1. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Flow of Genetic Information The flow of genetic information can be symbolized as DNA RNA protein Ch 8-4

2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu RNA Structure and Function RNA has the sugar ribose instead of deoxyribose RNA has uracil (U) in place of thymine (T) RNA is single stranded RNA is shorter than DNA

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of RNA –Cells have three major types of RNA: 1.messenger RNA (mRNA) 2.ribosomal RNA (rRNA) 3.transfer RNA (tRNA)

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of RNA 1.mRNA carries the genetic “message” from the nucleus to the cytosol 2.rRNA is the major component of ribosomes 3.tRNA carries specific amino acids, helping to form polypeptides (proteins)

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Transcription Making RNA from DNA DNA acts as a template 1.RNA polymerase binds to promoter site 2.2 strands of DNA unwind 3.Complementary RNA nucleotides are added

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Transcription

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Genetic Code identifies the specific amino acids coded for by each three-nucleotide mRNA codon Ch 8-5

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Translation –Making Proteins from RNA –amino acids are assembled from information encoded in mRNA 1.mRNA codons move through the ribosome 2.tRNAs add specific amino acids to the growing polypeptide chain 3.Process continues until a stop codon is reached 4.Newly made protein is released

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Translation: Assembling Proteins

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Translation: Assembling Proteins, continued

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Human Genome The entire gene sequence of the human genome is now known To learn where and when human cells use each of the proteins coded for in the approximately 30,000 genes in the human genome will take much more analysis