VIEWS: 4 PAGES: 8 POSTED ON: 4/18/2011
Life on Earth Bio 100 Chapter 1 & 2 Notes Why Biology???? •It’s the science of life –Helps us understand the human body –Helps to better inform you of controversial and ethical issues –Career opportunities –Depends our appreciation of nature Scientific Theory: A concept that joins together a well-supported & related hypothesis. It’s a speculated idea that is tested and proven to be facts or evidence-base The Scientific Process Research and Investigations •Observation – observation of an interesting pattern phenomenon, an occurrence of a natural event. Using inductive reasoning – questioning – using creative thinking •Hypothesis – a possible explanation for the natural event, making a prediction •Experiments – conducted and designed to collect data to support or refute the hypothesis •Data – the results of the experiment that are measured in statistical values •Conclusion – was the hypothesis supported by the data or not? Biological Organization •Atoms •Molecules •Cell •Tissue •Organ •Organ systems •Complex organisms Life •Living things are complex and organized. – Structured by non-living & living matter (atoms, molecules, & cells) •Living things grow & reproduce •Living things respond to stimuli •Acquire and use materials and energy •Use DNA to store information Diversity of Life •Diversity of life (variety of life forms) occurs because of evolution •Evolution changes groups of organisms from generation to generation •Caused by natural selection – a process in which unequal survival and reproduction or organisms, favor individual with particular traits causing them to become more common in a population. Inorganic Molecules: the basic chemistry of life BIO 100 Chapter 2 Atoms and Molecules Chemical Molecules •Elements = a substance that can neither be broken down nor converted to other substances by ordinary chemical means. •What are atoms? The basic building blocks of matter that make up everything (desk, air, tissue, even you) •Atoms combine to form molecules Components of the Atom. Atoms are made up of 3 basic particles •Protons – positive charge •Neutrons – negative charge •Electrons – negative charge •Protons & Neutrons join together to form the nucleus – atomic nucleus Also have: •Atomic number – the number of protons in nucleus •Isotopes – atoms of the same elements, with diff. Number of neutrons •Radioactive isotopes –lease energy that break apart forming diff. Types of atoms. So How Do Atoms Form Molecules? By interacting between other atoms and when their outmost electron shells have a vacancy. –Chemical bonds – hold atoms together by gaining or losing a shared electron –Chemical reactions – making and breaking of chemical bonds The Electron Shells •Chemical bonds – are attractive forces holding atoms together to form molecules –The elements have chemical bonding properties arising from the arrangements of the outer shell •Inert – non reactive •Reactive – unstable • – positive or negatively charged atoms. Molecules & Compounds •Ionic bonds – occurs when atoms loose or gain electrons during a reaction; opposite charges are electrically attracted between positive and negative charged ions. Easily broken bonds •Covalent bonds – share electrons instead of loosing or gaining; uncharged ions. Strong bonds •Hydrogen bonds – electrical attraction (polarized) between in water molecules; negative charged O2 atoms is attracted to a positive charged H atom in water. Forms a weak covalent bond. Covalent Bond - atoms sharing electrons Water and Living Things •Water – is the most abundant life sustaining substance in living organisms •Comprises of 60-70% of body weight •It is an Essential inorganic molecules – for water, acids, and bases •Universal solvent for biological chemical reactions •Polarity of water causes many characteristics beneficial to life Water and Living Things are Characterized bystics of water polarity: Liquid – remains liquid in our bodies. Universal solvent – facilitate chemical reactions in/out of our bodies Cohesive properties – helps water base- solutions fill blood vessels Without hydrogen bonding taking place between water molecules,body fluids would be a gaseous form. Water has Characteristics of water polarity •Ability to change temperature slowly – prevents drastic changes •Vaporization – keeping body temperature from overheating •Ability to freeze – becomes less dense and in weight. Acid – Base •Water breaks up (dissociates) equal number of hydrogen (H) and hydroxide (OH) ions •Acid solutions – release H –Tomato juice, coffee, vinegar; which gives it that Sharp, sour taste associated with indigestion •Basic solutions – release OH and gain H –MOM, ammonia, household cleaners & detergents –Bitter taste, become slippery when wet pH Scale is Used to indicate acidity or alkaline base •Neutral – 7.0 (H & OH ions are at equal state) •< 7.0 becomes an acid state •> 7.0 becomes a basic state •pH needs to be maintain in humans in order to maintain homeostasis (Internal balance) Buffers are Bicarbonate ions that Stabilize pH within normal limits by taking up •Take up excess H+ or OH- molecules to resist pH changes •Bufferin, shampoos, deodorants Important elements for molecules in living organisms Carbon * Phosphate Sodium Hydroxide Potassium Hydrogen Chloride Bicarbonate Calcium Organic Molecules have Carbon in their molecular makeup •Carbon combines with other atoms to form different molecules like: •Charbohydrates, Polysaccharides, Proteins, fats, and starches & glycogen Organic molecule Structure: The molecules of life always: –Are important to living organisms –Always contain carbon and hydrogen –Macromolecules – (polymers) a large molecule structure containing many molecules joined together –Micromolecules - (monomers) simple organic molecule or a subunit of a polymer Polymers & Monomers Polymers – are macromolecule, monomers are linked or covalently bonded together •Carbohydrate (starch), Protein, Nucleic acid (DNA), Lipids (a polypetide is a polymer of monomers called amino acids) •Carbohydrates sugars •Lipids glycerol and fatty acids •Proteins amino acids Cells use these monomers to build their own macromolecules Organic molecules Synthesis and Degradation reactions in macromolecules Dehydration synthesis – BUILDS UP –Links monomers together to form a polymer –2 hydrogens and an oxygen atom are removed from subunits creating covalent bonds - the reaction of ions combine to form water –Water is also always a byproduct •Hydrolysis – BREAKS DOWN –Polymer is broken down to monomers - B –Water is required to replace 2 hydrogens and the oxygen Carbohydrates •General structure –Composed of C, H, and O2 –Important energy source for most organisms •Functions –Principal energy source for cells –First function for short term energy storage –Structural components in some cells –Cell to cell recognition- surface antigens Carbohydrates Simple carbohydrates Monosaccharides and dissaccharides –Monosaccharides: simple sugars such as •glucose (blood sugar) •fructose (fruits, corn sugar) –Dissaccharides: 2 monosaccharides bonded together •sucrose (glucose + fructose) •lactose (milk sugar = galactose) •galactose (glucose + lactose) •maltose (glucose + glucose) Carbohydrates Polysaccharides 3. Starch & glycogen already stored forms of glucose stored in the liver Released in between meals to maintain blood glucose levels (0.1%) Cellulose functions in plant cell wall structure unable to digest, acts as fiber or roughage Lipids •General characteristics –Extremely diverse group of organic molecules: fats, oils, steroids, waxes, phospholipids –Common characteristic - nonpolar molecules which are insoluble in water –Contain more calories of energy per gram so are ideal energy storage molecules –Also functionS as structural components, insulation, cushioning of organs, and hormones Lipids •Fats and oils (most common) –Oils tend to be liquid at room temperature and are usually of plant origin –Fats tend to be solid at room temperature and are usually of animal origin –Fats are important in energy storage –Insulation against heat loss –Protective cushion around major organs Lipids •Emulsification –Fats are nonpolar; they do not dissolve in water and tend to form “globules” (oil and vinegar dressing) –Emulsifier breaks down the globules of fat into smaller droplets –Emulsifiers have a nonpolar end which attaches to the fat, and a polar end which interacts with water molecules so that the droplets can disperse Lipids •Saturated and Unsaturated fatty acids –Saturated have no double bonds between carbon atoms, and tend to be more solid at room temperature –Unsaturated have at least one double bond between carbons –Polyunsaturated have multiple double bonds- the more polyunsaturated the fatty acids, the more liquid the fat will be at room temperature The Good & the Bad – and the Ugly •Good cholesterol: HDL has more protein and less lipid. –Circulates to the liver where it is removed from the bloodstream •Bad cholesterol: LDL has less protein and more lipids –Circulates to cell (forming fat) and also deposit in artery walls (atherosclerosis, arteriosclerosis). Lipids •Phospholipids –Attached phosphate gives “polarity” –Has a hydrophilic (water-soluble) head and a hydrophobic (water-insoluble) tail –Important components of cell plasma membranes •Steroids –Composed of 4 carbon rings –Cholesterol is a steroid which functions in membrane structure and hormone synthesis Steroids Proteins •General characteristics –Composed of one or more amino acids –There are 20 different amino acids which join by dehydration synthesis to form a molecular chain –Various functions – either a hormone, an enzyme or a structural protein –3 dimensional shape which gives proteins their function: primary, secondary, tertiary structure Levels of protein organization Proteins Functions: •Keratin – builds hair, nails and collagen •Hormones – cellular metabolism •Actin & myosin – movement of cells and muscular contractility •Hemoglobin – transports oxygen in blood •Antibodies – bind foreign subtances to prevent the destruction of cells •Enzymes – speed up chemical reactions in the body Proteins Peptides •The bonds between amino acids called peptide bonds •Peptide bonds are polar covalent bonds Protein structure •The final shape of a protein molecule is often critical to its function –its what enables it to perform its function •Extreme conditions (exposure to heat; pH) can change the shape of the protein molecule •Denaturation = irreversible change in shape –Disruption of the proteins shape •When normal bonding between the R groups have been disturbed, denaturation has occurred •Once protein loses its normal shape it become dysfunctional. Nucleic Acid Molecule •Deoxyribonucleic (DNA) Acid Molecule & Ribonucleic Acid (RNA) •DNA is in every cell of your body •Contained in the nucleus of the cell •Genetic material - Instructional Manual for your body •Mostly composed of carbon, hydrogen, nitrogen and phosphorus •Role of DNA: to reproduces & build proteins in the body DNA structure Nucleic Acids •Long chains of similar, but not identical, nucleotides •All nucleotides have: 5-carbon sugars (ribose or deoxyribose) Phosphate Nitrogen •Form DNA and RNA Basic Chemistry •Matter is composed of element •Over 110 elements in the periodical chart •Each element - composed of one type atom •Atoms have: – mass dependent upon protons & neutrons –chemical properties dependent upon the number of electrons –React with one another forming ionic, covalent or hydrogen bonds Molecules Inorganic molecules: –Constitute nonliving matter –Necessary for living things –Like water and salt Molecules Organic molecules: –Are important to living organisms –Necessary for living things –Always contain carbon and hydrogen –Include: •Charbohydrates •Polysaccharides •Proteins •Fats •Starches & glycogen
"Life on Earth ch 12"