bio 1AL- lab 8 bioinformatics

complementation group

strains that fail to complement (they are mutated in the same gene)

• all streaks which fail to grow are in one complementation group

• streaks that grow could be one group but we don’t know unless they are crossed

cDNA

complementary DNA- it is complementary to the mRNA, used during sequencing

reverse transcription

process of getting cDNA from mRNA

• carried out by reverse transcriptase

finding a reading frame

must start with start codon, and not have a stop codon for a long time

• start codon: AUG

missense mutation

point mutation, changes type of protein expressed

nonsense mutation

introduces stop codon (UAG, UAA, UGA)

frameshift mutation

inserts an extra letter, causing everything downstream to change

silent mutation

point mutation that keeps the same protein expressed

reading frame

3 different ways of starting to read, which may be different lengths/different amino codons

• the correct one will have a long open reading frame starting with AUG and ending with a stop codon

hemoglobin 

• 2x alpha globin

• 2x beta globin

homologs

genes related by descent from a common ancestral DNA sequence

• classified as paralogs or homologs

paralogs

homologous genes that arose from a gene duplication event within a single genome

• Same/related species

• encode proteins with different functions

orthologs

homologous genes that arose from a speciation event

• different species

• encode proteins with same functions

Sanger DNA sequencing

PCR in vitro

• mixes small amount of ddNTP (chain terminating dideoxy nucleotides) with dNTPs

• results in different length strands of DNA which are separated by electrophoresis and read by laser excitation (electropherogram)

ddNTP

dideoxynucleotides: nucleotide that terminates DNA extension in Sanger sequencing

four types of ddNTP

ddATP, ddTTP, ddCTP, ddGTP

random chain termination

a mixture of dNTPs and ddNTPs causes chains terminated at each nucleotide termination step