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Biology exam #2

Chapter 7 & 8

Cell Membrane Separates ICF from ECF environment is semipermeable (selective ) which means that it allows certain substances across
Phospholipids Make up the cell membrane calling it the phospholipid bi-layer -makes the membrane semipermiable b/c of fatty acid tails -are amphipathic molecules containing both hydrophilic and hydrophobic regions
Structure of a phospholipid contains 1 glycerol +2 fatty acids + phosphate + polar head group
Substances that can cross the cell membrane Lipid soluble substances like gases and cholesterol can easily pass through ex) estrogen non polar molecules ex) CO2 &O2
Substances that CANNOT cross the cell membrane ions cannot pass because of their charge carbohydrates cannot pass b/c they are to big and are not able to cross either w/ out protein channels Polar molecules
Other components of the cell membrane consists of cholesterol & proteins that contribute to the membrane rigidity (stiffness)
Cholesterol in the cell membrane adds support to the membrane by getting in through the openings in the lipid layers it helps add fluidity to the cell membrane when in different tempertures
Proteins in the cell membrane there are 3 types - Integral transmembrane proteins -Lipid anchored proteins are made of single fatty acids in & out of the bilayer -Peripheral membrane proteins
Function of the proteins in the cell membrane as receptors they are activated by ligands ex)epinephrine and act as (CAMs) cell adhesion molecules to anchor cells towards eachothers ECM
Fluid Mosaic Model Says that the membrane fluid structure has various proteins embedded in it thus making tempertures affect the state of the cell membranes must be fluid & unsaturated than saturated in order to work
membrane transport primary factor is is to create cell membrane permiability -the cell must be able to exchange materials in and out of the membrane
Trans membrane protein functions 1) Transport as a channel or carrier protein 2) Receptor that detects chemical stimulas 3) cell adhesion Molecules (CAMs) help stick to other cells
Aquaporins are water allowing protein channels through the membrane
Types of membrane transport Passive transport or active transport
Passive transport this transport does not require energy to move substances across it may or may not require a trans membrane protein -does require a concentration gradient of high to low ex) diffusion , facilitated diffusion
Active transport Requires energy to move substances across the membrane -does not require a concentration gradient b/c it uses energy and trans membrane proteins to get across ex) sodium potassium pump ,pumps Na out of the cell & K into the cell like a revolving door
Diffusion Focuses on the movement of solutes from a high concentartion to a low one until it reaches equilibrium
Concentration Gradient Is the difference btwn 2 solute concentrations
Equilibrium depends on concentration not volume
Diffusion for ions and lipids b/c ions have a charge an ion channel is required for ions to move across the membrane lipids are able to diffuse though the membrane because the membrane is lipid soluble
Osmosis is a special type of diffusion it requires a semi permeable membrane b/c it focuses on the movement of water in the direction of a high [solute] until equilibrium is reached -this is important in our cells b/c our cells are 99% made of water
Osmotic pressure is exerted by a solution on a cell -is the ability of the ECF to cause a cell to gain or lose water from the cytosol/ICF b/c of the movement of water the cell can lyse, or rupture due to swelling
Tonicity is the movement of water that creates pressure on the cell membrane there are 3 types 1) Isotonic solution 2) Hypotonic solution 3)Hypertonic solution
Isotonic Solution this solution does not cause the cell to gain or lose water b/c the [solute] are equal in and out of the cell there is no net movement but the water is moving to both sides
Hypotonic solution In this solution water is able to pass freely into the cell causing the cell to gain water and lyse -the ECF [solutes] is less than the ICF [solute]
Hypertonic solution this solution has a higher [solute] outside the cell causing it to lose water (shrink/ shrivel) -the ECF [solute] is greater than the ICF [solute]
Carrier Mediated Transport is the transport of ions and compounds across the cell membrane by trans membrane proteins (carrier/channel) may or may not require ATP 2 types 1)facilitated diffusion 2) active transport
Facilitated Diffusion is a type of passive process requiring no energy -does require a carrier protein and a [gradient] example is glucose transporter carries glucose from a high [glucose] to a low [glucose] the mvment is limited depending on # of carrier proteins
Vesicular Transport are tiny lipid packages used to transport molecules -these are derived from the cell membrane or Golgi apparatus 2 types of transport 1)Endocytosis 2)Exocytosis
