Microbio chpt 3 (second half)

What are aquaporins?

Transmembrane proteins of bacteria that are used for the movement of water

What is facilitated diffusion?

water movement with the use of a transmembrane protein

What does energy transformation help to power?

Active transport, flagellar movement, ATP synthesis

What is active transport?

Any type of movement that requires energy (transport of molecules against their concentration gradient)

What is primary active transport?

Active transport that uses ATP as fuel

What is secondary active transport?

Active transport that uses an ion gradient/proton motive force as fuel

What is group translocation?

Active transport of a molecule where the molecule must be modified on its way to its destination

What do bacteria use group translocation for?

Bringing glucose into the cell, adds a phosphate group

What is the Major Facilitator super family?

The group of proteins that uses proton motive force to transport molecules

What is secretion?

How bacteria transport large macromolecules, secrete proteins in a line and once it is outside of the cell it unfolds so that it can do its function elsewhere

How do bacteria know which proteins to secrete?

Proteins that need to be secreted contain a signal sequence

Where is cell wall located in bacteria?

outside of the cell membrane

What are the characteristics of a prokaryotic cell wall?

Rigid/provide structure, have unique structures, and they are present in most bacteria

Why is knowledge of the structure of the prokaryotic cell wall of clinical significance?

Knowing which cell wall a bacterium has can help determine which antibiotic will be most effective in treating it and it can distinguish our cells from bacteria that antibiotics are supposed to destroy

What are the bacteria cell wall types?

Gram positive, Gram negative, and acid fast

Gram positive cell wall

stain purple, thick layer of peptidoglycan

Gram negative cell wall

stain pink, thin layer of peptidoglycan

Acid fast cell wall

very hydrophobic, full if waxy lipids which makes it hard for antibiotics to target

Where is peptidoglycan found?

In ALL bacteria that have a cell wall

What is the structure of peptidoglycan?

glycan chain composed of N-acetylglucosamine (NAG) and N-acetyl muramic acid (NAM)

How are NAG and NAM connected in peptidoglycan?

Glycosidic B1,4 linkage

How do adjacent polymers of peptidoglycan connect?

NAMs connect through crosslinking using a peptide bond/covalent linkage

What do penicillin binding proteins do?

Catalyze binding of the crosslinks between polymers of peptidoglycan

What does penicillin (antibiotic) do?

Targets penicillin binding proteins so no crosslinks can form leading to weak cell walls and the death of the cell

Can penicillin break crosslinks after they are formed?

No

What is lysozyme?

Part of our immune response (tears and sweat), breaks the B1,4 linkages that join NAG and NAM together causing a weak cell wall and cell death

Characteristics of Gram-positive cell walls

contains 30 layers of peptidoglycan (all layers are crosslinked=3D and rigid, fully permeable) teichoic acids, and lipoteichoic acids (negatively charged acids that anchor peptidoglycan to cell wall)

Gram-negative cell wall characteristics

only 2-3 layers of peptidoglycan and an outer membrane

Outer membrane of Gram-negative cell walls

located outside of the peptidoglycan layer, selectively permeable which makes it hard for antibiotics to penetrate, special phospholipid bilayer

What is special about the phospholipid bilayer of outer membrane of Gram-negative cell walls?

outer leaflet is made of a lipopolysaccharide (endotoxin) which creates an extreme inflammatory response

What do the porin proteins embedded in the outermembrane of Gram-negative cell walls do?

help transport molecules into the cell membrane

Which bacteria lack cell walls?

Mycoplasma and Ureaplasma

What do bacterium that lacks cell walls have instead?

Sterols (lipids) in their cell membranes

Can bacteria make their own sterols?

No they use what is available to them

Characteristics of archea cell walls

more diverse in structure and composition, have no peptidoglycan but some have psuedopeptidoglycan

What is glycocalyx

additional layer outside of the cell wall that some bacteria have

Functions of glycocalyx

help retain water and stick to surfaces

What is a very thick layer of glycocalyx called?

A capsule (helps bacteria spread infection)

What is a thin layer of glycocalyx called?

slime layer

What are flagella (prokaryotes)?

Filamentous protein appendages that are rigid and act as propellors to help the cell move

Do all bacteria have flagella?

No, only motile ones

Filament of flagella

The part that extends from the cell

Hook of flagella

What the filament attaches to

Basal body of flagella

anchors flagella to the cell wall and acts as the motor that spins the flagella

What is a monotrichous arrangement of flagella?

One flagellum on one pole/end of the cell

What is an ampitrichous arrangement of flagella?

One flagellum attached to either pole of the cell

What is the lophotrichous arrangement of flagella?

tufts of flagella on either pole of the cell

What is the peritrichous arrangement of flagella?

multiple flagella that are attached all over the cell

What are pili?

