Eukaryotic cells have organelles.

Eukaryotic Cells

• Eukaryotes differ from prokaryotes in several ways:1) separation of nucleus from cytoplasm by

double membrane (nuclear envelope)2) DNA organized into distinct chromosomes (X-shaped)

3) complex membrane-bound organelles (e.g., mitochondria)

Three Functional Categories of Eukaryotic Organelles

1) Manufacturing

Nucleus – genetic control center

- DNA & RNA synthesis and ribosome assemble

ribosomes: assemble amino acids into polypeptides (proteins/enzymes)

Three Functional Categories of Eukaryotic Organelles

1) ManufacturingRough Endoplasmic Reticulum (Rough ER) - network of interconnected membrane-

bound sacs

- “rough” appearance because ribosomes stuck to membrane surface

Three Functional Categories of Eukaryotic Organelles

1) ManufacturingGolgi Apparatus (GA) “cell’s warehouse/factory”

- stacks of membrane-bound sacs

- work in close association with ER

- receive, store, modify products of ER

Three Functional Categories of Eukaryotic Organelles

2) Breakdown of Material

Lysosomes

- produced by Rough ER & GA

- digest nutrients within cellVacuoles

- plant cells

- digest nutrients & storage sac

Three Functional Categories of Eukaryotic Organelles

3) Energy Processing

Chloroplasts

- plant cells

- site of photosynthesis

- absorb sun light & transform this energy to food

- light absorbed in grana (stacked “solar packs”)

Three Functional Categories of Eukaryotic Organelles

3) Energy Processing

Mitochondria – “cell powerhouse”

- cellular respiration

- double membrane

- folds (cristae) of inner membrane

- matrix is the inner fluid

Advantages of membrane-bound organelles

• 1. compartments • 2. unique chemistry in different compartments

• 3. membranes themselves have enzymes embedded)

• 4. provides localized environment

Advantages of membrane-bound organelles

• 1. compartments • 2. unique chemistry in different compartments

• 3. membranes themselves have enzymes embedded)

• 4. provides localized environment

Origin of Eukaryotic Cells from Prokaryotes – Additional Evidence Supporting the

Endosymbiotic Hypothesis

• 1. Mitochondria and Chloroplasts contain DNA and ribosomes similar to bacteria

• 2.Double membrane• 3. Circular DNA• 4. Looks like bacteria• 5. Reproduces by binary fission

Road to Modern Organisms1st life was bacteria unicellular prokaryotes

Photosynthesis changed Earth’s atmosphere released O2 - cyanobacteria!!!!

2nd was unicellular eukaryotes Endosymbiotic Theory

3rd was multicellular organisms

Origin of Eukaryotic cells

• The endosymbiotic theory is a theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms