study guide 1 - o Monozygotic twins (identical twins, share...

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Unformatted text preview: o Monozygotic twins (identical twins, share 1 placenta) o Dizygotic twins (fraternal twins, 2 placenta’s) • Mendel’s Laws o Segregation Cells can contain two versions for the same trait (gene) Different versions è alleles Alleles are separated in the gametes. o Independent Assortment Alleles for different traits sort independently • By 1950 chromosomes identified as hereditary material o DNA and proteins o DNA seemed too simple o Were proteins the hereditary material? • Hereditary material must: o Be capable of being replicated o Allow information to be accessed. • Watson and Crick model: o 1953 o DNA was the hereditary material o Explained replication and information access o Two DNA strands Form double helix A binds with T; G binds with C • Strands are complementary o Can be copied o Each used as template o Copied by DNA polymerase • ‘Coding strand’ carries information for proteins in a code • The DNA is the basis of Mendel’s laws Diploid – 46 (somatic cells) Haploid – 23 (gametes) • Cells and chromosomes replicate in two ways o Mitosis (somatic cells) o Meiosis (gametic cells) • Segregation of chromosomes o Diploid organisms è two copies (alleles) of each gene o One copy to each gamete • Independent sorting o Organisms have multiple chromosomes o Chromosomes sort independently during meiosis • Mitosis o Occurs in somatic cells o One round of DNA synthesis o One round of cell division o 2N (mother cell) è 4N è 2N (daughter cell) o Daughter cells are genetically identical • Meiosis o Occurs in germ cells è gametes o One round of DNA synthesis o Two rounds of cell division o 2N (mother cell) è 4N (DNA synthesis) è 2N è N o Chromosomes are independently sorted o Gametic cells are genetically different • The importance of sex o Most animals/plants: haploid (gametes)/diploid Sexual reproduction Asexual reproduction è More efficient/simpler o Sex results in enormous variability Genetic lottery Individuals that can survive Genetic experiment o Upside and downsides • Mutations o Changes in bases of DNA 3 Billion bases per haploid genome • changes in proteins o Some mutations beneficial Most deleterious Most recessive o Good news: Diploid – hides recessive mutations o Sexual reproduction – disclose mutations o Dominant – one copy needed o Recessive – two copies needed • Two genetic diseases o Cystic fibrosis o Tay Sachs o Recessive genetic disorders o Small mistakes in specific genes o Lethal • Cystic Fibrosis o Occurrence One of most common fatal diseases(1:4,000) Carrier 1 in 31 (Caucasian) 50% die before 30 o Cystic fibrosis affects the entire body – but especially lungs o Mutation in a chloride channel (CFTR protein) (CFTR = cystic fibrosis transmembrane conductance regulator ) o Found in cell membrane o Large biological molecules are polymers Subunits = monomers o Polymers and monomers DNA and RNA – nucleotides (e.g., ATP, GTP) DNA and RNA – nucleotides (e....
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This note was uploaded on 04/20/2008 for the course BSC 1005 taught by Professor Brist during the Spring '08 term at University of Central Florida.

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study guide 1 - o Monozygotic twins (identical twins, share...

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