Introduction to the cellIntroduction to the cell

Cells in GeneralCells in General

The cell is the fundamental The cell is the fundamental structural structural unit of all living organismsunit of all living organisms..

Some cells are Some cells are complete organismscomplete organisms, , such as the unicellular bacteria and such as the unicellular bacteria and protozoa; others, such as nerve and protozoa; others, such as nerve and muscle cells, are muscle cells, are specialized specialized componentscomponents of multicellular organisms. of multicellular organisms.

Cells range in size from the smallest Cells range in size from the smallest bacteria-like organism, which are 0.1 bacteria-like organism, which are 0.1 micrometer in diameter to the egg yolks micrometer in diameter to the egg yolks of ostriches (8 cm). of ostriches (8 cm).

Single celled protozoans

A nerve cell

Common cell structuresCommon cell structures

Although they may differ in Although they may differ in appearance and function, all cells appearance and function, all cells have a external have a external cell membranecell membrane and an internal, watery substance and an internal, watery substance called the called the cytoplasmcytoplasm..

Within the cell is genetic material, Within the cell is genetic material, deoxyribonucleic acid (deoxyribonucleic acid (DNADNA), ), whish is the instructions for the whish is the instructions for the behavior and reproductionbehavior and reproduction of the of the cell. cell.

Cell membraneAnd cytoplasm

Cell compositionCell composition

Cells are composed of Cells are composed of OO22, H, H22, ,

C, and NC, and N22 which combined into which combined into

organic compounds such as organic compounds such as proteins, nucleic acids, lipids proteins, nucleic acids, lipids (fats) , and carbohydrates(fats) , and carbohydrates. . WaterWater makes up makes up 65 percent65 percent of of the cell, since it is a favorable the cell, since it is a favorable environment for biochemical environment for biochemical reactions.reactions.

Water is essential for alllife since it is a major component of the cell.

Frog eggs in water

Cell functionCell function

Cells use energy to Cells use energy to perform cell functions: perform cell functions: movement, growth, movement, growth, maintenance and repair maintenance and repair of cell structure, of cell structure, reproduction of the cell, reproduction of the cell, and manufacture of and manufacture of specialized cellspecialized cell products products such as enzymes and such as enzymes and hormones. hormones. Bacteria cells on a head on

pencil

DNADNA

Within the cell is Within the cell is genetic material, genetic material, deoxyribonucleic acid deoxyribonucleic acid ((DNADNA), which is the ), which is the instructions for the instructions for the behavior and behavior and reproductionreproduction of the of the cell.cell.

Types of cellsTypes of cells

Cells are of two Cells are of two distinctly distinctly different types, different types, prokaryotesprokaryotes and and eukaryoteseukaryotes..

Prokaryotic

Prokaryotic cellsProkaryotic cells

Pro- “before”Pro- “before”A cell smaller than A cell smaller than eukaryoticeukaryoticIt has a simple interior It has a simple interior organization with a single organization with a single strand of hereditary material strand of hereditary material (DNA, RNA)(DNA, RNA)Prokaryotic cells do not have Prokaryotic cells do not have a cell organelles a cell organelles Ex bacteriaEx bacteria

Bacteria- a prokaryote

Eukaryotic cells Eukaryotic cells

Eukaryotic cells are more Eukaryotic cells are more diverse and complexdiverse and complexAll eukaryotic cells All eukaryotic cells possess membrane-possess membrane-bound organelles which bound organelles which are like small cell organsare like small cell organsThe DNA of eukaryotes is The DNA of eukaryotes is stored in the nucleusstored in the nucleusMost living cells such as Most living cells such as plant, animal, fungus and plant, animal, fungus and protists are eukaryotesprotists are eukaryotes

Most plants, fungus and animals areeukaryotes