AP Bio unit 3

Metabolism

A cell's ability to acquire energy and use it to build, store, break apart, and eliminate substances in a controlled manner

Catabolic

breaks down carbs, proteins, and lipids, large to small molecules, energy released, ex: cellular respiration

Anabolic

simple sugars to complex carbs, small to large molecules, energy taken in, ex: photosynthesis

Energy

The capacity to cause a change in the environment. Kinetic energy is energy in motion, while potential energy is stored energy.

1st law of thermodynamics

energy can't be created or destroyed, it can only change forms

2nd law of thermodynamics

every energy change causes some energy to be lost, entropy (disorder) to increase, and thermal energy produced

Endergonic

energy goes in (anabolic)

Exergonic

energy is released (catabolic)

Energy coupling

ADP is combined with a phosphate to form ATP. The energy released from the hydrolysis of ATP into ADP is used to perform cellular work, usually by coupling the exergonic reaction of ATP hydrolysis with endergonic reactions.

Activation energy

The amount of energy required to start the reaction and break bonds in the reactants

Enzyme

An enzyme is a naturally occurring catalyst that speeds up chemical reactions by lowering the activation energy needed. Substrates will go into an active site where catalysis happens, turn into a product, then leave the active site.

Induced fit model

after a substrate goes into the active site, the enzyme will envelop the substrate and change its own shape slightly to be more effective.

Enzyme denaturing

Too low/high of a pH or temperature can cause the enzyme to denature, meaning it will unravel and no longer work. Enzymes work best in a pH of 6-8 and a temperature of around 37 degrees Celsius.

Substrate concentration vs. enzyme concentration

An increase in substrate concentration leads to an increase in the rate of reaction. As the enzyme molecules become saturated with substrate, this increase in reaction rate levels off until more enzymes can be added.

Competitive inhibitors

compounds that actively fight the substrate for the active site, but will be released eventually when the enzyme realizes it doesn't fit. The reaction will take longer, but will eventually reach the normal rate of reaction.

Noncompetitive inhibitors

compounds that go to another active site on the enzyme, and when they lock in it pushes on the other active site, making the substrate no longer fit there. The reaction will never reach its full potential reaction rate.

Allosteric site

a regulatory site that stabilizes an enzyme into its active or inactive form. Enzyme activators stabilize the active form, while inhibitors stabilize the inactive form, meaning it behaves like a reversible noncompetitive inhibitor.

Feedback inhibition

when a metabolic pathway is switched off by its end product. This prevents cells from wasting energy and resources. A→B→C→D. The presence/build up of D turns off the production of A

Autotroph

organisms that make their own energy from organic molecules and energy

Heterotroph

organisms that consume other organisms for energy

Photoautotroph

organisms that make their own energy from the sun

Chemoautotroph

organisms that make their own energy from inorganic/chemical substances

Epidermis

a waxy cover that protects the mesophyll from the environment and keeps water in

Stomata

lets carbon dioxide enter the leaf and oxygen exit

Mesophyll

contains the chloroplasts

Vein

transport water and nutrients from the roots to the leaves

Thylakoid

allows for the light dependent cycle of photosynthesis

Grana

stack of thylakoids

Stroma

allows for the Calvin cycle

Chlorophyll

absorbs sunlight

Reduction

the gaining of electrons, this occurs when the P680 and P700 get energy transferred from the chlorophyll and eject the electron, giving it to the primary electron acceptor

Oxidation

the loss of electrons, this occurs when P680 and P700 lose their electrons and get it replaced by water via photolysis

Light reaction

Light independent reactions occur in the thylakoid. Water, CO2, and light energy go in. O2, ATP, and NADPH are produced. What happens is light energy makes the chlorophyll move, and they send that energy to the P680 to make it eject its electron to the primary electron acceptor. Then it sends those electrons through the electron transport chain, where it helps carry hydrogen ions into the thylakoid so it can power ATP synthase, phosphorylating ADP and a phosphate. The ETC replenishes the electron in the P700, which again ejects its electron to the primary electron acceptor. That goes through another ETC, and produces NADPH, which goes on to the calvin cycle.

