Microbio midterm

What is a prokaryote?

unicellular organism that lacks a nucleus

what is a eukaryote

single or multicellular organism with a nucleus

What is a chromosome?

coiled chromatin containing essential

what is a plasmid

non essential circular piece of DNA

What is the genome of an organism?

entire genetic material of that organism - including plasmids

how do bacteria store Dna

in nucleotide

what is a nucleoid

A dense region of DNA in a prokaryotic cell with no membrane

how many chromosomes do bacteria have

1 circular chromosome usually

What are the 3 domains of life?

Bacteria, Archaea, Eukarya

What are archaea?

prokaryotes that live in extreme conditions. share some bacterial traits (like single cell) and some eukaryotic traits (like transcription and translation factors)

What are introns? What are exons?

Introns are noncoding regions or mRNA and exons are coding regions of mRNA.

do archaea have introns

no

What is a gram stain?

It is a test to determine if a bacteria is gram positive or gram negative.

What is gram positive bacteria?

bacteria with thick cell walls with large amounts of peptidoglycan PURPLE

What is peptidoglycan?

a network of sugar polymers made of cross-linked NAG and NAM polymers

what is a major component of gram positive cells

Lipotechoic Acid (LTA)

how does the immune system identify gram positive bacteria

through the lipotechoic acid it has

What is gram negative bacteria?

bacteria with thin cell walls and less peptidoglycan. have an outer 2nd membrane. PINK

How are Gram positive and Gram negative bacteria different?

Gram positive cell walls contain a thick peptidoglycan layer with techoic acids. Gram negative cell walls contain a thin peptidoglycan layer (without techoic acids) that is surrounded by a thick plasma membrane.

What is the core polysaccharide of a gram negative bacteria?

KDO

what is Lipid A

an endotoxin

what mechanism could an antibiotic use to kill cell

stop cell wall biosynthesis- leads to unstable and vulnerable bacteria (vancomycin)

what does the 2nd membrane of a gram negative bacteria have

lipopolysaccharide (LPS)

What is LPS?

Lipopolysaccharide is the outer half of the outer membrane and is made of Lipid A, core polysaccharide (KDO) and O antigen.

why is KDO not found in gram positive bacteria

they don't have the 2nd membrane that would house KDO

why don't gram stains work on eukaryotes

no peptidoglycan

What is a bacteriophage?

A virus that infects bacteria

what are bacterial ribosomes

location of protein synthesis. made of rRNA and protein

what size units do bacteria ribosomes have

30s and 50s

what size units do eukaryote ribosomes have

40s and 60s

how does transcription and translation work in bacteria

coupled together and happen in same place

Which ribosomal subunits are particular to the prokaryotic cell?

50S+ 30S = 70S

which ribosomal subunit starts protein synthesis

30s, which later joins the 50s

what is a bacterial capsule

A sticky layer of polysaccharides and proteins surrounding the bacterial cell wall

what does the bacterial capsule do

binds water to prevent dessication, promotes colonization and adherence, promotes biofilm formation, and makes bacteria phagocytosis resistant

what does a bacterial capsule need

resources- sugars

are bacterial capsules always on

no - genes for it may not be expressed when nutrients are high

what are bacterial endospores

a thick-coated resistant structure containing the cell's DNA. can live in various locations

how do bacterial endospores work

puts cells into "hibernation" during hard times. come from inside bacteria

What are the components of an endospore?

exosphere, spore coat, core wall, cortex and DNA

How do endospores stay dry

have dipicolinic acid that binds calcium to promote core dryness

what is in an endospore's cortex

dried peptidoglycan and peptides

how do bacteria move

with flagella to rotate

are flagella genes always expressed

no - turned off when cell is doing good (high nutrients and shit)

how might a bacteria get around innate immune system

turn off or modify flagella expression to make it unrecognizable to immune system

What is peritrichous flagella?

flagella all around bacteria

Can bacteria move without flagella?

Yes! Two examples: via fluid or currents (blood, lymph, ocean currents) and via actin polymerization (bacteria produce "actin" tails)

can bacteria move backwards

no

What are promoters?

regions of DNA that have specific base sequences where RNA polymerase binds

what is an open reading frame

An open reading frame is a region of DNA that is likely to encode a protein, usually the DNA between a start and stop codon

What are operons?

