DNA, genome and inheritance Flashcards
What is a mutation?
A mutation is a permanent change in the nucleotide sequence of DNA.
Mutations happen continuously and normally only slightly affect proteins or don’t affect them at all.
Name an example of when a mutation is detrimental to protein function:
In enzymes, the substrate may no longer be able to bind to the active site. In structural proteins, their strength may be reduced.
What type of advantage can mutations possibly create?
More rarely, a mutation may give a SURVIVAL advantage, such as resistance to an antibiotic in bacteria.
What are Alleles?
Alleles are different forms of the same genes.
A _______ allele is always expressed, regardless of the identity of the other allele.
Dominant
A _________ allele is only expressed if the other allele is also ________.
Recessive
How are dominant alleles represented?
Upper case letter
e.g ‘B’ for brown eyes
How are recessive alleles represented?
Lower case letter
e.g ‘b’. It needs two copies to be present to be expressed (bb).
If b is the allele for blue eyes:
- A person can only have blue eyes if both their alleles are b.
What is a phenotype?
A phenotype is an observed characteristic of an individual.
What is the phenotype is determined by?
The phenotype is determined by the interaction between the genotype and the environment.
What is an example of a phenotype?
Earlobes being attached or free is an example of a phenotype, where the alleles present will determine a characteristic, unless the environment interferes.
What is a genotype?
Genotype refers to the combination of alleles an organism has.
If the two alleles are different, what do we say the person is?
We say that the person is heterozygous. (Bb)
If the two alleles are the same, what do we say the person is?
We say that the person is homozygous (BB or bb)
What is DNA?
DNA is a polymer made up of two long strands of small units that repeat throughout the structure, called nucleotides.
