Master Biology Flashcards

What is a quaternary structure? Result of two+protein subunits assembling to form a larger, biologically active protein complex. What a secondary structure? Describes alpha helices and beta sheets that are formed by hydrogen bonding between backbone atoms located near eachother in polypeptide chain. What is a tertiary structure? when protein folds into complex 3D shape stabilized by interactions between side chain R groups of amino acids. Primary structure. Sequence of amino acids in a protein. proteins are polymers of... amino acids. The secondary structure of a protein results from... hydrogen bonds. A competitive inhibitor... has a structure similar to the substrate that it can bond to the enzyme just like the substrate. Noncompetitive inhibitor... binds to a site on the enzyme that is not the active site. Irreversible inhibitor... forms a covalent bond with an amino acid side group within the active site which prevents substrate from entering the active site. Also prevents catalytic activity. The competitive inhibitor competes with the substrate for the _______ on the enzyme. Active site. When the noncompetitive inhibitor is bonded to the enzyme the shape of the _____ is distorted. enzyme. Name a polymer that is composed of amino acids. Proteins. Enzyme inhibitors disrupt normal interactions between an enzyme and its... substrate. What monomer makes up RNA? Nucleotides. Name a statement about the formation of polypeptides from amino acids... Bond forms between carboxyl functional group of one amino acid and the amino functional group of the other amino acid. True or false: Enzymes in the digestive tract catalyze hydrolysis reactions. True. The secondary structure of proteins results because of... hydrogen bonding between molecules in the protein molecules' backbone. How do enzymes work? by reducing Ea. What kind of inhibitor is one that is roughly the same shape as the substrate and binds at the active site? Competitive. Why does an enzyme alter the activation energy for a reaction but not the overall free-energy change? Enzyme brings reactants together in precise orientations and reduces free energy of transition state. Does not change free energies of reactants or products. What are molecules that are amphipathetic? regions that are hydrophobic and regions that are hydrophilic. Name 3 things that affect membrane permeability. Temperature. Saturation of hydrocarbon tails in membrane phospholipids. Amount of cholesterol in the membrane. Name something that does NOT affect membrane permeability. Polarity of membrane phospholipids. What distinguishes facilitated diffusion from simple diffusion? Membrane proteins help move molecules across the membrane. Sodium-potassium pump does not use passive transport to move molecules across the membrane. So how does it work? The pump uses energy provided by ATP hydrolysis to transport sodium and potassium ions across the membrane. True or False: Active transport differs from passive transport in that it does not require an input of energy. False. What membrane protein would be used to move glucose across a membrane from a region of higher concentration to one of lower concentration? Transporter. What is true about the charges after a net movement of an ion across a membrane passive diffusion of an ion through a membrane channel? The charge on the other side of the membrane is generally the opposite of the ion's charge. True or False: During active transport through the sodium-potassium pump, ATP hydrolysis provides the energy to pump three sodium ions into the cell for every two potassium ions pumped out of the cell. False. If something is moving against its concentration gradient, what kind of transport is required and why? Active transport because it requires energy. Name four molecules that can cross the lipid bilayer of a membrane directly without a transport protein or other mechanism. Carbon dioxide.Oxygen.Water.Lipids. Name two characteristics that belong only to channels. Provide continuous path across the membrane. Allow water molecules and small ions to flow quickly across the membrane. Name two characteristics that belong only to carriers. Undergo a change in shape to transport solutes across the membrane. Transport primarily small polar organic molecules. Name three characteristics that channels and carriers share. Provide a hydrophilic path across the membrane. Transport solutes down a concentration or electrochemical gradient. An integral membrane protein. Name the six steps of active transport by the sodium-potassium pump. Three Na+ ions from cytosol bind to pump. Binding of Na+ stimulates phosphorylation of pump protein by ATP. Phosphorylation causes conformational change in pump that moves ions against concentration gradient and releases them outside of cell. Release of the ions permits to K+ ions from outside cell to bind to the pump and release the phosphate group. Release of the phosphate group causes another change. This change in the pump moves to K+ ions against gradients and releases them into the cytosol. Pili Surface appendages that allow bacterium to stick to a surface. What is the function of a bacterium's capsule? Protection. Where is a bacterial cell's DNA found? Nucleoid region. In bacterium, where are proteins synthesized? Ribosomes. What name is given to the rigid structure, found outside the plasma membrane that surrounds and supports the bacterial cell? Cell wall. The _______ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell. Plasma membrane. For prokaryotic cells, which statement is correct concerning how the structure of a particular cell component correlates with its function? The cell wall consists of cross-linked polymers such as peptidoglycan, which protect the cell and give it shape/rigidity. The cell wall found in bacterial cells function to... protect the cell and provide its shape/rigidity. A eukaryotic cell overcomes the problem of its larger size by... compartmentalizing cellular functions into various organelles. The cilia and flagella of eukaryotic cells are composed of... microtubules.