nature and genetics

nature and genetics - 9/10/09 Song: we are family- sister...

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9/10/09 Song: we are family- sister sledge- genetics we are all family through genes Genetics Terms you should know : DNA- codes for proteins and we are made up of proteins Genes- sequences of DNA 26-28,000 genes (small number) Chromosomes- genes are organized into chromosomes (23 from mom-egg and 23 from dad-sperm for a total of 46 chromosomes) Mitosis- how cells are formed by dividing and replicate vs. Meiosis- reduction division where gametes are formed Homozygous- same genes from mom and dad for a trait Heterozygous- different genes from mom and dad for a trait Dominant- expressed trait for example curly hair gene is dominant Recessive- masked traits (carrier) Genotype- genes you actually have vs. Phenotype- trait you display 0. ex. Curly hair, straight hair 1. genotypes possible: CC, Cc, cc- use same letter for both phenotypes you display: CC, Cc = curly hair know phenotype from children cc= straight hair Range of reaction- like heritability- we ask if a trait has a broad or narrow range of reaction we ask if it is strongly or weakly canalized Canalized- depth of “canal” is range of reaction- if something is strongly canalized then it is really genetic and little range of reaction and vice versa 2. Examples: 0. height- not strongly canalized- can affect it environmentally 1. IQ- weakly canalized with wide range of reaction- our genes set the end point and the environment affects the range of reaction Examples of Human Inherited Diseases Dominantly Inherited Diseases- one parent has it and is heterozygote for gene-NO CARRIERS FOR DOMINANT DISEASE- you either have it or you don’t 0. Huntington’s disease- neurons die and die causing motor, social and cognitive problems and eventually death- born with it but symptoms appear later in life 1. Neurofibromatosis- tumors on nervous system and if they are big enough they can press on vital organs and cause problems Recessively Inherited Diseases- The uppercase letter is the normal gene- here there ARE CARRIERS- both parents have to be carriers 2. Cystic Fibrosis- affects Caucasian people more than others- most common genetic disorder resulting in death- mutation in a gene that
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results in a salt imbalance in your body and you get thick mucus build up and causes digestive and respiratory problems 3. Sickle Cell Anemia- red blood cells are sickle and elongated 4. PKU- all babies are tested for it if born in U.S hospital- not very common but if you are born with it you can’t metabolize certain proteins and as you eat those your brain tissue gets destroyed- phenylalanine- which is in most things 5. Tay-Sachs- found in small population of Ashkenazi Jews- as baby
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nature and genetics - 9/10/09 Song: we are family- sister...

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