Topic 6

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What is DNA profiling?
A technique that distinguishes individuals on the basis of slight differences in their DNA.
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What are introns?
A non-coding section of DNA, it does not give rise to an amino acid sequence.
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What are exons?
A coding section of DNA, it does gives rise to an amino acid sequence.
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What are short tandem repeats (STR's)?
A short DNA sequence repeated many times.
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Are STR's classed as introns or exons?
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What is a restriction enzyme?
One of a group of enzymes which is able to cut a DNA molecule at particular points along its length.
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What process makes copies of DNA?
Polymerase chain reaction (PCR)
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What is a DNA primer?
A small piece of single-stranded DNA. It acts a signal, binding to and marking the piece of DNA which is to be copied in the polymerase chain reaction (PCR).
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What is DNA polymerase?
An enzyme that catalyses the joining together of individual nucleotides to form a molecule of DNA.
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What is added to a DNA sample at the start of the polymerase chain reaction (PCR)?
1. DNA Polymerase 2. DNA primers with a fluorescent marker 3. Nucleotides
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At what temperature in PCR does the DNA strand seperate?
95 degrees.
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What bond is broken between the DNA?
Hydrogen bonds.
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At what temperature does the DNA primers attach to the STR's?
55 degrees.
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At what temperature does DNA polymerase attach to the stands of DNA?
70 degrees.
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What process separates the DNA fragments produced by PCR?
Gel electrophoresis.
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1. What is added to the double stranded DNA in the first stage of gel electrophoresis?
A buffer solution.
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2. Where are the double stranded fragments of DNA placed?
The wells of an agarose gel in a tank.
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3. What charge does DNA have?
Negative charge.
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3. What electrode is the DNA drawn to?
The positive electrode.
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4. What is the DNA transferred onto?
A nitrocellulose membrane.
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4. How many strands of DNA are transferred onto the nitrocellulose membrane?
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5. What is placed into a bag with the nitrocellulose membrane?
DNA probes.
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5. What is the function of the DNA probes?
They bind to fragments with a complementary surface.
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6. What ways can you view the DNA fragments?
1. The DNA probes are fluorescent and can be seen under a UV light. 2. The DNA probes are radioactive and can be seen under X-ray film.
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What factors effect post-mortem cooling of the body?
1. Body size 2. Body position 3. Clothing 4. Air movement 5. Humidity 6. Temperature of surroundings.
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What is it called when your muscles stiffen after death?
Rigor mortis.
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1. First stage of rigor mortis?
Muscles starved of O2, O2 dependent reactions stop.
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2. Second stage of rigor mortis?
Respiration ---> anaerobic = lactic acid
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3. Third stage of rigor mortis?
PH falls = inhibiting enzymes ---> anaerobic respiration
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4. Fourth stage of rigor mortis?
ATP for muscle contraction gone --->bonds between muscle proteins become fixed.
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5. Fifth stage of rigor mortis?
Proteins can no longer slide ---> fixes muscles and joints.
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What is autolysis?
When the bodies enzymes break down it's own cells.
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What causes a green discolouration after death?
Sulphur haemoglobin.
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What effects does bacteria have on the body after death?
It causes the body to smell and become bloated.
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What conditions speed up the decaying process and which don't? 1. Well heated room. 2. Injuries to the body. 3. Intense heat.
Speed up = A ---> Increase enzyme activity. B ---> Allows entry of bacteria. Decrease = C ---> Destroys bacteria + denatures enzymes.
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How do insects on a dead body help forensic scientists?
They can be taken back to the lab to be grown to find the time of death. The insects could be specific to a certain area, helping find the place of death.
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How does succession on corpses help forensic scientists?
If there are insects that feed on organisms that are initially on the body (bluebottle) you can tell the body has been there for a while.
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What does TB stand for?
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Is TB a virus or bacteria?
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What does HIV stand for?
Human immunodeficiency virus.
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Is HIV a virus or bacteria?
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What does AIDS stand for?
Acquired immune deficiency virus.
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What type of cell is a bacterium?
A prokaryotic cell.
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How are prokaryotic cells simpler than eukaryotic cells?
1. No nucleus. 2. Lack membrane bound organelles. 3. Don't produce spindle during cell division.
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What two features does a basic virus have?
1. Protein coat. 2. Nucleic acid (RNA/DNA).
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How does bacteria reproduce, and what process do they use?
Asexually via binary fission.
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How do virus's reproduce?
Hijacking a host cells protein synthesis.
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How is TB transmitted?
Via droplets of saliva and mucus released from a person when they sneeze or cough.
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How is HIV transmitted?
1. Sharing needles. 2. Unprotected sex. 3. Blood-to-blood transfer (Paramedics) 4. Maternal transmission (Mother ---> unborn child & Mother via breast milk).
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What is an antigen?
Any molecule the body recognises as not being of its own self.
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What are the types of non-specific immune responses?
1. Lysosomes. 2. Inflammation. 3. Phagocytosis. 4. Antimicrobial proteins
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What are the types of specific immune responses?
1. B-cells (make antibodies). 2. T-cells.
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Where are lysosomes found, and what do they do?
In tears. Breaks down bacteria that lands on your eyes.
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Where does inflammation occur, and what does it do?
Cuts and grazes. Damaged WBC's release histamine, causes arterioles to increase blood flow, attracting more WBC's and antibodies to the site.
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What is a phagocyte, what does it do, and where are they found?
A white blood cell. Engulfs bacteria and other foreign matter. The blood
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What are the two types of phagocytes?
1. Neutrophils. 2. Macrophages.
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Card 2


What is DNA profiling?


A technique that distinguishes individuals on the basis of slight differences in their DNA.

Card 3


What are introns?


Preview of the front of card 3

Card 4


What are exons?


Preview of the front of card 4

Card 5


What are short tandem repeats (STR's)?


Preview of the front of card 5
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