Prokaryotes & Endosymbiosis

Question 1

Prokaryotes are ubiquitous meaning?

Answer 1

They can be found virtually everywhere.

Question 2

How big are prokaryotes?

Answer 2

Microscopic.

Question 3

What are the two major domains that prokaryotes can be divided into?

Answer 3

Bacteria and Archaea.

Question 4

What are the three most common shapes of bacteria?

Answer 4

Spheres (cocci), Rods (bacilli) and Spirals (spirilli).

Question 5

What is the size range of bacteria?

Answer 5

0.5-5μm (micrometres).

Question 6

What is the purpose of the cell wall in a prokaryote?

Answer 6

Protects cytoplasm, maintains cell shape, protects cell from physical damage and harsh chemicals and prevents it from bursting.

Question 7

What eukaryotes also have a cell wall?

Answer 7

Fungi and Plants.

Question 8

What do bacterial cell walls contain the plants and fungi don’t?

Answer 8

Peptidoglycan: which is a network of sugar polymers cross-linked by peptides.

Question 9

What does the gram stain do?

Answer 9

Differentiates between two major groups of bacteria that differ in their cell wall composition.

Question 10

What do gram-positive bacteria have?

Answer 10

Simpler walls with a thick layer of peptidoglycan.

Question 11

What do gram-negative bacteria have?

Answer 11

Thinner layer of peptidoglycan surrounded by an additional outer membrane.

Question 12

What is the additional outer membrane on gram-negative bacteria composed of?

Answer 12

Lipopolysaccharide.

Question 13

What colours are the two different bacteria represented by on the gram stain?

Answer 13

Gram-positive - blue and Gram-negative - red.

Question 14

What is taxis?

Answer 14

The ability to move towards or move away from a stimulus.

Question 15

What is an example of stimuli?

Answer 15

food sources or toxic chemical repellents.

Question 16

What is the difference in chemotaxis from taxis?

Answer 16

The stimuli is a chemical.

Question 17

How do prokaryotes move?

Answer 17

Some move by gliding and others propel themselves by rotating a flagellum or cluster of flagella.

Question 18

What are bacterial flagellum composed of?

Answer 18

Motor, hook and filament.

Question 19

What is exaptation?

Answer 19

Where existing structures take on new functions through descent with modification.

Question 20

What is an example of exaptation?

Answer 20

Flagella most likely evolved as existing proteins were added to an ancestral type III secretory system.

Question 21

What is an example of a protein with an internal membrane?

Answer 21

Nitobacter which is an aerobic soil bacteria or Nostoc which is a photosynthetic cyanobacteria.

Question 22

What are the granules in a granular cytoplasm composed of mostly?

Answer 22

Ribosomes.

Question 23

How many base pairs are there in a usual prokaryotic genome?

Answer 23

10-12 million.

Question 24

What do most prokaryotic genomes consist of?

Answer 24

A single, circular chromosome.

Question 25

How can antibiotics inhibit the bacteria cell growth in a human without affecting the human’s cell processes?

Answer 25

Due to the differences in DNA replication, transcription and translation between the cell types.

Question 26

How do most bacteria divide?

Answer 26

By forming a septum at the mid-point of the cell.

Question 27

What is binary fission?

Answer 27

The process of a bacteria cell dividing by forming a septum at the mid point of the cell.

Question 28

How many domains of life are there?

Answer 28

3.

Question 29

E-coli has an identical ribosomal subunit sequence as?

Answer 29

Salmonella.

Question 30

On the phylogenetic tree of life, what do longer branches represent?

Answer 30

Greater evolutionary distance.

Question 31

Where do Eukaryotes come from?

Answer 31

Archaea and Bacteria coming together.

Question 32

What is the endosymbiotic theory?

Answer 32

Primitive eukaryotes engulfed aerobic, respiring bacteria which were later co-opted for their current role in cellular respiration.