Bio 102 Bacteria and Archaea

What do all members of Domain Bacteria and Archaea have in common?

Both are prokaryotes and lack a true nucleus

What are believed to be the descendants of the first organisms on Earth?

Prokaryotes (4-3.5 billion years old)

Where do Prokaryotes exits?

Everywhere (ubiquitous)

Cell size of prokaryotes?

1-10um in length (smaller than Eukaryotes)

What is the general structure of the prokaryotic cell?

Cell envelope, cytoplasm, and appendages

What does a prokaryotic cell envelope do?

Encloses the inner cytoplasm and consists of the plasma membrane, cell wall, and glycocalyx.

What is a prokaryotic plasma membrane?

a phospholipid bilayer that regulates the entrance and exit of molecules.

How do some bacteria increase membrane surface area?

fold their plasma membrane inward to create thylakoids

Why do some bacteria fold in their plasma membrane?

increase membrane surface area for processes like photosynthesis

What does the cell wall in prokaryotes do?

provides support, maintains cell shape, and prevents the cell from bursting in hypotonic surroundings.

glycocalyx (or capsule)

is a gel-like polysaccharide layer outside the cell wall that may also include protein.

What does the capsule do?

protects cells from predators or host immune systems, holds colonies together to form biofilms, and aids in communication.

Cytoplasm

A semifluid solution containing water, solutes, and ribosomes (the site of protein synthesis).

nucleoid region

the location of the single large looping bacterial chromosome.

Plasmids

smaller loops of DNA also present in the cytoplasm.

What organelles do Prokaryotes lack?

lack membrane-bound organelles such as an endoplasmic reticulum or Golgi apparatus.

Fimbriae

hairlike bristles that allow cells to adhere to surfaces.

A conjugation pilus

an elongated, hollow appendage used to transfer DNA to other cells

Flagella

rotating filaments that propel the cell.

How do prokaryotes reproduce?

asexually through binary fission

Binary fission

the cell enlarges, doubles its DNA, and divides so each new cell receives a copy in as fast as 12 minutes.

What three methods does genetic recombination occur through?

conjugation, transformation, and transduction

conjugation

swapping DNA plasmids via a pilus

transformation

pulling in found DNA

transduction

DNA inserted by a virus or other instrument

Obligate aerobes

prokaryotes that are unable to grow in the absence of free oxygen.

Obligate anaerobes

unable to grow in the presence of free oxygen.

Facultative anaerobes

able to grow in either the presence or absence of free oxygen.

Photoautotrophs

use light energy to convert inorganic $\text{CO}_2$ into organic molecules through processes like photosynthesis.

What are chemoautotrophs?

Organisms that use energy from inorganic compounds to convert inorganic CO2 into organic molecules.

Where can chemoautotrophs commonly be found?

In deep-sea environments, such as living on volcanic vents.

Chemoheterotrophs

break down organic materials for carbon and energy, such as saprotrophs that decompose dead organic matter.

What is mutualism?

A symbiotic relationship where both organisms benefit.

Give an example of mutualism.

Bacteria living in root nodules fixing nitrogen from the air for plants.

What is commensalism?

A relationship where one organism benefits while the other is neither helped nor harmed.

Can you give an example of commensalism?

Obligate anaerobes living in animal intestines due to low-oxygen conditions.

What is parasitism?

A relationship where one organism benefits at the expense of another.

What are disease-causing parasites referred to as?

Pathogens.

What organism causes Rocky Mountain spotted fever?

Rickettsia rickettsii.

What do pathogens produce?

endospores

What are endospores?

Dormant cells surrounded by a thick protein coat.

What is one characteristic of endospores?

They are capable of surviving for a very long time.

Name a bacterium that produces endospores.

Bacillus anthracis

Name another bacterium that produces endospores.

Clostridium difficile

Name another bacterium that produces endospores.

Clostridium botulinum

Name another bacterium that produces endospores.

Clostridium tetani

What are biofilms?

Cooperative colonies of microorganisms.

What is the glycocalyx layer?

A protective layer that holds biofilm cells together.

What functions do biofilms serve?

They allow cells to communicate, protect against threats, and thrive collectively.

What are the characteristics of Bacteria?

Single-celled organisms, unbranched phospholipids in their membrane, lipids, and cell walls containing peptidoglycan, lack a nuclear envelope and membrane-bound organelles, but possess ribosomes and some introns.

Characteristics of Archaea?

Single-celled organisms possessing varied branched lipids in their membranes and cell walls without peptidoglycan. lack a nuclear envelope and membrane-bound organelles, but contain ribosomes and some introns.

What types of organisms can Eukarya be?

Eukarya can be single-celled or multicellular.

What type of phospholipids do Eukarya feature in their membrane lipids?

Eukarya feature unbranched phospholipids in their membrane lipids.

Do Eukarya always have cell walls?

Eukarya may or may not have cell walls.

What structure do Eukarya possess that separates their genetic material?

Eukarya possess a nuclear envelope.

What type of organelles do Eukarya have?

Eukarya have membrane-bound organelles.

What type of ribosomes do Eukarya possess?

Eukarya possess ribosomes.

What genetic feature do Eukarya have that is not typically found in prokaryotes?

Eukarya have introns.

Why were Archaea separated from bacteria in 1977?

due to distinct ribosomal RNA sequences that make them more stable in extreme environments and energy efficient

Which evidence suggests that Eukaryotes diverged from the Archaean evolutionary line?

Because Eukaryotes share certain modified ribosomal traits with Archaea

Which domain lacks peptidoglycan in its cell walls and features branched tails on their membrane phospholipids?

Archaeans

extreamopiles

Archaeans that prefer harsh conditions most other organisms cannot tolerate, though they are also found in moderate environments

Types of extremopiles?

Halophiles, Thermoacidophiles, Methanogens

Halophiles

archaeal cells that prefer high salt content environments.

What type of environment do thermoacidophiles prefer?

Hot environments exceeding 80 degrees Celsius.

What pH range do thermoacidophiles thrive in?

Highly acidic conditions with a pH of 1 to 2.

Where can thermoacidophiles typically be found?

In environments such as geysers and volcanic vents.

Methanogens

Create methane (CH4) as a metabolic by-product in anaerobic environments like swamps.

Defining feature of the Domain Bacteria?

is the presence of peptidoglycan in their cell walls, which prevents rupture in hypotonic environments.

The Gram stain test

categorizes bacteria based on the amount of peptidoglycan in their cell walls using violet and pink dyes

What type of bacteria have a thick peptidoglycan layer?

Gram-positive bacteria

What stain do Gram-positive bacteria retain?

Dark purple crystal violet stain

What antibiotic are Gram-positive bacteria vulnerable to?

Penicillin

What is a characteristic of Gram-negative bacteria regarding peptidoglycan?

They have less peptidoglycan.

What type of outer envelope do Gram-negative bacteria possess?

They possess a thin outer envelope (second membrane).

What happens to Gram-negative bacteria during the Gram staining process?

They lose the purple stain and retain a pink counterstain.

Are Gram-negative bacteria resistant to penicillin?

Yes, they are resistant to penicillin.

three Bacterial primary cell shapes

Bacilli, cocci, spirilli

What are cyanobacteria?

A subgroup of photoautotrophic Gram-negative bacteria.

Do cyanobacteria have chloroplasts?

No, they lack chloroplasts.

What do cyanobacteria use to capture light for photosynthesis?

Various pigments and internal thylakoid membrane folds.

The original photosynthesizers?

Cyanobacteria

Can form mutualistic relationships with fungi to create lichens?

Cyanobacteria