Lab 3

Question 1

Differences between eukaryotes and prokaryotes

Answer 1

a. Prokaryotes have few organelles, no true nucleus, single circular chromosome
b. Eukaryotes have many organelles, compartmentalized, membrane bound nucleus

Question 2

How do Archaea and Bacteria differ?

Answer 2

Archaea differ from bacteria by their cell wall, plasma membrane lipids, ribosomal proteins and RNA polymerase

Question 3

Halophiles

Answer 3

salt lovers

Question 4

Thermophiles

Answer 4

heat lovers

Question 5

Methanogens

Answer 5

obtain energy by CO2 to oxidze H2 releasing methane as waste

Question 6

Bacteria

Answer 6

a. Prokaryotic
b. Cells are small
c. Motile by flagella
d. Diversity of shapes
i. Cocci – spherical
ii. Bacilli – rod
iii. Spirilla – helical
e. Most unicellular
f. Cell wall contain peptidogylcan
g. Binary fission reproduction
h. Produce endospores
i. Most chemoheterotrophs
j. Some obligate aerobes, anaerobes, or facultative anaerobes
k. Cyanobacteria are photoautotrophs

Question 7

4 Modes of Nutrition

Answer 7

a. Photoautotrophs: light energy + build own organic compound
b. Chemoautotrophs: chemical energy + build own organic compound
i. Unique to prokaryotes
c. Photoheterotrophs: light energy + ready-made organic compound
i. Few marine prokaryotes
d. Chemoheterotrophs: chemical energy + ready-made organic compound
i. Prokaryotes

Question 8

Obligate aerobes

Answer 8

need oxygen to live

Question 9

Obligate anaerobes

Answer 9

cannot survive with presence of oxygen

Question 10

Facultative anaerobes

Answer 10

can use oxygen if its available

Question 11

Gram Positice

Answer 11

Gram positive whose cell walls stain purple because the peptidogylcan is thick in the cell wall. Thick peptidoglycan layer traps the stain crystal violet within the cytoplasm.

Question 12

Gram Negative

Answer 12

Gram Negative whose cell wall stains pink because the peptidogylcan in thin so the dye leaks out. Cell wall sandwiched between the plasma membrane and an outer membrane. Outer membrane contains lipopolysaccharides.

Question 13

Endospores

Answer 13

are thick walled dormant cells which can withstand extreme temperatures, desiccation, and treatment with chemicals. With favourable condition they can germinate and continue growth

Question 14

Zone of Inhibition

Answer 14

Determine zone of inhibition (the area in which none of the bacteria are able to grow due to the effect of the antibiotic diffusing out of the disk into the medium). Large zone means that the antibiotic is effective at a relatively low concentration of antibiotic. With small or no zone means that the bacterium is resistant to the antibiotic.

Question 15

Antibiotic Resistance

Answer 15

Antibiotic resistance occurs because pathogens undergo evolutionary processes. This alters the phenotype and genotype so the antibiotic cannot target it. Once the bacteria can resist the antibiotic it can spread more quickly. Bacteria acquire genes that encode proteins that shield or protect them from the effects of antibiotics. These genes may have arisen by mutation in existing genes or they may have been acquired from other resistant bacteria through the transfer of genetic info between bacteria.

Question 16

Why do Antibiotics no kill human cells?

Answer 16

Ribosomes within eukaryotic cells and prokaryotic cells differ. Prokaryotic have ribosomes that are smaller and differ in protein and RNA content. Antibiotics are effective at killing bacterial cells because they only target ribosomes in prokaryotes rather than eukaryotes. Without ribosomes to produce protein the cell won’t have enzymes and won’t be able to function.

Question 17

Cyanobacteria

Answer 17

Cyanobacteria is an important subgroup. It is widespread and can exist under extremely harsh conditions. They were the first photosynthetic bacteria to evolve which produced oxygen as a by-product of photosynthesis. Following the evolution of oxygen dependent eukaryotes was able to occur because of accumulation of this oxygen in the atmosphere. They can also convert fixed nitrogen by converting atmospheric nitrogen to ammonia.

Question 18

Why can some people eat yogurt but not drink milk?

Answer 18

Most people can’t drink milk but can eat yogurt because the bacteria in the yogurt is digesting the lactose for you.