Unit 4: Prokaryotes, bacteria, archaea

3 basic shapes of bacteria

1) Coccus: grape look-a-like

2) Bacillus: rods

3) Spirals

- Spirochete: cork screw look-a-like

- Spirilla: has tails

- Vibrio: worm look-a-like

Capsule

- Fairly disorganized sticky slime layer made of short-chain polysaccharides

- Used for adherence to hosts or other substrates

- Used for anti-desiccation

- Used for resistance to host immune system

Endospores

- Desiccated packages of bacterial DNA and ribosomes surrounded by a protein coat

- Can survive for centuries, resistant to heat, radiation, or further desiccation

FImbriae

- Used to fasten bacteria to their substrate

- Substrate: the surface upon which an organism is situated

- "Fingers" in latin

Pilus

Used to fasten themselves to other bacteria

Flagellum

- Whip-like motility device (like taxis)

- Posted outside membrane

Plasmids

- Small rings of additional DNA (only have a few genes on them)

- May code for a specific enzyme or structural protein

- R-plasmid: carries genes for specific antibiotic resistance

- D-plasmid: carry genes that confer ability to degrade toxic organic compounds not commonly found in nature

- F-plasmid: carries genes for making pili

Cell wall

- Not always present, consisting of peptidoglycan (carbohydrate/protein polymer)

- Structure revealed through "Gram staining" (negative, light-thin walls and positive, dark-thick walls)

Cytoplasm

Contains resources for bacterial metabolic function

Plasma membrane

- Made of phospholipids

- Acts as barrier between cell and surroundings and water able to penetrate

Nucleoid region

- Central area where DNA/genetic material is kept

- Bacteria does not have a clearly defined nucleus

Binary fission

- Asexual reproduction

- Extremely rapid reproduction

- rapid mutation rates

Sexual reproduction (recombination)

- Transformation

- Transduction

- Conjugation

Transformation

- Bacterial cells will essentially scavenge and use loose bacterial DNA floating in environment

- "Recombinant" cell formed

Transduction

- Bacterial DNA transferred from one bacterium to another by means of intermediary - the virus, or "bacteriophage"

- Recombinant cell formed

Conjunction

- Involves a "sex pilus" and gene called an "F-factor" (F means fertility)

- Relaxosome: a protein assemblage that unwinds plasmid DNA facilitating its copying and transfer

- Transfersome: a protein assemblage forming a pore connecting the membranes of two conjugating bacterial

Obligate Anaerobes

- Organisms that use fermentation only, or anaerobic respiration

- Use nitrate or sulfate instead of O2

- Oxygen is toxic to their metabolism

Obligate Aerobes

- Organisms that can only use aerobic (oxygen-based) cellular respiration

- Facultative anaerobes: organisms that use aerobic respiration if O2 is present, fermentation if O2 is not present

Chemolithoautotrophy

To obtain high energy electrons for carbon fixation from inorganic compounds in rocks

Nitrogen fixing

Biological process that converts nitrogen gas to ammonia and that to nitrite to nitrate

Heterocyst

Specialized nitrogen fixing bacterial cells that interact with the environment of symbiotic plants

Gram-positive bacteria

- Thick peptidoglycan cell walls that are cross-linked and hard

- Single phospholipid membrane

- Tend to be coccus-shaped, or bacillus-shaped

- Less likely to be pathogenic (but still possible)

Gram-negative bacteria

- Think peptidoglycan cell wall

- Secondary lipopolysaccharide membrane

- Usually bacilli

- More likely to be pathogenic

Who was responsible and are the prolific producers of atmospheric oxygen?

Cyanobacteria

Which are believed have given rise to eukaryotic mitochondria and chloroplasts?

- Proteobacteria to eukaryotic mitochondria

- Cyanobacteria to eukaryotic chloroplasts

Which bacterial group is responsible for most common human STD?

Chlamydia (chlamydiota), causing chlamydia trachomatis

Which is the deadliest bacterium to humans?

- Anthrax (?)

- Mycobacterium tuberculosis (most likely?)

Extremophiles

Often live in "extreme" places

- Extreme thermophiles (heat-loving_

- Extreme alkilophile (alkali-loving)

- Extreme halophiles (saline- loving)

- Extreme psychrophiles (cold-loving)

- Extreme acidophiles (acid-loving)

Methanogens

Archaea that produce methane instead of CO2 as a respiratory byproduct in low oxygen conditions

Haloarchaea

Live in highly salt-saturated environments and often use the pigment bacteriorhodopsin to take photon energy and use it to drive chemical processes without using photosynthesis

Producers

- Cyanobacteria: blue-green algae (oxygen producers)

- Major fixers of carbon -- organic matter

- Organisms that form organic matter by taking energy from abiotic (non-living) sources to make sugar or other organic compounds

Decomposers

- Soil bacteria that break down decaying organic matter

- Retain nutrients, preventing loss of nitrogen, phosphorus, and sulfur

- Lithotrophs or chemoautotrophs, obtain energy from compounds of nitrogen, sulfur, iron, or hydrogen instead of form carbon compounds

Pathogens

Organisms that can cause disease

Mutualists

Organisms that interact with one another such that benefits are obtained by each organism

Substrate

Surface to which an organism is located

Dessication

Complete dehydration

Symbiont

Symbiosis initiating organism that always benefits

Host

Organism the symbiont engages with, may benefit from relationship

4 major differences between archaea and bacteria

- Have plasma membranes made out of branched isoprene-based, ether-bonded phospholipids

- Have single-layered plasma membranes

- Do not have peptidoglycan cell walls. May have cell walls of pseudomurein and other molecules

- Replicate DNA using enzymes that are more simlar to the enzymes that eukaryotes used