Chapter 27

Question 1

Prokaryote features: (5)

Answer 1

• Non-membrane bound organelles
• Nucleoid
• Circular chromosomes
• Unicellular
• Much smaller than eukaryotic cells

Question 2

Gram-Positive:

Answer 2

Simple cell wall structure, thick layer of peptidoglycan = Purple

Question 3

Gram-Negative:

Answer 3

Less peptidoglycan because of more complex cell membrane = Red/Pink

Question 4

Gram-negative is harder to kill because…

Answer 4

… of the extra later of outer membrane and antibiotics target peptidoglycan.

Question 5

Capsules/slime layer:

Answer 5

Outer layer that allows bacteria to adhere to a substrate or to other bacteria

Question 6

Endospores:

Answer 6

Surround copies of chromosomes to protect them in sparse conditions and extreme environments

Question 7

Fimbriae:

Answer 7

Hairlike appendages that allow them to stick to substrate or other indivsuals

Question 8

Pili:

Answer 8

Longer than fimbriae, pulls cells together for exchange of DNA

Question 9

Flagellum:

Answer 9

Structure used by prokaryotes for movement

Question 10

Taxis:

Answer 10

movement towards or away from stimuli such as chemicals, temperatures, light, etc.

Question 11

Internal structure of prokaryotes: (6)

Answer 11

-Simple structure: non-membrane bound organelles
-Smaller genome: less DNA
-1 circular chromosome
- No nucleus, instead the chromosome is in the nucleoid
-May have plasmids: small rings of DNA floating in cytoplasm
- Differences in functions; replication, transcription, and translation compared to eukaryotes.

Question 12

Why do prokaryotes grow so quickly? (3)

Answer 12

• They are small
• They reproduce by binary fission
• They have short generation times (1 hr)

Question 13

3 factors responsible for genetic diversity in prokaryotes:

Answer 13

• Rapid reproduction: leads to mutations
• Mutation: rates are low but they happen faster because of rapid reproduction
• Genetic recombination: combining DNA from 2 sources

Question 14

3 methods of genetic recombination:

Answer 14

• Transformation: incorporation of foreign DNA from another species
• Transduction: viruses carry plasmids from one host cell to another
• Conjugation: DNA is transferred between two prokaryotic cells

Question 15

Conjugation is facilitated by…

Answer 15

…pilus: they attach, shorten, then join the cells together to share plasmid. Called the “mating bridge”.

Question 16

4 types of nutrition modes:

Answer 16

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

Question 17

Photoautotroph:

Answer 17

Light as energy source

Question 18

Chemoautotroph:

Answer 18

Inorganic chemicals as energy source (Thermal vents)

Question 19

Photoheterotroph:

Answer 19

Light as energy source but takes organic compounds through “eating” for carbon source.

Question 20

Chemoheterotroph:

Answer 20

Organic compounds for energy and needs a source of carbon (most bacteria)

Question 21

Extremophile:

Answer 21

Like extreme conditions. Much more likely to be archea than bacteria.

Question 22

Extreme Halophile:

Answer 22

Something that can live in a very salty environment.

Question 23

Extreme Thermophile:

Answer 23

Something that can live in a very hot environment.

Question 24

4 Ecological roles for Prokaryotes:

Answer 24

1. Decomposers break down organic materials
   - Symbiosis is when 2 different species have a close association to each other
2. Parasitism: when prokaryotes invade a host
3. Mutualistic: more than 1000 species of bacteria in the gut
4. Pathogenic: endotoxins causing tuberculosis, Lyme disease, cholera, salmonella etc.

Question 25

Why are bacteria able develop antibiotic resistance so quickly?

Answer 25

Due to horizontal gene transfer and the uptake of genes through recombination.