Download Changes in DNA can produce variation

Changes in DNA
can produce variation
Section 5.2
DNA sequence can change
• Differences in DNA are what make one
organism different from another
• The number of differences between two
species is large
Human
3 billion
Base pairs
Yeast cell
12 Million
Base Pairs
DNA sequence can change
• The number of differences between 2
individuals of the same species is small
•
(<0.1% variation)
DNA sequence can change
• There is a large number of DNA bases in any
organism that need to be copied
• Errors can occur when DNA is copied or
affected by environment
– UV radiation
– X-rays
– Toxins
DNA sequence can change
• Mutation – any change in DNA
• Cells have ways of fixing mistakes in DNA
• However some mistakes are not fixed
Possible outcomes when error occurs
in genes
No effect
– Some amino acids have more than one
code and may not change resulting protein
– May have enough protein being produced
Possible outcomes when error occurs
in genes
• Mutation is minor
– May only cause a change in appearance
Possible outcomes when error occurs
in genes
Mutation is great
– Could be good (Resistant to disease)
– Could be bad (genetic disorder or disease)
• Only 5% of human DNA is in genes
• If mutation occurs in a non-coding region,
then chances are that the mutation is neutral
Genetic Disorders
• Disease or condition caused by mutations that
affect normal functions of the cell
– Can be inherited (Tay-Sachs)
– Can occur during a person’s life (Cancer)
Genetic Disorders
• A person can carry a tendency for a disease
(diabetes)
• Sometimes a person’s
behavior can prevent
the disease (smoking)
Genetic Disorders
• Mutations can have more than one effect
– Sickle cell anemia
• Recessive disorder
• Prevents blood from carrying oxygen
• Prevents malaria
Genetic Disorders
• Pedigree – shows a family relationship for 2 or
more generations
Cancer
•
•
•
•
A group of disorders
Characterized by uncontrolled division of cells
Cells can spread to other tissues
Causes
– Inherited
– Carcinogens
– Radiation
– Series of mutations