All organisms are composed of cells Cells are the smallest living unit of living things All cells come from cells

The Cell Theory

Spontaneousgeneration

Cell theory Germ theory of disease Theory of evolution Atomic theory Heliocentric theory of the solar system Universal gravitation Theory of relativity Quantum theory String theory

Important Scientific Theories

Prokaryotes

Eukaryotes

What kinds of organisms are

they?

What are the characteristics of their cells?

The Prokaryotic Cell

Cell membrane (plasma membrane)• Boundary• Semi-permeable

The Prokaryotic Cell

Ribosomes• Not membrane-bounded• Protein synthesis

The Prokaryotic Cell

Cell wall • Rigid• Permeable

Nucleoid• Genetic material (DNA)

The Prokaryotic Cell

Flagella• Protein filaments• Motility

The Prokaryotic Cell

The Eukaryotic Cell

Ribosomes• Bound to ER (rER) – secreted proteins• Free – cytosol proteins

The Eukaryotic CellNucleus• Genetic material (DNA)• Chromatin (chromosomes)• Nuclear envelope (with pores)• Nucleolus

The Eukaryotic Cell

Mitochondria• Energy transduction• Aerobic respiration → ATP• 2 membranes• Own DNA (16,000 bp) & ribosomes• Reproduce independently by division

outermembrane

innermembrane

inter-membranespace

matrix

The Eukaryotic Cell

Chloroplasts• Energy transformation: photosynthesis• Photosynthetic eukaryotes only• 3 membranes• Own DNA & ribosomes• Reproduce independently by division

The Eukaryotic Cell

Endoplasmic reticulum• rough: synthesis of secreted proteins• smooth: lipid synthesis

sER

rER

vesicle

The Eukaryotic Cell

Golgi apparatus• Modification of secreted proteins• Distribution of secreted proteins

Vesicle• Transport of secreted proteins

The Eukaryotic Cell

Lysosomes• Small membrane sacs• “Recycling center”• Enzymes break down molecules

The Eukaryotic Cell

Vacuole• Storage• Phagocytosis• Water balance• etc.

The Eukaryotic CellCytoplasm• Everything outside the nucleus• Includes organelles

Cytosol• Gel-like fluid of cytoplasm• Does not include organelles•Proteins, amino acids, nucleotides, salts, small molecules…

Cytoskeleton• Networks of protein fibers•Structure, motility, organization, transport…

Similar in size to prokaryotic cells Two membranes Own DNA Own ribosomes, prokaryote-like Divide independently DNA sequence like prokaryotic genes

The Endosymbiosis Theory ancestral cell

membrane infoldingcreates nucleus, ER

endosymbiosisresults in mitochondria

ancestralanimal cell

ancestralplant cell

endosymbiosisresults in chloroplasts

Why are prokaryotes small and eukaryotes large?