DNA, RNA & Protein Synthesis & Genetic Engineering

1. DNA, RNA & Protein Synthesis & Genetic Engineering

2. Major Cell Activities Include: • Diffusion • Osmosis • Active Transport • Cell Energy • Photosynthesis • Cell Respiration • ATP • DNA Replication • RNA Formation • Protein Synthesis • Cell Division This unit covers these three

3. Pre-Notes, Background Info: • Nucleic acids • Store & transmit genetic info • DNA & RNA • Composed of repeating units called nucleotides DNA double helix

4. Pre-Notes, Background Info: • Nucleotides consist of: • a sugar • a phosphate group • one nitrogen base DNA molecule Nucleotide

5. I. DNA (Deoxyribonucleic Acid) • Found in almost all living cells –in the nucleus of eukaryotes(3 Feet/Cell) • 2 primary functions • Control protein (enzyme) production (ie. ATPase)-These enzymes then control chemical reactions in cells. • Duplicate itself for new cells that are created

6. Forms of DNA • Chromatin –Partially unwound when? (Normal Situations) • Chromosome – tightly wound DNA (Cell division)

7. Structure of DNA • Consists of two long strands that spiral • Each strand is a chain of nucleotides • Three parts to each nucleotide • 5 carbon sugar (deoxyribose) • Phosphate • Nitrogen base (4 different kinds of bases)

8. Nucleic acids are polymers of nucleotides. -nucleotide: sugar + phosphate + nitrogenous base DNA molecule Nucleotide

9. Nucleotide

10. All nucleotides have same sugar and phosphate • Four different kinds of nitrogen bases • Adenine – purine – double ring molecules • Guanine – purine – double ring molecules • Thymine – Pyrimidines – single ring molecules • Cytosine – pyrimidines – single ring molecules

11. Segment of DNA

13. DNA

14. Double Helix – Spiral ladder • Sides of the ladder = 5 carbon sugar and phosphates • Rungs of the ladder = nitrogen bases bonded together from each side

15. Rosalind Franklin’s X-ray Photo (1951)

16. Hydrogen bonds form between purines and pyrimidines creating “steps” of ladder • Adenine + Thymine = 2 hydrogen bonds =2 hydrogen bonds =3 hydrogen bonds b. Cytosine + Guanine= 3 hydrogen bonds Page 331 A T C G

17. DNA Replication WHY? -each cell must get same DNA copy when cells divide. • DNA helicase (enzyme) attaches to DNA molecule. • Helicase moves along DNA breaking hydrogen bonds- “unzips” DNA into two strands. • Each strand now has unpaired nitrogen bases.

18. Free floating nucleotides in the nucleus form hydrogen bonds with unpaired nitrogen bases. • DNA Polymerase (enzyme) bonds together nucleotides by connecting Deoxyribose(Sugar) to phosphate • Ligase (enzyme) repairs DNA • Final result = 2 exact copies of DNA * Each copy = 1 “old” strand and 1 “new” strand

21. Replication occurs at many (1000’s) of sites along DNA – speedy process • Replication very accurate – 1 error per billion nucleotides • Nitrogen bases: • Adenine (A) bonds with Thymine (T) • Cytosine (C) bonds with Guanine (G) If unzipped old segment = C-C-A-T-G-A-G-T What will the new segment be?

22. II. RNA (Ribonucleic Acid) • Structure of RNA *Different than DNA in 3 ways • RNA is a single strand – DNA = Double • RNA has ribose sugar – DNA =Deoxyribose • RNA has Uracil instead of Thymine DNA nitrogen basesRNA nitrogen bases Cytosine Guanine Cytosine Guanine Adenine Thymine Adenine Uracil

23. Nucleic Acids

24. 3 types of RNA *All made in the nucleus and travel to the ribosomes • Messenger RNA (mRNA) • Single straight strand • Transmits DNA information • Serves as template (pattern) for making proteins

26. Transfer RNA (tRNA) • Single folded strand • Complimentary bases pair up • Also involved in protein synthesis

28. Ribosomal RNA (rRNA) • Globular form • Part of ribosome structure

29. Transcription – process of making RNA from DNA • Protein enzyme called RNA polymerase binds to DNA. • RNA polymerase separates portion of DNA into two separate strands. • Free floating nucleotides in nucleus match their nitrogen bases with bases of “unzipped” DNA. DNA base code = C-G-A-T-A Complimentary RNA = G-C-U-A-U

30. RNA polymerase forms bonds (hydrogen) between nitrogen bases. • Polymerase connects nucleotides by bonding sugars to phosphates • Enzyme releases new RNA strand when it reaches “stop sign” on DNA.

