Exam 2 Review Slides

1. Exam 2 Review Slides Lectures 5-8 Chapters 3 and 22 (Sec. 22.1-22.4)

2. Cell Membranes Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

3. Passage of Materials through the Cell Membrane Carrier/channel proteins required for all but fat-soluble molecules and small uncharged molecules oxygen, carbon dioxide and other lipid-soluble substances diffuse freely through the membrane

4. Cellular Organelles Table 1 of 2

5. Cellular Organelles Table 2 of 2

6. Cell Death • Two mechanisms of cell death • Necrosis • Programmed cell death (PCD or apoptosis) • Necrosis • Tissue degeneration following cellular injury or destruction • Cellular contents released into the environment causing an inflammatory response • Programmed Cell Death (Apoptosis) • Orderly, contained cell disintegration • Cellular contents are contained and cell is immediately phagocytosed

7. Stem and Progenitor Cells • Stem cell • can divide to form two new stem cells • can divide to form a stem cell and a progenitor cell • totipotent – can give rise to any cell type (Embryonic stem cells) • pluripotent – can give rise to a restricted number of cell types • Progenitor cell • committed cell • can divide to become any of a restricted number of cells • pluripotent

9. Cancer • Two types of tumors • benign – usually remains localized • malignant – invasive and can metastasize; cancerous • Genes that cause cancer • oncogenes – activate other genes that increase cell division • tumor suppressor genes– normally regulate mitosis; if inactivated they will not regulate mitosis Oncology is the study of tumors

10. Cancer Metastasis is the spread of a cancer from its site of origin to other areas of the body

11. Lecture Review

12. Lecture Review

13. Osmotic Pressure/Tonicity Osmotic Pressure (Osmolarity) – ability of solute to generate enough pressure to move a volume of water by osmosis *Osmotic pressure increases as the number of nonpermeable solutes particles increases • isotonic – same osmotic pressure as a second solution • hypertonic – higher osmotic pressure • hypOtonic – lower osmotic pressure 0.9% NaCl5.0% Glucose Crenation The Oin hypotonic

14. Some Definitions… *Chromatin– combination of DNA plus histone proteins used to pack DNA in the cell nucleus • Gene – segment of DNA that codes for a protein or RNA • - About 30,000 protein-encoding genes in humans • - DNA’s instructions are ultimately responsible for the ability of the cell to make ALL its components • Genome – complete set of genes of an organism • Human Genome Project was complete in 2001 • Genomes of other organisms are important also Genetic Code – method used to translate a sequence of nucleotides of DNA into a sequence of amino acids

15. Structure of Nucleic Acids Purines: Adenine and Guanine (double ring) Pyrimidines: Cytosine, Thymine, and Uracil (single ring) Figure from: Alberts et al., Essential Cell Biology, Garland Press, 1998

16. Structure of DNA 5' 3' A double-stranded DNA molecule is created by BASE-PAIRING of the nitrogenous bases via HYDROGEN bonds. Notice the orientation of the sugars on each stand. 5' 3' *DNA is an antiparallel, double-stranded polynucleotide helix

17. Structure of DNA Complementary base pairing… Base pairing in DNA is VERY specific. - Adenine only pairs with Thymine (A-T) - Guanine only pairs with Cytosine (G-C) Note that there are: - THREE hydrogen bonds in G-C pairs - TWO hydrogen bonds in A-T pairs - A purine (two rings)base hydrogen bonds with a pyrimidine base (one ring) Figure from: Martini, “Human Anatomy & Physiology”, Prentice Hall, 2001

18. DNA Replication 5’ • THINGS TO NOTE: • DNA is replicated in the S phase of the cell cycle • New strands are synthesized in a 5’ to 3’ direction • DNA polymerase has a proofreading function (1 mistake in 109 nucleotides copied!) • Semi-conservative replication describes pairing of post-replication strands of DNA (1 new, 1 old) 3’ 5’ 3’ 5’ 3’ 3’ 5’ 3’ Figure from: Martini, “Human Anatomy & Physiology”, Prentice Hall, 2001 5’

19. RNA • RNA is a polynucleotide with important differences from DNA • Uses Uracil (U) rather than Thymine (T) • Uses the pentose sugar, ribose • Usually single-stranded • There are three important types of RNA • mRNA (carries code for proteins) • tRNA (the adapter for translation) • rRNA (forms ribosomes, for protein synthesis)

20. Transciption/Translation • Transcription • generates mRNA from DNA • Occurs in nucleus of the cell • Uses ribonucleotides to synthesize mRNA • Translation • generates polypeptides (proteins) from mRNA • Occurs in the cytoplasm of the cell • uses tRNA and ribosomes

21. The Genetic Code • Codon – group of three ribonucleotides found in mRNA that specifies an aa • Anticodon – group of three ribonucleotides found in tRNA that allows specific hydrogen bonding with mRNA • AUG is a start codon and also codes for MET. UAA, UAG, and UGA are stop codons that terminate the translation of the mRNA strand.

