ap bio unit 2

Cell membrane

A protective barrier that surrounds the cell and regulates what enters and exits. Ex: Keeps toxins out while letting nutrients in.

Chromosomes

Thread-like structures made of DNA and proteins that carry genetic information. Ex: Humans have 46 chromosomes.

Ribosomes

Small structures that make proteins by linking amino acids. Ex: Found floating in cytosol or on rough ER.

Cytosol

The fluid inside the cell where organelles are suspended. Ex: Like water in a swimming pool for organelles.

Compartmentalization

Organizing the cell into sections with membranes to increase efficiency. Ex: Lysosomes digest waste without harming other organelles.

LUCA

Last Universal Common Ancestor of all living organisms. Ex: Shared by bacteria, plants, and humans.

Genome

The complete set of DNA in an organism. Ex: Human genome has ~3 billion base pairs.

Nucleus

Organelle that contains DNA and controls cell activities. Ex: “Brain” of the cell.

Endoplasmic Reticulum (ER)

A network of membranes that helps make and transport proteins/lipids.

Smooth ER

ER without ribosomes, makes lipids and detoxifies. Ex: Liver cells have lots of smooth ER.

Rough ER

ER with ribosomes, helps make and fold proteins. Ex: Insulin production in pancreas.

Golgi apparatus

Packages, modifies, and ships proteins. Ex: Like a post office.

Vacuoles

Storage sacs in cells. Ex: Plant vacuoles store water for turgor pressure.

Lysosomes

Organelles with enzymes that break down waste. Ex: Digest worn-out organelles.

Autophagy

Process where lysosomes recycle cell parts.

Apoptosis

Programmed cell death. Ex: Cells between fingers die during development.

Endomembrane system

Network of organelles (ER, Golgi, vesicles, etc.) that transport materials.

Vesicles

Small membrane sacs that move molecules. Ex: Neurotransmitter vesicles in neurons.

Membrane-bound organelles

Organelles surrounded by membranes. Ex: Nucleus, mitochondria.

Mitochondria

Organelle that makes ATP through cellular respiration. Ex: “Powerhouse of the cell.”

Cristae

Folded inner membrane of mitochondria that increases surface area for ATP production.

ATP

Adenosine triphosphate, the cell’s main energy currency.

Chloroplasts

Plant organelles that carry out photosynthesis.

Photosynthesis

Process where plants make glucose using sunlight, CO₂, and water.

SA:V ratio

Surface area to volume ratio, affects cell efficiency. Ex: Smaller cells exchange materials faster.

Specialized structures for different functions

Unique organelles for certain tasks. Ex: Cilia for movement.

Phospholipid

Molecule with hydrophilic head and hydrophobic tail, makes up membranes.

Amphipathic

Molecule with both hydrophilic and hydrophobic parts. Ex: Phospholipid.

Peripheral proteins

Proteins on membrane surface. Ex: Enzymes or anchors.

Integral proteins

Proteins embedded in membrane. Ex: Transport channels.

Functions of integral proteins

Transport, signaling, recognition, joining, attachment.

Transport

Moving substances across membranes. Ex: Channel proteins.

Cell-to-cell recognition

Cells identifying each other. Ex: Immune system recognizing bacteria.

Enzymes

Proteins that speed up chemical reactions.

Signal transduction

Process where signals are passed into the cell through receptors.

Intercellular joining

Cells connecting through junctions.

Attachment for extracellular matrix or cytoskeleton

Proteins link the membrane to outside or inside structures.

Fluid mosaic model

Model of membranes as flexible with proteins floating in phospholipids.

Cholesterol

Molecule in membranes that regulates fluidity.

Glycoproteins

Proteins with carbohydrate chains, used for recognition.

Glycolipids

Lipids with carbohydrate chains, used for recognition.

Channel proteins

Proteins that form pores for molecules to pass.

Carrier proteins

Proteins that change shape to transport molecules.

Cell wall

Rigid outer layer in plants, bacteria, fungi.

Plasmodesmata

Channels in plant cell walls for communication.

Concentration gradient

Difference in concentration across space.

Equilibrium

When concentrations are balanced.

Passive transport

Movement across membranes without energy.

Active transport

Movement across membranes with energy (ATP).

Simple diffusion

Molecules move freely from high to low concentration.

Facilitated diffusion

Molecules move via channel/carrier proteins.

Endocytosis

Process of taking in large molecules by forming vesicles.

Phagocytosis

“Cell eating” – engulfing solids.

Pinocytosis

“Cell drinking” – engulfing liquids.

Receptor-mediated endocytosis

Endocytosis triggered by specific molecules binding to receptors.

Exocytosis

Vesicles fuse with membrane to release molecules.

Polarized cell membrane

Unequal distribution of charges across membrane. Ex: Neurons at rest.

Na⁺/K⁺ pump (Sodium-potassium pump)

Active transport protein pumping Na⁺ out, K⁺ in.

Osmosis

Diffusion of water across a membrane.

Aquaporins

Channel proteins for water.

Osmolarity

Concentration of solutes in solution.

Tonicity

Effect of a solution on cell water balance.

Hypertonic

Solution with more solutes

Isotonic

Solution with equal solutes

Hypotonic

Solution with fewer solutes

Turgor pressure

Pressure of water pushing against plant cell walls.

Turgidity

State of being swollen with water.

Osmoregulation

Control of water balance in cells/organisms.

Homeostasis

Maintaining stable internal conditions.

Water potential

Potential energy of water

DORA

Differences between prokaryotic and eukaryotic cells

Endosymbiotic theory

Theory that mitochondria/chloroplasts came from engulfed bacteria.

Endosymbiosis

When one organism lives inside another in mutual benefit.