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Chromosomes

Chromosomes. 1. Thomas Sutton in 1902 proposed that genes are located on chromosomes 2. Called the Chromosome Theory of Inheritance. 3. For most of the life of the cell, chromosomes are too elongated to be seen under a microscope & are  called chromatin

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Chromosomes

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  1. Chromosomes 1. Thomas Sutton in 1902 proposed that genes are located on chromosomes 2. Called the Chromosome Theory of Inheritance

  2. 3. For most of the life of the cell, chromosomes are too elongated to be seen under a microscope & are  called chromatin 4. Before a cell gets ready to divide, each chromosome is duplicated & condenses into short structures

  3. 5. Each chromosome is composed of a single, tightly coiled DNA moleculearound protein

  4. Mutations • A. Chromosomal Mutations (effect the number of chromosomes or large portion of an individual chromosome) • 1. Mutations are changes in genes or chromosomes that can be passed on to offspring (only if the occur in the sex cells – gametes) • 2. Mutations increase the number of variations that occur

  5. 3. Chromosomal mutations include changes in chromosome number and/or structure • 4. Monosomy - occurs when an individual has only one of a particular type of chromosome • 5. Turner syndrome (X0) is an example of monosomy

  6. Turner's Syndrome • Monosomy of Sex Chromosomes; XO female • Infertile • Dwarfism • Overweight • Some mental retardation • Webbed Neck

  7. 6. Trisomy - occurs when and individual has three of a particular type of chromosome 7. Examples of trisomy include Klinefelter's Syndrome (XXY) and Down Syndrome or Trisomy 21 where the individual has three 21st chromosomes

  8. Klinefelter's Syndrome • Trisomy of sex chromosomes; XXy male • Feminine Characteristics, Infertile • George Washington? • No Children – Sterile? • Dental Problems • Height – Very tall for generation • Still Inconclusive

  9. Down's Syndrome • Trisomy 21 • Mild to severe mental retardation • Distinct Facial Features • Heart Defects • Fingerprints – Sworl • Most Common Birth Defect – 1/700 births • Mother’s Age over 40 – 1/80 • Problems during Oogenesis

  10. Edward's Syndrome • Trisomy 18 • Elfin Appearance • Low set ears • Malformation of many organs – specifically heart/lungs • “Blue Babies” due to lack of oxygen • 90% die within first 6 months

  11. Patau's Syndrome • Trisomy 13 • Cleft Lip and Palate • Polydactyl – more than ten fingers/toes • 1/6000 births • Most die within first year

  12. 8. Both monosomy & trisomy result when chromosomes fail to separate during meiosis; called nondisjunction • 9. Monosomy and trisomy occur in plants and animals and may be lethal (deadly)

  13. Chromosomal Mutations

  14. 10. Polyploidy - where the offspring have more than two sets of chromosomes occurs often in plants (3n, 4n ...) 11. Environmental factors including radiation, chemicals, and viruses, can cause chromosomes to break causing a change in chromosomal structure

  15. 12. Inversion - occurs when a piece of a chromosome breaks off & reattaches to the same place but in the reverse order 13. Translocation - occurs when a chromosome segment breaks off & attaches to a different chromosome

  16. Chromosomal Mutations

  17. 14. Deletions - occur when the end of a chromosome breaks off & is lost 15. Cri du chat syndrome (results in retardation & a cat-like cry) is due to a deletion of a portion of chromosome 5

  18. Cri-du-chat • “Cat’s Cry” Syndrome • Deletion of a portion of Chromosome 5 • Mental Retardation

  19. Duplications - occur when a section of a chromosome is doubled • Fragile X Syndrome caused by an abnormal number of repeats (CCG) results in retardation & long, narrow face becomes more pronounced with age

  20. Karyotype • Karyotype: chromosomes are stained and photographed under the microscope, cut from photo and arranged by size and shape; can detect chromosomal abnormalities • Monosomy: a zygote with only 45 chromosomes; one copy of a chromosome • Trisomy: three copies of a chromosome; 47 chromosomes total • Both result from nondisjunction

  21. Gene Mutations 1. Def - Change in genes caused by change in structure of the DNA 2. DNA bases may be substituted, added, or removed to cause gene mutation

  22. 3. When genes are added or removed, the mutation is called a frame shift mutation

  23. 4. Adding or Removing genes is called a frameshift mutation

  24. Sickle cell anemia 5. (red blood cells are C-shaped so can't carry as much oxygen) is an example of a gene mutation in African Americans

