Ch 13: Prokaryotes and Viruses

Characteristics of Prokaryotes

Oldest living organism

Small cells

No nucleus

circular chromosome (nucleoid region)

Lack membrane-bound organelles

Cell wall

Distinctive shape

Reproduction

Autotroph or heterotroph

Aerobic or anaerobic

Pathogenic or beneficial

Bactera have _______ in their cells walls (not Archea)

peptidoglycans

Gram + vs Gram - bacteria

Positive = thick cells wall of petidoglycan

Negative = thin cell wall with inner peptidoglycan layer and an outer layer

Shapes of prokaryotes

Cocci (round)

Bacilli (pil-rod shaped)

Spirilla (spiral)

Types of Prokaryotic reproduction

Binary Fission - DNA replicates and divides into 2

Conjugation - (sex) bacteria transfer genetic material via direct contact

benefits of bacteria

Recycle nutrietns

Nitrogen fixation

Decomposers

global carbon balance

Cyano-bacteria internal features

Thylakoid

Chlorophyll a, carotenoids

Filaments, cells join together to form colony

Significant due to their ecological and evolutionary importance

Create O2 and CO2 (only prokaryote that can)

Produce chlorophyll a

Chloroplasts

Types of Cyanobacteira

Oscillatoria

Anabaena

Nostoc

Stromatolites

Oscillatoria

Filamentous (colonies)

Oscillate in movement

Reproduce via fragmentation, breaks into hormogoniums

Anabaena

Fix nitrogen in cells called heterocysts

Produce enlarged specialized cells called akinetes (resistance spores)

Nostoc

Gelatinous ball of filaments

Fix nitrogen in heterocysts

Stromatolites

Layred chalk deposits when colonies of cyanobacteria bind to calcium rich sediments

Archea facts

Primitive

Live in harsh environments (extremophiles)

Describe the 3 main groups of Archea

1) Methanogens - produce methane, strict anaerobic

2) Extreme halophiles - live in high salt concentration

3) Extreme thermophiles - live in hot environments

Viruses facts!

Not Alive

DNA or RNA surrounded by protein coat

Only can reproduce via a host

Virus Life Stages

1) recplicate inside hosts cells

2) spread to new hosts

types of plant virus symptoms

Mosaics - light green-yellow or white areas ranging in spots

Ringspot - dead tissues