The CellThe smallest functional unit of life

Animal Cell

Plant Cell

I. The Cell TheoryA. All living things are made of cells.B. Cells are the basic unit of structure

and functionC. All cells arise from preexisting cells.

II. Cell Size A. Small cells function more efficiently than

large cells.B. If a cell’s surface to volume ratio is too low,

substances can not easily enter or leave the cell.

Smallest cell – mycoplasma largest – ostrich egg yolk

III. Common Features of Cells

A. Cell membrane – encloses the cell and separates the cell interior from its surroundings

B. Cytoplasm – the cell interior which includes gases, nutrients and waste

C. Cytoskeleton – system of microscopic fibers that support the cell

D. Cell wall – outer structure which supports and protects the cell

E. Ribosomes – small structures in every cell where protein synthesis occurs

F. DNA – regulates cellular activities* some specialized cells like red blood cells lose their DNA

IV. Prokaryotes Smallest and simplest cells

A. Single celled organismsB. Lack a nucleusC. Lack membrane bound organellesD. Can live in a broad range of

environments

E. Have a cell wall F. Lack internal supportG. Many have flagella – long, threadlike

projections that enable movement

V. EukaryotesCells with internal compartments

A. Single celled or multicellular B. Have a nucleus where DNA is kept

C. Have membrane bound organelles that carry out specific functions within the cell.

D. Have a cytoskeleton which provides internal support.

E. Some have cilia – short, hair like structures that aid in movement

F. Includes animals, plants, fungi and protists.

VI. Cell OrganellesA. Cytoskeleton – network of protein filaments

that support the cell and aid in movement.B. Cytoplasm – region inside the membrane that

includes the fluid, the cytoskeleton and all the organelles except the nucleus.

C. Cell membrane – a phospholipid layer that covers a cell’s surface and regulates what comes into and out of the cell.

D. Nucleus – a membrane bound organelle that contains the cell’s DNA and regulates growth, metabolism and reproduction.1. Nuclear envelope – membrane which separates the nucleus from the cytoplasm2. Nuclear pores – channels which allow materialsto pass in and out of the nucleus3. Chromatin – coiled up DNA4. Nucleolus – produces

ribosomes

E. Ribosomes – tiny structures composed of RNA and protein that make proteins

F. Endoplasmic reticulum – a system of membranes that assist in the production, processing and transport of proteins and lipids.

F. Golgi Appartus – helps make and package materials to be transported out of the cell.

G. Vessicle – small sacs that hold and transport substances

H. Lysosome – vessicle which breaks down old and used cell parts (found in animal and fungal cells)

I. Mitochondrion – organelle surrounded by two membranes that is the site of cellular respiration, produces ATP (energy)

J. Centrioles – organelles which help in cell division

(found in animal cells)

VII. The Plant Cell

A. Cell Wall – rigid structure that surrounds the cell membrane and provides support to the cell.

B. Central Vacuole – large membrane bound space that stores water and other substances; provides rigidity

C. Chloroplast – found in plant and algae, contains a green pigment (chlorophyll) – where photosynthesis occurs

VIII. Organization of Living Things

IX. Cell SpecializationA. The design and shape of a cell is determined

by its function and the conditions under which it works.

B. Unicellular organisms tend to have fairly complex cells, which makes sense considering that these organisms must depend on only one cell to do everything.C. Multicellular organisms exhibit much greater specialization.

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The Endwww.cellsalive.com/cells/3dcell.htm