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Question 1

What is a chemoautotroph + some examples?

Answer 1

• Hydrogen, sulfur, and nitrifying bacteria, some archaea

Chemoautotrophs are able to synthesize their own organic molecules from the fixation of carbon dioxide. These organisms are able to produce their own source of food, or energy. The energy required for this process comes from the oxidation of inorganic molecules such as iron, sulfur or magnesium.

Question 2

What are photoautotrophs + some examples?

Answer 2

Using energy from sunlight, carbon dioxide and water are converted into organic materials to be used in cellular functions such as biosynthesis and respiration.

• Plants, algae and cyanobacteria use H2O as an electron source to reduce CO2, producing O2 as a by-product (oxygenic)
• Green sulfur bacteria and purple sulfur bacteria use H2S a an electron source; they do not produce O2 (anoxygenic)

Question 3

What are photoheterotrophs + some examples?

Answer 3

Photoheterotrophs obtain their energy from sunlight and carbon from organic material and not carbon dioxide

• Green nonsulfur bacteria and some purple nonsulfur bacteria, some archaea

Question 4

What are chemoheterotrophs + some examples?

Answer 4

Chemoheterotrophs are unable to synthesize their own organic molecules. Instead, these organisms must ingest preformed carbon molecules, such as carbohydrates and lipids, synthesized by other organisms. They do, however, still obtain energy from the oxidation of inorganic molecules like the chemoautotrophs.

• Aerobic respiration: most animals, fungi and protozoa, and many bacteria
• Anaerobic respiration: some animals, protozoa, bacteria and archaea
• Fermentation: some bacteria, yeasts and archaea

Question 5

What are the five stages of an infectious disease?

Answer 5

• Incubation period (no signs or symptoms)
• Prodromal period (vague, general symptoms)
• Illness (most severe signs and symptoms)
• Decline (declining signs and symptoms)
• Convalescence (no signs or symptoms)

Question 6

What are the rules of Koch’s postulates?

Answer 6

1. The pathogen must be present in every individual with the disease
2. A sample of the microorganism taken from the diseased host can be grown in pure culture
3. A sample of the pure culture causes the same disease when injected into a healthy host
4. The microorganism can be recovered from the experimentally infected host

Question 7

What is an example of fungi?

Answer 7

Trichophyton spp (causes ringworm)

Question 8

What is an example of Helminths?

Answer 8

Ancylostoma duodenale (hookworm)

Question 9

What is an example of a bacteria?

Answer 9

Bacillus anthracis

• Gram positive
• Endospore fomring
• Rod shaped

Question 10

What is an example of a protozoa?

Answer 10

Plasmodium spp (malaria parasites)

Question 11

What are Cytotoxins?

Answer 11

Strepholysin which is a extracellular enzyme is produced by the bacteria such as staphylococcus pyogenes which causes the complete lysis of red blood cells (Beta hemolysis)

Question 12

What are Neurotoxins?

Answer 12

Botulinum produced by the bacteria such as Clostridium botulinum which causes paralysis

• Very deadly
• Stops neurotransmitters from being released from the axon terminal

Question 13

What are enterotoxins?

Answer 13

Shiga toxin is produced by the bacteria Shigella dysenteriae and causes severe dysentery (infectious diarrhea)
- Spreads through contaminated food and water

Question 14

Mendel’s 1st Law

Answer 14

Segregation

Question 15

Mendel’s 2nd law

Answer 15

Independant alsortment

Question 16

What does single stranded DNA binding protein do?

Answer 16

Function 1: protect the DNA from being degraded by other enzymes.

Function 2: Keep the DNA single stranded (keep them from snapping back together)

Question 17

What does topoisomerase do?

Answer 17

Release of tension generated by unwinding the DNA helix

- Rejoins DNA strands

Question 18

What does DNA polymerase 1 do?

Answer 18

Carries out two activity:
- RNase H is an endonuclease enzyme that recognises DNA:RNA hybrids and degrades the RNA part (RNase activity)

• Synthesises DNA by adding nucleotides (complementary to the parental DNA template of the lagging strand (DNA polymerase activity)

Question 19

What is a Cline?

Answer 19

The gradual geographic change in genetic/ phenotypic composition
- Natural selection acting differently in different geographical areas

Question 20

What happens during Annealing in PCR?

Answer 20

Temperature is decreased to allows primers to base pair to complementary DNA template

Question 21

What happens during Extension in PCR?

Answer 21

Polymerase extends primer to from a new DNA strand

• An exponential increase in DNA molecules
• Adds complementary bases in the 5’ to 3’ direction

Question 22

What is familial down syndrome and what is it caused by?

Answer 22

Translocation of an extra chromosome 21 onto one of the acrocentric chromosomes, usually chromosome 14. Carriers of this translocation phenotypically normal by produce a variety of gametes which can give rise to downs syndrome, normal or more carrier zygotes (as well as zygote lethality)

Question 23

What is the X-ray diffraction pattern of DNA?

Answer 23

• Helical structure
• Bases perpendicular to the length of the DNA molecule
• Double stranded

Question 24

What is the watson crick model of DNA stucture?

Answer 24

DNA has a double stranded helical structure
The sugar phosphate backbone is on the outside The bases are on the inside
Stabilised by hydrogen bonds
The two polynucleotide strands are orientated in opposite directions