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Unit 3 Cellular Genetics Cheat Sheet (DRAFT) by

AP Bio unit 3 cellular genetics

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Cellular Energy

Potential Energy
stored energy
chemical energy
energy stored in chemical bonds, more bonds, greater potential energy
Kinetic Energy
moves
heat
thermal energy is transfered from one object to another
light
another form of energy
first law of thermo­dyn­ami­cs/law f conser­vation
energy cannot be destroyed or created
exergo­nic­/ex­oth­ermic
energy is released during the chemical reaction, ΔG is < 0 (negat­ive), reaction is sponta­neous.
enderg­oni­c/e­ndo­thermic
energy is absorbed during chemical reaction, ΔG is > 0 (positive)
complex cellular reactions
exergonic and endergonic chemical reactions are coupled.

inhibition of enzymatic reactions

Enzymes that have already been produced are regulated by compet­itive or noncom­pet­itive inhibition
compet­itive inhibition
compeitive inhibi­tors, by preventing or limiting the substrate from binding to the enzyme.
Noncom­petive Inhibi­tio­n/a­llo­steric regulators
binding of the inhibitor to the altern­ative site, changing the shape of the enzye, inhibiting the enzyme from catalyzing substrate into product. Feedback inhibition: the end product of the pathway is the allosteric inhibitor for an enzyme that catalyzes an early step in the pathway. (graph)
Cooper­ativity
type of allosteric activa­tion, cause the enzyme to atbilize in active form, amplifying response of the enzyme. (graph)

Photos­ynt­hesis

light energy is converted to chemical bond energy, and carbon is fixed into organic compounds.
6⁢CO2+­12⁢­H2O­→li­ght­C6⁢­H12­⁢O6­+6⁢­H2+6⁢O2
Photos­ynt­hesis is a reduction reaction because CO2 gains hydrogen from water.
two main processes of photos­ynt­hesis: the light-­dep­endent and the light-­ind­epe­ndent reactions.
light dependent reaction
use light energy directly to produce ATP.
Light Indepe­ndent reaction
consist of the Calvin cycle, use ATP formed by light reactions to produces sugar.
Photos­ynt­hetic pigments
chloro­phylls and carote­noids. Chloro­phyll a and chloro­phyll b are green and absorb all wavele­ngths of light in the red, blue, and violet ranges. The carote­noids are yellow, orange, and red. They absorb light in the blue, green, and violet ranges. Different types of chloro­phyll give a plant greater flexib­ility to exploit light as an energy source.
 
Chloro­phyll a : partic­ipates directly in the light reactions of photos­ynt­hesis; head surrounded by altern­ating double and single bonds, attached to a long hydroc­arbon tail. (graph) The double bonds within the head. They are the source of the electrons that flow through the electron transport chains during photos­ynt­hesis.
Chloro­plast
enclosed by double membrane. contains grana (light- dependent reactions occur), and stroma (light­-in­dep­endent reactions occur). grana consist of layers of membranes called thylakoids, the site of photos­ystems I and II.
 
contains photos­ynt­hetic pigments that, along with enzymes, carry out photos­ynt­hesis.
Photos­ystems
few hundred photos­ystems in each thylakoid.
 
consists of a reaction center containing chloro­phyll a and a region containing several hundred antenna pigment molecules that funnel energy into chloro­phyll a.
 
PS II(P680) operates first, followed by PS I(P700).
Light dependent reactions
electron flow
Noncyclic Photop­hos­pho­ryl­ation
electrons enter two electron transport chains. The products are ATP and NADPH.
 
1. light energy absorbed by PHOTOS­YSTEM II—P680. electrons captured by primary electron acceptor.
 
2. Photolysis: splitting of water. It provides electrons, H2O → 2H+ + 2e − + O2 ↑(waste product)
 
3. ETC: This flow of electrons is exergonic and provides energy to produce ATP by chemio­smosis, photop­hos­pho­ryl­ation.
 
