MOLECULAR BIOLOGY OF THE GENE Flashcards
how many codons are there?
64
how many amino acids are there?
20
which base is degenerate?
3rd
what is the start codon?
AUG codes for methionine (Met)
1st AA in a polypeptide
what is the one gene -one protein hypothesis?
o
what is alternative splicing?
exons can be joined together in a
variety of ways
what can errors in gene expression cause?
many uncommon disorders
can also influence the predisposition of many common diseases such as breast cancer, lung cancer, prostate cancer and blood cancer
how do transcription errors lead to disease?
Over-expression of the TF MYC is found in numerous cancers
If one copy of the gene encoding the TF is mutated this can also lead to disease
what is haploinsufficiency?
where one copy of the gene is not enough e.g. p53 gene
what is dominant mutation?
where a change in the gene sequence generates change in the protein that exerts dominance over the wild-type e.g. TFCP2L3 gene and genetic deafness
how do mRNA processing errors occur?
involves errors in alternative splicing
how does cystic fibrosis occur?
Mutations found in the exon 7 of SMN1 gene.
As a result, the exon 7 is skipped and the protein produced is non-functional
what are mRNA translation errors?
Mutations that affect translational efficiency
give examples of mutations in key translation proteins that lead to diseases
Translation initiation factors, e.g. eIF2 gene - a neurodegenerative disease called VWM
Release factors, e.g. eRF3 gene – gastric cancer
Mutations affecting the tRNA transfer proteins or the ribosome itself
what is Gel Electrophoresis of DNAs/RNAs?
g
how does gel electrophoresis work?
DNA is negatively charged (-):
Anode (-)
Cathode (+)
So will move from the anode to the cathode
what is produced from gel electrophoresis?
A gel image loaded with DNAs
what is western blot?
w
what is western blot used for?
to detect proteins
what are the steps involved in western blotting?
Sample preparation Gel Electrophoresis Blotting (or transfer) Blocking Antibody Probing Detection
how can we detect gene expression?
Polymerase Chain Reaction (PCR)
what is PCR?
p
what does PCR allow?
Enables the amplification of a specific region of DNA from just a single molecule of starting material
what does gene expression profiling allow?
Detects how many copies of a gene (genes) you have
Idea of the regulation of gene expression at a given time
what is PCR used for?
Diagnostics
Gene cloning
Legal disputes
