Ch 19 Genetics
True or false: It is healthy for a human to acquire new DNA mutations, because they are the driving force for adaptive evolution.
False; Although mutations can be beneficial this is very rare. Most mutations are harmful and can cause diseases such as cancer.
A missense mutation in the β-globin gene is responsible for sickle cell disease. This mutation causes the polypeptide sequence to
contain a substituted amino acid of the wrong type.
Cells that give rise to the gametes such as eggs and sperm are called ___ ___.
germ line
A mutation that does not change the amino acid sequence of a polypeptide is known as a(n) ___ mutation.
silent
Cells of the body other than germ-line cells are called ______ cells.
somatic
If the patch of white hair in this child were larger, that would indicate a
somatic mutation that occurred earlier during embryonic development.
Mutations in body cells that do not go on to form gametes are known as
somatic mutations
Mutations in eukaryotic genes that change the ___ recognition sequences may affect the order and/or number of exons contained in the mature mRNA.
splice
The term germ line is used to describe
the cells that produce sperm and eggs.
Examples of somatic mutations include a mutation occurring in a(n)
Brain, adult muscle, and embryonic kidney cell
Which of the following statements about promoter mutations is true?
Down promoter mutations decrease the affinity of transcription factors to the promoter Up promoter mutations cause the promoter sequence to be more like the consensus sequence
What type of mutations involve a change from a normal codon to a stop codon?
Nonsense mutations
In this figure, the normal DNA coding sequence of a gene is shown on top, along with four different mutations. Match the mutation to its appropriate description.
Silent Missense Nonsense Frameshift
What is responsible for silent mutations?
The degeneracy of the genetic code
The embryo on the left carries a germ-line mutation; the one on the right carries a somatic mutation. Which embryo(s) will be able to pass this mutation on to future progeny?
The embryo on the left
Mutations in the 5'-UTR or 3'-UTR of an mRNA molecule are most likely to affect what?
The stability of the mRNA The mRNA's ability to be translated
A germ-line mutation is one that occurs in
a sperm or egg cell
Silent mutations are possible because the genetic code is
degenerate
In a neutral mutation, a negatively-charged amino acid is substituted
for another negatively-charged amino acid.
The addition or deletion of a number of bases that is not a multiple of 3 causes a(n) ___ mutation.
frameshift
If an individual possesses a germ-line mutation, then ______ of the gametes produced by the individual will carry the mutation. If an individual possesses a somatic mutation, then ______ of the gametes produced by the individual will carry the mutation.
half;none
A new mutation in a gene is MOST LIKELY to be ______ to the organism.
harmful
A mutant allele is best defined as an allele that
has a different DNA sequence from the wild type.
A genetic mosaic is an individual that
has regions of the body that are genotypically different from each other.
A base substitution in DNA that ultimately leads to a change in the encoded amino acid is called a(n) ___ mutation.
missense
Sickle cell disease is caused by a
missense mutation in the β-globin gene.
A(n) ___ mutation is a missense mutation that has no detectable effect on protein function.
neutral
What can cause a frameshift mutation?
addition or deletion of nucleotides
A change in a single base pair in the genetic material is known as a(n) ___ mutation.
point
An allele that has a DNA sequence different from that of the wild type is called a(n) ___ allele.
mutant
A(n) ______ mutation refers to a mutation in which just one base is changed within the DNA sequence.
point
A change of one base for another is described as a base ___ mutation.
substitution
The DNA sequence of the coding strand of a gene is depicted in the top of this figure. Below it are four different types of mutations. Which of them are transversion mutations?
II III I
A mutation in a gene may affect the phenotype of the organism in a way that is ______ for its survival.
either beneficial, harmful, or neutral
Which of the following base changes are transversion mutations?
A to T A to C G to C
This figure best illustrates what type of mutation?
base substitution
True or false: The phenotypic effects of a mutations are either detrimental or neutral.
False
A mutation that results in a premature termination of the synthesis of a polypeptide is called a(n) ___ mutation.
nonsense
A(n) ___ is a type of base substitution that involves a change of a pyrimidine to another pyrimidine, or a purine to another purine.
transition
A base substitution in which a purine and a pyrimidine are interchanged is called a(n) ___ mutation.
transversion
Mutations that occur in a promoter sequence can be divided into two types: ___ promoter mutations increase the transcription rate, while ___ promoter mutations decrease it.
up; down
In a natural population, a ___-___ genotype is the most common one.
wild-type
