1. Modern Biology©2009 Holt, Rinehart, & Winston Chapter 4
Biology: Cell Review
Modern Biology©2009
Holt, Rinehart, & Winston
Chapter 4

2. Cell History
Robert Hooke, 1665, saw cork under light microscope, and called individual units “cells”.
van Leeuwenhoek, 1673, saw living cells under microscope with 10x greater magnification
M. Schleiden, 1838, said all plants were made of cells
T. Schwann, 1839, said all animals were too.
R. Virchow ( ) said all cells came from preexisting cells

3. Cell Theory Has 3 essential parts:
Cells come only from reproduction of existing cells.
Cells are basic unit of structure & function in organisms.
All living organisms are composed of 1 or more cells.

4. Cell Structure
Form follows function: Shapes evolve to allow cells to perform their function.
Sizes range from nm to 2 m in length, but average cells are 10 – 50 mm.
Surface-area-to-volume ratio limits size.
Volume increases more quickly.
Cells’ need for nutrient intake & waste disposal depends on proximity to cell membrane.

5. Cell Types Two basic types Prokaryotic Eukaryotic
Has no membrane-bound organelles or nucleus
Is divided into 2 domains
Bacteria – similar to 1st cellular life forms
Archaea
Eukaryotic
Has membrane-bound organelles, including nucleus

6. Plasma Membrane Phospholipid bilayer Regulates passage in/ out of cell
Outer & inner phosphate heads are polar
Inner portion composed of lipid tails
Regulates passage in/ out of cell
Separates cellular activities from environment
Interfaces with environment
Includes integral & peripheral proteins & lipids (sterols)  Fluid Mosaic Model

7. Cellular Organelles & Functions
Nucleus: houses/protects genetic info (DNA)
Nucleolus: site of ribosomal RNA production
Mitochondrion: energy production
Ribosomes: protein production
Endoplasmic reticulum: intracellular highway
RER: phospholipids & proteins; SER: lipids + detox
Golgi apparatus: sort/package proteins + lipids
Lysosomes: digest large molecules & invaders
Peroxisomes: break down R-OH, f.a., bacteria

8. Cytoskeleton Network crisscrossing cytoplasm Gives shape to cell
Acts as system of internal tracks
Has 3 structural elements
Microtubules: made of tubulin; make flagella/cilia
Centrioles: organize microtubules in cell division
Microfilaments: made of actin, help in cell movement
Intermediate filaments: rods: anchor nucleus et al, make up hair shaft

9. Plant Cells Unique Structures but have no centrioles
Cell Wall: primary + secondary
Made of cellulose
Central Vacuole
Made as smaller vacuoles fuse together
Stores water, enzymes, wastes, etc…
Plastids
Chloroplast: site of photosynthesis
Chromoplast: has colored pigments + photosynthesis
Amyloplasts: store starch