II. Replication

1. II. Replication - The process of DNA making a copy of itself

2. Steps for Replication • 1. DNA helicase (enzyme) – breaks hydrogen bonds between bases separating the 2 strands • 2. The complimentary bases are brought to the single strand • 3. DNA polymerase connects the new DNA strand with the old and rezips the molecule

3. DNA Replication DNA polymerase old old new new T -- A – T -- A A -- T – A -- T G -- C – G -- C A -- T – A -- T G -- C – G -- C C -- G – C -- G T -- A – T -- A T -- A – T -- A DNA helicase DNA polymerase

4. Review 1.The making of more DNA is called ? 2. Which enzyme is used first in the making of more DNA – DNA polymerase or DNA helicase ? 3. This enzyme is like a glue – putting the base pairs back together. 4. Replicate this strand of DNA G – C A – T C – G T – A T – A 5. How would you describe the shape of DNA ?

5. III. RNA - ribonucleic acid - function : makes proteins • Differences between DNA and RNA DNARNA 2 strands 1 strand deoxyribose sugar ribose sugar thymine base uracil base B. 3 types of RNA 1. messenger RNA (mRNA) - straight strand - takes information from DNA in nucleus to the ribosome to make proteins 2. transfer RNA (tRNA) - folded strand - 20 different kinds - brings amino acid to ribosome to make proteins 3. ribosomal RNA (rRNA) - round - makes ribosomes

6. C. Transcription –making of RNA from DNA • Done in the nucleus then travels to ribosomes in cytoplasm • Uses RNA polymerase (enzyme) to break bonds between bases separating the 2 strands of DNA

7. G A U A A C U C U A U U G A mRNA mRNA DNA strand C – G T – A A – T T – A T – A G – C A - T RNA polymerase

8. Review 1. What are the 3 types of RNA. 2. Give 3 differences between RNA and DNA. 3. The process of making more DNA is called ________ while the making of RNA is __________. 4. How does a cell know it is making RNA from DNA instead of making more DNA from DNA ? 5. Change the following DNA strand into mRNA T-T-A-A-G-C-G-A-T-C 6. RNA is used in the making of ___________. 7. There are 20 different kinds of this type of RNA.

9. III. Protein Synthesisthe making of proteins using information coded from DNA and carried out by RNA. • A. Amino Acids - basic building blocks of proteins - 20 different ones - joined together by peptide bonds - carried by tRNA • B. Codon – 3 bases in a row within a mRNA strand that call for a specific anticodon that codes for a specific amino acid. *** AUG is the universal start codon for all organisms.

10. C. Translation – process of making proteins by using mRNA amino acids Start alanine leucine alanine tRNA anticodon U A C C G C A A C C G A occurs in ribosomes A U G G C G U U G G C U mRNA codon

11. Review • Change the following DNA strand into mRNA. A-T-C-G-C-G-T-T-A-G-C-T • Assemble the protein from the mRNA sequence from your answer to #1.

12. **errors do occur but rarely – about 1 per billion nucleotides • Factors that damage DNA a. excessive body heat (fever) b. radiation (UV & X-rays) c. chemicals (carcinogens) -- DNA has proofreading enzymes that constantly try and repair mistakes in base pairing.

13. Human Genome Project - project with scientist all over the world to map out the sequence and location of all traits (genes) on all human chromosomes. Humans have 3.5 billion base pairs per sex cell.