CH13

Question 1

What are the characteristics common to all living organisms?

Answer 1

• Ordered structure
• Transformation of energy
• Growth+development
• Adaptation
• Responsiveness
• Reproduction
• Homeostasis

Question 2

Define

Life cycle

Answer 2

Generation-to-generation sequence of stages in the reproductive history of an organism, from conception to production of its own offspring

Question 3

What are the different groups that populated the Earth and when did they originate?

Answer 3

• Prokaryotes: 3.9 bya
• Protists/eukaryotes: 2.1 bya
• Animals: 700 mya
• Fungi: 500 mya
• Plants: 500 mya
• Viruses: multiple origin times

Question 4

What groups of organisms are the most diverse?

Answer 4

• Animals
• Plants
• Fungi
• Protists

Question 5

How many kingdoms were there originally, what were they and why did some fail?

Answer 5

5: Monera, Protista, Plantae, Fungi, Animalia
Some prokaryotes differ as much from each other as they do from eukaryotes, based on their rRNA sequences

Question 6

Define

Horizontal gene transfer

Answer 6

Process in which genes are transferred form a genome to another through mechanisms such as transposition, viral infection, fusion of organisms (endosymbionts)

Question 7

What is the difference between bacterial cell walls and archaeal cell walls?

Answer 7

Bacterial cell walls contain peptidoglycan: polymer composed of sugars crossed-link by short polypeptides
Archaeal cell walls have no peptidoglycan: they only have polysaccharides and proteins

Question 8

Describe

Gram staining

Answer 8

• Experiment that allows for the classification of bacteria by the composition of their cell wall
• Gram-positive: stains purple, simpler walls with lots of peptidoglycan
• Gram-negative: stains pink, less peptidoglycan, more complex, outer membrane of lipopolysaccharides (carbs and toxic lipids)

Question 9

Define

Fimbriae

Answer 9

Hairlike appendages with which prokaryotes stick to their substrate or to one another

Question 10

Define

Pili

Answer 10

Appendage that pulls two cells together before DNA transfer

Question 11

Define

Endospore

Answer 11

Sleeping cell containing copy of original chromosome, released after lysis. Creation due to unfavorable circumstances

Question 12

Define

Flagella

Answer 12

Structure used by prokaryotes who move under their own power (50% of them). Allows prokaryotes to perform taxis, movement towards or away from a stimulus

Question 13

Where is genetic information stored in prokaryotes?

Answer 13

In the nucleoid, a lighter region of the cytoplasm in which the chromosome is located or in plasmids

Question 14

How do prokaryotes reproduce?

Answer 14

They reproduce by binary fission in favorable environments and can’t do so forever, because of exhaustion of nutrient supply, poisoning by metabolic waste or predation/competition

Question 15

What are the 4 ways in which prokaryotes can obtain energy?

Answer 15

• Phototrophs: energy from light
• Chemotrophs: energy from chemical bonds
  X
• Autotrophs: only need CO2 as carbon source
• Heterotrophs: require at least one organic nutrient

First prokaryotes were chemoautotrophs

Question 15

What are the factors that promote prokaryotic genetic diversity?

Answer 15

• Rapid reproduction and mutation: short generations and low mutation rate in huge populations
• Genetic Recombination: tranformation (uptake of foreign DNA), transduction (phage infections) and conjugation (F+ cells or Hfr cells)

Question 16

Define

Extremophiles

Answer 16

Organisms that love extreme conditions (halophiles with salt, thermophiles with heat). They represent a small part of the Archaea domain

Question 17

Define

Symbiosis

Answer 17

Relationship in which two species live in close contact with each other (host+symbiont). Can be mutualism (good for both), commensalism (neutral) or parasitism (bad for host)

Parasites that cause diseases are called pathogens