Cells: Structure and Function
Chapter 6
2 Types of Cells
• Prokaryotic cells
– bacteria
• Eukaryotic cells
– Animals
– Plants
– Fungi
– Protists [single cell organisms]
The People
• Jansen made the first microscope.
• Anton van Leewenhoek discovered
microorganisms.
• Hooke discovered cells.
• Virchow and Schleiden developed the cell
theory.
Cell Theory
• All living things are:
– Cells
– Or are made of cells
• All cells come from pre-existing cells
First cells were Prokaryotes
Prokaryotes
• Appeared about 3.5 billion years ago. Layers of bacteria
growing on top of each other.
Prokaryotes, bacteria
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No nucleus or organelles.
Nucleoid region is where DNA is located.
Ribosomes change genetic info. into proteins.
Flagella for movement
Cell wall, support and protection.
Plasma membrane control entry/exit.
Capsule protection, may cause disease.
Pili allow attachment to host or surfaces.
Biofilms optional report
Prokaryotic cells needed to do all life
functions.
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Eat/Digest
Remove wastes
Reproduce
Move
Make organic molecules
Make ATP
Single cells must do it all.
Eukaryotic cells
Eukaryotes
• Arose from existing prokaryotes 2.1 billion
years ago.
• Cells contain organelles doing specific tasks.
• Endosymbiotic theory. [When an organism was eaten by a
cell (phagocytosis) it was not digested but instead became an organelle in
the cell that ate it. Mitochondria and Chloroplasts have their own DNA
and ribosomes]
Nucleus, contains DNA and nucleolus
Nucleolus, creates new ribosomes
Mitochondria, makes ATP
Chloroplast, make sugar by photosynthesis
Ribosome, joins amino acids into proteins
Golgi, modifies and packages chemicals
Smooth E.R. production fats and steriods
Rough E.R. makes/packages proteins
Plasma Membrane, controls movement of materials in/out of cell
Lysosome, intracellular digestion
Cytoskeleton, maintain cell shape & internal organization
Vacuoles, compartment for storing wastes or water or starch, etc.
Cell Wall, support and protection
Cytoplasm, liquid part of cell interior (water, salt, proteins, etc.)
Centrioles, allow DNA to separate during cell division
Flagella, cell movement
Plant cells vs Animal cells
• Plant
Animal
• Chloroplasts
• Cell Wall
• Central Vacuole
Centrioles
Single Eukaryotic cell
Cooperation
• Cells living together may gaining some survival
advantage.
• Cells specialize.
• Example, Colonial Volvox
Volvox Colony
Volvox
• Many cells living as a single organism
Size = protection
• Offspring protected within.
• No specialized cells.
Reproduction
Multicellular organisms
Made from many cells that have specialized
functions.
Some cells digest food.
Some cells allow for movement.
Division of Labor
More Specialization
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Specialized cells for different tasks.
Do not do everything.
More Efficient
Cells specialize into Tissues, layers of cells.
Tissues, cell layers [in a sponge]
Levels of structure
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Cells
Tissue, Similar cells with a common function.
Organs, Heart-different tissues working together. Heart.
Organ Systems, Circulatory system-Heart, Veins,
arteries, capillaries.
• Organisms, Human, different organ systems working
together-digestive sistem, nervous system, circulatory system,
etc.
Organ
Organ System, excretory system
Organism
Levels of Structure
• Population, members of the same Species.
• Community, the different species living in the
same environment.
• Ecosystem, the biotic (living organisms) and the
abiotic factors (light, oxygen level, temperature,
etc.) in the same area.
• Biomes, regions of the world with similar climate
(weather, temperature) animals and plants. There
are terrestrial biomes (land) and aquatic biomes,
both freshwater and marine.
Population
Community
Ecosystem
Biomes