(SCIENCE) Mutations-that-occur-in-sex-cells.pptx

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1. Mutations that occur in sex cells as being heritable

2. Mutation Is the change in genetic material. It can be a source of beneficial genetic variation or it may have dangerous effects. Mutations can result from DNA copying mistakes made during cell division, and the exposure to ionizing radiation like gamma rays from radioactive elements such as Uranium and Plutonium.

3. Another case of mutation DNA copying mistakes is direct exposure to chemicals or through infections by bacteria and viruses. The different types of agents, whether they are in the form of physical or chemical that can cause the alteration of the structure of sequence of DNA, are called mutagens

4. Mutations occurring in Sex cells Mutations that occur in sex cells can be passed from parent to their children. Chromosomes carry information about the characteristics inherited from parents. Chromosome is made up of a chemical substance called DEOXYRIBONUCLEIC ACID or DNA

5. Types of Mutation Chromosomal mutations any change in the number or structure of a chromosome. Gene mutation only a single gene is affected which happens during the replication of DNA.

6. Most of the cells in the body contain 23 pairs of chromosomes (46 sets of chromosomes) The sex cells contain half this number. When a sperm and egg cell unite, the fertilized egg ends up with 46 chromosomes, which are 23 chromosomes from each parent. The chromosome contains many genes that determine a single trait. Genes are the basic unit of heredity.

7. Somatic and Germinal Mutation Eukaryotic organisms (cells with nucleus), such as mammals, humans, etc. have two primary cell types: the germ and the somatic. Germ cells – (reproductive cells such as egg and sperm) Somatic cells – (cells that are not reproductive cells) 22 pairs of chromosomes

8. Somatic and Germinal Mutation Mutation in somatic cells is called somatic mutation. It occurs in non-reproductive cells and will not be passed onto the offspring; mutation will not be passed along to the next offspring by sexual means. Germinal mutation is an alteration of the nucleotide sequence of the DNA that makes up a gene. The germ cells give rise to sex cells that will carry the mutations when successful mating happens.

9. Human Female

10. Chromosomal Mutations Chromosomal mutations are departures from what is normal or desirable set of chromosomes either for an individual or a species. It refers also to changes in the number of sets of chromosomes (ploidy) and changes in the number of individual chromosomes ( somy ) and their appearance. There are several kinds of chromosomal mutations

11. Chromosomal Mutations 1. Insertion is a genetic material added from another chromosome.

12. 2. Translocation happens when part of a chromosome breaks off and is combined to another chromosome. This type of disorder is due to chromosomal-level mutation.

13. 3. Deletion happens when there is loss of part of a chromosome. Ex. Cri du chat

14. 4. Duplication happens if there are extra copies of part of a chromosome.

15. 5. Inversion happens when the direction of a part of a chromosome is reversed.

16. Genetic Disorders Recessive Disorders – happen when child receives two defective genes from each parent. A person who receives one defective recessive gene is called a carrier.

17. Sex-linked Disorders Are more common in men because they have only one X chromosome, so all defective genes on the chromosome will be expressed. A woman who has this kind of disease may pass it on to her children. The most common sex-linked disorder is color blindness and hemophilia.

18. 3. Human Genetic Syndromes There are some genetic disorders that are caused by having few or too much chromosomes.

19. Cri du chat syndrome is caused by the deletion of part of the short arm of chromosome 5. Babies who have this disease have wide-set eyes and a small head and jaw.

20. Cri du chat karyotype

21. William Syndrome is the result from the loss of a segment in chromosome 7 . They have large ears and facial features that make them look like elves.

22. Down syndrome (trisomy 21 ) is known as mongolism. A child receives an extra chromosome (Chromosome 21) and has a distinctive appearance.

23. Down syndrome Karyotype

24. Edward Syndrome (trisomy 18) happens when there is an extra number 18 chromosome . It shows mental retardation and physical abnormalities to the child and can live beyond one year.

25. Patau syndrome (trisomy 13) is caused by an extra copy of the number 13 chromosome. Based on the study, about 90% of babies with this syndrome do not survive in infancy, severe mental-retardation occurred to those who survive.

