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Bio 160 Week 5 notes

by: Alex

Bio 160 Week 5 notes Bio 160

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This set of notes contains topics such as enzymes and how they react with substrates as well as transduction, communication between cells. Definitions and explanations for terms such as exergonic, ...
Biological Sciences I
Class Notes
Biology, bio160, symula, Enzymes, transduction




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This 10 page Class Notes was uploaded by Alex on Saturday October 1, 2016. The Class Notes belongs to Bio 160 at University of Mississippi taught by SYMULA, REBECCA E in Fall 2016. Since its upload, it has received 100 views. For similar materials see Biological Sciences I in Biology at University of Mississippi.


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Date Created: 10/01/16
Bio- enzymes SN= slide name Energy available for work decreases as reactions occur o First law of thermodynamics, the same amount of energy put in, comes out. It may be in different forms but same energy amount o Free energy- the work you can do from potential energy o Everytime you go through a chemical reaction, you lose some energy every time. Free energy has reduced o We want to take energy out of chemical bonds to do work o Entropy- how freely a molecule or atom can move around (if a carbohydrate is broken down into two sugars, the sugars can move around more freely than the bulky carbohydrate Entropy (disorder) increases with the number of reactions SN  2ndlaw of thermodynamics Total energy includes usable and unusable energy SN H=G+TS total energy  Enthalpy (H)-  Free energy (G) Or H=G+S  Entropy (S)  Temperature (T) G=H-TS how much free energy Every molecule has “G” for the reactions and also the productis ATP C6H12O6 C6H12O6P Gp-Gr =(delta)G (G of products – G of reactants) Delta means change- reactants and products cannot have a (delta)G You can have positive or negative (delta)G Free energy can be used or released SN o G reactantsreactantreactants o Products=products-products o (delta)G=Gp-Gr o Positive (delta) G: energy is consumed (reducing entropy) o Negative (delta) G: energy is released (increases entropy) Free energy depends on (delta)H and (delta)S SN o (delta)G=()H-T()S o Condensation- reduce the entropy ()S o Hydrolysis- increased the entropy ()S o You lose some of the energy from breaking down molecules to entropy o Consistently investing the energy in our tissue (losing it) Chemical reactions release or consume energy SN o – () G releasing energy. This is called exergonic or catabolic reactant Energy released product o +() G absorbing energy. This is called endergonic or anabolic o Photosynthesis- energy is light (that we invest) o Change in entropy is less product (delta) G reactant Chemical reactions are reversible and can reach equilibrium SN o The energy to do the action and the reverse of it will require the same amount of energy o They will go forward and reverse at the same rate- equilibrium o Equilibrium=()G=0 o See example on slides ATP is the molecule used for cellular work SN o Ribose+adenine- Adenosine o Adenosine triphosphate (3 phosphates) ATP o Adenosine diphosphate (2 phosphates) ADP o Adenosine monophosphate (1 phosphate) AMP o The phosphate area of the nucleic acid is very unstable because all of the negative phosphates together hate it ATP hydrolysis releases energy SN o Break off the last phosphate and causes the free energy to be released to do work o Atp----reaction-----ADP+ P o exergonic Atp synthesis is endergonic SN See slide Endergonic and exergonic reactions can be “coupled” SN o coupling- hydrolysis of ATP to fuel another reaction for synthesis o ()G ATP= -7.3 o You cant couple reactions unless you have smaller values Week 1 of second exam- Transduction lecture Definitions are in red Signal transduction- the ability to cell to communicate with each other Membranes are fluid mosaics Signals can alter behavior or cell activity Signal transduction pathways allow cells to respond to signals Communication Specificity Form and function Transducer The signal has a specific shape The order of response of signal: Signal---receptor----response The bond between the signal and the receptor is a weak molecular bond (not permanent) The signal induces a change in the shape of the receptor once it binds After the change, the signal has no more purpose. It is not modified nor does it cause the change. The receptor causes the change Type of response effects whether the change is long or short term Chemical signals can come from the environment or other cells Autocrine- producing a chemical to effect itself (produces signal for itself) Justacrin- one cell secretes a chemical and it effects its neighbor Paracrine- produced by cells and travels slightly farther than justacrin Endocrine- secreting a signal into the blood (hormones)to go to a lot of cells To respond to signals, cells must have a specific receptor for the specific signal Binding site- where the signal bonds to the receptor Reversible, it can