Microbiology Chapter 3

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1. Cytoplasm
2. Cytoplasmic Membrane
3. Nucleus (Ekuaryote) or Nucleoid (Prokaryote)
4. Ribsomes
5. Cell Wall

Basic Cellular Structures

Ribosomes

Used in protein synthesis and are NOT organelles

Prokaryote and Eukaryote

Two types of cells

Prokaryote

Simpler internal structure and lack membrane-enclosed organelles

Bacteria and Archaea

Examples of Prokaryotes

Eukaryote

Larger, more complex and have membrane-enclosed organelles

Algae, Fungi, Protozoa, Animals

Examples of Eukaryotes

Viruses

Non-cellular, reproduce only inside of a host cell, and lack many characteristics of living things

What virus causes colds?

Rhinoviruses

What virus causes rabies?

Rhabdovirus

In a bacterial cell, the cytoplasm is surrounded by this lipid membrane boundry

Envelope

What contains DNA in the cytoplasm of a Bacterial Cell?

Nucleoid

Cytoplasmic Membrane

"Fluid" selective permeability barrier made of phospholipids and proteins that form a bilayer with a hydrophillic exterior and hydrophobic interior

"Leaflet"

Each layer in the phospholipid bilayer of the cytoplasmic membrane is called a?

Phospholipid

Glycerol with ester links to 2 fatty acids

Hydrophilic

Group that faces the cytoplasm or periplasm
(dissolve in water)

Hydrophobic

Fatty acids lined up inside the membrane
(don't dissolve in water)

Selective Permeability

The result of the attraction of nonpolar fatty acid portions of one phospholipid layer for other layer

Integral Membrane Proteins

These span the cytoplasmic membrane

Peripheral Membrane Proteins

These are bound to the surface of the cytoplasmic membrane

1. Permeability Barrier
2. Structural Support
3. Energy Conservation

Functions of the Cytoplasmic Membrane

Permeability Barrier

Prevents leakage of cytoplasmic metabolites into the environment and transportation of substances (nutrients and waste products) into and out of the cell

Water and small, uncharged particles

What are the only things that can freely diffuse through the membrane due to the hydrophilic outside and hydrophobic inside?

Structural Support

Site of many proteins involved in transport, bioenergetics and chemotaxis

Energy Conservation

Site of generation and use of the protein motive force

Mitochondria

Generates energy by respiration in eukaryotes

Cytoplasmic Membrane

Where does respiration occur in prokaryotes?

Respiration and Photosynthesis

Two forms of energy conservation

Chloroplasts

Photosynthetic eukaryotes carry out photosynthesis here

Cytoplasmic Membrane

Photosynthetic prokaryotes carry out photosynthesis here

Sterols

What do eukaryotes use to reinforce their cytoplasmic membrane?

Cholesterol

What is an example of a sterol?

Hopanoids

What do Bacteria use to reinforce their cytoplasmic membrane?

Terpanoids

What do Archaea use to reinforce their cytoplasmic membrane by increasing the stability at high temperatures and low pH?

Peptidoglycan (murein)

A porous cage-like structure that makes up the bacterial cell wall.

Sacculus

The bacterial cell wall

N-acetylglucosamine (NAG) and N-acytelmuramic acid (NAM)

Two sugars that make up the backbone of peptidoglycan

Crosslinks

Short chains of amino acids that hold the sugars together

Meso-Diaminopimelate (mDAP)

Unusual amino acid found in the crosslinks of Gram negative bacteria

Provides rigidity and shape to the cell and prevents it from exploding due to high pressure inside the cell

Function of Peptidoglycan

Antibiotics

Since peptidoglycan is unique to bacteria, what is it a great target for?

Transpeptidase

What does Penicillin inhibit that is the crosslink for the peptides?

Beta-lactamase

This is produced by many organisms and it cleaves the lactam ring of penicillin, inactivating the penicillin

Archaea

Lack peptidoglycan so their cell walls are made of other polysaccharides such as pseudopeptidoglycan, have a paracrystalline surface layer cell wall, or have S-layers

Gram-Negative Bacteria

Only have a few layers of peptidoglycan--thin

Gram-Positive Bacteria

Have many layers (up to 40) of peptidoglycan

Teichoic Acids

The cell walls of Gram-positive Bacteria are reinforced by these negatively charged acids

L-lysine

The crosslinks within peptidoglycan of Gram-positive bacteria contain this

Lysozyme

Enzyme that destroys peptidoglycan, leading to cell lysis

Lysozyme

What is found in animal secretions and is thought to be major line of defense against infections by bacteria?

