AP Biology - Metabolism

Metabolism

The sum of chemical reactions in the body (molecules we break down vs. molecules we are putting together)

Anabolic

Putting molecules together

Catabolic

Breaking down molecules

Aerobic reactions

Reactions that require oxygen

Anaerobic reactions

Reactions that don’t require oxygen

∆G

Change in energy

∆H

Change in enthalpy

∆S

Change in entropy (chaos, particles spreading out)

T

Temperature (In Kelvin, celsius plus 273)

∆G=∆H-T∆S

Gibbs free energy equation

When ∆G<0

Reaction is exergonic, spontaneous, occurs without outside energy, usually molecules being broken down, ex. cellular respiration

∆G>0

Reaction is endergonic, not spontaneous, needs outside energy to occur, usually molecules being put together

Exergonic

Releases energy

Endergonic

Takes in/stores energy

ATP

Adenosine triphosphate, energy molecule

Oxidization

Losing electrons, charge goes up

Reduction

Gaining electrons, charge goes down

Reducing agent

The thing being oxidized

Oxidizing agent

The thing being reduced

What is being oxidized in this reaction:

Fe²⁺ + Ce⁴⁺ → Fe³⁺ + Ce³⁺

Fe²⁺

What is being reduced in this reaction:

Fe²⁺ + Ce⁴⁺ → Fe³⁺ + Ce³⁺

Ce⁴⁺

What is the reducing agent in this reaction

Fe²⁺ + Ce⁴⁺ → Fe³⁺ + Ce³⁺

Fe²⁺

What is the oxidizing agent in this reaction

Fe²⁺ + Ce⁴⁺ → Fe³⁺ + Ce³⁺

Ce⁴⁺

Glycolysis

First step of cellular respiration, happens in cytosol, doesn’t need oxygen (the other parts of cellular respiration do), divided into two phases - energy investment and energy payout

Purpose of cellular respiration

Create energy for the cell

Glycolysis energy investment phase

5 steps, starts with glucose, uses two ATP (converted to ADP), ends with the six carbon, two phosphate chain splitting into 2 G3P

Phosphofructokinase

Adds second phosphate in energy investment phase of glycolysis, won’t add if cell has too much excess ATP which shuts off glycolysis

Glycolysis energy payout phase

Starts with G3P (happens twice per glucose), converts NAD+ to NADH, converts 2 ADP to 2ATP per G3P (4 per glucose), Glycolysis ends with 2 pyruvate and 2 net ATP per glucose molecule

In-between step

Pyruvate enters mitochondria through the membrane, releases a carbon dioxide, a NAD+ becomes NADH and the remaining 2 carbon chain bonds with coenzyme A to make Acetyl CoA

Citric Acid Cycle

Happens in the matrix of the mitochondria, starts with acetyl CoA and starts and ends with oxaloacetate, those two molecules combine to make citric acid (citrate), ends with 6 NADH, 2 FADH₂, and 2 ATP per glucose molecule

Cristae

Folds in inner mitochondrial membrane, allow for more diffusion to occur

Oxidative phosphorylation

The electron transport chain and chemiosmosis, happens on the inner membrane of the mitochondria, ETC is active transport (protons go through proton pumps, low to high concentration), chemiosmosis is passive transport (protons go through ATP synthase from high to low concentration, protons become ATP)

Electron transport chain

Controls the release of energy so there is no combustive reaction, made up of protein complexes 1-4, complexes 1 3 and 4 are proton pumps (integral proteins), 2 is a surface proteins, Coenzyme q (ubiquinone) carries the electrons from complex 1 to 3 and cytochrome C carries the electrons from complex 3 to 4, the protons left over combine with oxygen to make water

Chemiosmosis

H+ diffuses through ATP synthase, which acts as a water wheel (a part is anchored and a part spins), as it spins it grabs ADP and a phosphate and hooks them together, perfect world is one ATP per hydrogen ion (proton)

