Biology - Gr.11 🦁 (UNIT 2: DIVERSITY) - Bacteria

Pili (fimbria)

small hairs that help the bacteria stick to other cells and surfaces, used for conjunction

Flagellum

type of tail that helps the movement of bacteria

Capsule (slime layer)

sticky material that reduces water loss, resists temperature and blocks Ab and viruses

Cell wall

mainly composed of peptidoglycan to create a rigid and protective wall

Plasma (cell membrane)

plasmic membrane forms a barrier b/w the cell and its environment; has selective permeability

Plasmid

small loop of DNA, can carry genes that produce Ab resistance *responsible for mutations

Ribosomes

organelles responsible for protein synthesis

Inclusions

particles of aggregated protein. Important function in the metabolism of bacteria and viral replication

Chromosome

large chromosomal lop of genetic information (DNA) necessary for the normal function of the cell found in the nucleoid region

Label this diagram

A: Pili

B: Flagella

C: Nucleotide (DNA)

D (lower arrow/not labelled): plasmid

E(right): cytoplasm

F(right): ribosomes

G: Cell membrane

H: Cell wall

I: Capsule

What are the THREE layers of Bacteria?

• capsule

• cell wall

• plasma membrane (cell membrane)

What are the THREE common shapes of bacteria?

• coccus

• bacilli

• spirilla

COCCI

→ sphereical (round-shaped) bacteria

• coccus

• diplococci

• streptococci

• staphylococci

BACILLI

→ rod-shaped bacteria – they look like little sticks or straight capsules under a microscope.

• bacillus

• diplobacilli

• streptobacilli

SPIRILLA

→ spiral-shaped bacteria. They look like corkscrews or wavy lines under a microscope.

2. Gram staining techniques

Gram-Positive (+)

• thick protein that stains purple

• more susceptible to antibiotics

• many causes diseases

Gram-Negative (-)

• thin layer of protein which stains pink

• complex layer (blocks antibiotics)

How does the Gram staining technique work?

Purpose: used to tell the difference between two types of bacteria based on their cell wall structure

Why would the cell wall turn purple?

thick peptidoglycan layer holds the purple dye

Why would the cell wall turn pink?

thin wall + outer membrane loses purple, takes up red dye instead (thin layer)

3. Bacteria can live WITH or WITHOUT oxygen with what aerobes?

• Obligate aerobes

• Facultative anaerobes

• Obligate anaerobes

Obligate aerobes

must HAVE OXYGEN available to survive (such as animals & plants)

Facultative anaerobes

CAN live WITH or WITHOUT oxygen

Obligate anaerobes

CANNOT live in the PRESENCE of oxygen

4. What are endospores

→ a rigid wall that can be formed (a protective structure)

• under favorable conditions, bacteria will condense its chromosomes and all the other necessary components (wrapping them inside a rigid and resistant wall)

• other components of the cell will disappear, leaving a small endospore that can withstand extreme environments for long periods of time

5. Reproduction in bacteria

Asexual reproduction by: Binary Fission

Binary Fission

→ where a single parent cell divides into two identical daughter cells

1. Prokarytotic parent cell initiates replication

2. A copy of the cell’s DNA is created

3. Cell elongates and cross wall forms

4. Cross wall forms completely and daughter cells seperate

   *takes only 20 mins

Conjugation

→ A form of sexual reproduction in which 2 cells share genetic information when one cell copies a gene from a plasmid and transfers is intiated when cilili (pili) attach

Transformation

→ a complete strand of DNA is transferred from dead bacteria (or from the environment) to a living bacteria

→ Physical contact is NOT required

→ A newly “transformed” bacteria can now perform the funnctions of a dead bacteria ex. can now become pathogenic (disease-causing)

What are some bacterial diseases?

Diptheria, cholera, tetanus, leprosy, strep throat, tuberculosis, botulis, potato ring rot

Who discovered antibiotics and how?

→ Alexander Fleming by accident in 1928

→ Observing a contaminated petri dish, the Penicillium mould released a toxin that inhibited the growth of bacteria in a petri dish. This was called ‘penicillin’

→ Disadvantage: can kill beneficial bacteria and if used incorrectly, development of ‘antibiotic resistant bacteria’

What is antibiotic resistance?

→ Antibiotics are designed to to kill most bacteria but sometimes, a few bacteria develop a mutation that helps them survive the antibiotic. These surviving bacteria multiply and pass on the resistant and overtime, causing more bacteria to become resistant. This causes the problem of infections becoming harder to treat.

Antibiotics

→ can be used to kill bacteria

→ These are chemical compounds produced by certain strains of bacteria or fungi

Do viruses belong to a kingdom? True or false?

False

Are they alive or not?

→ NON-LIVING!! They need a host to reproduce and they don’t have distinctive organelles

Viruses that infect bacteria are called ____

• bacterrophages

→ This process is called TRANSDUCTION

How do infections occur?

→ All viruses work by forcing the host cell to make hundred or thousands of copies of themselves (as this takes place, host cell is able to perform normal functions and results in an ‘infection’)

When an infection spreads locally, it’s called ____

an epidemic

When an infection spreads globally, it’s called ____

a pandemic

What does some viruses contain?

• nucleic RNA instead of DNA

  → RNA causes most serious diseases

Diseases caused by DNA virus

EXAMPLE: hep B, cold sores, chicken pox, tumours

Diseases caused by RNA virus

EXAMPLE: measles, mumps, polio, HIV (AIDS), colds, rabies

What are two ways phages reproduce?

1. Lytic Cycle

2. Lysogenic Cycle

Lytic cycle

“Fast and destructive”

1. The virus enters a cell, takes over, and makes lots of copies of itself.

2. Then it bursts (lyses) the cell open, releasing new viruses.

3. The cell dies.

• The host cell is completely destroyed by _____

Lysis

Reproduction is fast in ____

the lytic cycle

In animal cells, the ____ enter the host

full virus

Steps in the lytic cycle

• Binding (attachment)

• Entrance

• Replication

• Assembly

• Lysis and Release

1.Binding (attachment)

proteins on the surface of the virus attach to protein receptors on the surface of the host cell membrane

2.Entrance

The virus injects its genetic material (RNA or DNA) into the host cell or the full virus enters

3.Replication

The host cell makes more DNA or RNA and proteins

4.Assembly

New viral particles are assembled

5.Lysis & Release

The host cell bursts and releases new viruses

Lysogenic cycle

“Sneaky and slow”

1. The virus enters a cell but instead of attacking, it hides its DNA inside the cell’s DNA.

2. The cell copies the viral DNA whenever it divides.

3. The virus can stay hidden for a long time.

4. Later, it can switch to the lytic cycle and destroy the cell.

Vaccine

A vaccine is a weakened or inactive version of a virus or bacteria (or just a small piece of it) that’s injected into your body.

How do vaccines work?

1. Your immune system detects the vaccine as a “foreign invader.”

2. It produces antibodies – special proteins that attack the invader.

3. Your body also makes memory cells that remember how to fight that invader in the future.

4. If the real virus enters your body later, your immune system recognizes and destroys it quickly, so you don’t get sick (or not as badly).