Lab 5: Forensic Biology and Bioinformatics II

central dogma

theory that genetic information flows from DNA to RNA to protein,

• the cellular process of transcription generates messenger RNA (mRNA)

• translation of the mRNA template on ribosomes converts nucleotide-based genetic information into a protein product

protein sequences consist of ___ commonly occurring amino acids

20

what is each amino acid composed of?

• amino group (NH₃+)

• carboxyl group (COO-)

• side chain

what is variation in amino acid sequence (chain) responsible for?

enormous variation in protein structure and function

3/62 codons terminate protein synthesis called nonsense/stop codons

UAA, UAG, UGA

start/met codon

AUG

what does genetic code is degenerate mean?

an amino acid could be encoded by more than one nucleotide triplet, it is redundant

3 types of point mutations

silent, missense, and nonsense

silent mutations

the substitution doesn’t change the amino acid that the codon codes for

missense

the substitution changes the codon so that it corresponds to a different amino acid that it should

nonsense

the substitution changes the codon so that it signals an early stop of translation

point mutations

cause a single base pair to be exchanged for another

insertion mutation

when an extra base is inserted into a sequence

deletion mutation

a base is removed from the sequence

frameshift mutations

when a base is added or removed, the entire codon sequence following the mutation changes

2 types of frameshift mutations

insertion and deletion mutations

phylogenetic tree

a diagram showing the evolutionary relationships among biological species based on similarities and differences in genetic or physical traits or both

what do internal nodes represent?

an ancestor: points in evolution when an ancestor has diverged to form two new species. the length of each branch is proportional to the time elapsed since the split

branch

the point where a split occurs

what does a branch represent

where a single lineage evolved into a distinct new one

basal taxon

a lineage that evolved early from the root that remains unbranched

sister taxa

two lineages stemming from the same branch point

what 3 factors influence gel electrophoresis?

1. charge of molecule

2. size of molecule

3. density of gel

charge of molecule

DNA carries a negative charge so it is attracted to positive

size of molecule

smaller molecules/fragments will travel faster and farther

density of gel

the denser the gel is, the slower the fragments will move. we want gel that is dense enough to separate bands but wont take too long to run

DNA with loading dye

the dye weighs down, so it can sink to the bottom of the wells and not float in the buffer solution

buffer

stabilizes the pH and Mg₂+ which most enzymes, including DNA polymerase, require in order to function

SYBR green (in gel)

dye used in molecular biology techniques to stain nucleic acids. Binds to dsDNA, resulting in a complex that absorbs blue light and transmits green light