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Genetics

Genetics. DNA Structure, function and replication. Agenda 3/17. HSAP bell ringer Concept 1 Notes Pages 2-4 DNA Model Pages 5-6. Wake up work #1. What sugar is used in DNA? Which statement do we now know is correct? Bella : "I think DNA is found on genes."

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Genetics

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  1. Genetics DNA Structure, function and replication

  2. Agenda 3/17 • HSAP bell ringer • Concept 1 Notes • Pages 2-4 • DNA Model • Pages 5-6

  3. Wake up work #1 What sugar is used in DNA? Which statement do we now know is correct? Bella: "I think DNA is found on genes." Kyra: "I think chromosomes are found on genes." Kurt: "I think genes are found on DNA." Joan: "I think chromosomes are found on DNA.“ In DNA; A always binds with _______, while G always binds with C. In RNA; A always binds with _______, while G always binds with C.

  4. Agenda 3/19/2014 • HSAP Review/Wake Up Work #1 • Finish Concept 1 Notes, p.4DNA Replication • Finish DNA model • Turn in your section and pages 6-7 for a grade! • Practice—keep these for review day/one of these will be graded for accuracy: • Page 8—(*top half*) answers: 6.b 7.g • Page 9—8 down answer: Crick • Page 10

  5. 1st Block Partners William and Jasmine Alyssa and Jason Isaac and Nina Austin and John Meme and Jarome Kari and Chyna Brianna and Sid Nick and Christian Matthew and Qualyn

  6. Think About It… Four friends were talking about human DNA, genes, and chromosomes. They each had different ideas about where these structures were found. This is what they said: Bella: "I think DNA is found on genes." Kyra: "I think chromosomes are found on genes." Kurt: "I think genes are found on DNA." Joan: "I think chromosomes are found on DNA." Whom do you agree with most? Be able to explain WHY!!

  7. DNA is a Nucleic Acid • Nucleic Acids are a type of macromolecule that is made up of repeating units (monomers) called nucleotides. • Nucleic Acids contain genetic info, which includes instructions for building proteins and controlling cell function. • There are two types: • DNA—DeoxyriboNucleic Acid • RNA—RiboNucleic Acid *WHERE DO WE FIND DNA?*

  8. Nucleotides • Sugar: • Ribose in RNA • Deoxyribose in DNA • Phosphate • 5 different nitrogen bases: • A: adenine • T: thymine (ONLY FOUND IN DNA) • G: guanine • C: cytosine • U: uracil (ONLY FOUND IN RNA)

  9. DNA Structure Nucleotides link together through the phosphates and sugars to form a long chain. This is called the sugar-phosphate backbone – it forms the sides of the “ladder” shape.

  10. DNA Structure Two chains of DNA are bound together by weak hydrogen bonds between the nitrogen bases (ATCG). These form the “steps” of the ladder and give the DNA its double helix shape.

  11. Double Helix – 2 strands of DNA wind around each other. The strands are complementary They fit together & are opposite of each other. Double Helix

  12. Complementary Base-Pairing Rules Only certain bases will bind with each other: Aalways binds with TC always binds with G We call these the complementary base-pairing rules.

  13. RNA Function The purpose of RNA is to carry a copy of DNA’s message out of the nucleus so the instructions can be used to make proteins. RNA is a “copy” of DNA.

  14. RNA Structure RNA is a single strandof nucleotides made up of a sugar-phosphate backbone and exposed nitrogen bases. RNA follows the same complementary base-pairing rules when it binds with DNA to make a copy, exceptRNA has U (uracil) instead of T (thymine). Base pairing rules for RNA: A always binds to UC always binds to G

  15. Using the Base-Pairing Rules T A G C G T A T T A A G C C G A T A

  16. DNA versus RNA

  17. Basics of Heredity • Chromosomes: • DNA is stored in the nucleus in long, tightly coiled strands called chromosomes. • Different organisms have different numbers of chromosomes. • Humans have 23 pairs of chromosomes (23 chromosomes from our mother and 23 chromosomes from our father; 46 total) • Dogs have 37 pairs of chromosomes (37 from their mother and 37 from their father; 74 total) • The information stored in DNA forms the basis for heredity – the transmission of traits from parent to offspring.

  18. Basics of Heredity • Genes: • Small segments (pieces) of DNA carry the instructions to make specific proteins. • A piece of DNA that has the instructions to code for one protein is called a gene. • One chromosome can contain thousands of genes linked together! *Humans are thought to have between 30,000 and 40,000 genes*

  19. Chromosomes and Genes

  20. Why does DNA need to be replicated/copied? When does DNA replication take place? DNA Replication

  21. When a cell is ready to divide, it must first copy its DNA. The process of making an identical copy of DNA is called DNA Replication. DNA replication happens during the synthesis phase (interphase) of the cell cycle. Replication assures that every cell has a complete set of identical genetic information. DNA Replication

  22. Each chain contains a very specific sequence of nucleotides (ATCG bases) that must be copied exactly Since the two strands are complementary, a new copy can be made by splitting the DNA molecule in half, then using base-pairing rules to match new nucleotides to the exposed bases. Hydrogen bonds b/w 2 strands are easily broken. Each single strand then serves as template for new strand. DNA Structure Helps Explain How it Duplicates

  23. Step 1: Unzip the DNA Step 2: Enzymes help find complementary bases and bind them according to base-pairing rules Step 3: Two identical DNA molecules are formed, each with an “old” strand and a “new” strand. We call this Semi-Conservative Replication (because part of the molecule is conserved/saved)

  24. Semi-Conservative Model • Each parent strand remains intact. • Every DNA molecule is half “old” and half “new”.

  25. DNA replication happens often, so it has to be fast. In humans, 50 nucleotides are added every second. DNA polymerase will detect errors and replace incorrect nucleotides. Replication is Fast

  26. http://www.johnkyrk.com/DNAreplication.html http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf

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