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Flashcards by hannawin98, updated more than 1 year ago
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Created by hannawin98
almost 8 years ago
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| Question | Answer |
| What are gene technologies? | Techniques used to study genes and their function |
| What is PCR be used for? | To make millions of copies of fragments of DNA |
| Outline the first step of PCR | 1. A reaction mixture is set up |
| What is contained in this reaction mixture? | 1. DNA Sample 2. Free Nucleotides 3.Primers 4. DNA Polymerase |
| What are primers? | Short pieces of DNA that are complimentary to the start of the fragment you want. |
| What is DNA Polymerase? | An enzyme that aids in the creation of new DNA strands. |
| What is the second stage of PCR? | 1. The DNA mixture is heated to 95 degrees to break the hydrogen bonds between the two strands of DNA 2. The mixture is cooled to 50-65 degrees so the primers can anneal to the strands |
| What is the third stage of PCR? | The reaction mixture is heated to 75 degrees so DNA Polymerase can work |
| What does the DNA Polymerase do? | Lines up free DNA nucleotides alongside each template strand. Complimentary base pairing means new complimentary strands are formed. |
| What is produced in the first cycle of PCR? | Two new copies of the fragment are formed. (this doubles with every PCR cycle) |
| What do restriction enzymes do? | Isolate (cut out) fragments of DNA from an organisms DNA. |
| What are palindromic sequences? | Antiparallel base pairs (base pairs that read the same in opposite directions) |
| How do restriction enzymes work? | They recognise specific palindromic sequences (recognition sequences) and cut the DNA at these places. |
| How can you isolate a piece of DNA using restriction enzymes? | If there are recognition sequences at either end of the fragment you can cut at both ends through hydrolysis, isolating the DNA fragment |
| What does hydrolysis of DNA sometimes leave? | Sticky ends |
| What are sticky ends? | Small tails of unpaired bases at each end of the fragment. |
| What can sticky ends be used for? | Anneal the DNA fragment to another piece of DNA that has sticky ends with complimentary sequences. |
| What is gel electrophoresis? | A technique used to separate the DNA fragments by size/length |
| Why is a fluorescent tag added to the DNA fragments in gel electrophoresis? | So the fragments can be viewed in UV light. |
| What is the DNA placed in during gel electrophoresis? | A well in a slab of gel and covered in a buffer solution that conducts electricity. |
| Why do DNA move to the positive electrode in gel electrophoresis? | Because they're slightly negatively charged. |
| Why does this technique separate the fragments by size? | Because the smaller fragments of DNA move to the anode faster, therefore travel further through the gel. |
| What are DNA probes used for? | Identify DNA fragments that have specific sequences of bases e.g locate specific genes on chromosomes. |
| What are DNA probes? | Short single strands of DNA. They have a specific base sequence that's complimentary to the target sequence. |
| What are the most common labels used in DNA probing? | 1. Radioactive label (detected using x-ray) 2. Fluorescent label (detecting using UV light) |
| Outline the process of DNA probes that are labelled with a UV label. | 1. A sample is digested into fragments using restriciton enzymes 2. The fragments are separated into size by electrophoresis 3.The fragments are transferred onto a nylon membrane and incubated with a fluorescent probe. 4. The mebrane is exposed to UV light. |
| What is genetic engineering? | The manipulation of an organisms DNA |
| What is recombinant DNA? | DNA formed by joining together DNA from different sources. |
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