Mutations (Inheritance) Flashcards
What does polymorphic mean?
occurrence of 2 or more clearly different forms or alternative phenotypes in the population of a species
What causes a mutation or makes a mutation more likely?
errors in DNA replication, exposure to mutagens (e.g. radiation), viral infection, alleles providing different phenotypes
What is natural selection?
certain characteristics are more useful for survival in a species, so these are more likely to reproduce and pass on this gene
In a DNA sequence what is a substition?
it is a direct swap of base sequences
In a DNA sequence what is a insertion?
a base sequence is added, this causes a frame shift
In a DNA sequence what is a deletion?
a base sequence is removed, this causes a frame shift
In a DNA sequence what is an inversion?
Where in a sequence of 3 bases that code for an amino acid they are the same bases but occur in a different order
Compare rates of mutation in Orangutans, Bacteria, and Peas
Rates of mutation across all organisms are slow, However because bacteria reproduce at a fast rate they have the highest rate of mutations because they are more likely to occur with increased reproduction. Because of this peas have next slowest and Orangutans have the slowest.
What do mutagens do? examples?
Mutagens increase rate of mutation (DOES NOT CAUSE MUTATIONS) e.g ionising radiation, chemicals in smoking
What are carcinogens?
mutagens that result in a cancer
How does a tumour form?
mutated cells that are not destroyed by the immune system divide to produce many clones containing the mutation which then grow out of control
What does Benign mean?
tumour stays in one place, uncontrolled division in one area
What does Malignant mean?
travel in blood/lymph and will cause uncontrolled division in many areas so multiple tumours form
What causes sickle-cell anaemia?
a mutation in the haemoglobin-beta gene found on chromosome 11 which create sickle-shaped red blood cells
What are symptoms of sickle-cell anaemia?
anaemia, Swelling of hands and feet, episodes of pain, frequent infections, delayed growth or puberty, vision problems
What causes down syndrome?
people with down syndrome have an extra copy of chromosome 21 also called trisonomy 21 - they have 3 copies instead of 2, replication of this cell will always have an extra chromosome
what are the symptoms of down syndrome?
A flattened face (especially bridge of nose), Almond-shaped eyes that slant up, A short neck, small ears, a tongue that tends to stick out of the mouth, tiny white spots on the iris of the eye, small hands and feet, a single line across the palm of the hand (palmar crease), small pinky fingers (sometimes curve towards the thumb, poor muscle tone or lose joints, shorter in height than as children and adults.
What are some of the effects of down syndrome?
slow growth, slow muscle development, intermediate to moderate learning, short life expectancy, heart and cardiac problems.