31. GENE

32. Protein Synthesis –ribosomes make proteins using information coded in RNA“AKA Translation” • Proteins • Many amino acids linked by peptide bonds • 100’s to 1000’s of AA’s per protein • 20 different AA’s • Sequence of AA’s determine structure and function of each protein

33. Codon – a group of 3 sequential nitrogen bases of an mRNA molecule. • 64 different combinations = 64 codons • mRNA u c u u a g c u a g c g -How many codons? • Each codon codes for: • 1 of the 20 amino acids • Start or stop codons

35. Anticodon -Region of tRNA that consists of bases which are complimentary to codon bases of mRNA

36. Translation – putting amino acids (AA’s) together to build protein from information encoded in mRNA • mRNA and tRNA transcribed from DNA in nucleus. • This RNA exits the nucleus through pores. • mRNA travels to ribosomes.

37. Free floating AA’s are brought to ribosomes by tRNA. • Protein always starts with methionine (aug) AA • A second AA on tRNA enters ribosome. Codon and anticodon pair up and peptide bonds form between AA’s.

39. *This process of linking AA’s continues until ribosome reaches a stop codon on mRNA. What are the stop codons? uaa uag uga

41. Biotechnology • Plasmids: circular double-stranded DNA • Separate from chromosomal DNA • Contain genes which code for less essential traits (ex. Adaptive traits) • Common in bacteria

42. Recombinant DNA • This is the union of DNA from 2 different organisms

43. Restriction endonuclease (RE): enzymes in cells which cleave (cut) DNA into pieces • We can use this enzyme to cut and splice genes

44. Procedure of recombinant DNA technology • Isolate desired gene from a donor cell • Cut out desired gene using RE • Extract plasmid from bacterium using lysozyme • Using RE cut out DNA segment from plasmid creating sticky ends • “paste” desired gene “sticky” ends into plasmid opening

45. Insert recombinant plasmid into healthy bacterium • Allow bacteria to multiply (cloning) by incubating with nutrients • Bacteria will transcribe and translate new gene, producing desired proteins

47. What are some desired proteins? • Insulin • Vaccines • Hemoglobin • Hemoglobin Protein Molecular Formula: • C3032H4816O872N780S8Fe4 • Glycine (typical AA): C2H5N1O2

48. Some Products Made Using Biotechnology • Human growth hormone is used to treat dwarfism. It previously took the pituitary glands from over 50 cadavers to make one dose. • Human Insulin is used to treat diabetes. • Tissue plasminogen activator  dissolves blood clots in heart attack victims. • Clotting factor VIII will soon be available. Most cases of hemophilia are due to the absence of this factor. • Human lung surfactant is used in premature infants with respiratory distress syndrome. • Atrial natriuretic hormone can be used to treat hypertension. • Bovine growth hormone (bGH) increases milk production in cows by about 10%. • A vaccine for hepatitis B is now produced using biotechnology. • Vaccines for chlamydia, malaria and HIV are being developed. • Vaccines for hoof-and-mouth disease and scours (a form of dysentery) have been developed for farm animals. • Bacteria have been produced that inhibit the formation of ice crystals. These bacteria have been released onto crop plants to protect them from frost damage. • A bacteria species that normally colonize corn roots have been given a gene that enables it to produce an insect-killing toxin. • Bacteria are being developed that do a better job at breaking down oil. • Bacteria have been developed that are capable of removing some kinds of toxins from the air and water. • Bacteria have been engineered to extract metals from low-grade ore (bioleaching). • there are 50 types of genetically engineered plants that resist insects, viruses, and herbicides. • A weed called mouse-eared cress has been designed to produce a biodegradable plastic called polyhydroxubutrate (PHB). • Pharmaceutical companies are developing techniques to produce chemicals using animals. The drug is produced in the milk of females. For example, goats have been developed to produce antithrombin III, used to prevent blood clots. Clinical trials of this drug will begin soon. • A pig has been produced that can produce human hemoglobin. Artificial blood may soon be a reality.

50. DNA fingerprinting • Analysis of DNA sequences to determine identity