General Exam II Qs Flashcards
How do we recognize reduction/oxidation?
Hs follow electrons, more Hs reduction
Less Os, reduction
More Os, oxidized
O2-
superoxide ion, very toxic bc it wants to grab more electrons from DNA and proteins
Cellular Defense against O2- (superoxide) ?
superoxide dismutase
H2O2
Hydrogen peroxide, highly toxic bc wants more electrons, steals from DNA and proteins in cell
Cellular defense against H2O2?
Catalase (enzyme) breaks it down into O2 and water
Why don’t all bacs use oxygen as an electron carrier?
They lack one or both of the two enzymes that defend against superoxide (O2-) and hydrogen peroxide (H2O2) (catalase/superoxide dismutase)
(facultative anaerobes probably have one, obligate anaerobes have neither)
Plasma membrane
(function and composition)
found on outside, outer boundary of cell, thin selectively permeable barrier that surrounds and encloses the contents and controls the movement of materials into and out of the cell (((the cell chooses that goes in, what comes out)))
Composed of: phospholipids and proteins (hopanoids rather than sterols in some bacs)
Phospholipids
(function and composition)
Major lipid component of membrane, glycerol, two fatty acids, and a phosphate group
(Phospohlipids in bacteria have an ester bond)
review slides for structure reveiw
Amphipathic structure-
(function and composition)
((hint the plasma membrane has this))
hydrophobic and hydrophilic (polar head and non polar tails)
-Forms lipid bilayer
-water can pass through, molecular oxygen can pass through, CO2 can, glycerol cannot pass through
-proton won’t make it through, it’s charged but mainly it’s always surrounded by a cage of water
Rules for freely passing through the plasma membrane? (sans protein help)
Rules for passing through:
1) Small (<180 Daltons MW)
2) Non-polar or weakly polar
3) Non-ionic
Glucose/fructose pass through bc they have a protein to help
Hopanoid
(structure and function)
(looks like cholesterol but with OHs instead)
-Sterol like lipid present in some bacteria (similar to cholesterol)
-amphipathic (polar and non-polar parts)
-Maintain membrane homeoviscosity (regardless of environmental conditions)
-Bacteria add more hopanoids to increase fluidity of membrane, -
-disrupts tight packing between phospholipids ((when cold)) ((fatty acid tails))
-Holds glycerol heads together when hot
Fatty Acid Saturations, ideals for cold/hot?
Saturated- ideal for heat, keeps from slippin and slidin
Unsaturated- good for cold, prevents stiffening and breakage (usually ~kinky~ ooo)
Fatty Acid Length ideals cold/hot
Cold- Ideally short, want to minimize van der waals
Hot- Ideally long, want to maximize van der waals
Plasma membrane: What percentage proteins and phospholipids?
Equal, ~50/50
Define Simple diffusion
(just goes on through the cell membrane) must be small, non-polar or weakly polar, and nonionic
Facilitative diffusion:
Something goes through cell membrane with the help of a protein
Diffusion
- going from high concentration to a low concentration
Active transport
-usually ATP, against the gradient, low to high
How do diffusion and active transport work in relation to equilibrium?
Diffusion works toward equilibrium
Active transport works against equilibrium
Attempt to explain the cup of MnMs example (representing the electron transport chain)
-the Mnms represent the energy, cup is the electrons
-everytime an electron is transferred from one molecule to another, they lose energy (this can be used to do work, or just generate heat)
-protons pumped to outside, proton gradient used to drive ATP synthesis
-dump empty cup into waste receptacle, O2, becomes H2O
Respiration
-Membrane and membrane proteins being used to capture energy in the form of a gradient
*ATP synthase there synthesizing ADP + Pi (inorganic phosphate) into ATP
-O2 reduced to H2O
-NADH oxidized to NAD+
ADP+Pi= ATP
(protons being ejected by protein channels in membrane)
Indirect Active Transport
transporting not ATP against the gradient, low to high
The Lake on a hill proverb? (related to gradients)
whenever you have a gradient it’s a source of potential energy, like a lake on a hill
Photosynthesis-
Use of sunlight to drive the production of glucose from CO2 and H2O
ATP synthase is there synthesizing ADP + Pi (inorganic phosphate) into ATP
H2O oxidized (I think?)
NADP+ is reduced to NADPH
What allows a cell to perceive its environment?
**proteins
Cytoplasm:
function and 4 main things it contains
liquid stuff inside the cell
1) Water (primarily)
2) Macromolecules (proteins, DNA, RNA etc)
3) Molecular building blocks and metabolites (amino acids, nucleotides, sugars etc)
4) Inorganic ions- (K+, Na+, Cl- etc) (they help the DNA not hate itself)
-consists primarily of water
(after lysing cells, gets real snot like, slimeyness from proteins, dna and rna)
Signal Transduction
process in which binding of an extracellular messenger to the cell surface receptor is translated into changes in biochemistry, cell biology, and gene transcription that make it possible for the cell to respond to the information that was received.
(signaling molecule to cell receptor)
Nucleoid:
Define and what’s its deal
No membrane around the supercoiled DNA, so not a defined nucleus
-it’s all real negative so it doesn’t like being together
-(DNA is like tiny children in back of the van)
-Charges neutralized by adding Cations in the nucleoid, which will bind to negative charges of the DNA
-(no histones in bacteria!!)
-Nucleoid is very dynamic, when needs a gene it makes it available, then recoils back up
Topoisomerases
Initiates supercoiling (hydrolyzes ATP and twists the DNA)
makes things more curly and tightly bound
Inclusion bodies:
What are they?
What are they used for?
What are they not?
-Granules of a substance, used for nutrient storage
-Non-membrane bound
ex elements stored: carbon, nitrogen, phosphorous, sulfer
NOT organelles (despite functioning quite like them)
Sulfer Globules
Inclusion bodies in thiomargarita namibiensis
(sulfer storage, S0 which gives lower energy electrons than being oxidized straight from H2S for high energy electrons, but still good!
Polyhydroxybutyrate
(PHB)
Inclusion body
PHB: for carbon storage
in globules, not membrane bound
(used also for surgical sutures fun fact)
review slides for structure
(in spirillum often I think? or at least sometimes)
Cyanophycin
Inclusion body
-produced in excess of nitrogen
(used to be called blue green algae, they aren’t they’re cyanobacteria)
-probably original photosynthesizers
-has amino acids on the structure
-long chains of arginine (pirate amino acid)
-storing nitrogen
review slide for structure
Volutin
(and stained what color on slides?)
Inclusion body
Made by wide range of bacs,
-phosphorus storage (cells use for ATP synthesis, nucleotides, phospholipids etc)
-(stained red/purple on slide)
-join together in long chains in excess of phosphorous
see slides for structure if needed. but basically just phosphoruses (phosphates) holding hands
Definition of an organelle?
A small structure in a cell that is surrounded by a membrane and has a specific function
(Think of them as sacs with specific enzymes carrying out certain functions)
