Chapter 27

Question 1

First organisms to inhabit earth were

Answer 1

Prokaryotes - 3.5 billion years ago

Question 2

Bacterial cell walls contain

Answer 2

Peptidoglycan - a polymer composed of modified sugars cross linked by short polypeptides

Question 3

Gram positive bacteria

Answer 3

Have simpler walls with a relatively large amount of peptidoglycan

Question 4

Gram negative bacteria

Answer 4

Less peptidoglycan and are structurally more complex with an outer membrane that contains lipopolysaccharides

Question 5

why is gram negative bacteria more resistant to antibiotics

Answer 5

The outer membrane impedes entry of drugs

Question 6

Capsule

Answer 6

A sticky layer of polysaccharide or protein surrounding the cell wall of many prokaryotes
- Allow prokaryotes to adhere to their substrate or to other individuals in a colony

Question 7

Fimbriae

Answer 7

hairlike appendages allowing prokaryotes to stick to their substrate and one another

Question 8

pili

Answer 8

Appendages that pull two cells together prior to DNA transfer from one cell to the other

Question 9

Endospores

Answer 9

Resistant cells help bacteria withstand harsh conditions

Question 10

How are endospores formed

Answer 10

When bacteria lacks an essential nutrient. The original cell produces a copy of its chromosome and surrounds it with a tough multi layered structure forming the endospore.

Question 11

Taxis

Answer 11

About half of all prokaryotes are capable of taxis - a directed movement toward or away from a stimulus

Question 12

Chemotaxis

Answer 12

Change of movement pattern in response to chemicals - move toward nutrients and away from toxic substances

Question 13

3 main parts of the bacterial flagellum

Answer 13

Motor, hook, filament - composed of 42 different kinds of proteins

Question 14

Prokaryotes lack a membrane bounded nucleus, their chromosome is located in

Answer 14

the nucleoid - a region of cytoplasm that is not enclosed by a membrane
- cells may also have much smaller rings of replicating DNA molecules called plasmids

Question 15

Prokaryotes reproduce by

Answer 15

Binary fission

Question 16

Although mutations are a major source of variation in prokaryotic population, additional diversity arises from

Answer 16

Genetic recombination: The combining of DNA from two sources

Question 17

Horizontal gene transfer

Answer 17

Movement of genes when individuals are members of different species

Question 18

Transformation - bacteria

Answer 18

Genotype and possibly phenotype is altered by the uptake of foreign DNA from surroundings

Question 19

Transduction - Bacteria

Answer 19

Phages “bacteriophages” carry prokaryotic genes from one host cell to another