1. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb PowerPoint ® Lecture Slides prepared by Vince Austin, University of Kentucky 3 Cells: The Living Units Part D

2. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings What is DNA needed for? Genetic information is copied from DNA and converted to protein RNA molecules work as messengers that carry the info to the ribosomes who then make the Proteins.

3. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings DNA ( Deoxyribo Nucleic Acid) DNA is two long chains of Nucleotides A Nucleotide consists of: A phosphate Group A five carbon sugar (deoxyribose) A Nitrogenous Base

4. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings DNA  The sides of the DNA strand are the connection of the Phosphates to the Sugars.  Each Phosphate is connected to deoxyribose by a covalent bond.

5. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings DNA  There are four bases that make up the “rungs” of the ladder  Adenine  Guanine  Cytosine  Thymine

6. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Four bases... Each of the four bases has a specific shape. Purine bases  Adenine and Guanine  Two carbon rings Pyrimidine bases  Thymine and Cytosine  A single carbon ring A two carbon ring can only attach to a single carbon ring.

7. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings DNA  Each base pair is held together by a couple of hydrogen bonds.

8. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Base Pairing Rule  Adenine only pairs with Thymine and Cytosine only pairs with Guanine.  They are called complimentary base pairs.

9. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings DNA Molecules  Two polynucleotide chains are joined  Double helix, twisted in right handed way  Full circle in every 10 bases

10. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Histones Histones are proteins that The DNA strand coils around. This gives the chromosome as A whole some extra structural Support.

11. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The Genetic Code  Describes how nucleotide sequence is converted to protein sequence  Unit of three nucleotides = a codon  A codon codes for a specific amino acid (structural component of protein)

12. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Protein Synthesis  DNA serves as master blueprint for protein synthesis  Genes are segments of DNA carrying instructions for a polypeptide chain  Triplets of nucleotide bases form the genetic library  Each triplet specifies coding for an amino acid

13. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Transcription  Transfer of information from the sense strand of DNA to RNA

14. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Roles of the Three Types of RNA  Messenger RNA (mRNA) carries the genetic information from DNA in the nucleus to the ribosomes in the cytoplasm  Transfer RNAs (tRNAs) bound to amino acids base pair with the codons of mRNA at the ribosome to begin the process of protein synthesis  Ribosomal RNA (rRNA) is a structural component of ribosomes

15. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Transcription: RNA Polymerase  An enzyme called Polymerase. oversees the synthesis of RNA  Helicase Unwinds the DNA.  Polymerase starts the copy at the Promoter (regions on DNA that show where RNA Polymerase must bind to begin).

16. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Adds complementary ribonucleotide triphosphates on the DNA template  Joins these RNA nucleotides together  Encodes a termination signal to stop transcription

17. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 17 mRNA Transcript mRNA leaves the nucleus through its pores and goes to the ribosomes. copyright cmassengale

18. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 18 Translation  Translation is the process of decoding the mRNA into a protein.  Ribosomes read mRNA three bases or 1 codon at a time and construct the proteins copyright cmassengale

19. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 19 Step 1- Initiation  mRNA enters the ribosome and attaches to the tRNA. The tRNA has an anticodon that matches with the three “start” nucleotides.

20. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 20Initiation mRNA AUGCUACUUCG 2-tRNA G aa2 AU A 1-tRNA UAC amino anticodon hydrogen bonds codon copyright cmassengale

21. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Step 2 - Elongation  The ribosome moves down the mRNA strand.  The first tRNA detaches and leaves it’s amino acid.  Two new tRNA with their amino acids move into position (positions are called A and P)  The new tRNAs have the correct amino acid for that specific codon. Each amino Acid forms a bond. 21copyright cmassengale

22. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 22 mRNA AUGCUACUUCG 2-tRNA G Amino 1 Amino 2 AU A peptide bonds 3-tRNA GAA Amino 3 4-tRNA GCU Amino 4 ACU copyright cmassengale

23. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 23 mRNA GCUACUUCG Amino 1 Amino 2 A peptide bonds 3-tRNA GAA Amino 3 4-tRNA GCU Amino 4 ACU UGA 5-tRNA Amino 5 copyright cmassengale

24. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Dissaembly  When the stop codon is reached the ribosome falls off, the protein goes into the body, and the tRNAs go out to find more amino acids.  The ribosome will go find another strand of mRNA and the whole process starts over. 24

25. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 25 End Product –The Protein!  The end products of protein synthesis is a primary structure of a protein  A sequence of amino acid bonded together by peptide bonds 1 2 3 4 5 200 199 copyright cmassengale

26. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings From DNA to Protein Figure 3.34

27. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of Cells  All cells of the body contain the same DNA but develop into all the specialized cells of the body  Cells in various parts of the embryo are exposed to different chemical signals that channel them into specific developmental pathways  Genes of specific cells are turned on or off  Cell specialization is determined by the kind of proteins that are made in that cell

28. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of Cells  Development of specific and distinctive features in cells is called cell differentiation  Cell aging  Wear and tear theory attributes aging to little chemical insults and formation of free radicals that have cumulative effects throughout life  Genetic theory attributes aging to cessation of mitosis that is programmed into our genes