Microbiology Exam 2

what are the main differences between prokaryotes and eukaryotes?

prokaryotes have: no nuclear membrane, flagella are two proteins, glycocalyx is usually a slime layer or capsule, cell wall is complex and composed of peptidoglycan, no carbs or sterols in plasma membrane, no cytoskeleton, smaller ribosomes, singular and circular chromosome, no sexual recombination besides DNA transfer between cells

types of glycocalyx in bacteria

capsule, slime layer, S layer

capsule

composed of polysaccharides and tightly attached to cell wall. protects against the immune system

slime layer

mainly composed of polysaccharides that are loosely attached to the cell wall. protects cells from dehydration and nutrient loss

s layer

this can be paired with a capsule, and it is composed of proteins. It is tightly attached to the cell wall and it often activates the immune system.

what shape are coccus bacteria?

spherical

what shape are coccobacillus bacteria?

squished oval

what shape are bacillus bacteria?

they are rod shaped

what does strepto mean in terms of bacteria number?

it means that it is a chain of the bacteria type (streptococci)

what is the shape of vibrio bacteria?

comma shaped

what is the shape of spyrillum bacteria?

rigid spiral

what is the shape of spirochete bacteria?

flexible spiral

what color is gram positive bacteria?

purple

what color is gram negative bacteria?

pink

what are the four steps of gram staining?

Crystal violet → application of iodine→ rinse with alcohol→ counterstain with safranin

what is the difference between gram negative and positive peptidoglycan layers?

gram positive peptidoglycan layers are linked with 5 glycine linkages, there are multiple layers stacked on each other. Gram negative uses Diaminopimelic acid to connect each subunit of its cell wall, and it is one layer that is held together stronger.

teichoic acid

a compound that helps the cell wall layers bind in a gram positive bacteria

lipoteichoic acid

helps gram positive cell well bind together while also anchoring it it into the membrane

mycolic acid

causes gram positive bacteria to have a hydrophobic cell wall. this causes them to be slow growing as well as antibiotic resistant.

periplasm

the space between the inner and outer membranes in a gram negative bacteria.

lipopolysaccharide composition

composed of an O polysaccharide, core polysaccharide, and a membrane anchored lipid.

lipopolysaccharide function

It is an endotoxin that the bacteria release when they die. Additionally, it is a used by the cell to identify other bacteria that are compatible for DNA transfer. A downside is that the structure can be recognized by immune cells.

bayer junctions

connect the outer membrane and inner membrane

lipoprotein

hold cell wall to the outer membrane

what is the process for the development of the cell wall in a bacterium?

It is a DYNAMIC process where penicillin-binding proteins (PBPs) form peptide bonds. Concurrently, Autolysins are breaking down bonds to loosen the cell wall and allow for it to expand.

How does penicillin work?

penicillin binds and inhibits PBPs and stops the formation of cross bridges. However, this does not stop autolysins from degrading the cell wall. As a result, the cell shreds itself apart.

lysozyme

breaks the bond between glycan portions of cell wall. This makes the cells extremely susceptible to osmotic stress

what is it called when a lysozyme partially breaks down a bacterial cell wall?

spheroplast

What is it called when lysozymes full break down a cell wall in bacteria?

protoplast

what are some unique differences about archaeal cell walls?

they have charged carbohydrate chains that are stabilized by ions. They also don’t contain peptidoglycan

what is an important adaption bacteria have when it comes to their cell membrane?

the membrane can change its lipid composition very quickly! this helps it survive changing conditions

what is an important feature of archaeal cell membranes?

they are technically a monolayer, they are composed of BRANCHED carbon chains, and they are connected to glycerol via ether linkage

what is primary active transport?

it is facilitated by ATP driven pumps. This transports ions to create an electrochemical gradient.

How does co-transport function?

there are two molecules. one molecule is following a concentration gradient. the other molecule utilizes the protein activation to cross.

what is group transport?

it is an efficient biphasic process. pt. 1 moves a solute against a concentration gradient and pt. 2 modifies the solute as it is transported. EX: glucose is modified into glucose-6-phosphate and can immediately metabolize

what is binding protein transport in gram negative cells?

proteins with high affinity bind to lots of solute solute that come through pores. the binded protein brings the load of solute to a permease complex. It pulls the solute off of the protein and into the cell.

what happens to plasmids if they are no longer used? why?

they are degraded by the cell because they are energetically expensive.

why do most bacteria use DNA rather than RNA for their genetic information?

