Prokaryotic Cells

Question 1

What makes them different from eukaryotic cells?

Answer 1

don’t have nucleus
don’t have membrane-bound organelles
Classified: Bacteria and Archaea

Question 2

Archaea

Answer 2

unicellular
extremophiles - can live in places with high salinity, extreme temps
sort of in between a prok and euk
broad range of energy sources - organic compound, ammonia, metal, hydrogen - some are also photosynthetic

Question 3

Bacteria

Answer 3

some can be beneficial to humans, some can be harmful
there are like 10^30 bacteria on the earth
examples of some harmful ones: MRSA, Chlamydia, Yersinia pestis, Clostridium tetani

Question 4

Shapes/categories of bacteria

Answer 4

cocci, sphere shaped
bacilli, rod-shaped
spirilli, spiral-shaped

Question 5

Anaerobes

Answer 5

bacteria who do do not require oxygen for metabolism

true anaerobes means oxygen toxic to them, aerotolerant means anaerobes but oxygen not toxic

Question 6

Aerobes

Answer 6

bacteria that require oxygen for metabolism

Question 7

Structure of prokaryotes

Answer 7

have cell wall containing peptidoglycan
don’t have mitochondria, but for aerobic ones, the cell wall and cell membrane form the chambers required for ATP sythase/pump
have ribosomes but are made of 30S and 50S subunits
have flagella that are distinct from euk flagella - they rotate and are made up of a filament with flagellin, a basal body, and a hook
lack nucleus and genetic material is in a circular chromosome. also has plasmids which make it more virulent
reproduce via binary fission

Question 8

Gram staining

Answer 8

used to determine identity of bacteria
Gram-positive will stain b/c the cell wall of that type of bacteria has extensive cross-linked peptidoglycan
Gram-negative - thinner wall of peptidoglycan surrounded by lipopolysaccharide
crystal violet will bind with iodine wash and get trapped in the cell wall of bacteria. when you wash away with ethanol or acetone, the crystals stay trapped in gram-positive, but in gram-negative, it washes away the lipopolysaccharide, which allows for the crystals to wash away as well
Safranin is applied to counterstain - gram-negative turn pink, gram-positive turn deep purple

Question 9

Binary Fission

Answer 9

1. replication
2. segregation and growth of new cell wall - the two chromosome pull toward diff sides of cell
3. separation
   bacteria grow exponentially (log phase)

Question 10

Horizontal Gene Transfer

Answer 10

this is how bacteria get genetic diversity

takes place via transformation, transduction and conjugation

Question 11

Transformation

Answer 11

absorb genetic material from environment

Question 12

Transduction

Answer 12

virus-mediated gene transfer

Question 13

Conjugation

Answer 13

basically like bacterial sexual reproduction
transfer of a plasmid through bridge created when a sex pilus (F+) attaches to another bacterium (F-), you then create a new F+ cell - major mechanism to spreading antiobiotic resistance

Question 14

Viruses

Answer 14

have genetic material and a protein coat known as a capsid
some also have an envelop made up of phospholipid and proteins - the ones with an envelope can’t really survive in extracellular environments (ex: HIV)

very small - 20 nm to 400 nm
have single or double stranded DNA or RNA
lytic cycle: machinery hijacked, host cell killed b/c of all the virons produced that cause cell to burst
lysogenic: virus incorporates into host genome and waits - only in bacteriophages.