THE CELL

A VIEW FROM WITHIN

THE CELL

• The cell is the basic unit of structure and function on living things

• It was first discovered when the microscope was invented - Anton Van Leeuwenhoek

• Robert Hooke named the cell when he was looking at a piece of cork and saw that it was made up of “little chambers”

CELL THEORY

• ALL LIVING THINGS ARE COMPOSED OF CELLS

• CELLS ARE THE BASIC UNITS OF STRUCTURE AND FUNCTION OF LIVING THINGS

• ALL CELLS COME FROM PRE-EXISTING CELLS

CELL STRUCTURE

• Vary in size

– measured in micrometers (1 millionth of a meter)

– smallest 0.2 micrometers - mycoplasma

– largest 1000 micrometers - giant ameba, bird eggs

– average size: 5-50 micrometers

• basic structure in most cells:

– cell membrane: outer boundary

– nucleus: control center

– cytoplasm: material between the nucleus and the membrane

CELL MEMBRANE

• Regulates what enters and leaves the cell

• aids in protection

• supports cell

• made of lipids, proteins, and carbohydrates

– fluid mosaic model

CELL WALL

• Found in plants, algae, and some bacteria

• found outside the cell membrane

• protects and supports the cell

• very porous (things can pass through it)

• allow water, oxygen, and carbon dioxide to pass through it easily

• can be made up of layers

– pectin: cell glue

– cellulose: fibrous material - elastic

– tignin: rigid material - supports woody plants

NUCLEUS

• Found in most cells

• eukaryotic - cells that contain a nucleus

• prokaryotic - cells that do not contain a nucleus

• information center of the cell

• contains DNA (Deoxyribonucleic Acid)

• directs all activities in living cells

• also contains:

– nuclear envelope: surrounds nucleus, passage way in and out of the nucleus

– nucleolus: found on nucleus, contains RNA (ribonucleic acid)

– chromosomes: contains genetic information

CYTOPLASM

• MITOCHONDRION:

– Change energy to one form to another, food to energy

• CHLOROPLAST:

– Trap energy of sunlight and convert it to chemical energy in plants; sun to food

• RIBOSOMES:

– Structure in which proteins are made, composed of RNA and protein, small in size, free or attached

• ENDOPLASMIC RETICULUM:

– Complex network of channels that transport materials through the cells cytoplasm

• SMOOTH ER:

– Outer surface is smooth and contains enzymes

• ROUGH ER:

– Ribosomes on surface that synthesize protein

• GOLGI APPARATUS:

– Modify proteins; modifies, collects, packages, and distributes molecules made at one location in the cell and used in another

• VACUOLES:

– Stores water, salt, protein, and carbohydrates

• PLASTIDS:

– Found in plants; storage of food and pigments

• ENDOCYSTS:

– Ingests large particles; garbage trucks of cells; only found in animals

Plant and Animal Cells