Outer lipopolysaccharide (LPS) layer and inner phospholipid layer

What makes up the lipid bilayer of a Gram-Negative bacteria?

Proteins (porins)

These are found within the membrane of a Gram-negative bacteria and are used in transport

Endotoxin--lipid A

Toxic portion of the lipopolysacchardie (LPS) layer of the Gram-negative bacteria. It has a toxic effect on humans and is released when the cell dies

Porins

Transmembrane proteins that allow for permeability through the outer membrane by creating channels that cross the membrane

Non-specific Porins

Water-filled channels through which small substances can pass

Specific Porins

Channels with binding sites for certain molecules that only allow those molecules to pass through

Periplasm

Space between the outer and cytoplasmic membrane of a Gram-negative Bacteria

Hydrolytic enzymes and Nutrient Transporter Binding proteins

Proteins that are contained in the periplasm of a Gram-negative Bacteria

Capsule, S layer, Thick Cell wall, Thin Periplasm, and Cytoplasmic Membrane

The Gram-Positive Envelope from the outside in contains:

Capsule

Part of the Gram-positive and Gram-negative envelopes that is made of a polysaccharide; not all species have it

S Layer

Part of the Gram-positive envelope that is made of proteins

Thick Cell Wall

Part of the Gram-positive envelope that is made of amino acids crosslinks in peptidoglycan. Contains Techoic acids for strength

Capsule, Outer Membrane, Thin Cell Wall, Thick Periplasm, and Cytoplasmic Membrane

The Gram-negative envelope from the outside in contains:

Outer Membrane

Part of the Gram-negative envelope that is made of lipopolysacchardies

Thin Cell Wall

Part of the Gram-negative envelope that is made of amino acid crosslinks in peptidoglycan

Genome

A cell's complete set of genes

Chromosomes

What is DNA arranged to form?

Plasmids

Prokaryotes have a singular circular chromosome and sometimes circular extrachromosomal DNA called

Several Linear

Eukaryotes contain chromosomes.

Nucleus

Membrane-enclosed structure found in eukaryotes that contains the chromosomes

Nucleoid

Mass of DNA found in prokaryotes that is not bound by a membrane

The Bacterial Nucleoid

Single loop of double stranded DNA that is attached to the cell envelope--no membrane separtes DNA from cytoplasm
~4e6 bp in many bacteria.

Supercoiling

The bacterial nucleoid is compacted via

Binary Fission

The growth of most microorganisms occurs by

Septum

A cell elongates slightly as it grows and the cytoplasm pinches in the middle at this location

Crosswall

Where the cell actually divides and adds a new wall at the cell equator

Bidirectionally

This is how DNA replicates, allowing it to begin the next replication before the cell divides

Septation

Occurs at the equator of the cell so that there is an equal division and each daughter cell has the same shape

Divisome

Division apparatus in the cell formed by Fts proteins

Fts Proteins

Required for cell division and chromosome replication

FtsZ Protein

Defines the division protein plane in prokaryotes; polymerizes to form a ring where the cell division will occur

FtsA Protein

ATP-hydrolyzing enzyme; provides energy for assembly of other proteins to the ring

Ftsl Protein

Involved in peptidoglycan synthesis for the new cell wall. Activity is blocked by penicillin

MreB

Helps define cell shape by directionally exerting pressure against CM

Filamentous Sprial Shaped Bands

MreB forms these bands around the inside of the cell under the cytoplasmic membrane

MreB

Coccus shaped bacteria lack this gene and therefore take on the default spherical bacteria shape

Glycan Units

These are inserted into preexisting wall material to synthesize a new cell wall during bacterial growth

Autolysins

Creates openings in existing cell wall to make space for new cell wall glycans to be inserted

Autolysis (Spontaneous Cell Lysis)

May occur if there is an error in inserting new cell wall material

Bactoprenol

Hydrophobic lipid alcohol that binds N-acetylglucosamine, N-acetylmuramic acid, and pentapide peptidoglycan precursors. Helps transport these new glycan unites through CM to become part of the growing cell wall

Transpeptidation

Formation of peptide crosslinks between NAMs and bonds peptidoglycan precursors into expanding peptidoglycan layer. Reaction is inhibited by penicillin and cell lysis occurs

Inclusion Granules

Densley compacted in the cytoplasm

Cell Inclusions

Prokaryotic cells often contain these granules that function as storage material or to orient the cell

Magnetosomes

Intracellular particles of magnetite that allow the organism to respond to a magnetic field

Anaerobic areas like mud or at the bottom of lakes

Where can magnetosomes be found?

