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Cell Structure and FunctionBiology 103
I. The Development of the Cell Theory 1. Robert Hooke (1665) - observed cork
2. Anton van Leeuwenhoek (1673) saw microscopic life - blood cells, single cell organisms
3. Mathias Schleiden, Botanist & Theodor Schwann, Zoologist, (1839) published their cell theory …"The cells are organisms, and animals as well as plants are aggregates of these organisms arranged in accordance with definite laws."
4. Rudolph Virchow (1858) "omnis cellula e cellula" --all cells come from cells
II. Cell History1.The first cells were prokaryotic (= “before nucleus”) cells that appeared on the earth about 3.5 to 4.0 BYA.
2. More complex eukaryotic (=“true nucleus”) cells appeared about 1.5 BYA.
| euykaryotes | oxygen | first cells | formation of earth
5 4 3 2 1 0Billions of Years Ago
III. Eukaryotic Cell Structure
1. Cell membrane: surrounds cell, controls the movement of substances in and out, structure:
phospholipid bilayer with protein carrier proteins and receptors embedded (a fluid mosaic)
2. Nucleus: information storage: DNA synthesis, surrounded by nuclear envelope. May contain a nucleolus - indicates active protein synthesis
3. The Cytoplasm is everything in the cell except the nucleus,
4. Mitochondrion (plural = Mitochondria) converts carbohydrates into ATP (high energy molecules) Maternal origin, two compartments
Copyright 2008 John Wiley & Sons
The cell membrane surrounds the cell
The fluid mosaic model of the cell membrane
Copyright 2008 John Wiley & Sons
Copyright 2008 John Wiley & Sons
DNA is stored as chromatin• When not dividing, the nucleus is filled with threads
of chromatin– Chromosomes condense before cellular division
Copyright 2008 John Wiley & Sons
Nuclear Envelop surrounds the chromatin
The nuclear envelop is a double-walled membrane studded with nuclear pores
Most DNA is inside the nucleus
Copyright 2008 John Wiley & Sons
Large Molecules leave the nucleus through nuclear pores
Copyright 2008 John Wiley & Sons
The information in the nuclear DNA is copied to mRNA (messenger RNA). mRNA leaves the nucleus via nuclear pores
Copyright 2008 John Wiley & Sons
Once in the cytoplasm mRNA is used to direct protein synthesis in the rough endoplasmic reticulum
Mitpchondria make most of the ATP in the body
5. Special Mention: Chloroplasts chlorophyll and are the site of photosynthesis. Why are chloroplasts important? 6. Ribosomes: help make proteins during RNA translation, made of protein and RNA - give rough ER its appearance
7. Endoplasmic reticulum (two types): smooth - lipid synthesis rough - protein sorting processing
Copyright 2008 John Wiley & Sons
ER and membrane cycling
8. Golgi Apparatus: Packages and sorts proteins from rough ER for export from cell or to other cell compartments
9. Lysosomes and Peroxisomes: contain digestive enzymes
10. Cilia and Flagella: create movement
11. Centrioles: organize Cilia and Flagella
12.Cytoskeleton: supports cell: a),microtubules; b) microfilaments; and c) intermediate fibers
13. Plants have a cell wall, animal cells do not. Cell walls resist osmotic forces.
IV. Cell Junctions
1. Tight junctions 2. Gap junctions 3. Desmosomes
V. Transport functions
1. Diffusion2. Facilitated Diffusion3. Osmosis4. Active Transport: requires ATP5. Vesicular Transport: Endocytosis and Exocytosis
Copyright 2008 John Wiley & Sons
Diffusion equalizes solute concentrations
• Molecules diffuse down their concentration gradient from areas of high concentration to areas of low concentration.
Copyright 2008 John Wiley & Sons
Facilitated diffusion allows water soluble molecules to cross the
membrane with transport proteins that use no energy
Copyright 2008 John Wiley & Sons
Osmosis: movement of water
• Hypotonic solutions – Cells swell
• Hypertonic solutions– cells shrink
• Isotonic solutions– cells neither shrink nor
swell
Copyright 2008 John Wiley & Sons
Active transport takes ATP
Copyright 2008 John Wiley & Sons
Endocytosis (two types)
a. Pinocytosis (cell drinking)
b. Phagocytosis (cell eating)
Exocytosis Removes products from the
cell
VI. Surface to Volume Ratio