22. Find the AMINO ACID SEQUENCE that corresponds to the following gene region on the DNA: Template -> G A T T G A A T C Coding -> C T A A C T T A G

23. tRNAs Transfer RNAs (tRNA) function as ‘adapters’ to allow instructions in the form of nucleic acid to be converted to amino acids. Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001

24. Eukaryotic Genes The template strand of DNA is the one that’s transcribed. The coding strand of DNA is used as the complementary strand for the template strand in DNA and looks like the codons. Figure from: Alberts et al., Essential Cell Biology, Garland Publishing, 1998

25. Eukaryotic mRNA Modification Newly made eukaryotic mRNA molecules (primary transcripts) undergo modificationin the nucleus prior to being exported to the cytoplasm. 1. Introns removed2. 5' guanine cap added3. Poly-A tail added Figure from: Alberts et al., Essential Cell Biology, Garland Publishing, 1998

26. The Fate of Proteins in the Cell • Breakdown of proteins regulates the amount of a given protein that exists at any time. • Each protein has unique lifetime, but the lifetimes of different proteins varies tremendously. • Proteins with short life-spans, that are misfolded, or that become oxidized must be destroyed and recycled by the cell. Enzymes that degrade proteins are called proteases. They are hydrolytic enzymes. Most large cytosolic proteins in eukaryotes are degraded by enzyme complexes called proteasomes.

27. Enzymes • Enzymes are biological catalysts • Highly specific for their substrate • Lower activation energy needed to start a reaction • Are not consumed during reaction • May require cofactors/coenzymes • Effectiveness is greatly affected by temperature, pH, and the presence of required cofactors • Cofactors • make some enzymes active • ions or coenzymes • Coenzymes • complex organic molecules that act as cofactors (so coenzymes ARE cofactors) • vitamins • NAD+

28. General Reaction sequence in carbohydrate catabolism C6H12O6 + 6 O2 6 CO2 + 6 H2O + ENERGY OXIDATION REDUCTION Harnessing Energy from Carbohydrates Electrons (H·) “fall” in energy from organic molecules to oxygen during cellular respiration. That is, e- LOSE potential energy during this process and this energy is captured to make ATP However, electrons CANNOT be transferred directly from glucose to the electron transport chain. There are intermediates – activated carrier molecules

29. Energy for Metabolic Reactions • Energy • ability to do work or change something (potential, kinetic) • heat, light, sound, electricity, mechanical energy, chemical energy • changed from one form to another, butNEVER destroyed (law of conservation of energy) • involved in all metabolic reactions • Release of chemical energy • most metabolic processes depend on chemical energy • oxidation of glucose generates chemical energy • cellular respiration releases chemical energy slowly from molecules and makes it available for cellular use

30. Oxidation and Reduction Revisited Oxidation Is Loss of electrons; Reduction Is Gain of electrons “OIL RIG” • Oxidation • gain of O2 • loss of e- • loss of H (since a H carries an electron with it) • increase in oxidation number, e.g., Fe2+ -> Fe3+ • Reduction • loss of O2 • gain of e- • gain of H • decrease in oxidation number, e.g., Fe3+ -> Fe2+

31. ATP – An Activated Carrier Molecule • each ATP molecule has three parts: • an adenine molecule • a ribose molecule • three phosphate molecules in a chain These two components together are called a ? • ATP carries its energy in the form or P (phosphate) • ATP is a readily interchangeable form of energy for cellular reactions (“common currency”) High-energy bonds

32. NAD(H) – An Activated Carrier Molecule NAD+ NAD (and NADP) are specialized to carry high-energy e- and H atoms A “packet” of energy = H· NADH + H+ NAD+ NADH These packets of energy will be passed to oxygen in the electron transport chain, and their energy used to drive the synthesis of ATP Important carriers of e-in catabolism: NADH, FADH2 Figure from: Alberts et al., Essential Cell Biology, Garland Press, 1998

33. Summary Table of Cell Respiration

34. Summary of Catabolism of Proteins, Carbohydrates, and Fats Acetyl CoAis a common intermediate in the breakdown of most fuels. Acetyl CoA can be generated by carbohydrates, fats, or amino acids Acetyl CoA can be converted into fatty acids

35. Pyruvate is a Key Junction in Metabolism Pyruvate is used to synthesize amino acids and Acetyl CoA Pyruvate can also be used to synthesize glucoseviagluconeogenesis. Glycogenesis Lipo-genesis Glycogenolysis Lipolysis * Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

36. Carbohydrate Storage • Excessglucose can be • stored as glycogen by glycogenesis (liver and muscle cells) • stored as fat by lipogenesis • converted to amino acids

37. Terms to Know… -olysis  breakdown of -neo  new-genesis  creation of • Glycolysis – metabolism of glucose to pyruvate • Gluconeogenesis – metabolism of pyruvate to glucose (making CHO from non-CHO source) • Glycogenesis – metabolism of glucose to glycogen • Glycogenolysis – metabolism of glycogen to glucose • Lipogenesis – creation of new triglyceride (lipid, fat) • Lipolysis – breakdown of triglyceride into glycerol and fatty acids