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Mutations Hollywood’s images of mutation.

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Presentation on theme: "Mutations Hollywood’s images of mutation."— Presentation transcript:

1 Mutations Hollywood’s images of mutation

2 Mutations Actual Mutations in fruit flies

3 What is a mutation? A mutation is any change in a cell’s DNA
A mutation can occur in an individual gene - results in a single changed protein - cystic fibrosis a mutation in the protein that makes a type of ion channels in cell membrane - bacterial resistance to antibiotics is an example of a beneficial gene mutation

4 What is a mutation continued
A mutation can occur in a chromosome - a chromosome contains many genes - chromosomal mutations affect many proteins If a mutation occurs in a sex cell, the mutation will be passed to offspring Examples: Down Syndrome Edward’s Syndrome Cri-du-Chat

5 What Causes Mutations? Environment: Can be caused by mutagens- a physical or chemical cause of mutation. Examples: UV light, radiation, drugs, and benzene. Mutagens are often also carcinogens – anything that causes cancer Can be natural, random events. - mutations occur in 1/100,000 DNA replications (DNA mistakes) Mutations do not have to be bad (evolution)

6 Gene Mutations

7 Point Mutations A single nucleotide is altered. Can change one amino acid in a protein Milk – Mile GGACAATCA GGACCATCA proline -valine-serine proline-glycine-serine ***ONLY ONE AMINO ACID IS AFFECTED AS A RESULT OF POINT MUTATIONS!***

8 Frameshift Mutations A nucleotide is either inserted or deleted from a gene. -all of the triplets from the point of mutation onward will be changed

9 Frameshift Mutations Insertion
An insertion occurs when a nucleotide is added to a gene Example: A nucleotide is inserted The fat cat ate the rat The faa tca tat eth era t -the extra nucleotide shifts all of the triplets that follow

10 Frameshift Mutations Deletions
A deletion occurs when a nucleotide is removed from a gene. Example: A nucleotide is removed The fat cat ate the rat Thf atc ata tet her at

11 proline -valine-serine arginine-cysteine-stop Deletion
Insertion GGACAATCA GCGACAATCA proline -valine-serine arginine-cysteine-stop Deletion GGACAATCA GGAAATCA proline -valine-serine proline-leucine

12 Deletion Example: Cri du chat syndrome
Due to a deletion of part of the short arm of chromosome 5 Occurrence: 1/50,000 births Crying babies sound like cats; mental disability Death by about 4 years

13 Chromosome Mutations

14 KARYOTYPES Kary = nucleus
Karyotype = chart of metaphase chromosome pairs arranged according to length and location of the centromere Used to pinpoint unusual chromosome numbers in cells

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16 Nondisjunction Sometimes during meiosis, the homologous chromosomes fail to separate properly This can result in two types of chromosomal mutations: (1) trisomy (have an extra set of chromosomes) (2) monosomy (missing one set of chromosomes)

17 XYY Syndrome

18 Turner’s Syndrome

19 Down’s Syndrome

20 Klinefelter syndrome: 47, XXY males, sterile, feminine body characteristics. Normal intelligence.

21 Edward’s syndrome (trisomy 18):occurs in 1:6000 or 1:8000 live births; very few survive birth.

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