Lectures 11-14

Question 1

What are the traits that all prokaryotes share?

Answer 1

1) Cytoplasm
2) Cytoplasmic Membrane
3) Nucleoid

Question 2

What are the traits that most bacteria share?

Answer 2

1) Cell Wall - Most bacteria have a thick cell wall/envelope
2) Flagellum - Found only in motile bacteria

Question 3

What are pilli and what are their function?

Answer 3

Hair-like protein filaments used for attachment and/or the exchange and transfer of genetic material

Question 4

How is the nucleoid formed?

Answer 4

1-2 haploid chromosomes are organized into a series of supercoiled domains by Nucleoid-Associated-Proteins (NAPs)

Question 4

What are stalks and what are their function?

Answer 4

Stalks are extensions of the cell envelope and cytoplasm used to “anchor” bacteria in their environment (attachment organelles)

Question 5

What is the mode of transfer for prokaryotic genomes?

Answer 5

Horizontal Gene Transfer - The transfer of genes between organisms, outside of traditional reproduction

Question 6

What are the mechanisms of genetic diversity and recombination in prokaryotic genomes?

Answer 6

1) Transformation - Cells uptake DNA from the environment (broad)
2) Transduction - SNA transfers through bacteriophages that infect bacteria (specific)
3) Conjugation - Bacteria directly transfer DNA between cells via pilli

Question 7

True or False: Plasmids are extra-chromosomal DNA elements that not only replicate autonomously, but contain additional genetic information

Answer 7

True

Question 8

What is the difference between integral and peripheral proteins?

Answer 8

Integral Proteins - Appear on the inner and outer domain, and provides structural support, channels of nutrients, and intracellular pathways
Peripheral Proteins - Bound to the cytoplasmic membrane and act as receptors, enzymes, or cytoskeletons

Question 9

What are key differences between the membrane of archaea and the membrane of bacteria?

Answer 9

1) Archaea lipid tails are made of long isoprene chains with repetitive methyl sidechains, while bacteria has straight fatty acid chains without branches
2) Archaea have glycerol-ether-lipid bonds while bacteria have glycerol-ester-lipid bonds
3) Archaea are the mirror image (enantiomer) of bacteria

Question 10

What are the functions of the prokaryotic cytoplasmic membrane?

Answer 10

1) A diffusion barrier that separates the internal cell environment from the external environment
2) Serves as a protein anchor due to being the site of many proteins involved in transport, bioenergetics, etc.
3) Provides selective facilitation in and out of the cell
4) Site of proton motive force for energy conservation

Question 11

How do microbes protect the cell/cytoplasmic membrane?

Answer 11

The Cell Envelope

Question 12

What components make up the bacterial cell envelope?

Answer 12

1) Gram-positive bacteria - Thick cell wall
2) Gram-negative bacteria - Thin cell wall
3) Mycobacteria - Complex, multilayered cell wall
4) Peptidoglycan

Question 13

What are the functions of peptidoglycan?

Answer 13

1) Confers the cell shape
2) Withstands turgor pressure

Question 14

Archaeal Cell Walls do not contain peptidoglycan, but a variety of different cell wall types (if they have a cell wall) instead. What are they?

Answer 14

1) Pseudomurein
2) Proteinaceous S-Layer
3) Methanochondroitin