GENBIO 1ST SEM FINALS TOTOO NA

Phospholipid Bilayer

In water, phospholipids form a stable two-layer sheet with hydrophilic heads facing outward and hydrophobic tails inward.

The hydrophilic heads of phospholipids face .

outward toward water

Plasma Membrane

Boundary that controls movement of substances in and out of the cell; exhibits selective permeability.

The plasma membrane exhibits .

selective permeability

Fluid Mosaic Model

Describes the membrane as fluid (lipids and proteins can move laterally) and mosaic (diverse proteins embedded in phospholipids).

Glycoprotein

A membrane protein with attached sugars for cell recognition.

Glycolipid

A membrane lipid with attached sugars.

Membrane Proteins

Responsible for transport, signaling, enzymatic activity, and attachment to the cytoskeleton.

Passive Transport

Movement of molecules from high to low concentration without energy.

Osmosis

Diffusion of water across a selectively permeable membrane.

Hypertonic

Solution with higher solute concentration; water exits the cell.

Hypotonic

Solution with lower solute concentration; water enters the cell.

Isotonic

Solutions with equal solute concentrations on both sides of the membrane.

Facilitated Diffusion

Passive transport of molecules using specific transport proteins.

Active Transport

Movement of molecules from low to high concentration using energy (ATP).

Exocytosis

Export of bulky materials by vesicles fusing with the plasma membrane.

Endocytosis

Uptake of large materials by forming vesicles from the membrane.

Phagocytosis

“Cell eating” – engulfing solid particles into vacuoles.

Pinocytosis

“Cell drinking” – taking in fluid droplets into vesicles.

Receptor-Mediated Endocytosis

Specific uptake of molecules using receptor proteins in coated pits.

Adenosine Triphosphate (ATP)

Main energy currency of the cell that powers cellular work.

Hydrolysis of ATP releases .

energy

ATP Tasks

Chemical work (biosynthesis), transport work (ion pumping), and mechanical work (movement).

Oxidation

Loss of electrons.

Reduction

Gain of electrons.

Photosynthesis

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂; process where plants convert light energy to chemical energy in glucose.

Cellular Respiration

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP; process that releases energy from food.

Autotrophs

Organisms that make their own food; producers of the biosphere.

Heterotrophs

Organisms that consume other organisms for energy.

Chloroplast

Organelle where photosynthesis occurs; contains thylakoids, grana, and stroma.

Thylakoid

Disk-like membrane structures containing chlorophyll.

Grana

Stacks of thylakoids.

Stroma

Fluid surrounding thylakoids where the Calvin cycle occurs.

Chlorophyll

Green pigment that absorbs light energy for photosynthesis.

Chlorophyll a absorbs mainly and light.

blue-violet; red

Carotenoids

Yellow-orange pigments that absorb excess light energy and protect chlorophyll.

Photon

A packet of light energy; shorter wavelength = higher energy.

Fluorescence

Reddish glow emitted when chlorophyll’s excited electrons fall back to ground state.

Photosystem

A cluster of pigments and proteins that capture light energy to excite electrons.

Photosystem II

Reaction center pigment P680; initiates electron transport by splitting water.

Photosystem I

Reaction center pigment P700; produces NADPH.

Light Reactions

Convert light energy into ATP and NADPH, releasing oxygen; occur in thylakoid membranes.

The main products of light reactions are and .

ATP; NADPH

Calvin Cycle

Uses ATP and NADPH to fix CO₂ into glucose; occurs in the stroma.

The enzyme that fixes CO₂ is .

rubisco

C₃ Plants

Use only the Calvin cycle; produce 3-carbon (3-PGA) compounds.

C₄ Plants

Fix CO₂ into 4-carbon compounds to reduce photorespiration.

CAM Plants

Open stomata at night to conserve water; store CO₂ as acid.

The main purpose of C₄ and CAM adaptations is to minimize and conserve .

photorespiration; water