4. Chemio­mosis: ATP synthase channels, provides energy for calvin cycle later.
 
5. NADP: reduced, formed NADPH carries hydrogen to the Calvin cycle to make sugar in the light-­ind­epe­ndent reactions.
 
6. Photos­ystem I - P700**: Energy is absorbed by P700, this ETC produces NADPH, not ATP.
Cyclic Photop­hos­pho­ryl­ation
only produce ATP (bc calvin cycle later comsumes a lot)
Light Indepe­ndent - Calvin Cycle
CO2 enters, then produces the 3-carbon sugar PGAL
 
occurs only in the light.
photor­esp­iration
Unlike normal respir­ation, no ATP is produced. Unlike normal photos­ynt­hesis, no sugar is formed. peroxi­somes break down the products of photor­esp­ira­tion.
 

Metabolism

sum of all chemical reactions
catabolism: break down molecules
anabolism: build up molecules

Enzyme­-co­ntr­olled reactions

enzyme serve as catalytic proteins that speed up reactions by lowering the energy of activation, EA (the amount of energy needed to begin a reaction).
The transition state is the reactive (unstable) condition of the substrate after sufficient energy has been absorbed to initiate the reaction.
Endergonic vs. Exergonic (graph)

Enzyme Charac­ter­istics

- enzymes: globular proteins, teritary structure
- substrate specific
- induce­d-fit model (change confro­ntaton)
- enzyme substrate complex
- are not destroyed during a reaction, but reused.
- are named after their substrate, ends in the suffix “ase.” (ex: lactase for lactose, sucrase for sucrose)
- catalyze reactions in both reactions
- require assistance from cofactors (inorg­anic) or coenzymes (vitamins)
- will not catalyze a reaction that would not occur otherwise.
- effciency is affected by temper­ature and PH. favor low temper­ature and low PH

Cell respir­ation

cells extract energy stored in food and transfer that energy to molecules of ATP.
anaerobic respir­ation(no oxygen(
glycol­yisis + alcoholic fermen­tation or lactic acid fermen­tation.
Aerobic respir­ation (oxygen)
Glycolysis + Krebs cycle + electron transport chain + oxidative phosph­ory­lation
reduction: gain of electrons (e – ) or hydrogen (H+ ), while oxidation is the loss of electrons or protons. In any redox reaction, one substance is reduced while the other is oxidized.
As hydrogen (with its electron) is transf­erred from glucose to oxygen, it is moving from a higher energy level to a lower one, releasing energy in stages. This free energy powers the synthesis of ATP.
ATP
adenosine (the nucleotide adenine plus ribose) plus three phosph­ates.
substrate level phosph­ory­lation
direct enzymatic transfer of phosphate to ADP.
When one phosphate group is removed from ATP by hydrol­ysis, a more stable molecule, ADP results, releasing energy
Glycolysis (graph)
2 ATP + 1 Glucose (6 carbon) → 2 Pyruvate (3 carbon) + 4 ATP, produce 2 ATP; occurs in cytoplasm, releases ATP without using oxygen. The end product, pyruvate, is the raw material for the Krebs cycle, the next step in aerobic respir­ation. Without glycolysis to yield pyruvate, aerobic respir­ation could not occur; ATP is produced by substrate level phosph­ory­lat­ion—by direct enzymatic transfer of a phosphate to ADP; If ATP is enough, it uses allosteric inhbition (inhibits PFK by althering the confro­ntation of the enzyme, thus stopping glycol­ysis), if ATP is less (as more cell activities uses), less less ATP is available to inhibit PFK and glycolysis continues, ultimately to produce more ATP.
Mitoch­ondrion(graph)*
Double membrane; outer membrane is smooth, but the inner or cristae membrane is folded. Inner membrane has two: outer compar­tment and matrix.
Aerobic respir­ation :glyco­lys­is(­ana­erobic) + Krebs cycle and oxidative phosph­ory­lation (aerobic).
Krebs Cycle
in matrix of mitoch­ondria, requires pyruvate (product of glycol­ysis), completes the oxidation of glucose to CO2, turn twice, generates 1 ATP per turn, the remainder of the chemical energy is transf­erred to NAD+ and FAD, then the reduced coenzymes, NADH and FADH2 , shuttle high-e­nergy electrons into the electron transport chain in the cristae membrane.
 
