L11B BACTERIA & ARCHAEA

Question 1

What type of cells are bacteria & archaea?

Answer 1

Prokaryotes.

Question 2

List the defining features of prokaryotes. (6)

Answer 2

1. Most are unicellular and small 0.5-10um
2. They lack a nucleus
3. They have a simple genome and one circular chromosome
4. Most have a cell wall
5. They have a ribosome structure different than eukaryotes
6. They reproduce asexually through binary fission.

Question 3

TRUE OR FALSE: Prokaryotes are only found in moist environments.

Answer 3

FALSE: Prokaryotes are everywhere and are the most abundant organism on earth.

think of bacteria when you think of prokaryote!!

Question 4

What are the two main variations in metabolic diversity of prokaryotes? What are the two sub-types of each?

Answer 4

Sources of energy (CHEMOtroph: energy from chemical bonds or PHOTOtroph: energy from sunlight.)

Sources of carbon (AUTOtroph: inorganic CO2 or HETEROtroph: organic compounds like sugar, fat, carb, AA, protein.)

Question 5

Fill in the blanks.

Answer 5

1. Photoautotroph
2. Photoheterotroph
3. Chemoautotroph
4. Chemoheterotroph

Question 6

Name the two types of -trophs that only prokaryotes use.

Answer 6

Photoheterotrophism and Chemoautotrophism.

Plants and some protists are photoautotrophic (photosynthesis), and all Animals & Fungi and many protists are chemoheterotrophic.

Question 7

Describe the different types of anaerobes found in prokaryotes.

Answer 7

1. Obligate aerobes: need O2 for cellular respiration
2. Obligate anaerobes: poisoned by O2.
3. Facultative anaerobes: can use O2 if present but is not necessary

Question 8

What is binary fission?

Answer 8

Process whereby prokaryotic cells reproduce. The DNA replicates and the cell grows, then it divides and each daughter cell receives identical copy of parental DNA.

Question 9

If bacteria reproduce asexually, how is there so much genetic diversity among them? (4)

Answer 9

4 different ways:
1. Mutation ie. horizontal gene transfer
2. Transduction ie. virus
3. Transformation ie. picking up DNA bits from environment
4. Conjugation ie. genetic material transfer thru sex pilus

Question 10

How do archaea siffer from bacteria? (3)

Answer 10

1. They lack peptidoglycan in their cell walls.
2. Their cell membranes have unique membrane lipids
3. Their DNA & RNA structures differ from bacteria.

Question 11

Name the three groupings within Archaea.

Answer 11

1. Methonogens live under anaerobic environments (ie herbivore gut) where they produce methane.
2. Halophiles live under high salt concentrations (ie great salt lake)
3. Thermoacidophiles live in hot acidic environments (ie hydrothermal vent)

Question 12

What is an extremophile?

Answer 12

Archaebacteria that lives in extreme environments.

Question 13

What is the relation between the circular DNA and the plasmid in prokaryotes?

Answer 13

The DNA in the nucleiod region holds the information necessary for the existence of the bacteria, and plasmids are smaller fragments of DNA that usually don’t carry genes essential for survival.

Question 14

What is transduction?

Answer 14

Transduction is a virus aka phage injecting its DNA into recipient cell’s chromosome.

Question 15

What is conjugation?

Answer 15

Transfer of genetic material (DNA and plasmids) between two bacteria via sex pilus.

Question 16

What is transformation?

Answer 16

Bacteria cell picks up pieces of DNA from surroundings.

Question 17

What is horizontal gene transfer?

Answer 17

The movement of genetic material through mating barriers between two bacteria.

Question 18

What is the use for plasmids?

Answer 18

They carry special genes useful in certain situations. IE plasmid can hold gene for antibiotic resistance, and when exposed those individuals will survive.

Question 19

How do bacteria survive extreme conditions?

Answer 19

By producing endospores: dormant, tough, NON REPRODUCTIVE structures that encloses cells until it can rehydrate in better environment.

Question 20

What is an endospore?

Answer 20

Structure that helps bacteria survive. It is tough and dormant and can survive extreme heat, cold, dryness, frozen environments. Will rehydrate and revive in mor favourable contitions.

Question 21

List economic benefits of bacteria (4).

Answer 21

1. Produces lactic acid that aids in curdling cheese & yogourt.
2. Act as probiotic in human gut microbiome.
3. Produce antibiotics
4. Used in BIOREMEDIATION: bacterial decontamination of a site (toxin breakdown)

Question 22

List ecological benefits of bacteria(4 basic).

Answer 22

1. Their major role is in decomposition
2. Eubacteria are pathogenic (disease causing)
3. Are mutualistic symbionts with many organisms.
4. Cyanobacteria are important producers of useable oxygen.

Question 23

relating to ecological significance

Describe different mutualistic symbionts between bacteria & other organisms. (3!)

Answer 23

1. Herbivores: they eat grass but dont have the enzyme needed to break down cellulose. bacteria break down the cellulose for them in exchange for shelter and food.
2. Humans: gut symbionts produce vitamins, aid in digestion, prevent pathogen invasion.
3. Plants: bacteria fixes unuseable N2 to useable NH3 or NO3 ions

Question 24

relating to ecological significance

What is commensalism?

Answer 24

An ecological relationship in which one species benefits and the other is not harmed or helped in any significant way.
We have commensal bacteria in our pores.

Question 25

Describe the 5 steps of nitrogen fixation.

Answer 25

1. Nitrogen Fixation: bacteria take N2, fix to NH4+
2. Ammonification: fungi decompose organic material to NH4+.
3. Nitrification: bacteria convert the NH4+ produced in steps 1 & 2 to useable NO3+ for plant use.
4. Assimilation: roots absorb useable NO3+ and NH4+.
5. Denitrification: reduction of nitrates resulting in gaseous N2 release.

Question 26

Why are cyanobacteria now considered bacteria instead of algae?

Answer 26

They lack a membrane-bound nucleus and chloroplasts.