Ch 12 DNA and RNA

1. Ch 12 DNA and RNA

2. What is DNA? • DNA (deoxyribonucleic acid)- a nucleic acid which stores genetic traits in the proteins it codes for. • All living things contain DNA. • DNA is a nucleic acid. • Nucleic acids are made of nucleotide subunits hooked together.

3. Nucleotides • Nucleotides- subunits of DNA made of: 1. Phosphate (PO4) 2. Sugar (deoxyribose). 3. Nitrogen base.

4. Nitrogen Bases • Four different nitrogen bases makes four different nucleotides: • Guanine • Cytosine • Adenine • Thymine • These four nucleotides make up the DNA of almost every single living thing.

6. Nucleotides

7. Chargaff’s Rule • He measured amounts of each base in various organisms and found: • % of adenine (A) = % thymine (T) % of cytosine (C) = % guanine (G) • Chargaff’s rule told us that A bonds to T and C bonds to G • If 20% of strand is A, what %T? %C?

8. Structure of DNA • Discovered by Watson and Crick • Double helix- 2 spiral strands of nucleotides bonded together

9. Structure of DNA • Siderail backbone is the sugar and phosphates of nucleotides • Rungs are the nitrogen bases of nucleotides • A----T • C----G • Hydrogen bonds between bases hold two strands together

10. What is DNA Replication? • Replicate = make “exact” copies. • DNA replication- copying of DNA so that a cell made divide • All DNA must be replicated before a cell can divide. Why?

11. Enzymes and Replication • Helicase- enzyme that unwinds DNA • DNA polymerase-enzyme that moves along each strand and brings in bases for new strand copy

12. DNA Replication • Can be a mistake in replication • Mutations-change in DNA • Mutagens- substances that cause mutations • X-rays • Toxins • Drugs • UV light, etc.

13. Mutations • 3 types of mutations that can occur during DNA replication: • Insertions -extra nucleotides • Deletions –missing nucleotides • Substitutions –placement of wrong nucleotides • Can be helpful or harmful mutations. Insertion Deletion Substitution

14. Most Destructive Mutation? • The bases, A, C, G, and T can be equated to letters of a “DNA sentence” THE DOG WAS HOT IN THE SUN • Substitution: THE DOG WAS NOT IN THE SUN • Insertion? THE DOG NWA SHO TIN THE SUN • Deletion? THE DOG ASH OTI NTH ESU N • Why should I care?

15. How Much DNA Is In OUR Cells? • Chromosome-strands of DNA coiled tightly • Human cell has 46 (23 pairs) • 23 from Mom • 23 from Dad • Other organisms have different numbers of chromosomes

16. 2 Types of Cells • Somatic cells –all body cells except sex cells • Diploidchromosomes are in pairs • 46=23 pairs for humans • 1 set (23) from mom, 1 set (23) from dad • Gametes - sex cells • Egg & sperm • Haploid no pairs (only 23 single chromosomes)

17. Human Chromosomes • If all body cells contain the same # of chromosomes, why are all cells so different? • Different cells make different proteins due to different “active” segments of DNA. • Heart cells make proteins needed for the heart to work properly • Brain cells make proteins needed for the brain to work properly

18. What is the Purpose of DNA? • DNA stores the genetic information that codes for proteins. • ALL CELL FACTORIES MAKE PROTEINS!

19. What is the Purpose of DNA? • Gene- a segment of DNA that codes for a protein. • DNA has 1000’s of genes to make many different types of proteins. • Why are proteins important? • Protein - polymer of amino acids aa—aa—aa—aa—aa—aa—aa—aa = protein

20. What is the Purpose of DNA?

21. RNA (Ribonucleic acid) _____DNA____ vs._____RNA___ Transmits the genetic code to the rest of the cell Single stranded Sugar of RNA nucleotides is ribose A, C, G, U (uracil) NO T! Different forms: mRNA, rRNA, tRNA Found all over cell Stores the genetic code in the nucleus Double stranded Sugar of DNA nucleotides = deoxyribose A, C, G, T “DNA is DNA” Found in nucleus only

22. DNA vs. RNA

23. Part 1of Protein Synthesis: Transcription • Transcription- copying of DNA to mRNA that occurs in the nucleus. • DNA complementary to mRNA • ATA-CGG-AAT (DNA) transcription in nucleus UAU-GCC-UUA (RNA)

24. Transcription cytoplasm Translation

25. Part 2 of Protein Synthesis: Translation: • Translation- converting mRNA to protein which occurs at ribosomes in the cytoplasm • mRNA codons translation by ribosomes a.a.---a.a---a.a (protein) cytoplasm

26. Part 2 of Protein Synthesis: Translation: • Codon-three bases of mRNA that code for an amino acid • UAU-GCC-UUA (3 mRNA codons) translation by ribosomes a.a.---a.a---a.a. (protein) • mRNA needs the help of tRNA to bring in the amino acids to be hooked together cytoplasm

27. Whole Process ATA-CGG-AAT (DNA) transcription in nucleus UAU-GCC-UUA (3 mRNA codons) translation in cytoplasm at ribosomes a.a.-a.a-a.a. (protein) How do we know what amino acid results? The Codon Wheel!!!

28. Part #1 Transcription cytoplasm Part #2 Translation

29. The Codon Wheel***How do we use the wheel? There are 2 clues.

30. The Codon Wheel

31. Whole Process DNA: ATA-CGG-AAT transcription in nucleus mRNA: UAU-GCC-UUA(3 codons) translation in cytoplasm protein: a.a.-a.a-a.a. tyrosine-alanine-leucine Protein Synthesis Animation! How do we know what amino acid results? The Codon Wheel!!!

32. Amino Acids • Where do our cells get these amino acids to build the proteins? • From FOOD! • We eat proteins, then these proteins are broken down (metabolized) into amino acids in our stomach. • We reuse these amino acids to build other proteins.