DNA Notes - WARM-UP#7 DNA(Deoxyribonucleic Acid Genetic...

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Unformatted text preview: WARM-UP #7 DNA (Deoxyribonucleic Acid) Genetic material of cells… Genetic • GENES – units of genetic material that GENES CODES FOR A SPECIFIC TRAIT CODES • Called NUCLEIC ACIDS Called NUCLEIC • DNA is made up of repeating molecules DNA called NUCLEOTIDES NUCLEOTIDES DNA Nucleotide DNA Phosphate Group Group O O=P-O O 5 CH2 O N C 1 C4 Sugar Sugar (deoxyribose) C3 C2 Nitrogenous base (A, G, C, or T) (A, A HISTORY OF DNA HISTORY SEE p. 292-293 • Discovery of the DNA double helix DNA A. Frederick Griffith – Discovers that a factor in diseased bacteria can transform harmless bacteria into deadly bacteria (1928) B. Rosalind Franklin - X-ray photo of DNA. (1952) C. Watson and Crick - described the DNA molecule from Franklin’s X-ray. (1953) Watson & Crick proposed… Watson •DNA had specific pairing between the DNA nitrogen bases: nitrogen ADENINE – THYMINE THYMINE CYTOSINE - GUANINE GUANINE •DNA was made of 2 long stands of DNA nucleotides arranged in a specific way called the “Complementary Rule” “Complementary DNA Double Helix DNA “Rungs of ladder” Nitrogenous Nitrogenous Base (A,T,G or C) “Legs of ladder” Phosphate & Sugar Backbone DNA Double Helix DNA 5 O 3 3 P 5 O O C G 1 P 5 3 2 4 4 2 3 P 1 T 5 A P 3 O O P 5 O 3 5 P Nitrogenous Bases Nitrogenous • PURINES 1. Adenine (A) 2. Guanine (G) A or G • PYRIMIDINES 3. Thymine (T) 4. Cytosine (C) T or C Chargaff’s Rule Chargaff’s • Adenine must pair with Thymine Thymine • Guanine must pair with Cytosine Cytosine • Their amounts in a given DNA molecule will be about the same. about T A G C BASE-PAIRINGS BASE-PAIRINGS H-bonds G C T A Genetic Diversity… Genetic • Different Different arrangements of NUCLEOTIDES in a NUCLEOTIDES nucleic acid (DNA) provides the key to DIVERSITY among DIVERSITY living organisms. living The Code of Life… The • The “code” of the chromosome is the The SPECIFIC ORDER that bases occur. SPECIFIC A T C G T A T G C G G… See p. 297 DNA is wrapped tightly around histones and coiled tightly to form chromosomes DNA Replication Replication • DNA must be copied • The DNA molecule produces 2 The IDENTICAL new complementary IDENTICAL strands following the rules of base pairing: A-T, G-C A-T, •Each strand of the Each original DNA serves as a template for the new strand See p. 298 See DNA Replication Replication • Semiconservative Semiconservative Model: Model: 1. Watson and Crick Watson showed: the two strands showed: of the parental molecule separate, and each functions as a template for synthesis of a new complementary strand. . Parental DNA DNA Template New DNA Replication Quiz A---? G---? C---? 2. When does replication occur? T---? 3. Describe how replication works. A---? G---? A---? 4. Use the complementary rule to G---? create the complementary C---? strand: A---? G---? T---? 1. Why is replication necessary? Replication Quiz A---T 1. Why is replication necessary? G---C So both new cells will have the correct C---G DNA T---A 2. When does replication occur? A---T During interphase (S phase). G---C 3. Describe how replication works. A---T Enzymes unzip DNA and complementary G---C nucleotides join each original strand. C---G 4. Use the complementary rule to A---T create the complementary strand: G---C T---A (1961) (1961) Watson & Crick proposed… • …DNA controlled cell function by DNA serving as a template for PROTEIN PROTEIN structure. structure. • 3 Nucleotides = a triplet or CODON Nucleotides CODON (which code for a specific AMINO ACID) See p.303 • AMINO ACIDS are the building blocks of proteins. of DNA Transcription Transcription • DNA can “unzip” DNA itself and RNA RNA nucleotides match up to the DNA strand. See p.301 strand. • Both DNA & RNA Both are formed from NUCLEOTIDES and NUCLEOTIDES are called NUCLEIC NUCLEIC acids. acids. DNA Translation Translation • The cell uses The information from “messenger” RNA to produce proteins to See p.304-305 We will We discuss details of this on a later date later 1. 2. 3. 4. 5. 6. Transcription/Translation Quiz Why is transcription necessary? Describe transcription. Why is translation necessary? Describe translation. What are the main differences between DNA and RNA. Using the chart on page 303, identify the amino acids coded for by these codons: UGGCAGUGC 1. Why is transcription necessary? Transcription makes messenger RNA (MRNA) to carry the code for proteins out of the nucleus to the ribosomes in the cytoplasm. 2. Describe transcription. RNA polymerase binds to DNA, separates the strands, then uses one strand as a template to assemble MRNA. 3. Why is translation necessary? Translation assures that the right amino acids are joined together by peptides to form the correct protein. 4. Describe translation. The cell uses information from MRNA to produce proteins. 5. What are the main differences between DNA and RNA. DNA has deoxyribose, RNA has ribose; DNA has 2 strands, RNA has one strand; DNA has thymine, RNA has uracil. 6. Using the chart on page 303, identify the amino acids coded for by these codons: UGGCAGUGC tryptophan-glutamine-cysteine AMAZING DNA FACTS… AMAZING • DNA from a single human DNA cell extends in a single thread for almost 2 meters long!!! long!!! • It contains information It equal to some 600,000 printed pages of 500 words each!!! (a library of about 1,000 books) (a LET’S REVIEW DNA… LET’S LM p.44 1. List the conclusions Griffith & Avery, List Hershey & Chase drew from their experiments. experiments. 2. Summarize the relationship between Summarize genes & DNA. genes 3. Describe the overall structure of the Describe DNA molecule. DNA 4. What are the 4 kinds of bases? ...
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