Chapter 15 Flashcards
What is a mutation?
A heritable change in the genetic material of an organism. When a mutation occurs, the order of nucleotide bases in a DNA molecule, its base sequence, is changed permanently, an alteration that can be passed from mother to daughter cells during cell division
What is a point mutation?
A mutation that affects only a single base pair within DNA or that involves the addition or deletion of a single base pair to a DNA sequence.
What is a base substitution mutation?
A mutation that involves the substitution of a single base in the DNA for another base.
Different types of base substitutions:
silent (no change), missense (one amino acid change), nonsense (changes a normal codon to stop codon)
silent mutation:
A gene mutation that does not alter the amino acid sequence of the polypeptide, even though the base sequence has changed.
missense mutation:
A base substitution that changes a single amino acid in a polypeptide.
What is sickle cell disease?
A disease due to a mutation in a hemoglobin gene that results in sickle-shaped red blood cells that are less able to move smoothly through capillaries and can block blood flow, resulting in pain and cell death of the surrounding tissue.
nonsense mutation:
A mutation that changes a normal codon into a stop codon; this causes translation to be terminated earlier than expected, producing a truncated polypeptide.
frameshift mutation:
A mutation that involves the addition or deletion of a number of nucleotides that is not a multiple of three and alters the reading frame of a protein-encoding gene.
What are germ-line cells?
Cells that give rise to gametes, such as egg and sperm cells.
What is a somatic cell?
The type of cell that constitutes all cells of an animal or plant body except those that give rise to gametes.
What does mosaic mean in reference to genetics?
An individual with somatic regions that are genetically different from each other.
What is a carcinogen?
An agent that increases the likelihood of developing cancer, usually a mutagen
direct repair:
A type of DNA repair in which an enzyme finds an incorrect structure in the DNA and directly restores the correct structure.
What is an induced mutation?
A mutation brought about by environmental agents that enter the cell and then alter the structure of DNA.
