MICROBIO Lecture 2 - Prokaryotes

What are the two domains used to classify prokaryotic cells? What is the difference?

Bacteria and Archaea

Archaea is more used in environmental conditions and handle extremes

What are the 3 core structure characteristics that define prokaryotes? How do they differ from Eukaryotes?

• Unicellular

• No membrane bound nucleus

• Lack membrane bound organelles

How can one identify a prokaryote for certain types of pathogens?

Monomorphic = 1 shape (most common)

Pleomorphic = mulitple

What is binary fission? What are the steps ?

It is the way Prokaryote cells reproduce into TWO IDENTICAL cells

• Asexual Reproduction —— A form of asexual reproduction where one bacterial cell copies its DNA and divides into two genetically identical cells.

What does “bacillus” describe?

A rod-shaped bacterial shape

What does “spirillum” describe?

A spiral-shaped bacterial shape.

What does vibro describe?

A coma shaped bacterial cell

What does “strepto-” mean in bacterial arrangement?

Chains of cells

Strepto = straight

What does “staphylo-” mean in bacterial arrangement?

Clusters of cells, grape like

Steps to Binary Fission. How fast is this process?

1. DNA Is copied - DNA replication

2. Cell grows - it elongates to opposite sides

3. Septum/separation - separation forms in the middle of the cell

4. Separation is complete by the septum - Daughter cells are formed

Very fast process, bacteria can multiple in a couple of hours

what are the barriers of prokaryotes ?

Plasma membrane

Cell wall

What structure is outside of the plasma membrane?

The cell wall - its is considered extracellular

What is the function of the Plasma membrane ?

It is made up of a phospholipid bilayer = protects the internal structure

• MAIN JOB - selective permeability

• controls what goes in and out of the cell

Membrane Proteins - relocate based on its needs

What can pass through the plasma membrane?

Gases, Water, small noncharged can diffuse through

What is the difference between gram negative and gram positive?

The components of their cell wall

Positive = thicker peptidoglycan

Negative = thiner peptidoglycan + outer membrane

What color does the gram stains turn for positive and negative gram staining?

Positive = purple (peptidoglycan retains the color)

Negative = pink (peptidoglycan doesnt retain the color when alcohol is used)

What is a disadvantage of the thick peptidoglycan cell wall in Gram-positive bacteria?

It is a target for penicillin, which can interfere with cell wall synthesis and kill susceptible bacteria. The more you have, the more it targets + no outer membrane. Penicilin attacks Peptidoglycan.

what is an advantage of the thick peptidoglycan cell wall in Gram positive bacteria?

• Moisture retention

• Protection

• Helps resist osmotic pressure, preventing the cell from bursting

• ACIDS

What does the outer membrane of a Gram NEGATIVE contain?

Lipopolysaccharides + porins

What is harder to kill with chemical agents? Positive or negative?

Negative

What is significant about Mycolic Acid ?

Its cell wall has a mycolic acid layer that is waxy/sticky so nutrients and gases do not pass through easy which means that it takes longer to reach the peptidoglycan. layer.

Multiple drugs to kill pathogens over a couple of months

stain is pink/red

What are two special kinds of bacteria and what is there exception?

Mycoplasma + L form

Mycoplasma = lack a cell wall

L forms = had a wall then lost it (happens with overuse of antibiotics)

How does chemotaxis work with flagella

Chemotaxis: Moving toward good stuff like food, or away from bad stuff like toxins.

How does phototaxis work with flagella

Phototaxis: Moving toward or away from light.

What are fimbriae and what is their main job?

Short, bristle-like protein structures that help bacteria STICK to surfaces and each other to form biofilms

How do pili differ from fimbriae structurally?

Pili are similar, but they tend to be LONGER, more RIGID, and FEWER in number.

What are the three main functions of pili?

1. STICKING to surfaces

2. MOVEMENT

3. GENE TRANSFER through CONJUGATION

What layer helps the cell prevent itself from dehydrating and lose nutrients

Slime layer .

what is located inside the outer membrane of spirochetes that help them move by causing the cell to twist?

Periplasmic flagella (axial filaments)

A sticky, carbohydrate-rich layer surrounding some bacteria that helps them attach to surfaces and provides protection.

glycocalyx

A tightly attached glycocalyx that helps bacteria stick to surfaces and protects them from white blood cells.

Capsule

What is the function of the cytoplasm + composed of ?

• a gel like substance, mostly water, also contains enzymes, salts, nutrients etc.

• FUNCTION: primary site for enzyme reactions, biochemical reactions

What is in the nucleiod region

A single circular chromosome. RNA + Proteins are present as well

What is another internal structure that contains extra chromosomal DNA and is not essential for viability ?

Plasmid.

What is the function of ribosome and what are their components?

RNA + Protein

Function: protein synthesis (making proteins by linking animo acids)

70S**

Antibiotics can specifically affect RNA so if it does then the cell gets destroyed therefore the antibiotic is effective.

Why are endospores so important for bacterial cells?

They can endure harsh environments.

When a bacteria is presented an extreme environment, it enters the sporulation phase where a protective coat is created around the bacteria, then when it is back to normal, it returns to a vegetative cell.

• during this all metabolic activity is put on pause! No division no grow