Genetics Week 10 Resource
March 22-26
Hi Everyone! As we begin Week 10 of Genetics, many students begin to have some trouble with the material being covered. Take comfort in this: genetics is an EFFORT class!!!If you put in the work, study smart, and push yourself to do your best, I am confident you can finish the course with the grade you want. Keep in mind that the Tutoring Center offers many services that you can take advantage of!
Also, make sure you come to Genetics group tutoring, every Tuesday at 6:30-7:30 You can check the Baylor tutoring website (baylor.edu/tutoring) for more information or to schedule a free, private, one-on-one tutoring appointment!
Keywords: PCR, cDNA library, blotting, short tandem repeats
Gene and Genomic Libraries
What is a gene library? It is a culmination of all of the genes in an organism.
Would promoters and enhancers be present in gene libraries? No! The gene library is only the CODING (transcribed) regions of the genome.
How is a gene library constructed?
1. Total RNA is isolated from the cells.
2. Reverse transcription (RT) is done to convert the RNA into cDNA.
3. The cDNA is inserted into plasmids using restriction enzymes.
4. Final Product: Plasmids containing all of the coding regions of your genome!
All figures, diagrams, and information are sourced from Pierce Genetics 7ed, unless otherwise stated.
How does a genomic library differ from a gene library?
While gene libraries only contain the coding regions of the genome, genomic libraries contain ALL parts of the genome (promoters, enhancers, introns, etc.).
How are genomic libraries created?
1. Restriction enzymes are used to cut random portions of the genomic DNA.
2. The cut DNA is placed into plasmids using restriction enzymes.
3. Final product: Plasmids containing short fragments of genomic DNA!
Polymerase Chain Reaction (PCR) Encyclopedia of Genetics PCR is a very, very commonly used technique in molecular biology labs and has a wide range of applications!
What is PCR? Polymerase chain reaction is a method of amplifying or identifying DNA. Essentially, it is DNA replication catalyzed by DNA polymerase, except in a tube instead of a cell!
How does PCR work?
All figures, diagrams, and information are sourced from Pierce Genetics 7ed, unless otherwise stated.
1. Denaturation (94-95C): Double stranded DNA is heated so hydrogen bonds holding nucleotides together are broken. This makes the DNA single stranded.
2. Annealing (50-56C): Primers bind to their complementary DNA sequence.
3. Elongation (72C): DNA polymerase adds nucleotides to the 3’ end of the primer to generate double stranded DNA.
4. Final product: 2n strands of DNA (assuming you start with a single DNA molecule), where ‘n’ is the number of cycles.
What are all the ingredients needed for PCR?
• Target DNA • dNTPs • Primers • DNA polymerase • Buffers (including MgCl2) • Thermocycler (machine used to vary temperature)
Short Tandem Repeats
These are repeats of a pattern of two or more nucleotides for a different number of times.
What makes these repeating sequences different from all the other repeats in the genome? These repeats are random in amount but are always the same in a person, this is why we can use these STRs to “fingerprint” someone. • Used to identify someone from a sample of their DNA (blood, saliva, etc.) in forensic analysis!
Review!
Do you remember the different types of blots? Fill in the target molecule for each blot below: 1. Northern: 2. Southern: 3. Western: 4. Eastern:
All figures, diagrams, and information are sourced from Pierce Genetics 7ed, unless otherwise stated.
(Trick question: Eastern blotting doesn’t exist!)
That’s it for this week! I hope this is useful for you all and please do not hesitate to reach out if you have any questions. Also, remember that past resources can be found and downloaded from the tutoring center website:https://www.baylor.edu/support_programs/index.php?id=967950
All figures, diagrams, and information are sourced from Pierce Genetics 7ed, unless otherwise stated.