Abnormal Cell Division & Cloning

1. Abnormal Cell Division & Cloning

2. Abnormal Meiosis • Non-disjunction: When two homologous chromosomes move to the same side of the cell before telophaseI, resulting in 1 daughter cell with an extra and another missing that chromosome • Non-disjunction can occur during mitosis as well but is much less devistating during mitosis • Trisomy: When a 24 chromosome gamete combines with a 23 chromosome gamete creating a 47 chromosome zygote. The resulting zygote has 3 chromosomes for a trait that should have 2. • Monosomy: When a 22 chromosome gamete combines with a 23 chromosome gamete creating a 45 chromosome zygote. The resulting zygote has 1 chromosome for a trait which should have 2.

3. Down Syndrome • Trisomy of the 21 chromosome • People with down syndrome can be identified by several common traits, a round full face, enlarged creased tongue, short height and large forehead • 1 in 600 babies • More common in order parents

4. Turner Syndrome • When sex chromosomes undergo non-disjuction • Monosomic disorder producing a female with a single X chromosome. • In the ovum, both X cells move to the same side of the cell during Meiosis I • If the egg cell is fertilized by a sperm cell carrying an X chromosome a zygote with 45 chromosomes is formed • Most turner syndrome babies are miscarried • If not the baby with be female but not develop fully sexually • They tend to be short, have thick necks

5. Klinefelter Syndrome • Caused by nondisjunction in sperm or egg cell • Child inherits 2 X and 1 Y chromosomes creating a 47 chromosome zygote (trisomy) • Appearing male at birth, they will produce a large amount of female sex hormones at sexual maturity • Stella Walsh competed in the 1932 and 1936 Olympics as a female sprinter winning a Gold and then a silver • She was murdered and the investigation revealed that she was actually male. She had Klinefelter Syndrome.

6. Cloning • Forming an identical offspring from 1 single cell of tissue (unlike the normal process with 2 contributors - mom and dad) • Should be identical or nearly identical to the parent but some clones show accidental changes in genetics

7. History of Cloning • In 1958 Fredrick Stewart created a plant from a single carrot cell • It is used intentionally with plants to create plants that have predictable strains of characteristics (most orchids are made through cloning)

8. Cloning Example • Organ cloning for transplants • Scientists are developing ways to clone organs for transplant, not very close to being used yet but hve made progress • Also attempting to make genetically modified pigs with organs that could be used in humans • This would make the organ donation decrease substantially and be great if we can figure out how to make it work and resolve the ethical issues associated with it

9. Genetic Engineering • Intentional production of new genetic material by substituting or altering existing material • Also called genetic modification • An organism that has been created using genetic modification is called a GMO (genetically modified organism) • Heavily used in farming • Seeds are modified so their product will not supply the farmer with seeds for the next year (farmer then needs to purchase seeds yearly) – seedless watermelon • Modification are made to create bigger product (tomatoes) • Crops are “super crops” resistant to disease and environmental conditions

10. Concerns about GMOs • Not sure what the effect will be on people long term (although scientists do not think their will be any problem) • Effects insects/animals that would not normally harm the crops (butterflies) • Allergies, depending on how foods are modified (using genes from something someone is allergic to and putting them into something they can normally consume) – proper labeling is in the works • Issue came up when an idea of using brazil nut characteristics in soy beans was considered. They did not do this because of the allergic reaction issues.

11. Designer Babies • In an effort to save their child’s life an Australian couple was given legal permission to design and identical child so umbilical cord blood could be taken and given to their older, sick child. • Very controversial because if it works, why not let everyone chose the characteristics wanted in future child? • Parents could eventually choose dads eyes, moms hair, sex, height, etc. • Also prevents many possible disorders