Short attachments on bacteria that help them attach to surfaces and move across solid surfaces (gliding or twitching)

What are sex pili/F pili?

attachments that are only found in bacteria that have a gram-negative cell wall that help them transfer genetic information

What are the internal cytoplasmic structures of prokaryotes?

Chromosomes, plasmids, ribosomes, storage granules, and gas vesicles

Prokaryotic chromosomes

hold bacteria’s genetic information, found in the nucleoid region

What shape is bacteria DNA?

closed, supercoiled, circular, double-stranded

Why is bacteria’s DNA supercoiled?

Because Bacteria’s DNA is huge compared to the rest of the cell

How many copies of DNA do bacteria have in their chromosome?

One, they are haploid

What are plasmids?

carry small circular DNA with nonessential genetic information, so they could be taken out, and the cell would still survive, but some of its genetic info can give bacteria an advantage

Do plasmids replicate with chromosomes?

No they replicate separately

Ribosomes

made of rRNA and proteins, have 2 subunits, thousands per cell, extremely important for protein synthesis

What are ribosomes a target for?

antimicrobial antibiotics that bind to the ribosome and therefore inhibit protein synthesis

Storage granules

Glycogen, B-hydroxybutyrate, and volutin

Gas vesicles

only found in aquatic bacteria (cyanobacteria), allow for buoyancy that allows them to rise and fall in the water column depending on how much sunlight they need

What are prokaryotic endospores?

formed through sporulation, the most biologically resistant form of life that we know of

Sporulation

when conditions become unfavorable bacteria make a spore coat, growth of the cell stops and DNA is replicated, septum forms and divides the cell unevenly, when growth conditions become favorable the first cell ruptures and releases the endospore

Clinically significant endospore producing bacteria

clostridium botulinum, clostridium tetani, bacillus anthracis, bacillus cereous

Eukaryotic cell membrane structure

made of phospholipid bilayer and proteins for transport, have glycoproteins and sterols

Glycoproteins

receptors for ligands that help with signaling

Sterols

help maintain the stiffness of the cell membrane

What type of sterol do animals use?

Cholesterol

What type of sterol do fungi use?

ergosterol

What type of sterol do plants use?

phytosterols

What type of transport do eukaryotic cell membranes use?

active transport (primary), facilitated diffusion (have aquaporins), endocytosis and exocytosis

Types of endocytosis

Pinocytosis and Phagocytosis

Pinocytosis (cellular drinking)

small molecules get brought in through the cell membrane surrounded by pocket of water

Phagocytosis

internalization of large particles

Exocytosis

Fusion of internal vesicle with cell membrane expelling the contents

Lysosomes

help digest molecules that are being brought into the cell membrane

Eukaryotic cytoskeleton

provides support and highways for transport

Microtubules

can function as highways and are made up of individual proteins (tubulin), make up flagella and cilia

Actin filaments

rapidly disassemble and reassemble which changes the shape of the cytoplasm, used for cytoplasmic streaming and pseudopods

Intermediate fibers

scaffolding to strengthen the cell, made up of proteins and do not change much after they are made

Eukaryotic cilia and flagella

9+2 arrangement of microtubules all around a central pair, flexible and whip like

How do eukaryotic flagella and cilia work?

Dyneins (motor proteins) walk down the microtubules causing them to bend and move

Do eukaryotes have membrane-bound organelles? and if so what are they?

Nucleus, mitochondria, chloroplasts, endoplasmic reticulum, Golgi apparatus, lysosomes and peroxisomes

Nucleus

contains eukaryotic chromosomes, has a double phospholipid bilayer with nuclear pores for transport

Nucleoplasm

larger part of the nucleus, genes for proteins, and small RNAs

Nucleolus

where the ribosomal RNA genes are

Eukaryotic Chromosome

linear and multiple, have histones

Histones

bind to and condense chromosomes

Eukaryotic semi-autonomous organelles

Mitochondria and chloroplast

Mitochondria

site of the CAC and ETC =, smooth outer membrane and a folded inner membrane, have their own chromosome and ribosomes

Chloroplasts

site of photosynthesis for plant cells, have a granum of stacked thylakoid disks, stroma, also has own chromosome and ribosomes

Endosymbiosis

theory that mitochondria and chloroplasts kind of evolved from bacteria invading early eukaryotic cells (which would be why they have their own chromosomes and ribosomes)

Endoplasmic reticulum

made up of smooth ER and rough ER

Rough Endoplasmic Reticulum

site of most protein synthesis, ribosomes are 80s, and transport to golgi apparatus

Smooth endoplasmic reticulum

lipid synthesis and degradation, calcium ion storage, transport to golgi apparatus

Golgi apparatus

protein modification center

Lysosomes

membrane bound organelles that contain digestive enzymes, destruct phagocytized material, and cellular debris

Peroxisomes

contain oxidizing agents, degradation of lipids and toxic chemicals