L7 BACTERIA & ARCHAEA

What are the two types of prokaryotic microorganisms?

Bacteria and Archaea

Nucleoid

Stores genetic instructions (DNA)

Pilus

Attaches to surfaces and transfers DNA to other cells

Ribosomes

Protein production

Flagellum

Rotating filament that pushes the cell forward

Plasmid

Small circular DNA that stores antibiotic resistance genes

Cytoplasm

Support cell materials / chemical reactions

Cell Wall

Provides support, shapes the cell, prevents damage to the cell

Capsule

Slime coating that provides extra protection

What structures are found in all bacteria?

Cytoplasm, ribosomes, cell membrane, and nucleoid

What shape are cocci bacteria and what is one advantage?

Spherical (resist drying)

What shape are bacilli bacteria and what is one advantage?

Rod-like, allows for increased surface area for absorption

What shape are sprilla bacteria and what is one advantage?

Spiral, move easily in fluids

What does “diplo-” mean in bacterial arrangement?

Pairs

What does “staphylo-” mean in bacterial arrangement?

Cluster

What is the arrangement / shape of diplococci?

Two round structures

What is the arrangement / shape of staphylococci?

Cluster of round structures

What does Gram-positive mean?

Thick peptidoglycan layer; stains purple

What does Gram-negative mean?

Thin peptidoglycan layer + outer membrane; stains pink

What is an autotroph?

Bacteria that can make their own food

What is a photoautotroph?

Bacteria that uses light energy to produce food from carbon dioxide

What is a chemoautotroph?

Bacteria that uses energy from chemical energy of inorganic compounds to produce food from CO₂.

What is a heterotroph?

Bacteria that takes in food made by other organisms

What are decomposers (saprotrophs)?

Bacteria that feed upon decaying organic matter

What are symbiotic bacteria?

Bacteria that absorbs nutrients from their hosts, while also benefitting the host

What is plasmid?

Small loop of DNA that carries info to help bacteria survive stressful environment

What is binary fission?

Asexual reproduction where one cell divides to form two identical cells

What is conjugation?

Sexual Reproduction - A form of genetic transfer (not reproduction) where one bacterium transfers plasmid DNA to another using a pilus. The cell with new DNA will reproduce by binary fission

What is an endospore?

A dormant, tough, non-reproductive structure

Why do bacteria form endospores?

As a survival mechanism to protect their DNA during unfavourable environmental conditions such as a lack of nutrients. It allows the bacterium to survive and remain in a dormant state, without metabolizing or reproducing until conditions improve. Once favourable conditions return, the endospore swells and releases a functional bacterial cell.

What are the structural layers of an endospore?

Coat, Outer Membrane, Cortex, Spore Wall, Inner Membrane

How are Archaea different from Bacteria?

Archaea often live in extreme environments, are autotrophic (photosynthetic or chemosynthetic)

What are the five types of extremophiles and their habitats?

• Thermophile: Heat-loving (hot springs)

• Halophile: Salt-loving (salt lakes)

• Methanogen: Anaerobic, produce methane (cow intestines)

• Acidophile: Acid-loving (human stomach)

• Cryophile: Cold-loving (glaciers)

What is an antibiotic, and what does it target?

A chemical used to kill or inhibit bacteria by targeting organelles like the bacterial cell membrane

What is antibiotic resistance?

When bacteria have a mechanism to avoid the harmful effects of antibiotics

Where is the antibiotic resistance gene typically stored?

Plasmid

How do bacteria gain antibiotic resistance genes?

• Mutation – random changes in DNA

• Conjugation – direct gene transfer in plasmid

• Transformation – acquire gene from dead bacteria

• Transduction – transfer via viruses (bacteriophages)

What happens when an antibiotic or antibacterial substance is used?

Good and bad bacteria will die

What happens when antibiotics are overused or misused?

Good bacteria die, resistant bacteria survive, and multiply without competition, and resistance spreads to other people