Flashcards in 1.4 Protein, mutations & genetic disorders Deck (41):
How many proteins are there within the human body and what do they do?
there are thousands of proteins which do a wide range of important tasks
What chemical elements do all proteins contain?
What other chemical element do some proteins contain?
What are proteins held in?
a 3D shape by peptide bonds, hydrogen bonds and interactions between individual amino acids. (e.g. sulphur bridges)
What do polypeptide chains do to form the 3D shape of protein?
What are the 2 types of protein structure and describe them?
fibrous proteins - flat sheets
globular proteins - wound into ball
What will having polypeptide chains arranged in different ways give rise to?
the large variety of structures and shapes of proteins and ultimately contribute to their different roles (e.g. structural and enzymes)
Give 2 examples of structural proteins?
Give 2 examples of enzymes (include substrate and products)?
hydrogen peroxide (catalase)-----> oxygen + water
starch (amylase)-----> maltose
What is a mutation?
a change in the structure or composition of an organism's genome.
What is an organism's genome?
all the genes it contains
What can a mutation either result in?
no protein or a faulty protein being expressed.
When do mutations occur?
randomly and rarely
What do mutagenic agents do?
Increase the rate of mutations
Give some examples of mutagenic agents?
What is a genetic disease?
a disorder which can be directly related to a person's genotype.
What can a mutation cause a change in?
the sequence of amino acids in a gene, which result in the protein it codes for not functioning as it should.
What do most genetic disorders drastically affect?
a person's phenotype
What do single gene mutations involve?
the alteration of a DNA nucleotide sequence as a result
of the substitution, insertion or deletion of nucleotides.
What is a single gene mutation that replaces an amino acid called?
a point mutation
What are the 3 types of point mutations?
Why do missense mutations occur?
as a result of a substitution mutation (when one nucleotide is substituted with another). This replaces one amino acid codon with another, meaning that a different amino acid with be placed in the protein chain.
Why missense mutation called that?
Because they make sense, the altered codons still code for amino acids, but they don't make the right sense, a different amino acid will be placed.
Give an example of a missense mutation?
What nonsense mutations caused by?
a substitution mutation , this mutation occurs when one nucleotide is substituted with another and the resultant codon is now a stop codon.
Why are nonsense mutations called that?
Since the protein chain is stopped before all of the amino acids are in position, nearly all nonsense mutations lead to non-functional proteins.
Give an example of a nonsense mutation?
Ducheme muscular dystrophy (DMD)
What do splice-site mutations alter?
codons that trigger the removal of introns from the primary transcript in translation. A s a consequence, these introns will not be cut out, and will remain in the mRNA sequence, coding for amino acids that would not normally appear in the polypeptide chain. This results in an altered protein that doesn't function properly.
What are frame-shift mutations ad give the 3 types?
These mutations occur when nucleotides are added or removed from the nucleotide sequence.
Nucleotide sequence repeat expansion
Describe deletion mutation?
A nucleotide is removed from the sequence. This alters all of the triplets and therefore the amino acids from this point on.
Give an example of a deletion mutation?
Describe insertion mutation?
An extra nucleotide is added to the sequence. This alters all of the triplets and therefore the amino acids from this point on.
Give an example of an insertion mutation?
Describe nucleotide repeat expansion?
Some insertion or deletion mutations cause repetition of a triplet of bases. These can result in the production of a defective protein or no protein at all.
Give an example of nucleotide repeat expansion?
What can mutations also directly affect?
The structure of a chromosome
What can changes in chromosome structure sometimes be?
Substantial resulting in the mutation being lethal
What are the 3 different categories of chromosome structure mutations?
Describe deletion as part of a chromosome structure mutation?
A segment of a chromosome is lost resulting in the loss of several genes.
Describe duplication as part of chromosome structure mutation?
Genes from segment of a chromosome are repeated