26-28 Jan Bio Notes
26-28 Jan Bio Notes BIO 151
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This 12 page Class Notes was uploaded by Chelsea Notetaker on Thursday January 14, 2016. The Class Notes belongs to BIO 151 at Central Michigan University taught by Professor Learman in Winter 2016. Since its upload, it has received 14 views. For similar materials see Human Biology in Biology at Central Michigan University.
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Date Created: 01/14/16
January 26/28 Bio 151 Notes Human Composition Water Water has several special properties, which are dependent on its ability to form hydrogen bonds. -called the ‘solvent of life’—all known living things require it to survive -It’s resistant to temperature change , and can absorb or lose large amounts of heat without changing your internal or overall body temperature. This helps the body maintain a constant temperature in varying external conditions—the body’s ability to regulate its internal temperature is part of its constant efforts of maintaining homeostasis. > Imagine hot sand versus the warm water on beaches—water has a high heat capacity, and sand has a low heat capacity, meaning X amount of energy put into water will not get it as hot as X energy gets sand. > The reason for this high heat capacity is due to how the energy is used among the water molecules. Instead of causing the molecules simply to vibrate, creating heat, the molecules break their hydrogen bonds and recreate them, break and recreate them, so the energy is expended through that constant movement as opposed to vibration. -Water is a solvent: > all chemical reactions imperative for living things take place in a watery environment. > molecules of life are characterized by whether or not they interact with water (through charge interaction or hydrogen bonding) > water only interacts with specific things—this causes the organization and chemistry of life. 1 (Which in physics is called having a ‘high heat capacity’.) Class Activity Question One You see a drop of water and a drop of ethanol (alcohol) on a sheet of wax paper. Each drop behaves differently. Which do you think is which, and why. Image: You see a highly-rounded drop of clear fluid (A), and a flattened, spread drop of clear fluid (B). ^ A is water, B is ethanol. A is exhibiting water tension due to its hydrogen bonds, preventing it from spreading out. Water also resists interacting with the wax on the paper, like the way water and oil don’t mix. Question Two Drops of dye in hot water versus cold water. In the hot water the dye diffuses quickly, and in the cold it diffuses slowly. Why is this? ^Hot water molecules have more energy and are moving more quickly than cold water molecules, and help disperse the dye with their motion, as though they’re stirring it. *Solid water has a solid hydrogen bond. Liquid water has an unstable hydrogen bond. Gaseous water has no hydrogen bond. Question Three As water absorbs energy the molecules move more, and the status of the hydrogen bond changes. When the hydrogen bonds are fully broken, water evaporates; what happens to the energy? What purpose might this serve for the human body? ^The energy goes with the steam, expressed in heat since the hydrogen bonds are no longer breaking and reforming. This is an example of an exothermic reaction, since heat is released throughout it. When we sweat, heat is leaving the body as sweat evaporates, making our skin feel cool. Question Four Michael Berryman (an actor) has ectodermal dysplasia, a disorder of the skin, hair, teeth and sweat glands. Consider the nonfunctional sweat glands—why do people with this disorder have to worry about overheating? ^Without the ability to sweat it’s harder for the body to regulate its body temperature, and the body is more likely to dangerously overheat. Acids and Bases Acids release hydrogen ions (H+) when placed in water (creating H3O). Bases remove hydrogen ions when added to water (creating OH-). pH is a measurement of the amount of H+ ions in a solution. - [ammonia, baking soda, household cleaners] 14 (bases) > 7 (neutral) > (acids) 0 [battery acid, beer] Human blood and pure water have a pH of 7 Buffer: a substance that prevents changes in pH -removes or adds H+ ions -many body fluids have the buffering capacity to maintain homeostasis – a constant internal environment Molecules and Compounds Carbon – building block for life, fundamental unit within large biological molecules -unique bonding capacity allows it to make four different covalent bonds Biological Macromolecules -macro=big – the large molecules of life -composed of individual subunits; subunits come together to make large, complex macromolecules >carbohydrates, lipids, proteins, nucleic acids Carbohydrates: sugars and starches -subunit: monosaccharide -able to interact with water -short-term energy storage -play a structural role in cells; cell communication and recognition Can be simple or complex: -Simple sugar: monosaccharides >glucose: is in human blood, fruit, honey >fructose: fruit, honey >galactose: dairy, carbs -Simple sugars: disaccharides >sucrose (glucose+fructose): table sugar, apples >lactose (glucose+galactose): dairy milk -Complex sugars: polysaccharides >starch (glucose): energy storage in plants >glycogen (glucose): energy storage in humans (liver/muscle cells) >cellulose (glucose): structure in plants (humans can’t digest it; important form of dietary fiber in human nutrition) --What makes the sugars all different is how they hook together and form macromolecules Lipids (triglycerides, phospholipids, steroids) -all made with hydrocarbons, fatty acids -do not interact with water -long term energy storage -have a structural role in cells Triglycerides: dietary fats/oils -structure/function depends on whether the fatty acid chains contain double bonds between carbon atoms -double bonds cause fatty acid chain to ‘kink’ or bend -bent ones don’t pack together well—straight ones do Unsaturated fats: have double bonds and single bonds -are liquid at room temperature Saturated fats: have single bonds only -are solid at room temperature Unsaturated fats are generally ‘healthier’ in the human diet -don’t clump up as much—clumping blocks arteries, etcetera -can have ‘cis’ or ‘trans’ bonds >refers to the position of the atoms around the double bonds >’cis’ is more bent, ‘healthier’; ‘trans’ is straighter, less healthy (28 January) Phospholipids: important for cell membranes -cells are