Download - Bio Day 18
Biology Class Day 18: How do we make DNA copies in vitro? In the lab? Polymerase Chain Reaction (PCR): -‐a lab technique to amplify DNA, that is, to make many copies of a piece of DNA -‐what are some uses for the lab method PCR? -‐3 days ago…DNA evidence helps Oklahoma police make arrest in 1997 child abduction. Kirsten Hatfield, 8, disappeared from her home in Midwest City, Oklahoma, one night in May 1997. “new DNA techniques” match of 1 in 293 septillion 10!" -‐there are 2 main reasons why you want to amplify DNA: 1) simply create multiple copies of a rare species of DNA. for example, a forensic scientist may want to amplify a tiny piece of DNA from a crime scene 2) to compare two different samples of DNA to see which is more abundant. DNA analysis requires amplification in order for there to be enough DNA to give a detectable signal for quantification. if you amplify both samples at the same rate, you can calculate which sample had the highest copy number of the target of interest to begin with -‐what are some practical applications of PCR technology? -‐genotyping (gene testing), paternity testing, forensic analysis, disease testing (rapid detection of pathogens, especially important in testing for HIV, tuberculosis) -‐what’s the basic idea of PCR? -‐PCR is a technique for amplifying DNA -‐what will we need to do that?
Different segments of the gene: -‐Exons are part of DNA that are converted into mature messenger RNA (mRNA). The process by which DNA is used as a template to create mRNA is called transcription. -‐Introns are parts of genes that do not directly code for proteins. -‐Remember: introns are intervening sequences and exons are expressed sequences.
Transcription: -‐Transcription is making an RNA molecule that is complementary to one side of the DNA. What are some differences between DNA and RNA? -‐DNA: sugar deoxyribose, ATCG, double strand -‐RNA: sugar ribose, ACGU, uracil, single strand
-‐DNA is the permanent information storage molecule. Messenger RNA is a working copy of the gene for a protein. -‐How does RNA differ from DNA? -‐What enzyme makes RNA? -‐A gene codes for a protein. What type of information have to be in a code? -‐What are the elements in a code? -‐code is non-‐overlapping -‐either side of DNA could contain a gene but DNA is read only one side at a time
-‐What is the word length? -‐DNA has 4 bases: ATTCG -‐What is the start signal for translating the code? -‐AUG on mRNA is the start codon. That is the first triplet that is “read” in translation, and it sets the “reading frame” for the triplets.
