13.3 Mutations ( bio worksheet answers)
A gene that codes for one of the polypeptide chains of the blood protein hemoglobin lies on chromosome 11 in humans. A substitution mutation in that gene causes the amino acid valine to be incorporated into hemoglobin in a place where glutamic acid would normally lie. The result is sickle cell disease. Explain how a change in a single base in DNA can bring about such a serious disorder.
A single DNA base-pair change in a gene can create an incorrect codon in the mRNA molecule made from this DNA. When the incorrect codon is "read" on the ribosome, the wrong amino acid (in this case valine rather than glutamic acid) is placed into the polypeptide. With the wrong amino acid sequence, the protein does not form or func- tion properly.
Deletion can happen as a gene mutation or as a chromosomal mutation. what is the difference?
In a gene mutation, a deletion happens when a base is removed from the DNA sequence. In a chromosomal mutation, deletion involves the loss of all or part of a chromosome.
polyploidy is the condition in which
an organism has an extra set of chromosomes
Mutations are important to the evolution of a species because they
are a source of genetic variability
cancer is the product of a mutation that
causes the uncontrolled growth of cells
a mutation that produces an extra copy of all or part of a chromosome
duplication
a kind of mutation that can change every amino acid that follows the point of mutation
frameshift mutation
small changes in genes
gradually accumulate over time
the addition of a base to the DNA sequence
insertion
a chromosomal mutation that reverses the direction of parts of a chromosome
inversion
which of the following most accurtaely summarizes the effects of mutations on living things
many mutations have little or no effect, but some can be harmful or beneficial
a heritable change in genetic information
mutation
the cellular machinery that replicates DNA inserts an incorrect base
roughly once in every 10 million bases
The change of one base to another in a DNA sequence
substitution
what happens when cells cannot repair the damage caused by a mutagen
the DNA base sequence changes permanently
part of one chromosome breaks off and attaches to another
translocation
a possible mutagen is
ultraviolet light
complete the table to describe the processes and outcomes of the different types of gene(point) mutations
LOOK AT HANDOUT!!!
draw a normal blood cell and a sickle cell
LOOK AT HANDOUT!!!
a change in one or a few nucleotides that occur at a single point in the DNA sequence
point mutation
