5.1 All organisms are composed of cells

neuron

skeletal muscle

amoeba

sperm & egg

3 main features: plasma membrane nucleus or nucleoid cytoplasm

The plasma membrane surrounds

all cells

bilayer fluid mosaic

Singer, Nicolson 1972

Genetic Information

prokaryotes

DNA

chromosome

Nucleuseukaryotes

nucleoid

plasmids

during cell division

Cell TheoryCells are the unit of structure and function

Cells reproduce cells

Why are cells small?

As an object increases in size its volume increases as the cube (x3)of its diameterwhilesurface area increases as the square (y2)

The membrane (surface) must allow for sufficient & rapid exchange to support the cell contents

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Prokaryotic vs Eukaryotic

small & simpleribosomes, nucleoidpeptidoglycan wall3.5bya

large & complex organelles, chromosomescytoskeleton1.5bya

Features in common

Unique to eukaryotes, organelles allow for division of labor

Prokaryotes: so what?

Decomposition nutrition

disease sewage treatment digestion

soil contamination clean upnutrient recycling symbiosis normal flora

Energy transformers history of life genetic engineering human health

H-C tails are hydrophobic

Charged phosphate creates a polar ‘head’

6.1 THE PLASMA MEMBRANE IS BUILT OF PRIMARILY OF PHOSPHOLIPIDS

In solution, phospholipid molecules arrange with tails away from water (in cytoplasm and in the environment) and towards each other

A barrier to charged ions and polar molecules

Other molecules are interspersed in the bilayer, creating a

mosaic

i.e. channels carriers, porins

membrane stability

relay information in/out of cell

facilitate rxns

6.2 Membrane protein types/functions

Also: markers on cell surface

membrane stability

move molecules across