The Cell

• Cell Overview

• The Plasma Membrane

• Key Organelles

Numbers, Variety, Sizes• 50 – 106 Trillion cells in the body

• ~200 different kinds of cells in bodynerve, blood, muscle, liver, kidney

• Length: 2 microns over 1 meterPlatelets = 2 micronsnerve cells = over 3 feet long

Generalized Cell

Cellular Components

• Plasma Membrane

• Nucleus

• Organelles

• Cytosol: water, ions, nutrients, waste products

• Granules: glycogen, melanin

The Plasma Membrane

The Fluid Mosaic Model

Phospholipid bilayer structural support

Cholesterol fluidity, flexibility

Proteins (many kinds) receptors enzymes transporters ion channels specialized connections

Crossing The Plasma Membrane

Mechanisms:• Passive

NO ATP required

• Active

ATP Required

• Simple Diffusion (High -> Low concentration)

• Osmosis (water mvt)

• Facilitated Transport (transporter protein)

• Active Transport(Low -> High concentration)• Sodium/Potassium pump(Mvt of Larger molecules)• Endocytosis• Exocytosis

Key Organelles

Nucleus

Mitochondria

Ribosomes

Golgi

Endoplasmicreticulum

NucleusDouble plasma membrane with large pores

Nucleolus for ribosome synthesis

Chromatin(DNA-protein)Extended—barely visibleCondensed--visible

Ribosomes

Protein synthesis (translation of mRNA)

free or associated with endoplasmic reticulum

2 subunits made in nucleolus from nucleic acids and proteins

Endoplasmic ReticulumA continuous membrane system:

Nuclear Membrane-Rough ER-Smooth ER

Rough ER (Ribosomes, newly synthesized proteins)

Smooth ER (Lipid synthesis, transport)

MitochondriaPowerhouse of the Cell

Site of Aerobic respiration:O2 used in oxidation of glucose, fats to produce ATP

Vary in # and size within cells

Double membrane

Golgi Apparatus

Packaging & Transport