bind, be released, and rebound to other receptors “stimulated” – when the binding of the signal happens, it causes a change in the receptor (when they bind) Ligand- signal Adenosine- sugar and nitrogenous base. It will bind to receptor and cause you to relax. Caffeine has a very similar shape and blocks the binding site. Adenosine can’t bind to the site, therefore it keeps cell in a more active state Target cell refers to the fact that it has a receptor to take the signal Response depends how sensitive we are to something To make more sensitive, you add receptors and more signals to create a bigger response If there are too many signals, the receptors become saturated and the signal won’t have the same effect Receptors have an attraction to their signal Receptors undergo a change in shape after the chemical reaction Conformational change- changes in shape Some receptors don’t change to signal When the reaction happens, the signal doesn’t change at all, but the receptor changes shape Receptors can be in the cell membrane or in the cytoplasm Signals that are nonpolar and small go across the cell membrane to a receptor in the cytoplasm Most receptors in the membrane are transmembrane proteins 3 membrane receptor types: ion channels, protein kinase, g protein-linked Cytoplasm receptors- simple compared to membrane receptors Gated-ion channels are receptors that open in response to a signal Each ion channel would have a specific signal and only let specific ions in There are ion channels for every ion Gated ion Signal binds to receptor Causes Conformational change in receptor (it opens) Allows Ions to enter or exit the cell Gated Ion Protein kinase receptors phosphorylate proteins Kinase- an enzyme that is responsible for transferring phosphate functional groups from one place to another Phosphorylation often incites a physical change, also a transfer of energy to energize the energy Signal binds to receptor and as a result, it causes phosphoralization of the receptor. signal Phosphate groups Protein kinase energize Response d substrate g-protein linked receptors use g-proteins as an intermediate GDP- a molecule with a two phosphate tail GTP- a molecule with a three phosphate tail Peripheral protein (green) is G protein Effector protein- has effect in the cell (orange) integral protein After the binding og the receptor, it changes shape adds a phosphate group to GDP Converts GDP to GTP “activated” G protein Can then be transferred to the effector protein “activating” the effector protein transduced the signal into the cell GTP GD Bio- thermodynamics, G, and ATP G-protein linked receptors use G-proteins as an intermediate Cytoplasmic receptors are inside the cell and alter gene expression directly Signals are nonprotein molecules The signal has to be small and nonpolar to move directly into the cytoplasm through the membrane Has an effect on gene expression Genes code for one specific protein Not all cells use all the genes in the cells, so using it or not using it is referred to as gene expression RNA is transcribed and translated to make proteins A signal can turn on gene expression or turn it off The signal goes through the membrane (whether straight through or through an ion channel) and reacts with a reactor protein in the cytoplasm. Then the protein changes shape after the reaction and enters the nucleus with a “chaperone” a chaperone protein. Receptor proteins are just floating around in the cell The chaperone protein is always attached to the receptor, but when a signal reacts with the receptor, the chaperone releases the receptor once they are in the nucleus Signal transduction can generate protein kinase “cascades” The product of one reaction causes another reaction- cascade Amplify (turn on) genes Second messengers amplify signals They are used to start kinase cascades Rapid amplification 1 signal=many responses There are a variety of second messengers Cyclical AMP Diacylyglycerol, inositol triphosphate Calcium ions Nitiric acid Don’t need to know specifics but be familiar. These can also be second receptors Their reactions are FAST Their reactions are also varied Signal transduction is regulated Regulation- turning on or off processes Phosphotase takes the phosphate of an active enzyme and makes it unusable Signal transduction alters cellular activities The same signal can result in completely different responses Direct or indirect An example of direct is the signal directly acting on the receptor and the receptor immediately changing something in the cell. Gene expression Indirect- kinase cascades. Has an indirect effect on the cell Energy is the capacity for change On a graph, its set up as such Y axis- energy X axis time Energy can be stored and then converted back into movement Potential energy- any energy that’s stored in bonds Kinetic energy- movement Metabolism is the sum of all chemical reactions Breaking vs building Energy is neither created nor destroyed 1 law of thermodynamics Chemical bonds Mechanical or (lipids ATP Biomechanical work carbohydrates,


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