Mutations Activity Biology Worksheets

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Mutations Activity
Introduction: DNA is genetic material made of nucleotides. Last unit we saw how proteins were created
through transcription (DNAmRNA) and translation (mRNAlinked amino acids). However, in this unit we
want to see how those processes can “go wrong” and create mutations. In this activity you will investigate a
gene mutation in which there is a change in one nucleotide. This can be a point mutation called a substitution,
where a base pair is “swapped” with the incorrect base. Or it can be an insertion or deletion: which will cause a
frameshift mutation. You will see how these changes affect the way the message is transcribed to RNA and
translated to protein. Explore the effects of gene mutations.
Concepts: By the end of this lab you should
-be refreshed on transcription and translation
-understand how a point mutation can alter a gene
-understand the different types of point mutations
Background:DNA is an example of a complex biological polymer called a nucleic acid, which is made up of
small subunits called nucleotides. There are four possible nitrogen bases in DNA—adenine (A), guanine (G),
cytosine (C), and thymine (T). The nitrogen bases will preferentially bond with only one other nitrogenous
base–adenine with thynine and guanine with cytosine. The bonded nitrogen bases are called a base pair. This
DNA is used to complete protein synthesis.
During protein synthesis at the ribosome, mRNA sequences are read and translated into amino acids.
Another area of the tRNA transports a specific amino acid. The amino acids are linked together into chains by
enzymes to form proteins.
Depending on the DNA sequence The 20 amino acids are brought to the ribosomes by transfer RNA
(tRNA). An infinite variety of proteins can be formed from the 20 amino acids, which can occur in any number
and in any order.
These amino acids are specified by codons (or three nucleotides in a row on mRNA). If the mRNA is
copied incorrectly during transcription a mutation will occur. A gene mutation is a change in a single base pair
of a gene. Point mutations, or single nucleotide polymorphisms (SNPs), involve only one nitrogen base change
of the three nitrogen bases in a codon. Perform this activity and witness the change a single gene mutation in the
DNA can have on a resulting protein.
Pre-lab Questions
1. This lab shows the effect of point mutations, which will cause a gene mutation (only effects one gene).
What is the difference between this and a chromosomal mutation?
2. Describe each of the mutations:
a. Substitution
b. Insertion
c. Deletion
3. Write the correct type of mutation that occurred in creating the mRNA strand for each of the following
examples. Original DNA: ATCCGCTTACG
a. UUGGCGAAUCG: __________________
b. UATGGCGAAUCG: _________________
c. UGGCGAAUCG: ___________________

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