BIOTECHNOLOGY OJddddddddddhfhjllT 7.pptx

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1. TYPES OF GENE MUTATION

2. At the end of the lesson, the students must be able to: Explain the different types of gene mutation (frameshift and point mutation). Participate in the class activities and class discussion Take and pass the mastery level of 75% OBJECTIVES

3. In the previous learning activity, you learn that causes of mutation can either be in two reasons. First if the DNA fails to copy accurately and second if there are external influences that can trigger it to happen. Knowing the causes of mutation and having an idea of what is it all about, this time you will learn the types of gene mutation and some of its examples.

4. The first type of gene mutation is known as the frameshift mutation. A frameshift mutation involves the insertion or deletion of a nucleotide in which the number of deleted base pairs is not divisible by three. "Divisible by three" is important because the cell reads a gene in groups of three bases. Each group of three bases corresponds to one of 20 different amino acids used to build a protein. If a mutation disrupts this reading frame, then the entire DNA sequence following the mutation will be read incorrectly.

5. It is the second type of gene mutation that happens when a single base pair is altered. Point mutations can have one of three effects. First, the base substitution can be a silent mutation where the altered codon corresponds to the same amino acid. Second, the base substitution can be a missense mutation where the altered codon corresponds to a different amino acid. Or third, the base substitution can be a nonsense mutation where the altered codon corresponds to a stop signal. Point mutation

6. Activity 1: Picture Analysis

7. Describe what is the picture all about? ____________________________________________________________________ ____________________________________________________________________ In what way point gene mutation sequence is different from normal DNA sequence? Explain your answer. ____________________________________________________________________ ____________________________________________________________________

8. 3. Describe what is the picture all about? ____________________________________________________________________ ____________________________________________________________________ 4. In what way frameshift mutation sequence is different from normal DNA sequence? Explain your answer. _______________________________________________________________________ _______________________________________________________________________

9. Frameshift Mutation and Point Mutation Frameshift mutations are among the most deleterious changes to the coding sequence of a protein. They are extremely likely to lead to large-scale changes to polypeptide length and chemical composition, resulting in a nonfunctional protein that often disrupts the biochemical processes of a cell. Frameshift mutations can lead to a premature end to translation of the mRNA as well as the formation of an extended polypeptide.

10. The amino acid sequences downstream of the frameshift mutation are also likely to be chemically distinct from the original sequence. When such errors occur, the cell often perceives the lack of functional protein and tries to compensate by upregulating the expression of the mutated gene. This can even overwhelm the translation machinery of the cell, result in a large number of misfolded proteins that could eventually lead to large-scale impairment of all functions or even cell death.

11. Diseases caused by frameshift mutations in genes include Crohn’s disease, cystic fibrosis, and some forms of cancer. On the other hand, when some proteins become dysfunctional, they could have a protective effect, as seen in the resistance to HIV in people with a chemokine receptor gene (CCR5) containing a frameshift mutation. Since frameshift mutations are usually changes to the genetic material in every cell, it is rare to find a cure.

12. A point mutation is a type of mutation in DNA or RNA, the cell’s genetic material, in which one single nucleotide base is added, deleted or changed. DNA and RNA are made up of many nucleotides. There are five different molecules that can make up nitrogenous bases on nucleotides: cytosine, guanine, adenine, thymine (in DNA) and uracil (in RNA), abbreviated C, G, A, T, and U respectively. The specific sequence of nucleotides encodes all the information for carrying out all cell processes.

13. In general, a mutation is when a gene is altered through a change in DNA structure; this may refer even to entire sections of chromosomes. A point mutation is specifically when only one nucleotide base is changed in some way, although multiple point mutations can occur in one strand of DNA or RNA.

14. Activity 2: Types of Gene Mutation A. Directions: Using the information learned from the readings above, complete the following statements and look for the hidden message. Clue: The hidden message contains either the first or second consonant and vowel of the answers . Changes to polypeptide length results to nonfunctional protein that disrupts ______________ processes of the cell. DNA or RNA is considered as the cell´s ___________ material. When some proteins become dysfunctional, they could have a protective effect as seen in the resistance to ______ in people. Frameshift ________ can lead to a premature end to translation of the mRNA as well as the formation of an extended polypeptide. A ________ mutation is specifically when only one nucleotide base is changed in some way. 6. The cell often perceives the lack of functional _______ and tries to compensate by upregulating the expression of the mutated gene. 7. Diseases caused by frameshift mutations in genes include Crohn’s disease, ______ fibrosis, and some forms of cancer. HIDDEN MESSAGE: ___________________________________________

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