BIOE 1010 Exam 2 Study Guide
BIOE 1010 Exam 2 Study Guide BIOE 1010
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This 6 page Study Guide was uploaded by Sara Littlejohn on Thursday March 3, 2016. The Study Guide belongs to BIOE 1010 at Clemson University taught by Dr. Vladimir Reukov in Spring 2016. Since its upload, it has received 66 views. For similar materials see Biology for BioEngineers in Bioengineering at Clemson University.
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Date Created: 03/03/16
BIOE 1010-Exam 2 Study Guide Red Text- This material will be on the exam Highlighted Text- key concepts or terms Module 4-1 Lipids: Structure and Function of Plasma Membranes Lipids: chemically diverse group of compounds o Common feature: insolubility in water (soluble only in organic compounds) Fatty acids have two regions. o Amphipathic molecules: possess both hydrophilic and hydrophobic regions o Can be saturated or unsaturated Saturated: has hydrocarbon chains connected by single bonds only Unsaturated: has one or more double bonds Each double bond may be in a cis or trans configuration o Cis: both hydrogens are on the same side of the hydrocarbon chain (Causes a kink in the chain) o Trans: hydrogens are on opposite sides Triacylglycerol (Triglycerides): formed by the joining of three fatty acids to a glycerol backbone Phospholipid: molecule with two fatty acids and a modified phosphate group attached to a glycerol backbone o Introducing a phosphate group makes phospholipid head very hydrophilic o The phosphate may be modified by the addition of charged or polar chemical groups o Two chemical groups that may modify the phosphate are choline and serine o Both choline and serine attach to the phosphate group at the position labeled R o They spontaneously aggregate and form bilayer membranes in water. Cholesterol o Cholesterol fits into the gap between two phospholipid molecules in an lipid bilayer and modulates its fluidity o Factors that affect fluidity of the membrane: Temperature Cholesterol o Because it’s a short and rigid molecule, cholesterol tends to stiffen the membrane making it more rigid and less permeable Fluid Mosaic Model o The lipid bilayer gives the membrane its basic structure and serve as a permeability barrier Cell Membranes: separate and protect chemical composition Internal Membranes: enclose intracellular compartments to form organelles Plasma Membranes and internal membranes are barriers: they prevent molecules on one side from mixing with those one the other side. Membrane Proteins: carry out most membrane functions o Transport nutrients o Anchor the cell o Receptors o Enzymes catalyze specific reactions Transmembrane Protein: hydrophobic regions liein the interior of the bilayer, near the hydrophobic tails of the lipids o Hydrophilic regions are exposed to the aqueous environment on either side of the membrane The plasma membrane is a barrier BUT cells need to exchange molecules with their environment: Import nutrients, Eliminate waste, regulate the intracellular concentrations of inorganic ions. ONLY Small uncharged molecules diffuse across the membrane. o The smaller and more hydrophobic, the more rapid the diffusion through the lipid bilayer. Simple Diffusion: Diffusion through a permeable membrane moves a substance from an area of high concentration down its concentration gradient (into cytoplasm). Transport Classification 1: o Transporters (Carriers): solute molecules fit into specific binding sites; when proteins change conformation, the solute is releases on the other side of the membrane. o Channels (Provide Corridors): discriminate ions based on size and electric charge; channels can be opened or closed by the cell, as needed. Much faster than transporters Transport Classification 2: o Single Uniporter: carries one molecule or ion. o Coupled Symporter: carries two different molecules or ions, both in the same direction Antiporter: carries two different molecules or ions, but in different directions Transport Classification 3: o Passive: transport occurs down the concentration gradient aided by proteins; gives energy o Active: transport occurs against the concentration gradient; needs energy Electrochemical Gradients: when voltage and concentration gradients exist o Primary active transport moves ions across a membrane, creating an electrochemical gradient. Module 4-2 The Na/K pump uses the energy of ATP hydrolysis to pump Na+ out and K+ in, both against their electrochemical gradients. o Outside the pump is more positive, while inside the pump is negative. Ion channels have highly selective hydrophilic pores. o They make the membrane permeable for selected inorganic ions depending on: Diameter and shape of the channel Distribution of charged amino acids that line the channel o They have a HUGE transport rate because the protein doesn’t need to change conformation with each ion it passes o They are gated, which means they open in response to changes in membrane voltage. o They are essential for signaling in nerve cells. o These channels are only one way; neurons cannot transmit signal both ways. An action potential is triggered by a brief pulse of current (depolarizing stimulus). o Resting Potential is always around -60 through -70 mV Variation in the resting potential can be either inhibiting or excited. o Threshold is always around -55 mV o Action Potential is always around 40 mV -Need to be able to label: Resting potential Depolarization Repolarization Action potential Threshold Hyperpolarization Module 5-1 DNA and RNA are polynucleotide chains Nucleotides contain a base (B), sugar (S), and a phosphate group (P) The nitrogen-containing bases come from two cyclic chemical compounds o Pyrimidine Cytosine (Found in RNA and DNA) Thymine (Found in DNA only) Uracil (Found in RNA only) o Purine Adenine Guanine There are two kinds of pentoses (sugars) o Ribose (Found in RNA) contains 1 more oxygen than deoxyribose Ribonuecleotides: A, G, U, C o Deoxyribose (Found in DNA) Deoxyribonucleotides: A, G, T, C Complementary base pairs: Be able to complete a sequence o A-T o G-C of nucleotides given a template. o This enables the base pairs to be packed in the interior of the sugar-phosphate backbones DNA is replicated semi conservatively. This means that each daughter DNA strand is composed of one original parent strand and one newly synthesized strand. DNA Strands are antiparallel: parallel but moving A Leading Strand leaves its 3’ open and replication flows smoothly. A Lagging Strand is broken into fragments and does not leave the 3’ open. Module 5-2 Mutations: heritable changes in the nucleotide sequences o Example: sickle-cell anemia The sequence of nucleotides encodes the information regarding the unique sequence of amino acids in a protein DNA directs the synthesis of all proteins. A gene is a segment of DNA that contains the information required for the synthesis of one type of protein. o Can be all sizes A genome is the total genetic information carried by DNA in a cell o It contains the information necessary for the synthesis of all types of proteins in the body DNA is transcribed into RNA which is translated into Protein. (The Central Dogma of Molecular Biology) Each gene contains: o Coding nucleotide sequences (Exons) o Non-Coding nucleotide sequences (Introns) The Genetic Code is the rules by which the nucleotide sequence of a gene, through mRNA, is translated into the amino acid sequence of a protein. The amino acid doesn’t bind directly to the mRNA; it needs an “adaptor molecule” called transfer RNA (tRNA). Other Key Concepts Nerve impulses can only travel ione direction. The plasma membrane of many animal cells contains open K+ channels, yet the K+ concentration in the cytosol is much higher than outside the cell.
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