Chapter 4 Cell Structure

4.1 Studying Cells

Cells are small 1-100 mm Small size maximizes surface area to volume ratio. Required the development of microscopes First light microscopes developed in 1600’s. Anton Van Leeuwenhoek first observed tiny living organisms. Robert Hooke first used term “cells”.

Cell Theory developed from centuries of observations 1800’s Schleiden and Schwann developed Cell Theory 1. All organisms are made of cells 2. Cell is basic unit function of organisms 3. Cells com form preexisting cells. Virchow first described cell division

Cell Structure All cells contain outer phospholipid plasma membrane DNA chromosomes Cytoplasm

4.2 Prokaryotic Cells

The presence of a cell nucleus All cells contain DNA as its hereditary material Prokaryotes simplest cell lacking a membrane bound nucleus or other organelles DNA coiled in a circular chromosome External structure include cell wall and flagella. Include Bacteria and Archaea

4.3 Eukaryotic Cells

Larger more complex cells Membrane bound nucleus found in all Eukaryotes Linear coiled chromosomes Other organelles with specialized function. Ribosomes (also in Prokaryotes) – assemble proteins Mitochondria – produce energy Peroxysomes – help metabolize lipids and amino acids Vacuoles store and transport materials

Plant cells Contain Cell wall Chloroplast – site of photosynthesis Large central vacuole which stores water Lack Centrioles and Lysosomes

4.4 Endomembrane System

Membrane extensions of the nuclear membrane Rough Endoplasmic reticulum contain ribosomes Smooth Endoplasmic reticulum lack ribosomes Golgi Apparatus – Assist in protein modification and storage Vesicles help transport materials between these structures