26. Klinefelter syndrome (XXY) is another genetic disorder. A male who has this syndrome has two or more X chromosomes in addition to their Y-chromosomes . They lack facial hair and their testes including prostate gland are underdeveloped.

27. Turner syndrome is characterized by having 45 chromosomes. About 96-98% do not survive birth

28. Impact of Mutation on Phenotype PHENOTYPE is the observable trait of a person, phenotype examples include earwax type, height, blood type, eye color, freckles, and hair color.

29. Impact of Mutation on Phenotype Mutations of the chromosomes directly affect the genes, which can cause human genetic disorders. The gene can no longer do its tasks normally once it breaks up due to mutation. Gene mutation has a great impact on the organism. For instance, substitution occurs in a coding region of DNA. If substitution happens, the enzymes are not able to bind their substrate; the mutation directly affects protein folding thus damaging the protein’s function. There are also a premature stop codon.

30. POINT MUTATION A point mutation occurs in a genome when a single base pair is added, deleted or changed. While most point mutations are benign, they can also have various functional consequences, including changes in gene expression or alterations in encoded proteins.

31. SICKLE CELL ANEMIA Is a genetic blood disorder. A person who inherits two defective genes will have normally shaped red blood cells and may die at an early stage. TAY-SACHS DISEASE is characterized by the lack of an important chemical in the brain. Infants who have this kind of disease usually die within their first five years.

32. PHENYLKETONURIA OR PKU is a rare genetic disorder that can cause serious mental retardation in infants. An Infant who have this kind of disorder cannot breakdown phenylalanine. CYSTIC FIBROSIS is a disease in which some glands produce too much mucus that it clogs and damages the lungs. This disease is fatal among children because it causes difficulty in breathing.

33. OKAY PO!

34. POINT MUTATION

35. NONSENSE MUTATIONS  occur when a premature nonsense or stop codon is introduced in the DNA sequence. When the mutated sequence is translated into a protein, the resulting protein is incomplete and shorter than normal. Consequently, most nonsense mutations result in nonfunctional proteins.

36. A nonsense mutation occurs when one nucleotide is substituted and this leads to the formation of a stop codon instead of a codon that codes for an amino acid. A stop codon a certain sequence of bases (TAG, TAA, or TGA in DNA, and UAG, UAA, or UGA in RNA) that stops the production of the amino acid chain. It is always found at the end of the mRNA sequence when a protein is being produced, but if a substitution causes it to appear in another place, it will prematurely terminate the amino acid sequence and prevent the correct protein from being produced.

37. Like a nonsense mutation, a missense mutation occurs when one nucleotide is substituted and a different codon is formed; but this time, the codon that forms is not a stop codon. Instead, the codon produces a different amino acid in the sequence of amino acids. For example, if a missense substitution changes a codon from AAG to AGG, the amino acid arginine will be produced instead of lysine. A missense mutation is considered conservative if the amino acid formed via the mutation has similar properties to the one that was supposed to be formed instead. It is called non-conservative if the amino acid has different properties that structure and function of a protein.

38. Missense mutation happens when a point of mutation, In which a single nucleotide changes, results to different codes of amino acid. GENETIC CODES

39. In a silent mutation , a nucleotide is substituted but the same amino acid is produced anyway. This can occur because multiple codons can code for the same amino acid. For example, AAG and AAA both code for lysine, so if the G is changed to an A, the same amino acid will form and the protein will not be affected.

40. Gene mutation sometimes do not affect an organism’s phenotype due to many codon codes for the same amino acid. A mutation that has no effect on the protein is called silent mutation . Most amino acids of silent mutation are encoded by many different codons. For instance, if the third base in the TCT codon for serine becomes different to any one of the other bases, it can still be encoded.

41. It is called a silent mutation since there is no change or the product cannot be detected without sequencing the gene.

42. Impact of Mutations on Offspring Mutations occurs in the body cells and in germ cells. Mutations in body cells damage only the organisms in which they occur, while germ cells, mutation may be passed on to the offspring. In some cases, mutation results in a more beneficial phenotype due to being favored by natural selection and increase in population.

43. Causes of mutations Smoking can raise risks of genetic mutation Effects of old age on offspring Chemotherapy External Influences – chemicals and radiations