2007-2008 AP Biology

Prokaryotes

Domain Bacteria

Domain Archaebacteria

DomainBacteria

DomainArchaea

DomainEukarya

Common ancestor

What characteristics make Archaea more like eukaryotes than prokaryotes?

No peptidoglycan in cell wall

More than 1 RNA polymerase

Some introns Met is 1st amino acid in

protein synthesis Ribosomes more like

eukarytoes (Streptomycin does not kill archaea)

DomainBacteria

DomainArchaea

DomainEukarya

Common ancestor

Bacteria live EVERYWHERE! Bacteria live in all ecosystems

on plants & animals in plants & animals in the soil in depths of the oceans in extreme cold in extreme hot in extreme salt on the living on the dead

Microbes alwaysfind a way to

make a living!

Bacterial diversityrods and spheres and spirals

Prokaryote Structure Unicellular

bacilli, cocci, spirilli

Size 1/10 size of eukaryote cell

1 micron (1um)

Internal structure:

prokaryotecell

eukaryote cell

Prokaryote vs. Eukaryote Chromosome

double helix

Prokaryote

Eukaryote

Genetic variation in bacteria Mutations

bacteria can reproduce every 20 minutes binary fission

error rate in copying DNA 1 in every 200 bacteria has a mutation you have billions of E. coli in your gut!

lots of mutation potential!

Genetic recombination bacteria swap genes

small supplemental circles of DNA

direct transfer of DNAconjugation

Metabolic Relation to Oxygen

How are bacteria categorized by the effect that oxygen has on growth?

Obligate aerobes Facultative anaerobes Obligate anaerobes What role do prokaryotes play in

nitrogen cycling? Only way that nitrogen gas can be

incorporated into organic molecules

Variations in Cell Interior

internal membranesfor photosynthesislike a chloroplast(thylakoids)

internal membranesfor photosynthesislike a chloroplast(thylakoids)

internal membranes

for respiration

like a mitochondrion

(cristae)

internal membranes

for respiration

like a mitochondrion

(cristae)

aerobic bacterium

mitochondria

cyanobacterium(photosythetic) bacterium

chloroplast

Origins of Metabolic Diversity Heterotrophs most likely came before

photoautotrophs (parsimony) Glycolysis was probably the first metabolic

pathway Natural selection favored autotrophs as

heterotrophs depleted food supply Cyanobacteria introduce chl a and oxygen

gas.

Cell Wall

What are the functions of the cell wall in prokaryotes?

Maintain cell shape Protection Prevent bursting in hypotonic environment Made of peptidoglycan Why is some food preserved by salting it? Hypertonic environment plasmolyzes

bacterial cells

Prokaryote Cell Wall Structure

peptide sidechains

cell wallpeptidoglycan

plasma membrane

protein

Gram-positive bacteria

Gram-negative bacteria

peptidoglycan

plasmamembrane

outermembrane

outer membrane of lipopolysaccharides

cell wall

peptidoglycan = polysaccharides + amino acid chainslipopolysaccharides = lipids + polysaccharides

That’simportant foryour doctorto know!

Prokaryotic metabolism How do bacteria acquire their energy &

nutrients? photoautotrophs

photosynthetic bacteria chemoautotrophs

oxidize inorganic compounds nitrogen, sulfur, hydrogen…

heterotrophs live on plant & animal matter decomposers & pathogens

Disease Disease –

exotoxins release poisons such as botulism and cholera

Endotoxins seen in outer membrane of gram neg. bacteria (Salmonella)

What are Koch’s postulates and why are they important?

Koch’s postulates used to isolate pathogen causing disease

Bacteria as pathogens Disease-causing microbes

plant diseases wilts, fruit rot, blights

animal diseases tooth decay, ulcers anthrax, botulism plague, leprosy, “flesh-eating” disease STDs: gonorrhea, chlamydia typhoid, cholera TB, pneumonia lyme disease

Bacteria as beneficial (& necessary) Life on Earth is dependent on bacteria

recycling of nutrients from dead to living only organisms that can fix N from

atmosphere needed for synthesis of proteins & nucleic

acids plant root nodules

help in digestion (E. coli) digest cellulose for herbivores

cellulase enzyme

produce vitamins K & B12 for humans

produce foods & medicines from yogurt to insulin

Germinating akinetes

2007-2008 AP Biology

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Got any Questions??Ask da’ Boss!

Are these bacteria Gram + or Gram –?

Gram positive

Gram negative