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The genes encoded in your DNA result in the production of proteins that perform specific functions within your cells. Various environmental factors and spontaneous events can lead to changes in genes. These changes, called mutations, can lead to alterations in the structure and activity of the proteins your cells use in their daily activities. In other words, changes to your genotype can result in changes to your phenotype. We all have mutations in most of our body cells—yet we are, for the most part, normal and functional human beings.
Mutations are the source of all new alleles in nature. Variations in alleles lead to variations in organisms within a population. Positive mutations lead to the organism having a better chance of survival, which means the mutation may be passed on to the offspring. Negative mutations may lead to an early death— probably before the organism can produce offspring. Therefore, changes in alleles from one generation to another form the basis of evolution.
Genetic Mutation POGIL Answers
How many nucleotides are a part of a codon?
3
Does an mRNA sequence that codes for “stop” actually count as an amino acid?
no
What is the result of a substitution mutation?
ONE codon changes which causes ONE amino acid to be different from the normal amino acid sequence
What is an insertion mutation?
An additional nucleotide is inserted in the normal sequence, which lengthens the sequence
What is a deletion mutation?
An existing nucleotide is removed in the normal sequence, which shortens the sequence
Would all substitution mutations lead to a change in the amino acid sequence?
No because if the last letter in a codon changed, the same amino acid is expressed than if the last nucleotide had not been changed.
Would all insertion or deletion mutations lead to a change in the amino acid sequence?
Yes because any new nucleotide that is inserted / deleted shifts the nucleotides, changing the letters of multiple codons.
Would a substitution or insertion mutation pose more damage (or a greater benefit) to an organism?
Insertion because it has the potential to change a majority of the normal amino acid sequence, as the reading frame shifts.
Would a deletion mutation at the beginning of a DNA sequence or at the end pose more damage (or a greater benefit) to an organism?
The beginning because the codons following would all change, whereas a deletion mutation at the end would not affect the codons that were present before.
What is the range of changes in the amino acid sequence that can result from a substitution mutation?
One amino acid may change but the others can remain the same; the amino acid sequence may be stopped too early; no protein will be translated because of a lack of a start codon
Gene mutations can be _____ or ______
misense or nonsense
Gene mutations can be ______ or ______ or _______
positive, negative, neutral
What are misense mutations?
An amino acid is still produced but the wrong amino acid is produced
What are nonsense mutations?
No amino acid is produced; causes a stop codon to occur
What is a neutral mutation?
The sequence is mutated but the same amino acid sequence is produced as the “normal” one
What is a positive mutation?
The mutation somehow benefits the cell
What is a negative mutation?
The mutation somehow harms the cell
What is the source of new alleles in nature?
Mutations
Which types of mutations, positive, negative, or neutral, are most likely to be seen in offspring several generations after the mutation occurred?
Neutral or positive because those help an organism survive and are passed on through generation.
Is a positive mutation inside a single bacteria cell likely to be passed on to the offspring of an organism?
Yes, because bacterial replication produces an offspring that is genetically identical to the parent. Also, positive mutations are favored in nature.
Is a positive mutation on a skill cell on a cat likely to be passed on to the offspring of an organism?
No because a skin cell is not involved in replication.
Is a positive mutation on a sperm cell in a whale likely to be passed on to the offspring of an organism?
Yes because this mutation could be passed through replication (meiosis)
If each cell has multiple mutations, why do most of us have normally-functioning tissues and organs?
Not all mutations are bad!
Why is only a tiny subset of mutations that we have passed on to our children?
Only mutations in the egg and sperm cell are passed down
Why are negative mutations in transcription or translation not as serious as mutations in a gene?
The mutations don’t change the DNA itself but rather an RNA molecule or a protein
What are insertion and deletion mutations also called?
Frameshift mutations
What is the reading frame?
Sets of three nucleotides of mRNA
1. When did Hershey and Chase find radioactivity inside the bacterial cells?
only when the phage DNA contained radioactive phosphurus
2. Which result did Frederick Griffith observe in his experiments?
forms
3. What did Oswald Avery learn from his experiments?
No bacterial information occurred when DNA was destroyed
4. What did Avery conclude was the transforming principle?
DNA
5. What kind of molecule did most scientists in the early 1900s think carried genetic material?
Protein
1. What is the term that describes a unit made of a sugar, a phosphate group, and a nitrogen-containing base?
nucleotide
4. What did Rosalind Franklin’s DNA x-ray suggest?
It was a double helix
During replication the other strand of DNA serves as a——
template
What is the goal of DNA replication?
To make sure each new cell has a complete set of DNA
3. What is the function of DNA polymerase?
to bond nucleotides together
4. What feature of replication ensures that DNA is copied quickly?
copied in thousands of places
5. How does a cell ensure that no errors are introduced during replication?
DNA polymerase proofreads and corrects the new DNA
1. What molecule carries information from a gene to the ribosomes?
Mrna
1. What molecule carries the amino acid coded by mRNA to the ribosome?
Trna
2. How many bases code for a single amino acid?
3
4. What happens if the mRNA reading frame is changed?
the amino acid sequence of the resulting protein changes
5. What forms the peptide bonds that link amino acids in a protein?
the ribosome
one base substitute
point mutation
deleted or added base
frameshift mutation
added base pair
Insertion
deleted base pair
deletion
results from an unequal crossing over
gene duplication
translocation
caused by the exchange of DNA segments bewtween non-homologous chromosomes
silent
no change in amino acids
missense
1 amino acid change
nonsense
premature stop codon
codon
set of three nucleotides
What type of mutation is a translocation?
chromosomal mutation
2. How many bases are affected in a point mutation?
1
no
is the stop codon coded for an amino acid
the codon changes which sometimes changes the amino acid that it was originally coded for
what are the effects of a substitution mutation
all letters move to the right one and the reading frame gets longer; possibility of new amino acids
what are the affects of an insertion mutation
all letters move to the left one and the reading frame gets shorter; possibility of new amino acids
what are the affects of an deletion mutation
substitution
mutation where two bases are switched
insertion
mutation where a base is added and your reading frame gets longer
deleted
mutation where a base is removed and your reading frame becomes shorter
true
T or F: there can be more than one codon for one amino acid
insertion/deletion
which type of mutation causes the most damage
no translation= no protein made
no start codon=
met
start codon
start codon
what must be present for translation to occur and for amino acids to be formed
better chances of survival
positive mutations lead to
gamete cells
which types of cells are mutations most commonly passed through
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