Cells: The Basic Units of Life

Robert Hooke was the first person to describe cells Anton van Leeuwenhoek was the first person to make a microscope. Cell Theory 1. All organisms are made of one or more cells. 2. The cell is the basic unit of all living things. 3. All cells come from existing cells.

PARTS OF THE CELL: Cell Membrane – protective layer that covers the cell’s surface and acts as a barrier Organelle – structures that perform specific functions within the cell DNA – deoxyribonucleic acid, genetic material that carries information needed to make new cells and new organisms Nucleus – encloses DNA

TWO KINDS OF CELLS: Two basic cell types: Prokaryotes – do not have a nucleus and do not have membrane-bound organelles (ex. eubacteria and archaebacteria) Eukaryotes – do have a nucleus and have membrane-bound organelles (ex. animals, plants, and fungi)

PROKARYOTES: EUBACTERIA AND ARCHAEBACTERIA: Prokaryotes are single celled organisms that have no nucleus, circular DNA, and no membrane-bound organelles. The most common prokaryote is eubacteria = bacteria. Bacteria world’s smallest cells live in places no other organisms could live Archaebacteria = archae are heat-loving, salt-loving, and methane-making

EUKARYOTIC CELLS: Eukaryotic cells are microscopic but are 10 times larger than most bacterial cells. Eukaryotes are the largest cells. All living things that are not bacterial are eukaryotes. Eukaryotes are multi-cellular with linear DNA, a nucleus, and membrane-bound organelles. multi-cellular = “many cells”

Prokaryotes Eukaryotes Number of Cells DNA Nucleus Organelles single celled multicellular circular linear nucleus present no nucleus no membrane-bound organelles present membrane-bound organelles present

Cell Wall the rigid structure that gives support and protection to the plant cell outermost structure of a plant cell found only in plants, algae, and fungi plants and algae cell wall made of cellulose fungi cell wall made of chitin helps the plant stand up right

protective barrier that encloses animal cells Cell Membrane protective barrier that encloses animal cells outermost structure of an animal contains proteins, lipids, and phospholipids main functions: 1) encloses cells and separates and protects the cell’s contents from the cell’s outside environment 2) controls movement of materials (food and water) into and out of the cell Security Guard or Border Patrol

Cytoskeleton a web of protein that give support and structure to the cell keeps the cell membrane from collapsing give the cell shape

Nucleus (control center) large dark structure in the cell contain the cell’s DNA directs all activities in the cell contains two membranes contains nucleolus which stores materials that will be used to make ribosomes

Ribosomes structures where proteins are made the smallest of the organelles more ribosomes in a cell than any other organelle not covered by a membrane all cells have ribosomes

Endoplasmic Reticulum (ER) system of folded membranes in which proteins, lipids and other materials are made transport materials inside the cell internal delivery system of cell rough ER (cover with ribosomes) makes proteins smooth ER (lacks ribosomes) makes lipids and breaks down toxic material that could damage the cell

Mitochondria the place where sugar is broken down to produce energy covered by two membranes the powerhouse of the cell stores ATP = energy has its own DNA

Chloroplasts (plants and algae only) place where photosynthesis takes place photosynthesis is the process where plants and algae use sunlight, carbon dioxide, and water to make sugar and oxygen has two membranes is green in color

Golgi Complex/Body packages and distributes proteins received proteins from ER final product is enclosed in a piece of the Golgi complex’s membrane membrane is pinched off to form a bubble (vesicle) Vesicle is a small sac that surrounds material to be moved into or out of a cell all eukaryotic cells have vesicles

Lysosomes contain digestive enzymes and responsible for digestion inside a cell destroy worn-out organelles get rid of waste materials (clean up department) protect the cells from invaders

Vacuoles large vesicles in plant and fungal cells, act like lysosomes (store digestive enzymes and aid in digestion) in some plant cells, stores water and other liquids (cell’s watering system)