Cellular Energy Review: ATP, Photosynthesis, Cellular Respiration, and Fermentation

A comprehensive vocabulary review of 47 essential concepts covering ATP structure and function, photosynthesis, cellular respiration, and fermentation.

Energy

The ability to do work.

Three Types of Energy

Light, mechanical, and chemical.

Chemical Energy

Energy stored in the bonds of chemical compounds; allows energy to be transported around the cell.

ATP

Adenosine triphosphate; the cell's energy currency that can store and transport energy from one location to another.

Three Parts of an ATP Molecule

Adenine, ribose (sugar), and 3 phosphate groups.

Mechanism of ATP Energy Release

The bond between the 2nd and 3rd phosphate groups is broken, releasing energy the cell can use.

Products of ATP Energy Release

ADP (adenosine diphosphate) + an independent phosphate ($P_i$).

ADP

Adenosine diphosphate.

Autotrophs

Organisms that make their own food from sunlight (photosynthesis).

Heterotrophs

Organisms that must consume other organisms for food.

Chlorophyll

Pigment found in chloroplasts that absorbs light energy (absorbs blue/violet and red, and reflects green and yellow).

Chloroplast

An organelle with 2 membranes where photosynthesis occurs.

Thylakoids

Stacks of sac-like membranes inside the chloroplast.

Stroma

The space surrounding the thylakoid stacks in a chloroplast.

Pigments

Molecules that absorb some colors of light energy and reflect others.

Two Major Stages of Photosynthesis

1. Light-dependent reactions 2. Light-independent reactions.

NADP+

Transport molecule that carries high-energy electrons from the light-dependent to the light-independent reactions.

Equation for Photosynthesis

$6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$ (with chlorophyll above the arrow).

Photosynthesis

Process in which autotrophs use light energy absorbed by chlorophyll in chloroplasts to energize electrons and create sugars for food.

Location of Light-Dependent Reactions

The thylakoids of the chloroplast.

Photosystems

Structures that collect light; composed of a combination of chlorophyll pigments and specialized proteins.

Electron Transport Chain (Photosynthesis)

A series of molecules that electrons move through, releasing energy that is stored as ATP.

Photolysis

Process in which $H_2O$ molecules are broken apart.

Location of Light-Independent Reactions

The stroma of the chloroplast.

Calvin Cycle

Another name for the light-independent reactions.

Inputs of the Calvin Cycle

$CO_2$, ATP, and NADPH (from the light-dependent reactions).

Product of the Calvin Cycle

Glucose, a 6-carbon simple sugar transformed from $CO_2$.

Cellular Respiration

Process by which all organisms break down glucose to gradually produce energy in the form of ATP.

Equation for Cellular Respiration

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$.

Three Key Steps of Cellular Respiration

1. Glycolysis 2. Krebs Cycle 3. Electron Transport Chain.

Location of Glycolysis

The cytoplasm.

Location of the Krebs Cycle

The mitochondria.

Location of the Electron Transport Chain (Respiration)

The mitochondria.

Aerobic Respiration

Process where oxygen is available, allowing all three steps of respiration to occur; yields about 36 ATP.

Anaerobic Respiration

Process where oxygen is not available, so glycolysis is followed by fermentation; yields only 2 ATP.

ATP Yield of Aerobic Respiration

About 36 ATP.

ATP Yield of Anaerobic Respiration

2 ATP.

Glycolysis

Process in which a glucose molecule is broken into 2 pyruvic acid molecules; produces 2 ATP.

Krebs Cycle

Stage of cellular respiration where pyruvic acid breaks down, releasing $CO_2$, ATP, and high-energy electrons.

Electron Carriers from the Krebs Cycle

FAD and NAD+, which carry high-energy electrons to the Electron Transport Chain.

Electron Transport Chain (Respiration)

Process where high-energy electrons are passed along a series of molecules to pump $H^+$ ions and create water.

ATP Synthase

Molecule turned by $H^+$ ions moving back across the membrane; generates large amounts of ATP.

Respiration Step That Makes the Most ATP

The Electron Transport Chain.

Fermentation

Process that recycles NAD+ so it does not run out and glycolysis can continue when oxygen is not available.

Two Types of Fermentation

Alcoholic fermentation and lactic acid fermentation.

Products of Alcoholic Fermentation

Ethyl alcohol and $CO_2$ (plus NAD+).

Products of Lactic Acid Fermentation

Lactic acid (plus NAD+).