Download The Cell Theory

Chapter 3 - Cell Structure and Function
Robert Hooke-First person to see cells, he coined the term "cell" for the great many boxes he saw under the
microscope
The Cell Theory
Endosymbiosis theory: All organelles seem
1. Every living organism is made of one or more cells
2. Cells are the functional unit of multicellular organisms
3. Cells arise from pre-existing cells
to share many properties with bacteria. Lynn
Margulis proposed endosymbiont hypothesis: that
organelles derived from ancient colonization of
large bacteria (became the eucaryotic cell) by
smaller bacteria (became the mitochondria,
chloroplast, etc.) Symbiosis = "living together".
*Mitochondria & Chloroplasts have their own DNA
Cell Size
atoms --> DNA --> virus --> bacteria -->mitochondria--> Eukaryotic cells
Cells must remain small in size due to the ratio of surface area and volume
As the cell increases in size, its surface area becomes too small to support its internal structures.
Oxygen and other important substances cannot diffuse fast enough. Cells that get too large, may
divide.
All Cells Have Three Basic Features: Cell Membrane,
Genetic Material, Cytoplasm
Plasma Membrane (aka Cell Membrane)
1. Isolates cytoplasm from external environment
2. regulates flow or material into and out of the cell
3. allows interaction with other cells
Genetic Material
1. provides cellular "blueprint" that controls the functions of the cell
2. In the form of DNA (Deoxyribonucleic acid)
3. DNA is universal for all cells, an all living things - evidence of common ancestry
4. Chromatin is the complex of proteins and DNA, it condenses into chromosomes
before cell division
Cytoplasm (aka cytosol)
1. inside plasma membrane
2. contains water, salts, and other chemicals
3. organelles float within this jelly-like substance
Organelles – specialized to
perform specific functions
Prokaryote vs Eukaryote Cells
Prokaryotes
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no membrane bound nucleus, chromosomes grouped together in an area called the "nucleoid"
no membrane bound organelles
smaller than eukaryotes
have cell wall and cell membrane, some have a capsule on the outside
ribosomes make protein
consist of bacteria and archaebacteria
Appendages include: fimbriae, pili, flagella
Eukaryotes
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has a membrane bound nucleus
has membrane bound organelles in cytoplasm
Organelles perform specific functions
much larger than prokaryotes
animals, plants, fungi, protists
A typical animal cell with organelles
Archaebacteria
 Have diverse shapes
 Cell wall differs from
eubacteria
 Live in extreme
habitats