MCAT BIO Lecture 3

hundreds can fit into a bacterium, and a bacterium is the size of a mit.

capsid (head) and nucleic acids inside

virus that infects bacteria

capsid, tail, tail fibers (legs)

mature virus outside the host cell

all living organisms can be infected with a virus

contains DNA or RNA

but never BOTH together

a lipid-rich envelope, which contains virus proteins

it cannot infect the host

i.e. there needs to be a chemical receptor for the virus to attach and begin infection

carries the enzyme reverse transcriptase in order to create DNA from RNA

injection of antibodies or injection of a non-pathogenic virus with the same capsid or envelope;

the latter allows the host's immune system to create its own antibodies in response

the type of organism that carries the virus

even if a virus were eliminated in all humans, a virus in an animal could still survive, and be able to reinfect the human population

ducks would be carrier population

both are prokaryotes, but Archaea have similarities to eukaryotes

organisms capable of using CO2 as their only source of carbon

organisms whose source of carbon is organic mlcls,

from eating other organisms

converting CO2 into energy mlcls

but it's energy-expensive, so only autotrophs can use CO2 as their sole source of carbon

organisms that acquire energy from light

organisms that acquire energy from oxidation of organic or inorganic mlcls

an inorganic source other than light (e.g. CO2)

cocci (round),

bacilli (rod)

DNA + RNA + protein complex of bacteria

(aka nuclear region, nuclear body)

single, circular double-stranded mlcl within a nucleoid

helically shaped bacteria, rigid

if flexible, called spirochetes

or any complex, membrane-bound organelles at all

but they do have organelles like ribosomes, nucleoid, mesosomes

sphere of phospholipids with all the tails pointing in

components can move laterally without separating from the membrane

prok. membranes differ only slightly from euks'

intrinsic proteins of the membrane

extrinsic proteins

slows diffusion but doesn't stop it

(depends on the cmpd diffusing)

size, polarity, or charge

on top of that, proteins within the membrane help

leaky channels

how mlcls just pass through, either b/c they are nonpolar or they sneak in through leaky channels (openings)

carrier proteins

refers to facilitated diffusion, which determines what large or charged mlcls can come in

the only thing that can get a mlcl to move AGAINST its electrochemical gradient

requires expenditure of energy - primary or secondary

either by direct expenditure of ATP for energy,

or by use of ATP to create a separate e-c-gradient and then using the energy of that gradient to send a mlcl up

- secondary active transport

the contents of a bacterium's membrane

surrounded by the bacterial envelope

hypertonic

the aqueous soln of their cytosol contains MORE particles THAN the aqueous soln OUTSIDE

disaccharide polymer chains with amino acids

make up the cell wall of a bacterium

long, hollow, rigid cylinders made from the protein flagellin

rotate counterclockwise to propel the bacterium

eukaryotic heterotrophs

spend most of their lives in the haploid state

asexually when conditions are good,

sexually when conditions are bad

live off of dead matter

but fungi don't distinguish between living and dead, so they can be pathogens (cause disease)

called septa

made from chitin

the tangled mass that fungi exist in during their growth state, consisting of branched thread-like structures called **hyphae**

haploid state

budding, aka cell fission

give rise to new mycelia

not always indicative of asexual reproduction

THICK peptidoglycan cell wall

=> purple stain

thin peptidoglycan wall => pink stain

second plasma membrane, very permeable

so they cannot reproduce sexually

asexual reproduction that some bacteria use

circular DNA is replicated

the cell then splits, leaving one circle of DNA in each daughter cell

=> the two daughter cells are genetically identical

requires that one of the bacteria have a plasmid with the gene that codes for the sex pilus

- the hollow protein tube that connects to the other bacterium and allows DNA to pass through

**the passage of DNA is ALWAYS from the cell that extends the pilus**

one strand of bacterial plasmid is always nicked; when replication begins, that strand separates from its complement

- this loose strand is replicated and fed through the pilus
- (semiconservative)

fertility/ F factor

a bacterium WITH the F factor is denoted F+

without, F-

bacteria can incorporate DNA from the external environment into their genome

living bacteria can gain the virulent DNA of heat-killed bacteria

when a virus accidentally incorporates DNA of the host into its capsid, and transfers that harmless DNA into another host

the virus is a vector is this case

highly resistant, asexual spore of gram+ bacteria that can lie dormant for years

typically-one-celled reproductive unit that gives rise to a new individual asexually