CELLS• Basic unit of structure and function of living things.• Many sizes: Average is 5-50 micrometers (µm)– Nerve cell in leg (1 m) – Mycoplasma (0.2 micrometers = 1 millionth of a meter)– Human egg no bigger than “dot” on letter i• Eggs are a single cell (Largest single cell is an ostrich

egg)– Red blood cell 1/10 egg cell– Common bacteria (fit 8,000 inside a red blood cell)

• Many shapes:

Shapes/Types of Cells

2 Major Types of Cells

PROKARYOTE vs. EUKARYOTE

Prokaryotic Cell lacks internal

structures:• No nucleus (just

DNA)• No organelles (cell

parts)

Eukaryotic Cell has internal structures:

• nucleus • Organelles

Basic Parts to a Eukaryotic Cell

• cell (plasma) membrane • cell wall (only certain organisms)

•nucleus • cytoplasm

Cell (plasma) Membrane

• regulates what comes in and out of a cell, aids in protection and support.

• made of a bilayer of lipids• proteins (stick in membrane or move

around) act as channels and pumps• carbohydrates (attached to proteins or

lipids) act as chemical identification cards

Cell Wall• surrounds cell membrane in plants, algae, and

some bacteria.• support and protection• very porous allowing water, food, air, and other

substances to pass through• made of 2 or more layers– first layer to form is where two plant cells meet

(gluey substance called pectin holds together)– primary layer is after pectin made of cellulose

(elasticity)– secondary layer made of cellulose and lignin (wood)

Nucleus• control center of cell• contains genetic material

Cytoplasm

• living area between nucleus and cell membrane

• usually a thicker substance

• contains many important structures

Prokaryotic cell (cyanobacteria)

Eukaryotic cell (typical animal)