Groups of bacterial genes that share one promoter

do eukaryotes have operons

No, each gene is regulated by its own promoter

what is regulated gene expression

gene is turned on or off as needed

what is constitutive gene expression

a gene is always expressed

what are transcriptional activators

proteins that controls transcription of a set of genes. only binds to dna

What is a sigma factor?

proteins that bind to RNA polymerase and DNA to promote transcription

how does a flagellum get energy

through Na+ pump

What is a genotype?

genetic makeup of an organism: the sequences of DNA in a cell

What is a phenotype?

physical characteristics of an organism: observable traits

ex of a polymeric structure

flagellum - 3 distinct components made of different proteins

what are the 3 components of a flagellum

basal body, hook/rod, filament

What is a basal body?

an organelle that forms the base of a flagellum or cilium. located in cell envelope. motor of flagellum

what is a hook/rod (flagellum)

flexible joint where filament attaches. anchored to cell envelope outside cell

What is the filament of the flagella?

long, thin, helical structure composed of protein flagellin. propeller of flagella. outside cell

what controls flagella expression

cell cycle and nutrient availability

what are early genes

FlhC2/FlhD2 complex. the master operon for flagellum expression

what is the FlhC2/FlhD2 complex

2 dimer proteins that form a tetrameric complex. entry level controller for flagella creation

what is flhCD gene expression controlled by

environment (cell state, temp, nutrients)

how many transcriptional start sites for flhCD gene

6+

what is a middle gene (class 2)

gene that controls structural components of hook and basal body.

what does flhc2d2 do

binds to dna and rna polymerase

what else do middle genes do

make a flagella specific sigma factor (protein that helps rna polymerase bind to specific promoters)

sigma factor

a protein that associates with RNA polymerase that facilitates its binding to specific promoters

what is made by middle genes

basal body and hook

what is made by late genes

filament

what are the middle genes

FlhC2D2 and sigma 70

What is FliA

a flagella specific sigma factor made from middle genes

What does FliA do?

confers specificity for late genes via rna polymerase

what is FlgM

anti-sigma factor. prevents expression of late genes

what would a mutation in any class 2 gene do

prevent flagella expression because it would keep flgm in the cell

how do flgM and FliA differ

Flgm prevents flagellum expression where fliA plays role in making flagella

how are Flia and flgm similar

both made at same time (both middle genes)

how does FlgM leave the cell so the flagella can be made

it is secreted thru the basal body/rod structure once it is completed

when does late gene expression start

when the basal body/rod structure is completed

explain development leading to gene expression

flgm senses that the basal body and hook is made and leaves the cell this allows flia to work and late genes to be expressed making the filament

What is antibiotic resistance?

the ability of a microorganism to withstand the effects of an antibiotic

What are antibiotics?

Drugs that kill or prevent the growth of bacteria without killing healthy body cells

What are colicins and holins?

proteins produced by bacteria that are toxic to other bacteria - like holes in membrane

how do colicins work

bind to target bacteria membrane to form depolarizing ion channels in membrane to inhibit cell wall synthesis

what should a good antibiotic target

bacteria unique features that are essential

what are the classes of antibiotics

methicillins, protein synthesis inhibitors, DNA/RNA effector, peptide

Example: Methicillin

amoxicillin

example of a protein synthesis inhibitor antibiotic

erythromycin

example of a DNA/RNA affecting antibiotic

ciprofloxacin

example of a peptide antibiotic

bacitracin

What are the beta-lactam antibiotics?

Antibiotics that have a beta-lactam ring. stop cell wall creation by inhibiting transpeptide linkage to peptidoglycan

How do beta-lactam antibiotics work?

weaken cell wall to make it easier for body to kill bacteria

What are beta-lactamase inhibitors?

clavulanic acid - compound that increases antibiotic efficiency

What is beta-lactamase?

an enzyme produced by some bacteria that make them resistant to beta lactam antibiotics

How does beta-lactamase work?

Cleaves Beta-lactam ring which prevents the Beta-lactam ring from working against transpeptidase