Lab Exam 2 Flashcards
Coding DNA
the type of DNA in the genome, encoding for protein-coding genes.
Significantly, it accounts for 1% of the human genome.
Coding DNA consists of the coding region of protein-coding genes; in other words, exons.
Noncoding DNA
The other type of DNA in the genome, accounting for 99% of the human genome. Significantly, it does not encode for protein-coding genes.
Thereby, it does not provide instructions for the synthesis of proteins.
Coding region of genome
encodes proteins that determine physical traits.
Non-coding region of genome
98-99% of human DNA; has short-tandem repeats (STRs)
Short-tandem repeats (STRs)
Unique repeating patterns in non-coding region of DNA; can be used to differentiate one person from another; present at specific locations, may be repeated , on everyone’s chromosomes (loci); 5-20% of people share the same DNA profile at any one STR site.
(CA)(CA)(CA)(CA)****
2-nucleotide repeat unit
(GCC)(GCC)(GCC)(GCC)****
3-nucleotide repeats unit
Steps to creating a DNA profile
Multiple STR regions from each DNA sample are amplified by Polymerase Chain Reaction.
These STR regions are then separated by gel electrophoresis based upon STR size.
DNA-binding fluorescent dyes allow visualization of a banding pattern.
Forensic scientists can use this information to identify criminals!
Polymerase Chain Reaction (PCR)
a method used for making billions of copies of a specific DNA sequence; using this technique, researchers can easily build up large quantities of genetic material for experimental use; a specialized DNA polymerase, Taq polymerase, is used in this reaction because of its ability to survive in high-temperature environments
PCR reaction components
1) DNA template
2) Primers
3) DNA polymerase
4) Deoxyribose nucleotide triphosphates (dNTPs)
5) Reaction buffer
6) Solvent PCR grade water
Primer in PCR reaction
short pieces of DNA specific to the sense or antisense strands; binds via hydrogen bonds
DNA polymerase in PCR reaction
Uses Taq polymerase; can withstand temperatures greater than 90^C
dNTPs in PCR reaction
will comprise the base pairs in growing strands; takes DNA base pairs and turns into dATP, dGTP, dCTP, dTTP
Reaction buffer in PCR reaction
maintains pH and contains important ions like manganese, magnesium, and potassium; stabilizes the reaction and provides important cofactors to the polymerase enzyme
Solvent PCR grade water in PCR reaction
is free of ions that can inhibit the reaction
DNA isolation steps
1) Saline + mouth rinse
2) Centrifuge
3) Discard supernatant (liquid), dont lose pellet
4) add Chelex resin and resuspend pellet
5) Place PCR tube in thermocycler for 10mins at 99^C to lyse the cells
6) Add some DNA sample into new tube and mix with master mix
7) thermocycle for 1hr
Thermocycler
has fine temperature control: ability to hold a precisely set temperature with little fluctuation; amplifies STRs in DNA
Chelex resin
absorbs ions that inhibit function of Taq polymerase (PCR)
Master mix contains
buffer, loading dye, deoxynucleotides, three pairs of primers, taq polymerase, water
Central Dogma
explains flow of genetic information to make a protein; the cellular process of transcription generates mRNA
Protein variation
Protein sequences consist of 20 commonly occurring amino acids
Different amino acids have different chemistries and structural constraints.
Each amino acid is composed of an amino group ( NH+3 ), a carboxyl group (COO-), and a side chain.
Variation in amino acid sequence (side chain) is responsible for the enormous variation in protein structure and function
Triplet codon
a three-nucleotide sequence that each amino acid is defined by
nonsense or stop codons
terminate protein synthesis; 3/64 codons
Point mutations
cause single base pair to be exchanged for another; can cause silent, missense, nonsense
