Species Diversity: Bacteria and Viruses

SBI3U (Secours) - #2 hyperdoc

Prokaryote

unicellular organism without nucleus and membrane-bound organelles

Bacteria are a _______ cell

prokaryotic

Pili

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

Flagellum

type of tail that helps bacteria move

capsule/slime layer (3 functions)

sticky material

• reduces water loss

• resists temperature

• blocks antibiotics and viruses

cell wall

mainly composed of peptidoglycan

chromosome

large chromosomal loop of DNA, necessary for the normal function of the cell

plasmid

small loop of DNA, can carry genes that produce antibody resistance

☆ responsible for mutations

Inclusions

particles of aggregated protein, important for metabolism and viral replication

4 important bacterium groups

1. proteobacteria (ancestors of mitochondria)

2. cyanobacteria (ancestors of chloroplasts)

3. gram-positive bacteria

4. gram-negative bacteria

Gram-Positive Bacteria

• cell walls have thick layer of peptidoglycan which is dyed purple when gram-stained

• more susceptible to antibiotics

• many of them cause diseases

Gram-Negative Bacteria

• cell walls have thin layer of peptidoglycan which is dyed pink when gram-stained

• complex, double plasma layer blocks antibiotics

Bacteria can be classified by their 3 common ______. These are ________, _______, and ______.

shapes, coccus, bacilli, spirilla

Bacteria are also classified by dyeing the cell walls, in a process called ______________.

gram-staining

3 arrangements of cocci bacteria

1. coccus

2. diplococci

3. streptococci

3 arrangements of bacilli bacteria

1. bacillus

2. diplobacilli

3. streptobacilli

what kind of bacteria shape is this?

spirillum

Why have bacteria been successful? (3 reasons)

1. can live with or without oxygen

2. occupy all ecological niches

3. can form endospores

Obligate Aerobes

organisms that need oxygen to survive

Facultative Anaerobes

organisms that can survive either with or without oxygen

Obligatory Anaearobes

organisms that cannot live in the presence of oxygen

Provide 2 examples of ecological niches occupied by bacteria. (multiple answers)

1) producers

2) decomposers

Endospores

• protective structure with a rigid wall

• formed when a bacteria condenses chromosomes and other necessary survival components, wrapping them inside a rigid and resistant wall

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

3 types of bacteria reproduction

1. Binary Fission

2. Conjugation

3. Transformation

Binary fission is _____, around __ mins

quick, 20

Conjugation

• sexual reproduction

• 2 cells share DNA when one cell copies a gene from a plasmid

• transfer is initiated when pili attach

Transformation

• complete strand of DNA is transferred from dead bacteria/the environment to a living bacteria

• physical contact is not required

☆ can now become pathogenic

Pathogenic

disease-causing

Antibiotics

chemical compounds produced by certain strains of bacteria or fungi that kill bacteria

Antibiotics were discovered by ________ ________ by accident

Alexander Fleming

The first discovered antibiotic was _______ , which is a toxin from Penicilliun _____

penicillin, mould

Advantages of bacteria (5 points)

• decomposers and producers, important in nitrogen and carbon cycles

• develop mutualistic relationships (ex: produce vitamins in digestive system)

• food (ex: yogurt, pickles)

• Chemical manufacturing

• Production of antibiotics

Viruses belong to which kingdom?

NONE

Why are virsues non-living?

they need a host to reproduce, and they don’t have distinctive organelles

Bacteriophages

viruses that infect bacteria through a process called transduction

All viruses work by forcing the _____ _____ to make copies of themselves, resulting in an ______ because the host cell cannot make the ______ needed to carry out _____ functions.

host cell, infection, materials, normal

Pandemic vs Epidemic

Pandemic = global infection

Epidemic = local infection

Animal viruses are classified into two types:

DNA viruses and RNA viruses

DNA vs RNA

DNA = double stranded

RNA = single stranded

DNA virus examples

chicken pox, hep B, cold sores

RNA virus examples (more serious)

Measles, HIV (AIDS), Rabies

HIV vs AIDS

HIV is the virus, while AIDS is the late stage of the HIV infection

In animal cells, the _____ ______ enters the host

full virus

The 2 ways bacteriophages reproduce

1. Lytic Cycle

2. Lysogenic Cycle

Lytic Cycle

A replication process in viruses where the genetic material uses the host cell's structures to make new viruses

Lysogenic Cycle

A replication process in viruses where viral DNA enters the chromosome of the host cell. The virus can remain latent (provirus) and activate later by ordering the production of new viruses by the host cell.

Provirus

the viral DNA that is part of the host cell’s chromosome

In the _____ cycle, reproduction is fast

lytic

Binding/Attachment

1st stage of the lytic cycle

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

Entrance

2nd stage of the lytic cycle

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

Replication

3rd stage of the lytic cycle

• the host cell makes more proteins and DNA or RNA

Assembly

4th stage of the lytic cycle

• new viral particles are assembled

Lysis

• Final stage of the lytic cycle

• The host cell bursts open and releases new viruses

How is the lysogenic cycle different and similar to the lytic cycle?

• the host is not lysed immediately

• the virus DNA is integrated into the bacteria’s chromosomes (as opposed to digesting the host’s DNA)

• follows the same stages except for the dormancy stage

Lysogenic cycle dormancy stage

1. Formation of the provirus

2. Cell division + replication

3. Return to lytic cycle (replication, assembly, lysis)

Archaea

a group of not well understood prokaryotes

Why are archaea often called extremophiles? Provide 5 examples of extremophiles.

because of their ability to live in extreme environments

• Methanogens (produce methane in hypoxic conditions)

• Halophiles (survive in high concentrations of salt)

• Extreme thermophiles (survive in high temp)

• Psychrophiles (survive in low temp)

• Acidophiles (survive in acidified environment)

Differences between bacteria and archaea

Bacteria	Archaea
cell wall w. peptidoglycan cause disease Ester carbon linkage of lipids mostly-circular chromosomes Glycerol-3-phosphate backbone	no peptidoglycan don’t cause disease Ether carbon linkage of lipids circular chromosomes Glycerol-1-phosphate backbone