Endocytosis Begins in cell membrane by folding it inward and bringing in large quantities of substances 3 types of ways 1)receptor mediated endocytosis 2) pinocytosis 3) phagocytosis
Receptor mediated endocytosis selective endocytosis/ a form of pinocytosis
Pinocytosis not selective endocytosis/ cellular drinking
Phagocytosis host defense/ cellular eating
Exocytosis begins at the Golgi apparatus where it is stored -it is also known as protein secretion b/c the vesicles fuse w/ the membrane resulting in a release of proteins
selective permiability allows some substances to move in the cell more easily than others by regulating transport
protein functions 1) transport 2)enzymatic activity 3)receptor 4)joins 2 cells 5)attached to the ECM
carrier proteins change their own shape while holding on to a substance during transport
ligands are any molecule that binds specifically to a receptor site on another molecule
Energy in cells is the ability to perform work, and cause change -is required to assemble and dissasemble compounds , transport & production of energy
2 types of energy Potential and kinetic energy
Kinetic energy the energy of movement -heat which can often be lost -light which is energy movement of photon particles
potential energy is stored energy that an object can contain -can power up a cell for example the process of cellular respiration the conversion of glucose to ATP
Cellular respiration equation Glucose + O2 ---> 6 H2O + 6 CO2 + 32 ATP
ATP is a type of energy or potential energy
chemical reactions lead to the making (synthesis) or breaking (disassociation) of a covalent bond
enzymes are proteins that catalyze /speed up chemical reactions that convert glucose into ATP in cells
What is thermodynamics the study of energy transformation
1st law of thermodynamics when the total amnt of energy of a system is constant - the energy cannot be created or destroyed also known as the conservation of energy
2nd law of thermodynamics when energy conversions increase entropy / the disorder of the universe heat is a type of entropy b/c it is sometimes lost in the cell and becomes unusable
making and breaking energy can be stored by making chemical bonds or released by breaking chemical bonds
Gibbs free energy is a living systems energy that can do work when there is a change in temp. and pressure in the cell
Changes in gibbs free energy energy to do work can be calculated by subtracting the final state from the initial state -or the products minus the reactants
Types of chemical reactions 1) endergonic reaction 2) exergonic reactions these chemical reactions couple up in order for both of them to occur
Endergonic reactions absorbs energy from the surroundings or by making stored energy the change is positive ex) ADP+p ---> ATP (non spontaneous )
Exergonic reactions breaks a covalent bond in order to release energy -the change is negative ex) ATP----> P+ ADP (spontaneous)
enzyme jobs to act on substrates and form or break chemical bonds with/out requiring alot of ATP -they speed up metabolic reactions by lowering energy barriers
Enzyme temp. changes -the enzyme works best at 37 degrees -they change shape and function if the temperature is not to their liking. - if it is to hot the enzyme will unfold and denature -if the temp is to low the enzyme will become inactive or slow down.
-ase... 2 types of enzymes that break down & then form new things 1) DNase breakes down to DNA & nucleotides 2)Sucrase breakes down to sucrose & fructose
Factors that effect enzyme functions 1) Co factors 2) Chelators 3) Temperture 4) pH 5) [Substrate] 6) Inhibitors
Co-factors are cations that can help an enzyme maintain its shape & function ex) Ca2+, Mg 2+, Cu 2+
Chelators remove cations from a solution to inhibit enzyme function called EDTA & PTU EDTA removes {Ca2+, & Mg2+} PTU removes {Cu2+}
Temperture body temp. is 37 degrees if it is increased to 100 or higher proteins unfold & denature if the temp decreases the enzyme works slower
Different pHs ex) In the digestive tract - in the stomach the enzyme pepsin has a pH of 2 -in the small intestine the enzyme Tripsin breaks down proteins with a pH of 8
Inhibitors 1) CI competative inhibitor : are small molecules that compete w/ substrates for an enzymes active site 2) Non Competative inhibitor : are molecules that bind to a region away from active site changing its shape and function ex) amino acid isolucine
Allosteric regulators control cell enzyme activity they are the relationship that a cell can have w/ another cell through a change in shape & activity
Switch for on & off in a cell is caused by a product in a cell that can lead to feedback inhibition during diff. stages of the protein structure
Allosteric Inhibitor binds to the regulatory site to keep enzymes in a stabilized in active form
Created by: Marlene0127



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