chapter 7,8,9

What are the three basic shapes of bacterial cells? 

What are the three basic shapes of bacterial cells? 

1. Coccus (sphere-shaped)

2. Bacillus (rod-shaped)

3. Spiral (spiral-shaped)

Which shape is most resistant to drying and why?

Coccus- has a low S/V ratio

Which shape is most sensitive to drying and why?

Spiral- high S/V ratio

What is the difference between virulence and a virulence factor? 

Virulence- the degree to which a pathogen CAUSES disease

Virulence factor- component of an organism that determines its capacity to cause disease

What is a prokaryotic glycocalyx? 

A sugar layer “coat” surrounding the cell

Made up of polysaccharides, polypeptides or both

Made inside cell

 

What two types of glycocalyx can you find in bacteria? 

capsule

slime layer

function of capsule

 

1. Capsule

   1. Firmly attached to cell wall

   2. Protects cells from phagocytosis.

   3. Attachment to tissue

   4. food source

   5. biofilm attachment

function of slime layer

1. Loosely attached to cell wall

2. Trap nutrients

3. biofilm attachment

What is a eukaryotic glycocalyx?  What is its function?

Made up of carbohydrates covalently bound to the plasma membrane

Function:

1. Strengthen cell

2. Attachment

3. cell to cell recognition

What is a flagellum, and what is its function

Long appendages for propulsion.

3 Basic Parts of Bacterial Flagella

1. Filament

2. Hook

3. Basal body

Movement of bacterial Flagella

Prokaryotic- propellor movement; counter or clockwise

Eukaryotic- Wavelike movement; sperm-like movement

 

Protein comp & arrangement of bacterial flagella

Made up of amino acids that are joined together by a peptide bond

Primary structure-sequence of amino acids (a polypeptide)

Secondary structure-alpha helix and beta pleated sheet (H bonds)

Tertiary structure-#3D structures (Disulfide S-S bonds)

Quaternary structure- two or more peptide chains

difference between composition

Eukarya

-          Enclosed by plasma membrane

-          Internal microtubules 9+2 arrangement

-          Long microtubule made of tubulin protein

 

Prokarya

-          Antigen (Ag) (immune system stimuli)

-          H Ag- Flagella

-          O Ag- LPS

-          K Ag- Capsule

What are the taxonomic divisions based on number and position of flagella?

Monotrichous-single flagellum

Amphitrichous- Flagella tuft @ each pole

Lophotrichouos- Flagella tuft @ 1 pole

Peritrichous- Flagella covering whole surface

What is taxis?  What are two types of taxis?

Bacterial movement

1.     Chemotaxis- chemical stimuli

2.     Phototaxis- Light stimuli

 

What is an axial filament?  How does it differ from flagella? In what type of bacteria do you find axial filaments?

-          Internal Flagella- a drill like structure wrapped around the cilia (drills through tissue to escape immune cells)

-          Flagella causes movement; axial filament only allows for movement

-          Only in spirochete bacteria

Compare and contrast fimbriae and pili (make-up and function).

Similarities

·       Short hair like appendages

·       Used for attachment

·       Gram negative only

·       Composed of pilin protein

·       Shorter-thinner than flagella

Compare and contrast fimbriae and pili (make-up and function).

Differences

Fimbriae

-          Polar position or over whole surface

-          100/cell

-          Function in adherence

-          Biofilm formation

Pili

-          Longer than fimbriae

-          1-2 per cell

-          Twitching motility

-          “Sex function” Transfer DNA (conjugation)

What is the function of the cell wall? 

Resist osmotic pressure, protects membrane and interior from inverse environmental changes, anchorage for flagella, contributes to ability to cause disease for some species, site of action for some antibiotics, and used to differentiate bacteria

What is the cell wall mainly composed of?  Be specific in the parts which make up this main component also.

 

The major component is peptidoglycan, made up of a disaccharide attached to polypeptides to form a lattice around the plasma membrane.

Disaccharides are N-acetylglucosamine (NAG) and N-acetylmuramic (NAM)

Pentapeptides are five amino acids that are attached to NAM that are cross-linked with peptide cross bridge

What is teichoic acid?  What type of bacteria do you find it in?  What is its function

Alcohol and phosphate parts

Found only in Gram + cells

Regulates cations in and out of the cell, regulates autolysins that degrade the cell wall, antigenic specifically for identification, and anchors the cell wall to the plasma membrane

What is lipopolysaccharide?  What type of bacteria do you find it in?  What does this molecules act as in the human body? 