surrounded by water and contain water -parts of the phospholipid will interact with water, some won’t -in cells, based solely on interactions with water, phospholipids organize themselves to form a double-circle lipid bilayer >cell contents on the inside, everything else on the outside Steroids, Hormones and Cholesterol -contain fatty acid portions but otherwise are diverse in structure/function >estrogen, testosterone >cholesterol >>aids in cell membrane structure/function >>high levels may increase your risk of heart disease Class Activity Considering the last paragraph ^, why do you think too much cholesterol can be bad for your body? ^Cholesterol is a fatty, waxy substance that forms clumps in the bloodstream and can cause clots. Plaque forms by the hardening of said cholesterol buildup, limiting the circulation, raising blood pressure, and overworking the heart. Atherosclerosis is a disease characterized by the accumulation of cholesterol-based plaques inside the arteries. Proteins: structural, protective, transport, contractile, regulatory -represent structure and function of living cells >proteins do not store information -Enzymes – special proteins -serve as catalysts for chemical reactions >chemical reactions would occur too slowly to sustain life without them Proteins are composed of amino acids (subunits) -chemistry depends on the type of amino acids involved, of which there are about twenty total -the order of amino acids (and interactions between them) makes each protein different >this determines each individual’s structure/function >the chain forms a specific shape for a specific purpose >if not shaped properly, it will not function -changes in the chemical environment of a protein (such as temperature or pH) can cause it to lose its structure—this is called denaturation >the denatured protein becomes sticky, and will stick to other proteins and cause them to denature, causing a snowball effect >>Alzheimer’s is a good example of this >denatured proteins cannot be broken down or removed from the body—you’re stuck with that broken stuff for life. Be nice to your proteins. Class Activity Fevers are an important defense against infections. However temperatures greater than 104 F are considered a medical emergency (102 for infants/new humans). This can lead to brain damage in death. Why is it that a person experiencing a high fever for an extended period of time is at serious risk for brain damage? ^High temps cause cells/proteins to degenerate, causing them to crash into and further denature each other, which leads to irreversible brain damage. Nucleic Acids: information storage -DNA -fundamental information storage molecules in cells -made of nucleotides, which are composed of: >five-carbon sugar: deoxyribose >nitrogen-containing bases: adenine and thymine, guanine and cytosine >A phosphate/sugar pair -composed of two strings of nucleotides, attached down the middle by hydrogen bonds *Adenine always bonds with thymine, guanine always bonds with cytosine DNA organizes in a genome -organized further into chromosomes 2 -functions for passing genetic material to offspring Humans have 46 chromosomes -all necessary information is contained on 23 of them >autosomes – non-sex related chromosomes: 22 >sex chromosomes: X and Y -you inherit 23 chromosomes each from your biological mother and father 2Also known as crotchfruit. -all 46 are needed for healthy functioning Genome size and number of chromosomes are not correlated to genetic complexity: goldfish have 94 chromosomes. Don’t feel bad. Nucleotides also function in carrying electrons and molecules between chemical reactions, cell communication and regulation -short-term energy storage >ATP Cells – the smallest unit of life, carrying out the functions of life -made up of the four macromolecules (lipids, proteins, carbohydrates, nucleic acids) -are compartmentalized, have organized functions -maintain homeostasis Prokaryotic cells: bacteria and archaea -small, simple cell structure; lack organization Eukaryotic cells: protists, plants, fungi, animals (that’s you) -are larger, more complex; have lots of organization -have more DNA, which is stored in chromosomes in the nucleus Prokaryotic cells don’t have membrane-bound organelles Class Activity What is an advantage of having organelles in eukaryotic cells? 3 ^Cells can carry out more complex, organized and efficient functions with more ‘parts’. 3Think wheelbarrow versus pickup truck. Humans have two main cells: -somatic cells: body cells, make up your body; utilize all organelles (but of course some types of cells use some organelles more than other types of cells would use them) -gamete cells: reproductive – sperm and egg; only use some organelles Animal Cells Plasma Membrane – separates outside from inside; maintains cell shape/structure, communication between cells, attachment to other cells, passage of substances in and out of cells, recognition between cells >made of: phospholipids (the basic structure) >proteins – which carry out their regular (and varied) functions >cholesterol – important to the structure of the cell >carbohydrates – cell ‘identity markers’ -these components create a ‘mosaic’ on the cell’s outer and inner walls -the components can move sideways through the bilayer somewhat >chemistry and fluidity of the membrane allows for passage of materials through the cell Cytoplasm – inside the cell -contains organelles >which have membrane-bound/enclosed compartments >and contain specific enzymes >and perform specific tasks -composed of 70-90% water Nucleus – directs cell activity and stores genetic info4 Ribosomes – where cells make proteins -NOT membrane-bound -scattered throughout the cytoplasm or attached to the E.R. Endoplasmic Reticulum (E.R.) – (Rough E.R.) packages and modifies new proteins -Smooth E.R. – stores calcium, synthesizes lipids Golgi Apparatus – carbohydrate synthesis, packages new proteins Cytoskeleton – network of protein fibers that allow for cellular movement and provide structure—moves things/molecules inside the cell, necessary to chromosome division and the contraction of muscles nd **REMEMBER we have two pieces of homework due on Tuesday the 2 : on Blackboard, turn in your chosen disease to research; do your macromolecules homework (it must be typed), print it and bring to class to put in ya folda. 4Doesn’t seem all that complex in comparison with the essay other cell parts require…..
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