid soluble proteins
Causes a new protein to be made
Signal transduction via G-protein receptors
- G protein is inactive, signal binds to receptor
- Signal binds, receptor changes shape, GDP gets kicked off protein, GTP binds, G protein changes shape, splits off
- G protein binds to enzyme, induces second messenger, triggers response
Signal transduction via RTK receptors
- Signal binds to RTK receptor causing them to dimerize
- RTK phosphorylates itself
- Bridging proteins bind to RTK and activate Ras by causing it to exchange GDP for GTP
- Ras triggers phosphorylation and activation of a protein kinase
- Phosphorylation cascade