DNA has a more stable sugar compound.

How does bacterial DNA replication take place?

replication starts at the origin point and ends at the terminus point. In the name of efficiency, bacteria will often start a second replication cycle before the first one is complete.

what are the sizes of bacterial ribosome subunits

small=30S, large=50S, compete ribosome=70S

what are the three forms of bacterial movement?

density changes, gliding, flagella

what are the three potential drivers of bacterial movement?

chemotaxis (move toward certain attractants), phototaxis (move for optimal photosynthetic conditions), magnetotaxis (for bacteria in soil to tell what is up/down)

peritrichous flagellar organization

all over the cell body

monotrichous and polar flagellar attachment

single flagellum on one end

lophotrichous and polar flagellar arrangement

one end contains a lot of flagella

amphitrichous and polar flagellar attachment

single flagellum at both ends of the bacteria

what is an axial filament?

it is a flagella contained in the periplasmic space (gram negative) of spirochetes

what is the function of an axial filament?

they are used for bacterial movement and because they are not on the surface of the cell, they hid from the immune system

basal body

anchored in the membrane(s) of the cell, it is a proton powered motor

hook (flagellar structure)

this is the connector between the basal body and the filament

how expensive is the basal body (in terms of protons)?

it costs about 300,000 protons a minute this is EXTREMELY expensive for the cell

filament (flagellar structure)

contains two proteins and 11 filaments to make up the structure, it is the propulsive force of the flagella

what is running (flagellar movement)?

when all flagella move counter clockwise. this creates a bundle of spinning flagella that propel the cell in one direction

what is tumbling (flagellar movement)?

the flagella move in the clockwise direction and cause the bacteria to be suspended in place

how long do bacterial running/ tumbling cycles last?

running phase usually lasts 1-2 seconds and tumbling phase is about .1-.2 seconds

MCP

methyl-accepting chemotaxis protein is either open to binding chemoattractant or phosphate depending on chemoattractant availability

CheR

attaches methyl groups to MCP. this changes the sensitivity of MCP

CheB

Through kinase reactions, it is phosphorylated. It is used to detach methyl groups from MCP. This increases sensitivity.

CheA

When there is CA attached to MCP, it becomes phosphorylated. As a result, no phosphors are transferred to CheB and CheY. This makes the bacteria tumble and become more sensitive to the CA. When there is no CA attached to MCP, it becomes dephosphorylated. It transfers its phosphors to CheB and CheY. This causes the bacteria to run and decrease sensitivity to the CA.

CheW

phosphorylates CheA with the use of ATP

CheZ

dephosphorylates CheY to help reset the signal

CheY

When phosphorylated, it causes the flagella to spin clockwise. This makes the bacteria tumble. When dephosphorylted, it causes flagella to spine counter-clockwise. This makes the bacteria run.

what is the function of plasma membrane invagination?

they increase the surface area to increase the effective space for photosynthesis.

pili

long hollow protrusions from bacteria that are used to attach to surfaces as well as exchange DNA with neighboring cells

fimbriae

protrusions that are used for attachment to surfaces

how and why do endospores form?

endospores form when gram POSITIVE cells are running out of nutrients. They replicate their DNA, form a membrane, form a second membrane, create a peptidoglycan layer, creates a spore coat, and they are released when the cell dies.

What is the most diverse form of Bacteria? What kinds of bacteria are within the group?

Gram-negative bacteria contain all proteobacteria and some other options

What are some characteristics of α-proteobacteria?

They can grow at low nutrient levels, they often have stalks or filaments, and they are agriculturally important.

What are our examples of α-proteobacteria?

Rickettsias, Caulobacter, Hyphomicrobium, Agrobacterium, Rhizobium

Rickettsia

α-proteobacteria that are obligate intracellular parasites. They struggle to produce their own ATP, so they invade target cells. They can either be spread throughout the cell or they can be grouped in the nucleus of the host.

Caulobacter

α-proteobaceria that differentiate. They begin as a flagellated cells in aquatic environments. When they find a spot with sufficient nutrients, they lose their flagellum and form a stalk structure that allows it to stick to surfaces. After settling, they begin to divide. The new cell pinches off of the top with a fully developed flagellum.

Hyphomicrobium

These are α-proteobacteria that look like fungi and bud while reproducing.

