Chapter 3 Cells as Units of Life

I Cell Theory

“Great unifying concept of biology”

3 Tenants of Cell Theory: 1. All Living Things made

of cells 2. Cells are Basic Unit of life3. New cells come from

pre-existing cells TimeLine:

1660's Robert Hooke observed & named cells Anton van Leeuwenhoek described

microorganisms (unicellular) 1838 Matthias Schleiden

“All Plants made of cells” 1839 Theodor Schwann

“All Animals made of cells” 1840 J. Purkinje

described protoplasm & organelles

II Studying Cells

MICROSCOPES Light Microscopes

Electron Microscopes

Scanning (whole specimen) Transmission (thin sectioned)

X-ray Crystallography Nuclear Magnetic Resonance

(NMR)

Improved visualization with: TISSUE STAINING RADIOACTIVE ISOTOPE LABELING

BASIC CELL REQUIREMENTS: 1. Cell Membrane “Plasma” 2. Cytoplasm 3. Genetic Information

AVERAGE SIZE OF CELLS: range 0.7um to 105 um

III Cell Organization A. Cell Types Prokaryotic vs EukaryoticNucleus

Genetic system

Size

Organelles

Cell division

Reproduction

Mode of Nutrition

B. Eukaryotic Components

1. Cell (Plasma) Membrane “Fluid-Mosaic Model”

2. Nucleus with nuclear envelope, pores & nucleoplasm

Chromatin Histones Nucleoli Ribosomes

3. Cytoplasm

Endoplasmic Reticulum (cisternae) Rough Smooth

Golgi Complex

Mitochondria (cristae)

Cytoskeleton

- microfilaments actin & myosin

- microtubules centrosome, centrioles, aster

- Intermediate Filaments

4. Cilia & Flagella

5. Pseudopodia

6. Specialized Junctions (Fig. 3-15)

Tight Junctions Desmosomes Gap Junction Microvilli

IV Membrane Function

Cell Membrane (Plasma or plasmalemma)

Overall Function:

- regulate materials in/out - partition off cell parts

(compartmentalize) - site of enzymatic reactions

Regulating Movement:

1. Diffusion/Osmosis

2. Mediated Transport

Facilitated Diffusion Active Transport

3. Endocytosis (import in)

Phagocytosis/Potocytosis

Pinocytosis

Receptor-Mediated Endocytosis (clathrin-coated pits)

4. Exocytosis (export out)

V

Fun- growth, reproduction, replacement

A. Mitos Somatic cells”

1. Chrom

Cellular Division

ction:

is “

osomal Structure

Chromosome - sister chromatids

Centromere - kinetochore - kinetochore microtubules

2. Mitotic Phases - 2 Distinct Stages:

A. MITOTIC DIVSION uclea

2. M

“division of n

1. PR

r chromosomes”

OPHASE ETAPHASE

3. ANAPHASE 4. TELOPHASE

B. CYTOKINESIS “division of cytoplasm”

Cleavage Furrow

B. Cell C Inte

G2 phase

Mitosis/Cytokinesis

Apoptosis (programmed cell death)

ycle

(Fig. 3-25) rphase

G1 phase

S phase