4.1Basic Characteristics of Cells and Life Forms

Chapter Outline

4.1Basic Characteristics of Cells and Life Forms

A. All living things are made of cells

B. Two cell types: prokaryotes and eukaryotes

1. Prokaryotes

a. Lack nucleus

b. Lack organelles

c. Mostly single cell forms

2. Eukaryotes

a. Membrane bound nucleus

b. Membrane bound organelles

c. Protists, plants, fungi, and animals

3. Viruses-not living and not cells

C. Cells are basic unit of living things

1. Heredity and Reproduction

a. Sexual Reproduction

b. Asexual Reproduction

i. Mitosis

ii. Binary Fission

2. Growth

3. Metabolism: Chemical and Physical Life Processes

4. Responsiveness

a. Movement

b. Irritability

5. Transport

6. Protection and storage

4.2Prokaryotic Profiles: The Bacteria and Archaea

A. Two major prokaryotic groups

B. Both have cell membrane, cytoplasm, ribosomes and a chromosome

C. Cell Extensions and Surface Structures

1. Flagella-motility

a. Flagellum structure- basal body, hook, filament

b. Flagellar arrangements- based on how many and orientation c. Flagellar responses

i. Chemotaxis

ii. Run-and-Tumble

d. Periplasmic Flagella/axial filaments found on spirochetes

2. Fimbriae and Pili

a. Attachment/Biofilm Formation

b. Sex Pilus: Conjugation

3. Glycocalyx-sugars and proteins

a. Slime Layer or capsule

b. Functions of the Glycocalyx

i. Protection from Phagocytosis

ii. Formation of Biofilms

4.3The Cell Envelope: The Boundary Layer of Bacteria

A. Cell Envelope= cell wall and the cell membrane

B. Structure of Cell Walls

1. Peptidoglycan

C. Gram Positive and Gram Negative Cell Walls

1 The Gram-Positive Cell Wall

a. Thick layer of peptidoglycan

b. Teichoic acids

2. The Gram-Negative Cell Wall

a. Outer Membrane: Lipopolysaccharide

b. Peptidoglycan

3. Nontypical Cell Walls

a. Acid-Fast Stain

b. Mycoplasmas and Other Cell-Wall-Deficient Bacteria

c. L Forms

D. Cell Membrane Structure

1. Fluid Mosaic Model

2. Functions of the Cell Membrane

a. Energy Reactions

b. Nutrient Processing

4.4Bacterial Internal Structure

A. Contents of the Cell Cytoplasm

1. Bacterial Chromosomes and Plasmids: Genetic Information a. Bacterial Chromosome: Circular, double-stranded

b. Nucleoid

c. Plasmids

2. Ribosomes: Sites of Protein Synthesis

3. Inclusions or Granules: Storage Bodies

4. The Bacterial Cytoskeleton

5. Bacterial Endospores: An Extremely Resistant Life Form

a. Endospore Formation and Resistance

b. Medical Significance of Bacterial Spores

4.5Bacterial Shapes, Arrangements, and Sizes

A. Shapes

1. Cocci-spheres

2. Bacilli-rods

3. Helical forms- vibrio, spirilla and spirochetes

B. Arrangements-result from cell division-binary fission

1. Cocci

a. Diplococci

b. Streptococci-chains

c. Staphylococci-clusters

2. Bacilli

a. Pairs

b. Chains

C. Strains or types-variant members of a bacterial species

4.6Classification Systems of the Prokaryotic Domains: Archaea and Bacteria

A. Bacterial Taxonomy Based on Bergey’s Manual

1. Phylogenetic or Evolutionary

2. Diagnostic Scheme for Medical Use

3. Species and Subspecies in Bacteria

4.7 Survey of Prokaryotic Groups with Unusual Characteristics

A. Bacteria with unusual adaptations and life cycles

1. Unusual Forms of Medically Significant Bacteria

a. Rickettsias

b. Chlamydias

2. Free-Living Nonpathogenic Bacteria

a. Photosynthetic Bacteria

b. Cyanobacteria: Blue-Green Bacteria

c. Green and Purple Sulfur Bacteria

d. Gliding, Fruiting Bacteria

B. Archaea: The Other Prokaryotes

1. Extreme environments similar to early earth

2. Ecologically and economically significant