Perfect world cellular respiration results

3 ATP per NADH (it goes through three proton pumps) 2 ATP per FADH₂ (it goes through two proton pumps), 2 ATP and 2 NADH created in glycolysis (per glucose), 2 NADH created in the in-between step, 2 ATP, 2 FADH₂, 6 NADH created in citric acid cycle

10 NADH total (3 ATP per NADH) = 30

2 FADH₂ total (2 ATP per FADH₂) = 4

30 + 4 + 4 ATP created in other steps = 38 ATP

Fermentation

An anaerobic process that regenerates NAD⁺ so glycolysis can continue to happen so some ATP can be generated (the citric acid cycle and ETC can’t occur without oxygen)

Obligate anaerobes

Organisms that can not do aerobic (requiring oxygen) respiration

Facultative anaerobes

Organisms that switch between doing aerobic and anaerobic respiration

Lactic acid fermentation

starts with glucose, creates 2 net ATP (from glycolysis), and 2 lactate: NADH gets recycled into NAD⁺ and the H turns pyruvate into lactate

Alcohol Fermentation

starts with glucose, creates 2 net ATP (from glycolysis) and 2 ethanol, also releases 2 CO₂, the pyruvate doesn’t directly interact with the NADH, there is an in between step after the CO₂ is released, recycles NADH into NAD⁺, in between molecule interacts with this H and becomes ethanol

EM spectrum from shortest to longest wavelength

Gamma, X-Ray, UV, Visible (violet to red), Infrared, Microwave, Radio waves

Stomata

Opening at bottom of leaf, where CO₂ goes in and O₂ goes out

Vacuole role in photosynthesis

Stores the water needed for photosynthesis

Chloroplast

Where photosynthesis occurs

Stroma

Fluid inside chloroplast

Thylakoid

Disc inside of chloroplast

Granum

Stack of thylakoids

Chlorophyll

Pigment in plants that absorbs light for photosynthesis (absorbs everything but green waves), chlorophyll A is most common

Light dependent phase of photosynthesis

Start to arrival at photosystem 1

Happens on the thylakoid, chlorophyll absorbs light (energy) and the energy is transferred through a photosystem where the energy is concentrated in the center. In photosystem 2 (P-680), that energy is used to split water: the oxygen is a waste product and hydrogen goes to ATP synthase to make ATP. The electrons are carried to the cytochrome complex by PQ. The cytochrome complex allows H⁺ to go through the membrane, into the thylakoid (active transport), PC carries electrons to photosystem 1

Light dependent phase of photosynthesis

After energy gets to photosystem 1

Light recharges the electrons at photosystem 1 but no water is split. FD (feredoxin) carries the energy to NADP reductase where NADP⁺ is changed into NADPH. The photosynthesis electron transport chain’s purpose is to bring hydrogen into the thylakoid and make energy. It makes NADPH, ATP, and has a waste product of O₂

Cyclic electron flow

Rare, few plants do this, all of photosystem 2 is cut out, light energizes photosystem 1, FD carries energy to the cytochrome complex to let protons (H⁺) in, FD goes back to photosystem 1. FD just goes back and forth, the protons go through ATP synthase and make ATP, this is less efficient than non cyclic

Three stages of the Calvin Cycle

Carbon fixation, reduction, regeneration

Car

Carbon fixation

Three CO₂ molecules are added to three RuBP molecule (5 carbon chain), then the now 6 carbon chains are split in half. Rubisco adds the carbons and splits the chain

Reduction in the Calvin Cycle

ATP is added which changes structure of the chains (3 carbons with a phosphate on each end), NADPH is added, and comes out as NADP⁺ and P, so the chains are back to three carbons with one phosphate, one of the 6 G3Ps are given off

Regeneration

Phosphates are added (through ATP) and the five remaining G3Ps become three RuBP molecules

Plant stomata in hot/dry places

C4 plants have the light dependent phase and calvin cycle happen in different cells and an in between molecule is created. This makes it easier to conserve water. CAM plants open their stomata only at night