1. Glycogen
2. Magnetosomes
3. Polyphsophate
4. Poly-B-hydroxybutyrate
5. Sulfur

What are examples of inclusion granules?

Polyphosphate

Inclusion granule that stores inorganic phosphate in prokaryotic cells

Glycogen and Poly-B-hydroxybutyrate

Inclusion granules that are used as a carbon and energy source

Sulfur

Inclusion granule that is used as an energy source in prokaryotic cells; some gram-negative prokaryotes can store this in its elemental form in globules in the periplasm

Fimbriae

Non-motile extensions that help bacteria attach to surfaces and to other bacteria; NOT for motility, strictly for attachment

Pili

Hollow, non-motile tubes made of protein called pilin that connect some cells. They are longer than fimbriae and shorter than flagella

Conjugation

PIli are used to move DNA from one cell to another by this process

Capsule/Slime Layer/Gycocalyx

Sticky polsaccharide layer surrounding the cell and helps the cell attach to objects

Phagocytosis and Dessication

The capsule protects the cell from:

Flagella

Long, helical protein filaments that is attached at the ends or over the whole cell

Proton Passage

Drives the CW or CCW rotation of the flagella to propel the cell

Rotate

Movement of bacterial flagella

Whip-Like Motion

Movement of eukaryotic flagella

Monotrichous

Single flagellum at one end; when it looks more like a tail

Lophotrichous

Several flagella at one or both sides

Peritrouchous

Several flagella all around the cell

Amphitirichous

One flagella on each end

Basal Body, Hook, and Filament

3 parts that make up the structure of the flagella

Basal Body

Imbedded within the cell envelope

Central Rod

The basal body is made of 2 or 4 protein rings connected by a

C ring

G+ and G-

MS ring

G+ and G-

P ring

G- only

L ring

G-only

C ring

Ring that is located in the cytoplasm and attaches to the inner surface of the cytoplasmic membrane

MS ring

Ring that is located in the cytoplasmic membrane

P ring

Ring that is located in the peptidoglycan layer

L ring

Ring that is located in the LPS layer

Hook

Curved structure made of protein; connects filament to basal body

Filament

Long, rigid, helical structures made of a protein call flagellin

Slime Secretion

Gliding can occur through this way that moves the cell along a solid surface

Chemotaxis

Directed movement of organisms in response to chemical signals

Phototaxis

Directed movement of organisms in response to light

Aerotaxis

Directed movement of organisms in response to oxygen

Osmotaxis

Directed movement of organisms in response to ionic strength

CCW rotation

Attractants cause what kind of rotation?

Flagella bundle together and push the cell forward ("run")

What occurs in CCW rotation?

CW rotation

Repellents cause what kind of rotation?

Flagella fly apart and "Tumble"--change direction

What occurs in CW rotation?

"Random Walk"

What do runs + tumbles cause?

Receptors

What detects attractant concentrations like sugars and amino acids?

Attractant Concentration

What increases and prolongs the run so that the net movement of bacteria is toward the attractants?

Phospholipids and Proteins

What is the cytoplasmic membrane made out of?

Hydrophilic

The outside layer of the cytoplasmic membrane is?

Hydrophobic

The inside layer of the cytoplasmic membrane is?

Transport, bioenergetics, and chemotaxis

The structural support function of the cytoplasmic membrane is the sit of many proteins involved in?

Peptidoglycan (Bacterial Cell Wall)

What consists of sugar chains wrapped in circles around the cell that are linked to each other by short chains of amino acids?

"Sweet"

"Glyco"=?

"Peptide"

Amino Acid=?

Chains

The backbone sugars of peptidoglycan are arranged in?

Between N-acytelmuramic acids

Where are the crosslinks located for peptidoglycan?

Peptidoglycan

What is a great target for antibiotics?

Resistant Straints

Widespread use of antibiotics selects for?

Pseudopeptidoglycan

Lysozome doesn't have an effect this, which is what some Archaea cell walls are made of

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