Biology Class 5 Flashcards
Pathway of secreted/lysosomal proteins
- Translation begins in cytoplasm, then finishes in rough ER
- Signal sequence is detected in membrane of rough ER, while ribosome binds to its receptor in cytoplasm
- Protein finishes translation & signal sequence is cleaved
- Protein goes to golgi body, then enters through plasma membrane, then goes to outside of cell
Pathway of membrane-bound proteins
- Translation begins in cytoplasm, then finishes in rough ER
- Has multiple of signal sequences and each time it is found on the membrane of the rough ER
- Ribosome binds to its receptor in cytoplasm
- Final protein is weaved in and out of the membrane of the rough ER
- Clatherin then cleaves and pulls the protein outwards and creates a vesicle
- Vesicle fuses with golgi body, then another vesicle fuses with plasma membrane
Signal sequence is not removed from final protein
Plasma Membrane components
- Phospholipids (head = polar, tail is non-polar)
- Proteins
- Carbohydrates
- Cholesterol (helps stabilize & creates fluidity
Electrolytes
Free ions in solution produced as a result of dissolving ionic substance
Van’t Hoff Factor (i)
- Cannot be 0
- # of ions produced per molecule of an electrolyte
Colligative properties
Properties that depend on amount of solute particles but not on the identity
- taste is not a colligative propertie
Examples of colligative properties
- Vapour pressure (decreases)
- Freezing point (decreases)
- Boiling point (increases)
- Osmotic pressure (increases)
Freezing point depression
Formula: freezing point ΔTf = i x m x Kf
Kf of water = -1.86
Fp ∝ [particles]
Vapour pressure depression
Pressure of the vapour that evaporates from the liquid
VP ∝ [particles]
- more solutes will keep the solvent grounded, therefore VP will decrease
Boiling Point Elevation
The temperature at which VP is equivalent to atm pressure
Formula: boiling point ΔTb = i x m x Kb
Kb of water = 0.5
bp = [particles]
Osmotic Pressure Elevation
Pressure required to resist the movement of water by osmosis
Formula: π = i x R X M X T
Diffusion vs Osmosis
Moving particles from high to low []
Moving water from high to low []
Hypotonic, Hypertonic, isotonic
Hypotonic: less particles than another solution
Hypertonic: more particles than another solution
Isotonic: equal amount of particles
Passive transport vs active transport
Passive
- doesn’t require energy
- moved down gradient
1. Simple diffusion
2. Facilitated diffusion
Active
- requires energy
- moves against gradient
1. Primary
2. Secondary
Primary vs Secondary active transport
Primary - uses ATP directly to move against gradient
Secondary - uses ATP indirectly to move against gradient
Simple vs facilitated diffusion
Simple
- doesn’t need help moving down the gradient
- moves hydrophobic, non-polar molecules
Eg. CO2, O2, steroids, cholestrol
Facilitated
- needs help moving down gradient (helper proteins)
- moved hydrophilic, polar molecules
Eg. amino acids, ions, glucose
Helper proteins
- Pores - not specific
- Channels - highly specific
- Shape shifters - bind, change shape, then pass through
Na+/K+ Atpase
- primary active transporter
- moves 2 k+ in and 3 Na+ out
- RMP is -70mV
- sets up Na+ for secondary transport
G-protein adenyl cyclase
- GDP is bound to g-protein if no ligand is bound to receptor. If a ligand is bound to the receptor, GDP leaves and GTP binds
- A subunit of the G-protein leaves and binds to adenyl cyclase
- Adenyl cyclase converts ATP to cAMP
- cAMP activates cAMP dependent kinases
- cAMP kinases phosphorylate enzymes
- Changes enzyme activity in cell and amplify signal which is fast & temporary
G-Protein phopholipase C
- GDP is bound to g-protein if no ligand is bound to receptor. If a ligand is bound to the receptor, GDP leaves and GTP binds
- A subunit of the G-protein leaves and binds to phospholipase C
- Phospholipase C breaks down phosphoinositol bisphosphate into inositol triphosphate & diacylglyceral
- I3 will increase intracellular Ca2+ levels
- Diacylglycerol will activate kinases which will change enzyme activity
Types of filaments of cytoskeleton
Microtubule
Microfilament
Intermediate filament
Microtubule
Protein(s): alpha & beta tubulin
Diameter: large
Use: mitotic spindle, cilia & flagella, intracellular transport
Microfilament
Protein(s): actin
Diameter: small
Use: muscle contraction, pseudopod formation, cytokinesis
Intermediate filament
Protein(s): several different protein types
Diameter: medium
Use: structural roles
Cilia vs flagella
Cilia moves things on surface of cell while flagella moves entire cell
Cell junctions
Desmosomes - small proteins that hold cells together (general adhesive junctions)
Gap junctions - cell to cell communication (eg. neurons, cardiac cells, smooth muscle cells); exchange of cytosol between cells
Tight junctions - seal lumens & separate environments (eg. intestines & b-b barrier)
Cell cycle Overview
Divided into 2 phases: interphase, mitosis
Interphase:
G1 phase - cell growth, cell activity (preparing for S phase
G1/S phase checkpoint - most regulated and if don’t have proper signals will not be able to replicate so go into G0 phase (eg. muscle cells, RBC)
S phase - replication
G2 phase - cell growth
Mitosis: Prophase metaphase Anaphase Telophase *Cytokinesis happens at end of anaphase and beginning of telophase
Interphase
- Chromosomes are homologous if same gene just different alleles
- Once it passes through S phase, will have sister chromatids connected by centromere
Prophase
Nuclear membrane breaks down, mitotic spindle forming, DNA condenses
Metaphase
Chromosomes align at cell center
Anaphase
Separate the sister chromatids (due to retraction of spindle) & begin cytokinesis
- ring of actin (microfilament) forming in center and causes cleavage furrow
Telophase
Form nuclear membrane, decondense DNA, break down spindle fiber & finish cytokinesis
- at the end you have 2 cells which are identical to each other and the parent
Cancer
Uncontrollable cell division that can metastasize to other tissues
Process of cancer
- Results from mutations in key genes
- Starts from a single mutant cell
- Grows & divides uncontrollably to form a tumor
- Spread to surrounding tissue
Types of cancer genes
Oncogenes (gain of fx) & tumor suppressor genes (loss of fx)
Proto-oncogenes
Genes normally present in the cell that code for proteins that regulate cell cycle
- normally inactive unless needed
Oncogenes
Mutated proto-oncogenes that are permanently on (always active)
- promote cell division inappropriately
Tumor Suppressor genes
- codes for proteins that slow down cell growth & cell cycle
- monitors genome of cells in cell cycle
- if DNA damaged, initiated DNA repair
- if not repairable, then tumor suppressor proteins trigger cell death
Caspases
- monitor apoptosis
- are proteases that normally exist as zymogens (inactive until needed)
- two types: initiator & effector
Extracellular/Intracellular signal –> initiator caspase –> effector caspases –> cell death
Steps of apoptosis
Disassemble cytoskeleton –> break down nuclear membrane –> break down genome –> phagocytic digestion
Why disassemble the cytoskeleton as the first step of apoptosis?
The breakdown of the cytoskeleton makes the cell smaller, pulls it away from neighboring cells and thus reduces the risk of damage to other cells as its phagocytic destruction continues. The filaments do not need to be recycled as part of apoptosis nor do they provide energy. Cytokines trigger apoptosis
When does meiosis & mitosis occur in parallel?
In the seminiferous tubules
Where does meiosis occurs?
In the gonads
- -> seminiferous tubules (males)
- -> ovaries (females)
