2.4.2 - Mutations Flashcards
What Is A Gene Mutation?
Change in the sequence of base pairs in DNA.
What A Mutations Caused By?
(2 Points)
~ Often caused by errors during DNA replication.
~ Mutations occur continuously and spontaneously.
What Are Types Of Errors That Occur During DNA Replication?
(5 Points)
~ Insertion.
~ Deletion.
~ Substitution.
~ Duplication.
~ Inversion.
Describe ‘Insertion’ As An Error Of DNA Replication
(3 Points)
~ Mutation that occurs when a nucleotide is randomly inserted into the DNA sequence.
~ It changes the amino acid that would have been coded for, by the original base triplet -> As it creates new, different base triplets.
~ Has a knock-on effect on other base triplets, by changing the triplets further on in the DNA sequence -> Causing frameshift mutations.
Describe ‘Deletion’ As An Error Of DNA Replication
(2 Points)
~ Mutation that occurs when a nucleotide is randomly deleted from the DNA sequence.
~ Causes frameshift mutations -> Changes triplets of bases in the DNA sequence.
Describe ‘Substitution’ As An Error Of DNA Replication
(2 Points)
~ Mutation that occurs when a base in the DNA sequence is randomly swapped for a different base.
~ Only changes the amino acid for the triplet in which the mutation occurs, doesn’t have a knock on effect.
Describe ‘Duplication’ As An Error Of DNA Replication
(4 Points)
~ Mutation that involves the production of one or more copies of a gene.
~ A whole gene or section of DNA is duplicated, so two copies of the gene will appear on the same chromosome.
~ Original version of the gene remains intact, therefore mutation is not harmful.
~ Overtime the second copy can undergo mutations, enabling it to develop new functions.
Describe ‘Inversion’ As An Error Of DNA Replication
(3 Points)
~ Mutation that involves a sequence of bases being reversed.
~ Usually occurring during crossing-over in meiosis.
~ Frequently result in a non-functional protein.
What Can A Mutation In The Primary Structure Of A Protein Cause?
(2 Points)
~ Could change the final 3D shape of the protein changing its function.
~ As the order of DNA bases in a gene determine the order of amino acids in a protein.
What Are Genetic Orders Often Caused By?
A mutation in a gene that results in a differently functioning or a non-functioning protein, altering the phenotype of the individual.
What Is Cystic Fibrosis?
(5 Points)
~ Genetic disorder of cell membranes caused by a recessive allele of the CFTR gene.
~ This gene codes for the production of chloride ion channels required for secretion of sweat and mucus.
~ A mutation on the CFTR gene leads to the production of non-functional chloride channels.
~ Reducing the movement of water by osmosis.
~ Results in large amounts of thick, sticky mucus in the air passages, digestive tract and reproductive system.
What Causes Cystic Fibrosis?
Mutation in the gene that codes for the CFTR protein, which is a channel protein.
Who Will Be Affected By Cystic Fibrous As A Result Of It Being Determined By A Recessive Allele?
(2 Points)
~ Heterozygous Individuals -> Unaffected by the disorder, but they are carriers.
~ Homozygous Recessive Individuals -> Affected by the disorder.
Where Does Cystic Fibrosis Cause Problems?
(3 Points)
~ Digestive system.
~ Respiratory system.
~ Reproductive system.
Describe How Cystic Fibrosis Affects The Respiratory System?
(5 Points)
~ Cilia are unable to move the mucus as it is so thick and sticky.
~ Mucus builds up in the airways.
~ Microorganisms are not efficiently moved -> Can cause lung infections occurring more frequently.
~ Mucus can block airways limiting gas exchange, reducing the SA available, causing breathing difficulties.
~ Physiotherapy to dislodge mucus and antibiotics to kill bacteria in the airways -> These can help support people.
Describe How Cystic Fibrosis Affects The Digestive System?
(3 Points)
~ Tube to the pancreas can become blocked, preventing digestive enzymes from entering the small intestine -> Digestion of some food may be reduced.
~ Mucus can cause cysts to grow in the pancreas which inhibit the production of enzymes -> Reducing digestion and absorption of nutrients.
~ Lining of small intestine is abnormally thick, inhibiting the absorption of nutrients.
Describe How Cystic Fibrosis Affects The Reproductive System?
(2 Points)
~ Men -> Tubes of the testes become blocked, preventing sperm reaching the penis.
~ Woman -> Thickened cervical mucus can prevent sperm reaching the oviduct to fertilise an egg.
