Flashcards in 1D Genes And Protiens In Health And Disease Deck (30):
What are proteins held together with?
They are held in a 3D shape by peptide bonds, hydrogen bonds and interactions between individual amino acids.
What shape do most proteins fold into?
Polypeptide chains fold to form the 3D shape of the protein.
What is a mutation?
An alteration to the original DNA sequence.
What happens if a mutation occurs?
A faulty protein or no protein is made.
Are mutations common?
No. They are random, rare and spontaneous.
Name three mutagenic agents.
Mustard gas, UV-Rays, UV Light and Gamma Rays.
Mutations occurring because of mutagens are said to be what?
An induced mutation.
How do single gene mutations arise?
By substitution, insertion or deletion.
What is a substitution gene mutation?
A nucleotide is substituted for another one.
What is the effect of a substitution gene mutation?
The amino acid coded for could be a missence mutation or a nonsense mutation. An incorrect protein will be made.
What is a missense mutation?
The mutation still codes for an amino acid but not the correct amino acid.
What is a nonsense mutation?
This mutation causes the codon to now code for a stop codon. This results in a shortened protein/faulty protein being made.
What is an insertion gene mutation?
A nucleotide is inserted into the DNA sequence.
What is the effect of an insertion gene mutation?
Frameshift mutation. All the codons after the point of mutation are altered and a faulty protein is made.
What is a deletion a gene mutation?
A nucleotide is deleted from DNA sequence.
What is the effect of a deletion gene mutation?
Frameshift mutation. All the codons after point of mutation are altered and a faulty protein is made.
What is a splice-site mutation?
Splicing is controlled by specific nucleotide sequences at splice sites on those parts of the introns that or next to the exons. If a mutation occurs at one of these splice-sites, codon for an intron-exon splice may be affected send an intron may to be retained in error.
What is the effect of a splice-site mutation?
Faulty protein is made.
What is a nucleotide sequence repeat expansion?
The insertion of a large number of copies of a nucleotide sequence (e.g. Several hundred repeats)
What is the effect of a nucleotide repeat expansion?
A faulty protein is made.
Diseases which are caused by a substitution mutation.
Phenylketonuria (PKU). It is an inborn error of metabolism.
What metabolic conversion does not take place in a person who has phenylketonuria (PKU)?
They cannot convert the amino acid Phenylalanine to Tyrosine.
What is the effect of a buildup of phenylalanine?
It is converted into toxins. The poisonous metabolites inhibit one or more of the enzymes that control the metabolic pathways of the brain. The brain fails to develop properly causing severe mental impairment.
What can be done to detect phenylketonuria (PKU)?
Babies are diagnosed with phenylketonuria, what are they prescribed?
A diet low in phenylalanine. They are not albinos as they still have tyrosine in their diets.
Name three types of chromosomal mutations.
Deletion, duplication and translocation.
Describe a deletion mutation.
I deletion mutation occurs when a chromosome breaks in two places and the segment becomes detached. The two ends join together giving a shorter chromosome.
Describe duplication mutation.
A segment of genes becomes attached to one end of the first chromosome or becomes inserted somewhere along its length.
Describe a translocation mutation.
A section of one chromosome breaking off and becoming attached to another chromosome that is not its (homologous) matching partner.