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41 Cards in this Set
- Front
- Back
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Deoxyribonucleic Acid (DNA)
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holds the heritable genetic information of an organism
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DNA encodes
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the proteins that determines an organism’s physical traits and influences their behavior |
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experiments by Hershey and Chase and Oswald Avery,
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in the 1940s revealed that DNA was responsible for genetic traits
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Hershey-Chase Experiment
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-The showed that DNA is the genetic material
-Only the DNA of the virus, and not the protein, enters an E. coli cell during infection |
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Structure of DNA
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DNA is a double helix - the shape of a twisted ladder
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DNA is made up of two anti-parallel strands
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5’ to 3’ is the coding strand 3’ to 5’ is the template strand
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The monomer of DNA
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is a nucleotide
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Nucleotides consist of:
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1.) Deoxyribose sugar 2.) Phosphate group 3.) Nitrogenous Base
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backbone of DNA
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Deoxyribose and phosphate
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Nitrogenous bases
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deoxyribose, bond together by weak hydrogen bonds
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The Race for the Double Helix – 1950s
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James Watson and Francis Crick are given credit for discovering the structure of DNA
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discovered the evidence that showed the structure of DNA
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Rosalind Franklin
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, taken by Franklin, revealed the structure of DNA
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Photo 51
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The Pyrimidines
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Cytosine “C” Thymine “T”
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The Purines
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Adenine “A” Guanine “G”
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Purines have a double carbon ring
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– larger than the single carbon ring pyrimidines
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Finished in 2003, the human genome mapped out the entire human genetic code
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Humans have about 3.1 billion base pairs
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Nucleotide Bonding
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In the 1940s Erwin Chargaff conducted experiments to discover which nucleotides bonded together
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Chargaff’s Rule:
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A bonds with T with two weak hydrogen bonds 2.) G bonds with C with three weak hydrogen bonds
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Gene:
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A region of DNA that controls a hereditary characteristic
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Humans have about
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20,500 genes
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DNA creates traits by
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coding for a specific protein
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1.) Melanin:
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animal pigmentation for hair, eyes, and skin
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The Y chromosome creates
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the protein TDF (testis determining factor) which transforms the fetus into a male
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Prolactin drives
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most vertebrates to take care of offspring
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Protein Synthesis
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Proteins (the polymer) are made up of combinations of the 20 different amino acids (the monomer)
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RNA (Ribonucleic Acid)
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Function:Decodes DNA and assembles amino acids into proteins
1.) Single Stranded |
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rRNA
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RNA (ribosomal): makes up the ribosome
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tRNA
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tRNA (transfer): transfers amino acids to the ribosome
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mRNA |
mRNA (messenger): takes the message from the DNA to a ribosome
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Step 1.) Transcription:
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RNA polymerase creates a mRNA molecule which then travels to the ribosome
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In eukaryotes –
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the mRNA is modified before it leaves the nucleus
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During RNA splicing –
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introns (noncoding regions of the mRNA) are removed and the exons (coding regions of the mRNA) are spliced (joined) together
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Step 2.) Translation:
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tRNA transfers amino acids to the ribosome which puts them together to create a protein
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The mRNA is read
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3 nucleotides at a time
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The tRNA code
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is the anticodon
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How DNA replicates
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DNA helicase breaks the weak hydrogen bonds between the two nucleotides and “unzips” DNA –making two separate
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How DNA REPLICATES 2 |
DNA polymerase adds new corresponding nucleotides to each of the single stranded DNA molecules
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Nuclease–
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repairs misplaced DNA pairsE.g. An A bonded to G would be switched to a C
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Genetic Mutation
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Mutation – any change in the nucleotide sequence of DNA
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Point mutation
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– a single nucleotide is replaced
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