Biology Cell Review Modern Biology 2009 Holt Rinehart

Cell History • Robert Hooke, 1665, saw cork under light microscope, and called individual units “cells”. • van Leeuwenhoek, 1673, saw living cells under microscope with 10 x greater magnification • M. Schleiden, 1838, said all plants were made of cells • T. Schwann, 1839, said all animals were too. • R. Virchow (1821 -1902) said all cells came from preexisting cells

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.

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.

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

Plasma Membrane • Phospholipid bilayer – 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

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

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

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