  25. Sickle Cell Anemia

  26. 6. Tay-Sachs • (a disorder where the nervous system deteriorates) is a fatal gene mutation in Jewish people of Central European Descent

  27. Phenylketonuria • 7. PKU occurs from the inability of a gene to synthesize a single enzyme necessary for the normal metabolism of phenylalanine and results in death

  28. Biotechnology 1. the combination of biology and technology has been making many products better for many years.

  29. DNA Extraction • Chemical treatments cause cells and nuclei to burst • The DNA is inherently sticky, and can be pulled out of the mixture • This is called “spooling” DNA

  30. “Spooled” DNA

  31. Cutting DNA • Restriction enzymescut DNA at specific sequences • Useful to divide DNA into manageable fragments

  32. 2. The procedures are often referred to as genetic engineering 3. DNA is the genetic material of all living organisms 4. All organisms use the same genetic code 1. Genes from one kind of organism can be transcribed and translated when put into another kind of organism 2. For example, human and other genes are routinely put into bacteria in order to synthesize products for medical treatment and commercial use

  33. 3. Human insulin, human growth hormone, and vaccines are produced by bacteria 4. Recombinant DNA refers to DNA from two different source 5. Individuals that receive genes from other species are transgenic

  34. Selective Breeding 1. many meat products have been bred to contain less fat. In addition, many of the fruits and vegetables we consume have been selectively bred to be larger, sweeter, hardier, and even juicier.

  35. How do farmers selectively breed their livestock and crops? 2. Out of thousands of bean plants, they might select a plant that produces many pods and then breed it with a bean plant that resists fungus infections; hoping for a plant which produces many pods and is resistant to fungus infections.

  36. Genetic Engineering C. A new technology that humans can use in order to alter genetic instructions (DNA) in organisms. • Usually done to give them more desirable traits. • Aka: Gene Manipulation.

  37. Is this a new technology? • The idea of altering the DNA is new; the idea to alter organisms is not new. • Old Technology = select the best plants or animals and breed them with a desirable mate (Example: race horses or dogs) Aka: Selective Breeding. • New Technology= scientists could add better genes (pieces of DNA) to an organism to give it better traits like bigger muscles. Aka: Genetic Engineering.

  38. How is it done? DNA Animal cell DNA (AKA: plasmid) Bacterial cell Recombinant DNA Restriction Enzyme (cuts the DNA)

  39. Restriction Enzymes • a. Restriction enzymes were discovered in bacteria • b. Bacteria use them as a defense mechanism to cut up the DNA of viruses or other bacteria c. Hundreds of different restriction enzymes have been isolated d. Each restriction enzyme or RE cuts DNA at a specific base sequence e. For example, EcoRI always cuts DNA at GAATTC as indicated below

  40. e. The sequence GAATTC appears three times in the DNA strand below. As a result, the strand is cut into four pieces

  41. 2. a restriction enzyme is used to cut a segment of DNA from a human cell. (This segment has the desired gene) 3. a circular piece is cut away from the bacteria’s DNA. 4. when the piece of human DNA is mixed with the bacteria’s DNA, they join in a closed loop. 5. The closed loop is inserted into another bacteria cell. 6. The DNA produces the mRNA with the correct sequence of bases, which in turn leads to the production of the correct protein. The DNA, RNA and protein will be produced every time the cell divides.

  42. How is Gene Engineering used? a. It is used to produce human insulin for Diabetics: • Previously, diabetics injected horse insulin, which would lower their blood sugar levels. • Now, scientists can inject insulin-producing genes into bacteria, and the bacteria produce the insulin, which diabetics can use. • This is a cheaper way to obtain insulin because it can be produced in greater amounts and there are smaller risks of side effects since the gene making the insulin is a human gene.

  43. It is also used to create fruits and vegetables with desirable characteristics: such as a tomato with a gene inserted that prevents the tomato from freezing (that scientists took the gene out of a flounder cell)

  44. Biotechnology Breakthroughs • Insulin (1982) • First commercial biotech product • Reliable, inexpensive source of insulin • Rice • Enriched with beta-carotene and iron • Bananas • Containing edible hepatitis vaccine

  45. Biotechnology Breakthroughs • Potatoes with higher solid content • Garlic that lowers cholesterol • Fruits and vegetables that reduce risks of cancer and heart disease

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