Chapter 27 terms/concepts

Question 1

Prokaryotes lack some parts found in eukaryotic cells, including which item ( or items)

A. Nuclear membrane
B. DNA
C: one or more chromosomes
D: a plasma membrane
E: All of the above

Answer 1

A

Question 2

Peptidoglycan

Answer 2

A polymer composed of modified sugars that are cross-linked by short polypeptides that make up bacterial cell walls

Eukaryotic cell walls are made of cellulose or chitin

Also not found in Archaea cell walls either

Question 3

What are the differences in cell wall composition between gram-postive and gram negative bacteria?

Answer 3

Gram-positive bacteria have relatively simple cell walls composed of a thick layer of peptidoglycan

Gram-negative bacteria, on the other hand, have a more complex cell wall with less peptidoglycan, with two membranes (the outer one contains lipopolysaccharides)

Question 4

What is a capsule?

Answer 4

It is a polysaccharide or protein outer layer of bacteria that is considered a “hard” layer which allows the cell to stick to other substances and serves as a means of protection

“A slime layer” is a non-hard/thick layer of similar orientation

Question 5

Endospores

Answer 5

Resistant cells that bacteria develop to withstand harsh conditions that allow them to remain viable while being metabolically inactive

Question 6

Taxis

Answer 6

About half of all prokaryotes are capable of undergoing taxis, a form of motility exhibited by prokaryotes via flagella or cilia

Question 7

How do the genetics of prokaryotes differ form eukaryotes?

Answer 7

They are simpler in both internal structure and physical arrangement of DNA

Prokaryotes have a singular circular chromosomes

They have a nucleoid instead of a nucleus, not enclosed by membrane

Prokaryotes also have plasmids, which are independently replicating DNA molecules only carrying a few genes

Question 8

How do prokaryotes’ internal structure differ from eukaryotes?

Answer 8

Prokaryotic cells lack complex compartmentalization of membrane-enclosed organelles, cytoskeleton

Question 9

How do prokaryotes reproduce?

Answer 9

Many prokaryotes reproduce by binary fission, reproducing asexually with short generation times

Question 10

If bacterial cells do not sexually reproduce and have low mutation rates, how come they are still genetically diverse?

Answer 10

Since binary fission allows for them to reproduce at faster rates than sexually reproducing species, and thus rare mutations are more impactful given the short generation times they have

Question 11

Genetic recombination

Answer 11

Another way (other than mutations) that prokaryotes can be genetically diverse: the combining of DNA from two sources.

Question 12

Horizontal gene transfer

Answer 12

The movement of genes from one organism to another when the individuals are members of different species

Question 13

Transformation

Answer 13

A type of genetic recombination where a prokaryotic cell’s genotype (and potentially phenotype) are altered due to the uptake of foreign DNA from surroundings

Replacing its allele with a foreign allele that was received (ie virulence or pathogenicity)

Question 14

Transduction

Answer 14

a type of genetic recombination where bacteriophages carry prokaryotic genes from one host cell to another

Question 15

Conjugation

Answer 15

a type of genetic recombination in which prokaryotic cells (usually of the same species) directly transfer DNA one-way between each other via a structure called a pilus

Question 16

F factor/plasmid

Answer 16

The genetic information that allows for a bacterial organism to form a pili structure to undergo conjugation

Cells with F factor are DNA donors, and cells without it are acceptors

Question 17

R plasmids

Answer 17

Genetic information that codes for the destruction / evasion of certain antibiotics, which causes antibiotic resistance in bacterial cells

They also can encode pili and enable DNA transfer between cells

Question 18

Phototrophs

Answer 18

Organisms that obtain energy from light

Question 19

Chemotrophs

Answer 19

Organisms that obtain energy from chemicals

Question 20

Autotrophs

Answer 20

Organisms that only need CO2 or related compounds as a carbon source

Question 21

Heterotrophs

Answer 21

Require at least one organic nutrient to make other organic compounds

Question 22

Photoautotroph

Answer 22

An organism that harnesses light energy to drive the synthesis of organic compounds from CO2

Question 23

Photoheterotroph

Answer 23

An organism that relies on light to create energy, but must obtain carbon through an organic source

Question 24

Chemoheterotroph

Answer 24

Organism that relies on organic molecules for both energy and carbon

Question 25

Chemoautotrophs

Answer 25

Organisms that rely on inorganic molecules for energy but need CO2 to derive a carbon source

Question 26

Heterocyst

Answer 26

A specialized cell that engages in nitrogen fixation in some filamentous bacteria that helps exchange metabolic products during metabolic cooperation

Photosynthesis and nitrogen fixation cannot undergo processes at the same time with one cell, which is why prokaryotes form chains to undergo both processes at the same time

Question 27

How do Archaea differ from both bacteria and eukaryotes?

Answer 27

Archaea do not have nuclear envelopes or membrane-enclosed organelles, have circular chromosomes similar to prokaryotes

Archaea do not have peptidoglycan in their cell walls, have introns in their genes, have several kinds of RNA polymerase, do not respond to antibiotics, have histones assoc. with DNA similar to eukaryotes

Some Archaea can grow at temperatures over 100 C, which is not present in either prokaryotes or eukaryotes

Question 28

Extreme thermophiles

Answer 28

Archaea species that thrive in really hot environments

Question 29

Extreme halophiles

Answer 29

Archaea species that thrive in highly saline environments

Question 30

Methanogens

Answer 30

Archaea that live in swamps and marshes that produce methane - they are strict anaerobes that are poisoned by oxygen

Question 31

Mutualism

Answer 31

A type of symbiosis where both organisms, the host and symbiont gain mutual benefit

Question 32

Commensalism

Answer 32

The symbiont benefits and the host is neither harmed nor benefited

Question 33

Parasitism / pathogens

Answer 33

The symbiont benefits and the host is harmed

Question 34

Exotoxins

Answer 34

Chemicals secreted by pathogenic bacteria - can cause disease even if the producers of the chemical are not present

Question 35

Endotoxins

Answer 35

Chemicals that are secreted by pathogenic bacteria when they die