Cell Structure and Function

Key terms and definitions

Prokaryotic Cell

A simple cell with no nucleus and no membrane-bound organelles

Eukaryotic Cell

A complex cell with a nucleus and membrane-bound organelles

Unicellular

An organism made of one cell

Multicellular

An organism made of many specialized cells

Surface Area to Volume Ratio (SA:V)

Affects how efficiently a cell exchanges materials

Volume

Space inside the cell (affects resource needs)

Surface Area

Total area of the plasma membrane (affects exchange rate)

Nucleus

Controls cell activities, stores DNA

Nucleolus

Creates ribosomes, found inside the nucleus

Ribosomes

Makes proteins (free = cytoplasm, bound = RER)

Rough Endoplasmic Reticulum

Folds and modifies proteins

Smooth Endoplasmic Reticulum

Synthesizes lipids, detoxifies toxins

Golgi Apparatus

Packages, sorts and modifies proteins for transport

Mitochondria

Site of cellular respiration, makes ATP

Chloroplast

Site of photosynthesis in plant cells

Lysosome

Contains digestive enzymes to break down waste

Vacuole

Storage of water and nutrients (larger in plants, smaller in animals)

Vesicle

Transports substances in the cell

Centrioles

Helps organize cell division in animal cells

Cytoplasm

Jelly-like fluid that holds organelles

Cytosol

Fluid part of cytoplasm (excludes organelles)

Plasma Membrane

Controls what enters and exits the cell

Cell Wall (plants, fungi, bacteria)

Rigid structure outside membrane, gives support and protection
Made of cellulose in plants

Cytoskeleton

Gives shape and support, helps movement

Simple Diffusion

Passive movement of small, non-polar molecules directly across membrane

Facilitated Diffusion

Passive movement of larger or charged molecules via proteins

Osmosis

Passive diffusion of water across a membrane from low solute to high solute concentration

Active Transport

Movement against concentration gradient using ATP and a carrier protein

Endocytosis

Bulk transport into the cell using vesicles

Exocytosis

Bulk transport out of the cell using vesicles

Phospholipid

Forms bilayer, hydrophilic head + hydrophobic tail

Cholesterol

Maintains membrane fluidity

Channel Protein

Allows passive movement of specific molecules (facilitated diffusion)

Carrier Protein

Transports substances via shape change (can be passive or active)

Peripheral Protein

Attached to surface, helps with structure or signaling

Transmembrane Protein

Spans the membrane, used in transport and signaling

Anchor Protein

Connects the membrane to the cytoskeleton or extracellular structures

Glycoprotein

Protein with carbohydrate, used in cell recognition

Glycolipid

Lipid with carbohydrate, used in cell recognition

Selective Permeability

Allows certain substances to enter and exit

Concentration Gradient

Difference in concentration across a space

Equilibrium

When concentrations are equal on both sides of the membrane