CHE 331 Module #1 Unity of Life.pdf

1 Dr. Lina Al Kury Biochemistry & the Unity of Life CHE 331 Module # 1  Key Messages 2 I. Organisms are fairly similar...

1 Dr. Lina Al Kury Biochemistry & the Unity of Life CHE 331 Module # 1  Key Messages 2 I. Organisms are fairly similar at the molecular level II. There is a limited number of elements at the atomic level that constitute living systems III. There are four major classes of biological molecules –Nucleic acids, Carbohydrates, Proteins and Lipids- in all life forms IV. The Central Dogma describes how information is transferred in living systems V. The major difference between Prokaryotic and Eukaryotic cells is in the sequestration of biochemical reactions  3 I- Unity of Life  Unity of Life 4 “Anything found to be true of E. coli must be true of elephants” - Jaques Monod, 1954 Organisms are remarkably uniform at the molecular level  5 II. There is a limited number of elements at the atomic level that constitute living systems Let’s look at the atoms first 6  7 Hydrogen+ Oxygen +Carbon = 98% of a living organism Why?  8 One reason that oxygen and hydrogen are so common is due to the fact that water is everywhere. But why carbon? Most large molecules in living systems made of carbon Carbon-carbon bonds are strong Ø Stable, can release more energy in combustion  9 we are 99% Hydrogen + Oxygen + Carbon+ Nitrogen Does that mean we don’t need other elements? Phosphorous, Sulfur, Iron, Magnesium, Manganese… Biological Periodic Table  10 III. There are four major classes of biological molecules –Nucleic acids, Carbohydrates, Proteins and Lipids- in all life forms  11 Human body has about 500,000 substances in it Imagine trying to figure out unity of life when you would have to figure the chemistry of so many compounds! Luckily, real life is not as complex as we fear it is. Nearly all the substances found in living cells are polymeric: built up by different combinations of a limited number of relatively small molecules So you just have to study four types of molecules and not 500, 000 Lucky you! Four Major Classes of Biomolecules 12 1) Proteins: Workhorses of the Cell Structure of the cell, its mobility, immune defense, signaling (both signals and receptors) and catalyze biological reactions  Four Major Classes of Biomolecules 13 2) Nucleic Acids: Command and Control Centre of the Cell Phosphate group, Ribose or deoxyribiose sugar, Nitrogenous base Store and transfer information for all cellular functions  Four Major Classes of Biomolecules 14 2) Nucleic Acids: Command and Control Centre of the Cell DNA: double-stranded (double helix), A=T, G=C RNA : single stranded, Uridine (U) instead of T, sugar has an additional -OH Four Major Classes of Biomolecules 15 3) Lipids: Cellular Fuels and Barriers Store energy, form membranes necessary for structure, and cell signaling Not quite polymers of repeating units as you will see later  Four Major Classes of Biomolecules 16 4) Carbohydrates: Double agents - Fuel and Information Glycogen Important fuel source for all living organisms – glucose is most common while glycogen is how it is stored in animals. Starch in plants Carbohydrate chains are important for cellular recognition  17 IV- The Central Dogma of molecular biology Biological Information Transfer: 18 Francis crick, 1958 Genome Heritable information Collection of genes (DNA) The selective expression of genes defines the function of a cell. Source: http://en.wikipedia.org/wiki/Central_dogma_of_molecular_biology Biological Information Transfer: 19 DNA Replication Buzz words: Genome, Gene, DNA polymerase, Replication Biological Information Transfer: 20 Transcription RNA polymerase, mRNA  Biological Information Transfer: 21 Translation translation of the information into real work on Ribosomes http://bcs.whfreeman.com/thelifewire9e/default.asp#542578__591304__  22 V- Eukaryotic and Prokaryotic cells  What is a Cell? 23 Basic unit of life Living organisms can be as simple as a single cell or as complex as a human body Can grow, replicate, interact with other cells and environment It is a unit because it is bound by the barrier - a membrane which is a lipid bilayer – plasma membrane Inside the cell, the chemistry is different from its environment - cytoplasm Are All Cells Similar? 24 Are All Cells Similar? 25  26 Nucleus The largest organelle in Eukaryote Nuclear membrane has pores for transport Information center of the cell Mitochondrion (plural motochondria) ATP factory 90% of the energy of a cell Chloroplast and vacuoles in plant cells Photosynthesis and nutrient storage  Some Organelles Process Proteins 27 Smooth ER: Processing exogenous chemicals including drugs Rough ER (+ribosome): Protein factory – transfer of protein from ER to Golgi complex by transport vesicles. Golgi complex: processing of proteins made in the rough ER, addition of carbohydrates Secretory granules: transport of proteins from Golgi to plasma membrane–Exocytosis  Exchange of Material 28 Endosome: Endocytosis of iron, B12 and cholesterol Phagosome: phagocytosis of large amounts of material including bacteria Lysosome: digestion factory (digestion of damaged intracellular organelles)