Calvin cycle

The calvin cycle uses the chemical energy of ATP and NADPH (products of light dependent reactions) to reduce CO2 into glucose. It takes 2 "turns" of the cycle to make 1 glucose. CO2 comes in through the stomata. ATP is made from hydrogen ions powering ATP synthase to combine ADP and a phosphate. NADPH is from the end product of the light dependent reaction. RuBP is regenerated each cycle by 5 G3P

1. Carbon Fixation

3 CO2s are each attached to 3 five carbon sugars called RuBP. The 3 new 6-carbon compounds are unstable and split into 6 3 carbon molecules, called PGA

2. Reduction

the 6 PGA molecules pick up electrons from 6 NADPH and energy from 6 ATP. This turns them into G3P, essentially the same thing. One G3P exits the cycle. This is G3P which is ½ of a glucose molecule

3. Regeneration

The 5 G3P molecules left undergo a series of reactions to form 3 RuBP using 3 ATP

C3 plants

occurs in all plants, optimal temperature 15 to 25° celsius, stomata stay open

C4 plants

occurs in 3% of vascular plants, optimal temperature 30-40° celsius, stomata stay open, minimizes photorespiration by performing carbon fixation in one part of the cell and the other steps of the calvin cycle in a different part

CAM plants

occurs in plants in dry environments, optimal temperature >40° celsius, stomata stay closed, minimizes photorespiration by carbon fixation during the night and the other steps during the day

Cellular respiration equation

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP Glucose and oxygen come from photosynthesis, CO2 is made in the Krebs cycle, water is made in oxidative phosphorylation, and ATP is made in all 3 stages of cellular respiration

Aerobic respiration respiration

requires oxygen, such as in the Krebs cycle.

Anaerobic

doesn't require oxygen, such as in glycolysis, alcohol fermentation, and lactic acid fermentation.

Glycolysis

releases chemical energy by oxidizing glucose into pyruvates. The energy that is released is used to phosphorylate (add a phosphate group) ADP into ATP. The electrons that are released are "picked up" by NAD+ which makes NADH. It occurs in the cytoplasm. For every glucose molecule, 2 (net) ATP, 2 pyruvates, and 2 NADH are made.

Conversion of pyruvate to acetyl

CoA - The pyruvates enters the mitochondria and NAD oxidizes it, turning into NADH. CO2 is also released, turning it into the 4 carbon molecule Acetyl CoA.

Krebs cycle

Acetyl CoA enters the cycle and reacts with 4-carbon oxaloacetate to form the 6-carbon citrate. The carbon compound is oxidized twice, each time forming NADH and releasing CO2. By the time it is a 4-carbon compound it is oxidized further to form FADH2, NADH, and ATP. For every glucose molecule, 2 ATP, 4 CO2, 6 NADH, and 2 FADH2 are made.

Cellular respiration ETC

NADH and FADH2 move electrons made from the glycolysis and the Krebs cycle to the ETC, where they are pumped into the intermembrane space via protein pumps. They then move back to their natural gradient, powering ATP synthase along the way. Once the electrons are back in the matrix, they are picked up by oxygen and water is made. For every glucose molecule, 26-28 ATP, 10 NAD, 2 FAD, and 6H2O are made.

Chemiosmosis

The diffusion of ions (usually H+) across a selectively permeable membrane, an example being hydrogen during the ETC in oxidative phosphorylation.

Cellular respiration final electron acceptor

Oxygen is the final electron acceptor. It forms water and it's so important because if the ions don't get out, the gradient will be messed with, and ATP will no longer form.

Endotherms

animals that depend on the internal generation of heat, such as humans. When ATP is created and used, these reactions release thermal energy.

Alcoholic fermentation

The glucose gets split into 2 pyruvates, and instead of going to the krebs cycle as Acetyl CoA, it turns into acetaldehyde, which then turns into ethanol. This happens in the cytoplasm. NADH is turned back into NAD+, and CO2 is produced

Lactic acid fermentation

The glucose gets split into 2 pyruvates, and instead of going to the krebs cycle as Acetyl CoA, they turn into lactic acid. This happens in the cytoplasm. NADH is turned back into NAD+