Cell Biology Flashcards
all transcription takes place where
- the nucleus
all translation begins where
- the cytosol
if you are a cytosolic protein you finish translation where
- in the cytosol
which proteins finish translation in the rough ER
- secreted (S)
- transmembrane (M)
- lysosomal (O)
- ER/Golgi resident proteins
- som proteins have a signal sequence and finish translation the rough ER.
secreted or lysosomal protein signal sequence
- first few amino acids translated
- removed from the mature protein after translation
transmembrane protein signal sequence
- signal can be any part of the protein
- signal may appear several times
- keep signal sequence. becomes transmembrane region of the protein.
signal sequence
- helps to pass through pore to go into cell
components of the cell membrane
- phospholipids- primary lipid of cell membrane
- cholesterol
- proteins - allow membrane to be a dynamic structure
- carbohydrates - unique cell surface markers on extracellular surface of membrane
cholesterol
- increase fluidity at low temps
- keep membrane stable
- prevents hydrocarbon tails from packing together
what can pass through the cell membrane
- small nonpolar CO2, O2
- lipid soluble
types of proteins
- peripheral - on the top
- transmembrane
- integral
types of barriers
- blood/brain barrier
- blood/testes barrier
- blood/placenta barrier
electrolytes
- free ions in solution as a result of dissolving ionic substances
van’t hoff factor (i)
- number of molecules/ions produced when dissolved in H2O
colligative properties
- properties that depend on the number of solute particles but not on their identity
- freezing point - decreases as number of particles increases
- vapor pressure - decreases as number of particles increases
- boiling point - increases as number of particles increases
- osmotic pressure - increases as number of particles increases
molality
moles of solute
_____________
kg of solvent
FP depression
Δ T_f = -k_f i m
k_f (water) = 1.9
Vapor Pressure Depression
- # of gas particles in equilibrium with the gas phase
- solute particles act as anchors
- how easy it is for things to evaporate from the surface of a liquid.
- because less solvent has evaporated, vapor pressure is lower.
less evaporation
- less gas particles = lower VP
Boiling point elevation
- in the presence of a solute, the BP of a solution increases
BP elevation ΔT_b = k_b i m
k_b = 0.5
- add the difference to the original boiling point.
osmotic pressure elevation
- pressure required to resist the movement of water by osmosis
- more solute causes increase water movement causing pressure to increase to resist that movement
π = i m R T
diffusion
- movement of particles from high concentration to low concentrated areas
- moving down a gradient
osmosis
- water moves from its high concentration to its low concentrated area
- where there are a lot of particles, there is not a lot of room for water. where there are fewer particles, there is lots of room for water.
hypertonic
- has more particles than
hypotonic
- less particles than
isotonic
- equal concentration
can sucrose or any sugars break down in water?
- no!
passive transport
- no energy required
- relies on a concentration gradient
- if there is no gradient, there will be no transport
- Na+, Cl-, Ca2+
- The salty C surrounds our cells
simple diffusion
- works well for small hydrophobic (nonpolar) molecules
- molecule moves according to gradient
- O2, CO2, lipid soluble, steroids
facilitated diffusion
- still moves down gradient
- small hydrophilic molecules
- needs a helper protein
- ions, glucose, AAs, large molecules, water
helper proteins
- pores
- channels
- porters
pores
- nonspecific holes in the membrane
- size based
channels
- highly specific holes in the membrane
- right ID to get through the channel
porters
- carriers
- undergo conformational change to allow a molecule across the membrane
active transport
- requires energy (ATP)
- move molecule against their concentration gradient
primary active transport
- uses ATP directly
Na+/K+ ATPase
- primary active transport
- maintains osmotic balance
- establishes electrical gradient (RMP = approx - 70 mV)
- sets up sodium gradient for secondary active transport
- 3 Na+ OUT. 2 K+ IN.
secondary active transport
- uses ATP indirectly
- relies on gradient set up by primary active transport.
- Na+/glucose cotransporter
G proteins adenylyl cyclase
- GTP replaces GDP upon binding of ligand to G-protein linked receptor
- GDP on alpha beta gamma subunit activates adenylyl cyclase to make cAMP
- increases cAMP
- activates cAMP dependent protein kinases
- enzyme phosphorylation
- modify enzyme activity in the cell
2nd messenger systems
- cAMP is the second messenger. First messenger is the ligand that couldn’t cross the cell membrane.
- signal amplification
- fast and temporary
G proteins phospholipase C
- ligand binds to G-protein linked receptor
- alpha beta gamma subunit activates phospholipase C to make DAG and IP3
- DAG activates kinases which changes enzyme activity
- IP3 increases intracellular calcium
cilia/flagella cross section
- 9+2 arrangment
- 9 pairs microtubules on the outside
- 2 microtubules on the inside
- connected via dynein - folds up and opens
desmosomes
- general adhesive junctions between cells
tight junctions
- seal lumens
- separate environments
- found near apex of cells
gap junctions
- cell-to-cell communication
- like a tunnel shared between cells
Cell Cycle
- Interphase
- Mitosis - separate the replicated copies
Interphase
- G1 - growth and normal cell activity (2n1x)
- S - synthesis, DNA replication
- G2 - growth and prep for division (2n2x)
G0
- stasis
- Ex. neuron
points of regulation
- between G1 and S - most regulated!
- between G2 and mitosis
prophase
- nuclear membrane breaks down
- build the mitotic spindle
- condense DNA
metaphase
- replicated DNA aligns at the metaphase plate at the cell center
- align randomly
anaphase
- separate the sister chromatids
- begin cytokinesis
- cleavage furrow made by microfilaments`
telophase
- reverse of prophase
- finish cytokinesis
end product of mitosis
- two daughter cells that are IDENTICAL to each other and IDENTICAL to the parent cell
cancer
- result from changes in the DNA sequence of key genes
- start from single cells with mutated DNA
- cells grow and divide without control
- migrate to surrounding tissues
TWO types of cancer genes
- oncogenes
- tumor suppressor genes
proto-oncogenes
- normal genes which control the cell cycle
- whole body growth
- healing
- cell turnover
oncogene
- mutated proto-oncogene that is permanently on
- gain of function mutation
tumor suppressor genes
- code for proteins that stop the cell cycle
- monitor genome of cells in the cell cycle
- if DNA damaged, initiate repair pathway
- if not repairable, then the tumor cells trigger apoptosis
- loss of function mutation
Caspases
- c-asp-ases
- cut the C terminus of Asp
extracellular death signals
- killer T cells
intracellular death signals
- caspases
secreted protein translation
- signal sequence comes at the very beginning
- as protein is being made it is being pushed through the translocator pore into the ER lumen
- has hydrophobic signal sequence in the ER membrane. protein folds and hangs off of it.
- after translation, clip protein off signal sequence, packaged up and sent to the Golgi for further processing
membrane bound protein translation
- may already have several amino acids translated ahead.
- signal sequence somewhere in the middle
- translation proceeds into lumen of ER
- signal sequence docks in ER and translation occurs on opposite side.
- everytime a signal sequence appears, translation occurs on the opposite side of the ER.
- protein being threaded through membrane
- signal sequences must remain
- vesicles bubbles up and pinches off to move outward.
relationship between osmotic pressure and particle concentration
- directly related
initiator caspases
- activated in response to intra- or extracellular signals
effector caspases
- activated by initiators to carry out process of apoptosis
