8 - Mutations SBI4U – Molecular Genetics

Date: ______

Mutations

  • A mutation is a change in______
  • Mutations are a natural process that changes a ______
  • Mutations in DNA sequences generally occur through one of two processes:
  • DNA damage from ______agents such as ______or ______radiation or certain ______
  • Mistakes that occur when a cell ______its DNA in preparation for cell division
  • Ultraviolet light, nuclear radiation, and certain chemicals can damage DNA by ______nucleotide bases so that they ______like other nucleotide bases

  • When the DNA strands are separated and copied, the altered base will pair with an ______and cause a ______
  • In the example, a “______" G now pairs with T, instead of forming a normal pair with C
  • Environmental agents such as nuclear radiation can ______DNA by ______the bonds between oxygen and phosphate groups

  • Breaking the phosphate backbone of DNA within a gene creates a ______form of the gene
  • It is possible that the mutated gene will produce a protein that functions ______
  • Cells with broken DNA will attempt to fix the broken ends by ______these free ends to other pieces of DNA within the cell
  • This creates a type of mutation called “______”
  • If a ______breakpoint occurs within or near a gene, that gene's function may be affected

  • Mutations result when the DNA Polymerase III makes a mistake, which happens about once every ______bases
  • The number of mistakes that remain incorporated into the DNA is even lower than this because cells contain special ______that fix many of the mistakes in the DNA that are caused by ______
  • The repair proteins see which nucleotides are paired incorrectly, and then change the wrong base to the right one

Types of Mutations

  • A gene is essentially a sentence made up of the bases ______that describes how to make a protein
  • Any changes to those instructions can ______the gene's meaning and ______the protein that is made, or ______a cell makes that protein
  • There are many different ways to alter a gene, just as there are many different ways to introduce ______into a sentence

Point Mutations

  • A point mutation is a simple change in ______base of the gene sequence
  • This is equivalent to changing ______letter in a sentence
  • Example: change the 'c' in cat to an 'h'

Frame Shift Mutations

  • In a frame shift mutation, one or more bases are ______or ______, the equivalent of adding or removing letters in a sentence
  • Because our cells read DNA in ______letter “______", adding or removing one letter changes each subsequent word
  • Generally result in a ______protein
  • This type of mutation can make the DNA ______and often results in a ______
  • Example: the 't' from cat is removed, but we keep the original letter spacing

Deletion Mutations

  • Mutations that result in ______DNA are called deletions
  • These can be small, such as the removal of just one “______," or longer deletions that affect a large number of ______on the chromosome
  • Deletions can also cause ______mutations


Insertion Mutations

  • Mutations that result in the ______of extra DNA are called insertions
  • Insertions can also cause ______mutations

Inversion Mutations

  • In an inversion mutation, an entire section of DNA is ______
  • A small inversion may involve only a few ______within a gene, while longer inversions involve large regions of a chromosome containing several ______

DNA Expression Mutations

  • There are many types of mutations that change not the protein itself but ______and ______much of a protein is made
  • These types of changes in DNA can result in proteins being made at the ______or in the ______
  • Changes can also occur that result in too much or too little of the protein being made

Page 4 of 4