Biology

CELL MEMBRANE

Controls entry/exit of substances; maintains homeostasis.

Fluid Mosaic Model

Describes the cell membrane as a mosaic of diverse components embedded in a fluid environment.

Hydrophilic head

The water-loving part of a phospholipid that faces the outside and inside of the cell.

Hydrophobic tails

The water-fearing part of a phospholipid that faces inward.

Passive Transport

Transport of substances from high to low concentration without using energy.

Diffusion

Movement of small molecules, such as O₂ and CO₂, from high to low concentration.

Facilitated Diffusion

Movement of polar or large molecules, such as glucose, through protein channels.

Osmosis

The diffusion of water towards a higher solute concentration.

Active Transport

Transport of substances from low to high concentration that requires energy (ATP).

Ion pumps

Examples include the sodium-potassium pump, which moves ions against their concentration gradient.

Photosynthesis

The process in chloroplasts where light energy is converted into chemical energy.

Overall Equation of Photosynthesis

6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂.

Light Reactions

The first stage of photosynthesis that produces ATP, NADPH, and oxygen.

Calvin Cycle

The second stage of photosynthesis that uses ATP, NADPH, and CO₂ to produce glucose.

Cellular Respiration

The process in mitochondria that breaks down glucose to produce ATP.

Overall Equation of Cellular Respiration

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP.

Glycolysis

The first stage of cellular respiration where glucose is broken down.

Krebs Cycle

The second stage of cellular respiration that produces electron carriers.

Electron Transport Chain (ETC)

The final stage of cellular respiration that produces the majority of ATP.

Fermentation

A process that occurs in the absence of oxygen to produce energy.

Lactic Acid Fermentation

Occurs in animals, producing lactic acid which can lead to muscle fatigue.

Alcoholic Fermentation

Occurs in yeast, producing alcohol and CO₂.

Energy Flow in Cells

Sunlight → Photosynthesis → Glucose → Cellular Respiration → ATP → Cellular Work.

Important Concepts for Exam

Membrane structure, transport processes, photosynthesis, and cellular respiration.