The flow of genetic information-transcription, translation and PCR Flashcards
What is the genetic code?
A, T, C, G in a certain order. Code that determines which amino acids are combined to form proteins and represented as RNA (T replaced with U)
What is transcription?
mRNA is made from the DNA in the nucleus and is complementary to the template strand making mRNA from DNA in nucleus.
How does transcription work?
Involves the unfolding of DNA near the region to be transcribed. RNA polymerase binds to the DNA template, slides along the DNA until it reaches a short sequence known to promote or switch on the mRNA transcription process. It catalyses the addition of bases to the 3’ growing strand until it reaches a G-C rich region and a string of A’s. It falls away and the mRNA travels to the ribosome where it is translated into proteins
What are the stages of transcription, translation and PCR?
Initiation, Elongation and Termination
How are the codons read?
Groups of 3’s that codes for the specific protein
What makes up a ribosome?
A large subunit and a small subunit
How does translation work?
It occurs at ribosome. tRNA molecules carry the correct amino acid to the ribosome. The ribosome moves along the mRNA strand, the correct amino acid is placed after the start amino acid (methionine) and the amino acid chain elongated, releasing the free tRNAs. The process will continue until a stop codon is reached and the mRNA is released.
What is PCR?
A method to copy and isolate any region of DNA as long as we known some of the sequence in the region near the gene
What does PCR need to work?
Requires a primer to initiate replication. Need 2 primers in opposite directions to copy the region of DNA we are interested in. Requires template DNA, primers, dNTPs, DNA polymerase and buffer to maintain pH
What are the temperatures needed in PCR?
95- Denaturing DNA to form single strand
55- Primers anneal to complementary sequence
72- Optimum for Taq polymerase, chain extension of DNA occurs
Why is PCR important in forensics?
Important for crime scene samples where only trace amount of DNA are found. We can make copies of the genes of interest for analysis
