Genetic Mutations Exam |18
Questions and Answers
Substitution mutation - -An incorrect nucleotide (base) is put in place of
another nucleotide in the DNA sequence.
- Insertion and deletion mutations are said to cause shifts in the "reading
frame" (the sets of three nucleotides) of the mRNA. Substitution mutations
do not cause these so-called 𝙛𝙧𝙖𝙢𝙚𝙨𝙝𝙞𝙛𝙩𝙨. Explain why insertions and deletions
are called frameshift mutations, using the terms reading frame, codons, and
amino acids in your answer. - -The mRNA is read in groups of three
nucleotides, called codons. You start reading in groups of three when you
see a start codon (AUG). This start codon sets the reading frame, (i.e., the
view through which you read groups of three). If a nucleotide is inserted into
the mRNA or removed from it, the groups of three are redefined from that
point onward. In other words, the reading frame shifts. Because there is now
a new sequence of codons, there will be a new sequence of amino acids,
since each codon codes for a specific amino acid.
- A gene mutation is a change in the sequence of nucleotides that occurs
during cell replication (mitosis and meiosis) within a single coding section of
DNA. Mistakes can also occur in the transcription of mRNA or the translation
of a polypeptide. However, these changes are not considered to be
mutations, because they are not permanent changes to the cell. Explain why
"mistakes" in transcription or translation are not as serious as mutations in a
gene. - -A mutation in DNA would be passed on to any daughter cells that
are produced from that cell. The polypeptides produced from the mutated
mRNA are not replicated in the daughter cells, so a mistake in translation
would not be carried into the daughter cells.
- Why is only a tiny subset of these mutations passed on to our children? - -
In order to be passed on to the next generation, mutations must be present
in egg or sperm. Errors that accumulate in skin or liver cells of a parent will
not be passed on to the child.
- If each cell has multiple mutations, why do most of us have normally-
functioning tissues and organs? - -Most of us have normally-functioning
tissues and organs because one, proofreading enzymes catch these
mutations. But when they don't catch them, the mutations are so small it is
unlikely that they will affect anything. To add on, not all mutations are bad.
There are positive, negative and neutral mutations so not all of these will
harm you. Furthermore, the only way mutations can be passed on due to
sexual reproduction is mutations in the reproductive cells.
Questions and Answers
Substitution mutation - -An incorrect nucleotide (base) is put in place of
another nucleotide in the DNA sequence.
- Insertion and deletion mutations are said to cause shifts in the "reading
frame" (the sets of three nucleotides) of the mRNA. Substitution mutations
do not cause these so-called 𝙛𝙧𝙖𝙢𝙚𝙨𝙝𝙞𝙛𝙩𝙨. Explain why insertions and deletions
are called frameshift mutations, using the terms reading frame, codons, and
amino acids in your answer. - -The mRNA is read in groups of three
nucleotides, called codons. You start reading in groups of three when you
see a start codon (AUG). This start codon sets the reading frame, (i.e., the
view through which you read groups of three). If a nucleotide is inserted into
the mRNA or removed from it, the groups of three are redefined from that
point onward. In other words, the reading frame shifts. Because there is now
a new sequence of codons, there will be a new sequence of amino acids,
since each codon codes for a specific amino acid.
- A gene mutation is a change in the sequence of nucleotides that occurs
during cell replication (mitosis and meiosis) within a single coding section of
DNA. Mistakes can also occur in the transcription of mRNA or the translation
of a polypeptide. However, these changes are not considered to be
mutations, because they are not permanent changes to the cell. Explain why
"mistakes" in transcription or translation are not as serious as mutations in a
gene. - -A mutation in DNA would be passed on to any daughter cells that
are produced from that cell. The polypeptides produced from the mutated
mRNA are not replicated in the daughter cells, so a mistake in translation
would not be carried into the daughter cells.
- Why is only a tiny subset of these mutations passed on to our children? - -
In order to be passed on to the next generation, mutations must be present
in egg or sperm. Errors that accumulate in skin or liver cells of a parent will
not be passed on to the child.
- If each cell has multiple mutations, why do most of us have normally-
functioning tissues and organs? - -Most of us have normally-functioning
tissues and organs because one, proofreading enzymes catch these
mutations. But when they don't catch them, the mutations are so small it is
unlikely that they will affect anything. To add on, not all mutations are bad.
There are positive, negative and neutral mutations so not all of these will
harm you. Furthermore, the only way mutations can be passed on due to
sexual reproduction is mutations in the reproductive cells.
