Downloaded 17 times
Uploaded byRobin Seamon
Human Genomics1: Karyotypes and Mutations
Karyotypes show the number and structure of chromosomes in an individual. The human karyotype contains 23 pairs of homologous chromosomes, including 22 pairs of autosomes and one pair of sex chromosomes. Abnormal karyotypes can result in genetic disorders due to an extra or missing chromosome. Mutations, such as substitutions, duplications or deletions in DNA, can also cause genetic disorders if they change the amino acid sequence of a protein.
More Related Content
Similar to Human Genomics1: Karyotypes and Mutations
![TOPIC-16-REVISION.pptx [Autosaved].pptx](https://cdn.slidesharecdn.com/ss_thumbnails/topic-16-revision-221104125847-33bbc1f2-thumbnail.jpg?width=640&height=640&fit=bounds)
More from Robin Seamon
Human Genomics1: Karyotypes and Mutations
- 1.
- 2. Karyotype- • an organizedprofile of chromosomes • arranged and numbered by size from largest to smallest
- 3. HUMAN KARYOTYPE • 23PAIRS of chromosomes called homologous chromosomes • 1 chromosome from each parent • That makes 46 total chromosomes
- 4. HUMAN KARYOTYPE • autosomes- chromosomes1-22 • sex chromosomes • chromosome 23 • X = female • Y = male
- 5. Karyotypes show us… •sex of the individual • genetic disorders caused by too few or too many of a chromosome
- 6. Nondisjuction too many ortoo few chromosomes are caused by a mistake in meiosis
- 7. Trisomy-21 • three of#21 • likelihood of Downs Syndrome increases with mother’s age DOWNS SYNDROME
- 8. • delayed physical andmental development • flattened face & eyes slanted upward
- 9. Female with a singleX • ovaries do not develop • do not mature sexually TURNER SYNDROME
- 10. Male with anextra X • less facial hair and muscles • no sperm KLINFELTER SYNDROME
- 11. Mutations- • a changein the DNA • causes changes in genetic code • can be… • an entire chromosome • in any cell • harmless, beneficial or harmful • lead to genetic variation • EXAMPLE: PTC tasters/non-tasters
- 12. PTC tasters &non- tasters • some people can taste this bitter chemical while others cannot • it’s genetic • tasters & non-tasters have slightly different receptors (proteins) on taste buds for bitter taste
- 13. CCG and CCG GTAand CCG GTA and GTA Tasters Medium Tasters Non-Tasters A change in DNA causes • change in the protein • which causes a change in function
- 14. Gene Mutations • mayinvolve large areas of DNA or a single nucleotide • Point Mutation (of a single nucleotide) • substitution • duplication • deletion • mutation can code for the wrong amino acid, leading to difference in function
- 15. What is themRNA codon that would pair with a DNA sequence of CTC? The paired mRNA codon is GAG What is the amino acid that it receives? glutamic acid THIS IS WHAT HAPPENS IN A NORMAL CELL SICKLE CELL ANEMIA TAKE OUT YOUR CODON CHART
- 16. In sickle Cellanemia, in CTC the T gets substituted with an A resulting in CAC What is the mutated mRNA codon? The paired mRNA codon is GUG What is the mutated amino acid that it receives? For a mutated (substituted) DNA sequence, the paired mRNA codon is Valine WRONG AMINO ACID makes the wrong protein SICKLE CELL ANEMIA
- 18. Frame shift mutation •point mutation • a nucleotide is deleted or inserted • all codons after that are affected… the frame shifts • subsequent reading gives a nonsense sequence of amino acids
- 19. ACTIVITY • THE OLDRED DOG WAS TOO BIG FOR HIS BED • Deletion that would delete the D in OLD… • THE OLR EDD OGW AST OOB IGF ORH ISB ED • Inversion of the word DOG... • THE OLD RED GOD WAS TOO BIG FOR HIS BED 19 FRAME SHIFT- confuses the whole message: bad mutation less of a problem
- 20. Chromosome Mutations MEIOSIS- • crossingover- pieces of chromosomes are exchanged • another source of genetic variation • new combinations of genes
- 21. Translocation • chromosome mutation • fragmentstrade with the wrong chromosome • not always a problem
- 22. Deletion • fragment islost (often in translocation) • Cri du Chat- deletion in chromosome 5; infants have the ‘cry’ of a cat
- 23. Inversion • fragment islost flips around • not always a problem
- 24. Duplication • sometimes a pieceis repeated • chromosome #4 has CAG repeated 10 to 30 times
- 25. • Gene hastoo many repeats of CAG • Forms a protein that clumps in the brain and kills nerve cells • protein formed does not work properly HUNTINGTON’S DISEASE (40 or more repeats)
- 26. Huntington’s Disease (HD) •Early symptoms are forgetfulness and irritability in 30’s or 40’s • Progressive deterioration of the nervous system • Leads to loss of muscle control and eventually death • Because of late onset, it is passed on unknowingly.
- 27. • traits foundon the sex chromosomes (X & Y) • carrier- “carries” the gene but does not have the disease (often on X chromosome) X-linked: genes on the X chromosome. Y-linked: genes on the Y chromosome. Most are recessive traits Sex-Linked Traits
- 28. EXAMPLES • baldness • hemophilia •muscular dystrophy • red-green color blindness Sex-Linked Traits red-green color blindness
- 29. Color-blindness is recessive. B= normal b = colorblind Father is colorblind. His wife is not. Father’s genotype is _____ Mother’s genotype is _____ What is the likelihood of them having a colorblind son? Colorblind daughter? XbY XBXB
- 30. • X-Linked Trait •blood does not clot properly • Any one of several mutations on genes for clotting factors • Treatment involves replacing defective clotting factor HEMOPHILIA