 

A molecule that has both lipid and polysaccharide parts that is found in Gram – cells

In humans, this is capable of producing fever, blood clots, weakness, shock, and even death due to hemorrhagic shock

What is a porin?  What type of bacteria do you find it in?

Channels for small anionic compounds or amino acids that are found only in Gram - cells

What is lysozyme?  What is its function? 

An enzyme that breaks down the NAM-NAG backbone in Gram + cells in order to destroy the cell wall

 

What is penicillin?  What is its function?  Where is its specific site of action (figure)?  What type of bacteria is it more active against and why?

Antibiotic that prevents crosslinking from occurring (synthesis of call wall)

Target the crosslinking between chains of polypeptides that is found in the peptidoglycan

More active against Gram + because it does not allow the forming of new cell walls but for Gram – the outer membrane blocks the penicillin from entering the peptidoglycan

What is the function of the plasma membrane?  What is it composed of to contribute to these functions?  What is the fluid mosaic model?

The function is to separate the environment from self, selectively permeable, ATP production in prokaryotes, and contain carbohydrates for eukaryotes

Made of a phospholipid bilayer and proteins

States that phospholipids and proteins move laterally and freely

Compare and contrast passive and active process transport mechanisms?

Passive transport

• No energy is required and moves with the concentration gradient

• Uses simple diffusion for small molecules and osmosis for water

• May use channel and protein carriers for larger molecules

Active process

• Energy required because of the movement against the concentration gradient

• Uses active transport- 1 protein not changed during or group translocation- multiple proteins and molecule is changed

 

Compare and contrast simple diffusion, osmosis, facilitated diffusion, active transport, and group translocation.

Simple diffusion- movement of small molecules

Osmosis- the movement of water across the membrane down a concentration gradient

Facilitated diffusion- transport of larger molecules like amino acids with a concentration gradient by using a plasma membrane protein

Active transport- a single protein is required, and the molecule is not changed during transport

Group translocation- multiple proteins may be required and molecule is changed during transport. Does not occur in eukaryotic cells

 

Define isotonic, hypotonic, and hypertonic.  Diagram a cell in each solution and the general solute and H2O concentrations and net movement of water.

Isotonic- solution with the same solution concentration as inside of the cell. Water will stay equal, net change=0, and water will go in and out of the cell equally

Hypotonic- Solution with a lower solute concentration than the inside of the cell. Water will go into the cell, cell may grow

Hypertonic- solution with a higher solute concentration than the inside of the cell. Water will leave the cell due to osmosis, cell may shrink

What is the cytoplasm?  What is the main component of the cytoplasm?

Contains proteins, carbohydrates, lipid, inorganic molecules, and low-molecular weight compounds, various organelles

80% water

 

Compare and contrast the genome of the prokaryote and the eukaryote. 

 

Prokaryotes-singular chromosome, circular, no histones (other proteins), found in nucleoid, plasmids

Eukaryotes-multiple chromosomes, linear, histones, found in nucleus, no plasmids (generally)

What is a plasmid?  What is the function of a plasmid?  In what type of cells would you find them?

Small, circular, extra chromosomal DNA that replicates independently of chromosomes

Can be transferred by conjugation and carries gene resistance and metabolism genes

Used as a cloning vector in biotechnology

What is a ribosome?  What is the function of a ribosome?

Site of protein synthesis that is composed of proteins and rRNA

Main target for antibiotics because they are different in eukaryotes and prokaryotes (80s and 70s)

What is an inclusion body and what is its function? 

Reserve deposits that are excess compounds insoluble in water that hold phosphates, sulfur, lipid compounds, etc.

 

What is an endospore?  In what type of cells do you find them? 

 

“resting” cell that is unique to bacteria

Under what conditions are endospores formed by bacteria? 

Cells detect some environmental change and then form endospores

What is the structure of an endospore?

Dehydrated, durable spore coat, contains DNA of a cell, Dipicolinic acid, no metabolic reactions

How can endospores be important in taxonomy? 

Classified based on where the endospore forms (terminal-to one side; central-in the middle; subterminal- in between terminal and central)

 

Provide some information about the Schaeffer-Fulton staining.

 

Drive malachite green into spore with heat

Rinse with water

Counterstain with safranin

Cells are stained reddish pink and endospores are green

What are some characteristics of endospores?

enable bacteria to lie dormant for extended periods, even centuries. When the environment becomes more favorable, the endospore can reactivate itself to the vegetative state.

How is sporulation different between bacteria and fungi? 

Bacteria- gram-negative, rod-shaped, aerobic

Fungi- various sizes, shapes, and other surfaces

What is the structure of an endospore

Dehydrated, durable spore coat, contains DNA of a cell, Dipicolinic acid, no metabolic reactions