2. WHAT IS A MUTATION?  A mutation is a permanent change in the DNA sequence of a gene. Alters the amino acid sequence of the protein encoded by the gene.

3.  MISTAKES……… when?  Replication  Crossing over  Meiosis

4. MUTATIONS IN REPLICATION OCCUR THROUGH ONE OF TWO PROCESSES: Mistakes that occur when a cell copies its DNA in preparation for cell division. http://learn.genetics.utah.edu/archive/sloozeworm/mutationbg.html

5. MUTATIONS FROM ENVIRONMENTAL AGENTS OCCUR THROUGH ONE OF TWO PROCESSES: DNA damage from environmental agents such as ultraviolet light (sunshine), nuclear radiation or certain chemicals EFFECT? A protein that functions differently

6. MUTATIONS – any change in the genetic composition of an organism Telematics 2013 Compiled by CG Oppelt 6

7. Like words in a sentence, the DNA sequence of each gene determines the amino acid sequence for the protein it encodes. Thesunwashotbuttheoldmandidnotgethi shat. = GENE The sun was hot but the old man did not get his hat.

8.  The DNA sequence is interpreted in groups of three nucleotide bases, called codons. Each codon specifies a single amino acid in a protein. triplet amino acid

9. SOURCES OF GENOTYPIC VARIATION Meiosis ReproductionMutations Crossing over during phase Prophase Random arrangement of chromosomes during phase Metaphase Fusion of many types of sperm cells and egg cells can produce many different types of offspring Gene mutations Alteration in the sequence of nitrogenous bases on DNA Chromosome mutations Extra chromosomes added  One or more sets of chromosomes are added (a)Lethal: the mutated organism dies and the harmful characteristics are not passed on to the next generation (b) Neutral: has no effect on the structure and functioning of the organism (c) Fixed: advantageous/sometimes the advantageous mutation wipes out all the other alleles controlling the same characteristic within the population Outbreeding

10. Outbreeding  /Gene flow Random assortment  /segregation/ recombination of chromosomes during meiosis in the formation of gametes OR meiosis  Crossing over  Chance/random fertilisation of gametes  /sexual reproduction Mutation 

11.  Mutations Molecular – changes gene: lethal, neutral, established/fixed Cellular – change to karyotype.

12. Telematics 2013 Compiled by CG Oppelt 12

13. 1. POINT MUTATION Telematics 2013 Compiled by CG Oppelt 13

14. Let’s write the DNA base triplets as three- letter words: Telematics 2013 Compiled by CG Oppelt 14

15. Let’s write the DNA base triplets as three- letter words: Telematics 2013 Compiled by CG Oppelt 15

16. Telematics 2013 Compiled by CG Oppelt 16

17. Telematics 2013 Compiled by CG Oppelt 17

18. Telematics 2013 Compiled by CG Oppelt 18

19.  WHEN MEIOSIS GOES WRONG Any change in the CHROMOSOME NUMBER or STRUCTURE Causes a change in the KARYOTYPE of a cell Telematics 2013 Compiled by CG Oppelt 19

20. 20 Telematics 2013 Compiled by CG Oppelt

21. Trisomy 21  Chromosomes of homologous pair 21 do not separate during meiosis  One gamete (♀) may have two chromosomes for chromosome 21 and the other (♀) does not have a chromosome 21. Telematics Life Sciences 2011 21

22.  Fertilisation: 2 x 21 (♀) + 1 x 21 (♂) = 3 x chromosomes 21  Extra chromosome 21 (trisomy) - baby  This process is called non- disjunction (failure to separate ) Telematics Life Sciences 2011 22 +

23. Telematics Life Sciences 2011 23

24. 24 Homologous chromosomes do NOT separate – Anaphase I Chromatids of single chromosomes do NOT separate – Anaphase II

25. 25 3 x chromosome 21- trisomy Telematics 2013 Compiled by CG Oppelt

26. Telematics Life Sciences 2011 26 3 sex chromosomes – XXY Trisomy - XXY

27. Telematics Life Sciences 2011 27 female has 1 X chromosome – monosomy Monosomy - X0

28. HOW DOES THIS OCCUR? Telematics 2013 Compiled by CG Oppelt 28  During Meiosis I, a homologous pair on chromosome pair number 21  did not separate / During Meiosis II a chromosome did not separate  As a result of non-disjunction during Anaphase I/ Anaphase II  And resulted in an extra chromosome /3 chromosomes  On chromosome pair number 21  Known as Trisomy 21/ Down Syndrome