BIOL 141 lecture 1 notes
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This 6 page Class Notes was uploaded by Camryn McCabe on Thursday January 21, 2016. The Class Notes belongs to Biol 141 at a university taught by Janelle Malcos in Spring 2016. Since its upload, it has received 209 views.
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Date Created: 01/21/16
Lecture 1 notes Homeostasis- how the body maintains a constant environment; maintains certain set point rangers o Large external fluctuations; ex. Temperature outside o Small internal fluctuations; ex. Body pH level o Maintains by negative or positive feedback loops Negative: change is detected by the body, body reacts to reverse the condition Ex. (outside of the human body) o A room drops below the set temperature of 72 degrees o The thermostat senses the change and turns on the furnace o The furnace warms the room back up to 72 o The thermostat senses that the room is back at 72 and turns off furnace Positive: self-amplifying cycles; an initial change leads to a greater change Used for rapid change in the body Ex. Contractions during labor o Baby’s head presses on cervix o Pressure promote stronger and stronger contractions o …until eventually the baby’s head is in the birth canal Chemistry o Subatomic particles atoms elements o Subatomic particles: protons, neutrons, electrons # of protons = atomic number of an element For neutral atoms: # protons = # electrons Located in nucleus: protons and neutrons o Ions- atoms/molecules where # protons ≠ # electrons Cations: (+) charge Easily give up electrons Take in positivity Anions: (-) charge Easily accept electrons Take in negativity - Also can be complex compounds (bicarbonate, HCO ) 3 Organic molecules (contain carbon) o Four primary categories: Carbohydrates Lipids/fats Proteins Nucleic acids o Monomer- single molecular unit of a polymer o Polymer- contains many repeating molecular units (the monomers) o Carbs Important functions Energy source o Immediate energy source (in form of glucose) o Stored energy (can be stored in form of glucose as well) Carb monomers Glucose (direct energy source) and fructose (can be made into glucose, but extra steps; comes from fruit; important in moderation and through fruits; not good in high-fructose corn syrup) Carb polymers (of glucose monomers) Starch- found in plants (how plants store glucose) Cellulose- found in plants (makes up structure of plants; cell walls; our body’s don’t break down cellulose well; not good source of energy) Glycogen- found in animals (form of storage of glucose; commonly stored in muscles for easy access of direct energy) o Lipids 3 main types Triglycerides Phospholipids Steroids Triglycerides- structure of 3 repeating structures (the polymer) Consist of fatty acids (3) (the monomer) o Primarily function as energy storage o And insulation (temp/organs) o What we think of as fat 3 fatty acids are connected by glycerol All single bonds o Different bonds present in different types of triglycerides o Saturated and unsaturated fatty acids Saturated v. unsaturated- depends on amount of hydrogen Single bond- completely saturated w/hydrogen o Double bond (anything more than single)- break a bond and add hydrogen; unsaturated- ability to add hydrogen o Unsaturated- contain megafatty acids (humans can’t make them, have to consume them) Phospholipids- cell/organelle membranes Consist of fatty acids, phosphate group, and glycerol Glycerol- backbone that holds everything together Difference from triglycerides- 2 fatty acids + 1 phosphate group (just look for P) Can interact w/water; at the same time is propelled by water Hydrophilic- phosphate group (attracted to water) (has – charge) Hydrophobic- fatty acid chains (fear water) (neutral charge) Steroids- found in membranes and as hormones Proteins- polymers of amino acid monomers o Control multiple reactions to help maintain homeostasis o Primary structure- sequence of amino acids Fold to make final protein shape o Enzymes- important for physiological processes Nucleic acids o Function in… Energy transport (ATP) Hereditary (DNA) Protein syntheses (RNA) o ATP- monomer consisting of adenine, a sugar, and 3 phosphate groups o DNA- polymer consisting of 4 different nucleotides (monomers) Adenine, thymine, guanine, cytosine A with T G with C o Gene expression- process of making proteins from our DNA Within DNA, nucleotides are arranged into genes Transcription- makes a working copy of the gene (to get RNA) (in nucleus) Translation- translate nucleotides to amino acids (take the working copy and make it into protein) (in ER) Cellular structure- composed of organelles o Cytoplasm- fluid inside cell Where many chemical reactions take place Ex. Cellular respiration o Nucleus- where DNA is o Endoplasmic reticulum- membrane Where translation takes place Via ribosomes (organelles made of proteins and RNA) o Golgi bodies- stacks of membranes Where packaging of proteins for transport into vesicles takes place o Mitochondria- ATP production Cell respiration Contain small circular piece of DNA o Cytoskeleton- network of proteins in cytoplasm Structural support Tracks for transport of vesicle Muscle function Actin allows for muscle contraction o Plasma membrane- made of phospholipids and cholesterol w/membrane proteins Bilayer is hydrophobic and hydrophilic due to lipids Selectively permeable Membrane proteins control what enters and exits Phosphate cell Hydrocarbon tails (fatty acids) Very little H2O in center, if any (why membrane is semi permeable Only things that can pass through without any help: very small, uncharged (AKA hydrophobic/non-polar) Transport of molecules across a membrane Passive- doesn’t require energy o Ex. Diffusion o Requires concentration gradient (movement of particles from high to low concentration) Simple diffusion- molecule can travel through the membrane (small and uncharged) Channel-mediated diffusion- protein creates a channel in the membrane for a molecule to travel through (can be larger and have a charge) Gated channel or non-gated channel (AKA leak channels OR open all the time) Carrier-mediated transport: facilitated diffusion Carrier proteins- move solutes down concentration gradient Solute (or molecule) must bind to the membrane protein Protein changes shape and moves molecule across membrane Active- requires energy (usually ATP) o Carrier-mediated transport o Pumps- membrane proteins involved Require ATP hydrolysis to function Ex. Na /K pump Both molecules are being pumped up their gradient o Molecules “up their gradient” (low high) Creates stockpile, huge gradient Osmosis- diffusion of water across a membrane o Membrane is partially permeable (only permeable to H O2 o Depends on how much “stuff” is dissolved in the water o Water diffuses from where IT is highly concentrated (dilute solute) to where IT is lowly concentrated (concentrated solute) o Always think “Where is the water going?” Water goes to where it is needed “Where is H O2high? Where is H O 2 low? If it’s low outside and high inside, it moves out of the cell (high low) o Hypertonic (more solute)- if A is hypertonic to B, A has more solute than B The solution is hypertonic to the cell) o Hypotonic (less solute)- the cell is hypotonic to the solution o Isotonic (the same)- the solutes are the same in both solutions
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