Agrobacterium tumefaciens

this bacteria creates tumors in plant cells with a tumor inducing (TI) plasmid. the signals it sends are activated by quorum sensing. they add DNA to the cell that contain plant hormones. These trigger cell division and the production of opeins. these are a compound that are only digestible by agrobacteria.

Rhizobium

α-proteobacteria that has a large root-nodule inducing (RI) plasmid. Once the nodules form, the bacteria will enter them and undergo a conformation change. The become bactenoids which function similar to an organelle that aids in nitrogen fixation. There is a symbiotic relationship between the plant and bacteria. The plant produces global and the bacteria create heme. This allows the nodule to keep a low oxygen environment. If there is too much oxygen, the enzymes responsible for nitrogen fixation will denature.

β-proteobacteria characteistics

these gram-negative bacteria which use nutrients that diffuse away from areas of anaerobic decomposition of organic matter such as H₂, NH₃, and CH₄.

types of β-proteobacteria

spirillum, sphaerotilus, bordetella, neisseria gonorroeae, and neisseria meningitidis

Spirillum

β-proteobacteria that is NOT a human pathogen

Sphaerotilus natans

β-proteobacteria that secrete glycocalyx in high amounts. This creates a sheath that allows them to filter contaminants. They can be found in sewer water decontamination processes.

Bordetella pertussis

β-proteobacteria responsible for whooping cough

Neisseria gonorrhoeae

β-protobacteria that is the cause of gonorrhea. Because they are in areas of high flow, they have lots of fimbriae to attach to vaginal walls.

Neisseria meningitidis

β-proteobacteria that cause meningitis and have a capsule.

γ-proteobacteria characteristics

these are metabolically diverse bacteria. They are also the largest subgroup of proteobacteria.

What are the groups and constituents of each group that fall under the umbrella of γ-proteobacteria?

There are the psudomonadales which include pseudomonas. There are the legionellales which include legionella pneumophila. There are vibrionales which include vibrio cholerae and vibrio Fischeri. There are enterbacteriales which include escherichia, salmonella, shigella, serrate, yersinia pestis, and proteus. There are pasteurellales which include haemophilus influenzae. There are thiotrichaceae which include thiomargarita magnfica.

pseudomonas

γ-proteobacteria that are overall harmless to humans. They have the ability to grow in burns. The main function of some strands is to break down oil. This type of bacteria is excellent at breaking down large carbon based compounds. In order to do this, they need to be exposed to air (aerobic)

legionella pnuemophilia

γ-proteobacteria that loves to inhabit the lungs. they require a LOT of specific nutrients to grow and thrive.

vibrio cholerae

γ-proteobacteria that is comma shaped and is the cause of cholera

vibrio fischeri

γ-proteobacteria that is utilized by deep-sea fish to generate light. This was useful in discovering the process of quorum sensing.

quorum sensing

the process by which bacteria notice a threshold of bacteria and change their function by sending chemical signals when this number is reached.

Escherichia Coli

γ-proteobacteria that naturally live in the guts of humans. They have a lot of fimbriae in order to hold onto the gut wall.They also have flagella in a peritrichous orientation. Some strains can cause health issues in humans

salmonella typhi

γ-proteobacteria found in birds and reptiles. This can be harmful if ingested by humans

shigella

γ-proteobacteria found I human gut. not dangerous to humans unless they burst. They release an exotoxin that makes the stomach more water soluble. They can also transfer DNA to E. coli and Salmonella

serratia marcescens

γ-proteobacteria that a reddish pigment when on nutrient rich media. they are overall harmless but can cause respiratory problems if inhaled.

yersinia pestis

γ-proteobacteria carried by fleas. this was the cause of the bubonic plague. it produces an exotoxin that is deadly to humans.

proteus mirabilis

γ-proteobacteria that forms concentric rings on plates. they have peritrichous flagella

haemophilus influenzae

γ-proteobacteria that causes pnuemonia

thiomargarita magnifica

γ-proteobacteria that are HUGE. they can be around a cm long. they have membrane bound DNA and they oxidize sulfur.

δ-proteobacteria (delta) features

they are often predators, participate in the sulfur cycle, and some produce spores

bdellovibrio bacteriovorus

δ-proteobacteria that can attach gram-NEGATIVE bacteria. they can reproduce through absorption, but they can also undergo schizogony in the PERIplasmic space

myxococcales

δ-proteobacteria that look similar to fungi. the aggregate like amoebae but they do not turn “slug like”. they form a mound that turns Ito a fruiting body containing myxospores