CytologyCytology

Cell TheoryCell Theory

• All living things are made up of at least one cell

• Cells are the basic units of structure and function in an organism

• Cells only come from the reproduction of other cells

Prokaryotic CellsProkaryotic Cells

• Bacteria• Extremely tiny (1-5 m)• Contain DNA, but lack

nucleus• Only has a cell

membrane-- no membrane bound organelles

Eukaryotic CellEukaryotic Cell

• Separate Domain than prokaryotes– Most fundamental

difference in classification

• Contain many membrane bound organelles

• 10-100x larger than prokaryotes

• Plants, Animals Fungi, Protists

CytoplasmCytoplasm

• Portion of the cell outside the nucleus

• Fluid inside of the cell• Water based solution• Nutrients needed for

life dissolved inside cell

• Includes organelles

Nucleus—Control CenterNucleus—Control Center• Contains the cell’s DNA—

genetic code– DNA bound in chromatin– Chromatin: thread like

structure of Protein and DNA

• Instructs cell how to make proteins

• Enclosed by Nuclear Envelope-- a membrane– Contain nuclear pores-- allow

certain materials to pass in and out of nucleus

• Nucleolus—dense structure where ribosomes are assembled

RibosomesRibosomes

• Where proteins are assembled

• No membrane (also found in prokaryotes)

• Made of RNA (ribose) and protein

• Can be either free floating or attached to endoplasmic reticulum

• Extremely tiny

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)

• Transport network• Moves molecules to

different parts of the cell• System of membranes• Rough ER-Ribosomes

attached • Easily transport newly

synthesized proteins• Smooth ER– no ribosomes

• Transport of other molecules

Golgi ApparatusGolgi Apparatus

• Modification and packaging of molecules

• Helps move materials into and out of cells

• Works closely with ER• Stack-like membranes• Form vessicles

– membrane bound sacs which hold material and move throughout the cell

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LysosomeLysosome

• Membranes that contain enzymes that break apart various molecules

• Digestion or clean up• Vessicles that contain enzymes

Vacuole (mostly plants)Vacuole (mostly plants)

• Large storage sacs for water, salts, proteins, and carbohydrates

• Pressure of large vacuoles allows plants to support large structures (i.e. leaves, flowers, etc)

MitochondriaMitochondria• Mitochondrion (s.),

mitochondria (pl.)• Transfer energy stored in

carbohydrates (and other organic molecules) into ATP.

• Contain DNA• Bound by double membrane

– Inner membrane folds to form christae

• Inherited from mother• Likely formed from

prokaryotes living within another cell-- endosymbiotic theory

Plastids (mostly plants)Plastids (mostly plants)

• Most common is chloroplast– Transform solar energy into

chemical energy— photosynthesis

– Contain chlorophyll—green pigment

– Thylakoid-- flat membranous sac where photosynthesis occurs

• Contain DNA• Bound by a double membrane• Likely originally prokaryotic cell

that lived within another (eukaryotic) cell

CytoskeletonCytoskeleton

• Gives cell shape and structure, also allow for movement

• Network of protein filaments—microtubules– Support cell and transport

materials – Also form cilia and flagella–

structures for propulsion

• Microfilaments– Smallest fibers, allow for

movement of cell