coenzyme A (a vitamin) to form acetyl-CoA, which does enter the Krebs cycle. The conversion of pyruvate to acetyl-CoA produces 2 NADH, 1 NADH for each pyruvate.
 
Each turn of the Krebs cycle releases 3 NADH, 1 ATP, 1 FADH, and the waste product CO2, two turns total
NAD+ and FAD
 
coenzymes that carry protons or electrons from glycolysis and the citric acid cycle to the electron transport chain.
 
NAD/FAD facili­tates the transfer of hydrogen atoms from a substrate to its coenzyme NAD+.
 
Without NAD+ to accept protons and electrons from glycolysis and the Krebs cycle, both processes would cease and the cell would die.
 
NAD+ is the oxidized form. NADre or NADH is the reduced form.
electron transport chain (ETC) (graph)
 
proton pump in cristae membrane of the mitoch­ond­rion.
 
thousands ETC due to the extensive folding of the cristae membrane.
 
final electron acceptor, through a series of redox reactions.
 
highly electr­one­gative oxygen pulls electrons through the electron transport chain.
 
NADH provides more energy for ATP synthesis than does FADH2 .
 
cytoch­romes used to trace evolut­ionary relati­ons­hips.
 
coenzyme Q, mobile electron carrier, diffuses within and along the membrane. If the cristae membrane were not fluid, Q could not move through it, and the ETC could not operate.
 
Exergonic reactions are coupled with endergonic ones. The exergonic flow of electrons toward the highly electr­one­gative oxygen provides the energy for the endergonic pumping of protons.
oxidative phosph­ory­lat­ion­/ch­emi­omosis (graph)
 
proton (H+ ) gradient from NADH and FADH2 to phosph­orylate ADP and produce ATP (ADP + P → ATP).
 
Protons are pumped from the matrix to the outer compar­tment, against a gradient, by the electron transport chain.
 
As protons flow down through the ATP synthase channels, they generate energy to phosph­orylate ADP into ATP.
 
Oxygen is the final hydrogen acceptor, combining and forming water, which is the waste product of cell respir­ation
Summary of ATP production
Substrate level phosph­ory­lation + Oxidative phosph­ory­lation
Glucose → NADre and FADre → electron transport chain → chemio­smosis → ATP
The catabolism (break­down) of glucose under aerobic conditions occurs in three sequential pathways: glycol­ysis, pyruvate oxidation, and the citric acid cycle.
Anaerobic respir­ation - fermen­tation (glyco­lysis + alcoho­l/l­actic acid fermen­tation)
2 types of anaerobes
Facult­ative: tolerate the presence of oxygen, Obligate: cannot live in an enviro­nment containing oxygen.
When there is an adequate supply of NAD+ to accept electrons during glycol­ysis, fermen­tation can generate ATP. Without some mechanism to convert NADH back to NAD+ , glycolysis would shut down.
Alcohol Fermen­tation
convert pyruvate from glycolysis into ethyl alcohol and carbon dioxide, oxidize NADH back to NAD+. (ex: bread baking to rise)
Lactic Acid Fermen­tation
pyruvate from glycolysis is reduced to form lactic acid or lactate, NADH gets oxidized back to NAD+. (ex: yogurt and cheese)
 
Ex: Human skeletal muscles, when the blood cannot supply adequate oxygen to muscles during strenuous exercise. Lactic acid in the muscle causes fatigue and burning. The, continues to build up until the blood can supply the muscles with adequate oxygen to repay the oxygen debts.