Biochemistry Membrane Transport

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selectively permeable
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An important function of membranes is to serve as barriers to separate and compartmentalize biological molecules and processes. However, at the same time, these barriers are _____
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selectively permeable
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allow transport of specific molecules in and out of the cell through the membrane
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passive transport and active transport
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membrane transport can be categorized as 2 main types
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passive transport
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no energy is required for this type of transport
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active transport
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energy is required for this type of transport. Transport is against a concentration gradient
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pores and channels
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ions and small molecules are transported through membranes via ____ and ____ during passive transport
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passive and facilitated
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2 types of passive transport
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passive diffusion
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transport through the membrane via simple diffusion through a “hole.” Type of passive transport
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facilitated diffusion
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transport facilitated by binding a transporter protein in the membrane. Type of passive transport
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saturable transport system
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At high concentrations of solute, the transporter protein becomes saturated w/ solute and cannot transport any faster.
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uniport, symport, antiport,
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The pathway of transport can be described in 3 ways. All of these describe both active and passive transport.
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uniport
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one molecule is transported into or out of the cell
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symport
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2 molecules moving in the same direction, either in or out of the cell
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antiport
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2 molecules moving in different direction
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aquaporins
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water transporters. It is an example of passive diffusion
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faster
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As a consequence of the solute binding the transporter protein, facilitated transport is much _____
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ATP sunlight redox reactions
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The exothermic reactions supply the energy for the endothermic reactions needed for solute transport. There are 3 exothermic reactions.
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primary and secondary active transport
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Two types of active transport
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primary active transport
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the exothermic reaction generating energy is directly coupled to the endothermic transport reaction
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secondary active transport
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The endergonic reaction of one transported solute is coupled to the exothermic reaction of another transported solute
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Na, K ATPase
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This is an example of primary active transport. It transports Na and K across cell membranes
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ATP
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virtually all animal cells internally maintain a lower concentration of Na and a higher concentration of K than is found in the surrounding medium. This process requires energy from ___.
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against
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both Na and K ions are transported ___ the concentration gradient in Na, K active transport
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glucose permease
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This is an example of secondary active transport. It transports glucose in human erythrocytes. Glucose is transported into the cell to provide energy.
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Na, K ATPase
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glucose permease is coupled to the _______
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membrane receptor
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membrane bound protein w/ a specific external binding site for the first messenger
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transducer
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transports the signal to the cytoplasmic side of the membrane bound effector enzyme
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cytoplasmic response
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regulation of a reaction or biochemical pathway in the cytoplasm, nucleus or organelle
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G proteins
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Many hormones regulating intracellular metabolism exert their effects through the _____
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GDP or GTP
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Binding of ____ or ____ alters the conformation of the G proteins and either activates or inactivates the protein.
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activating form and inactivating form
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There are two forms of the G protein
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activating
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An ____ form coupled to the receptor that binds the stimulatory hormone
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inactivating
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The _____ form coupled to the receptor that binds the inhibitory hormone
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single membrane protein
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The receptor, transducer, and effector functions of the tyrosine kinase pathway reside in a ______
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insulin
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The hormone ____ utilizes tyrosine kinase pathway
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insulin
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___ is a peptide hormone consisting of two small peptide chains linked by disulfide bonds and synthesized in the pancrease. It causes cells to take up glucose from the blood
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diabetes
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results from the loss of control of insulin levels
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type I diabetes
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insulin is no longer produced internally and requires administration of external insulin
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type II diabetes
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cells are often insulin resistant and suffer from insulin deficiencies. This can often be controlled by diet although some individuals require external insulin.
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monosaccharides
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single (CH2O)n unit
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oligosaccharides
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2-20 (CH2O)n units
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polysaccharides
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> 20 (CH2O)n units
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homoglycans
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polysaccharides with identical sugars
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heteroglycans
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polysaccharides with different sugars
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type of carbonyl group and number of carbon atoms
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carbohydrates are classified by (2)
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aldoses and ketoses
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type of carbonyl groups (2)
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oxidation
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loss of electrons or the loss of hydrogens
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chiral carbon
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carbon w/ asymmetric substitutions. 4 different bonded atoms/groups
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configurations
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require breaking carbon bonds
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conformations
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require no breaking carbon bonds. Rotation of a functional group around a single bond
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plane polarized light
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chiral carbons rotate _____
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glyceraldehyde
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a triose sugar
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stereoisomers
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the D and L configurations of glyceraldehyde are ______
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D
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naturally occurring sugars are _____
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yes
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Aldoses and ketoses typically possess between 3 and 9 carbons per monosaccharide unit. Is it possible to have a 2 carbon carbohydrate?
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fischer projection
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linearized presentation of monosaccharide structure
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haworth projection
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circularized presentation of monosaccharide structure. It shows the naturally occurring structure of monosaccharides
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pyranose
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6 carbon sugar
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furanose
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5 carbon sugar
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anomeric carbon
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The most oxidized carbon of a cyclized monosaccharide.
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glycosidic bond
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primary structural linkage of all monosaccharide polymers. It is a covalent linkage between anomeric carbon of one monosaccharide and one of several possible hydroxyls of a second monosaccharide
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alpha or beta configuration at the anomeric carbon and number of carbons of the glycosidic bond
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a glycosidic bond is designated by (2)
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reducing sugar
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monosaccharides and most disaccharides which possess a reactive carbonyl group
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non reducing sugar
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disaccharides with both anomeric carbons involved in glycosidic bond formation
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reducing and non reducing ends
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polymer chains of oligosaccharides and polysaccharides can define their directionality based upon their
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starch
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carbohydrate energy storage for plants
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amylose
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A homopolysaccharide. glucose that has an alpha (1->4) linkage and is unbranched.
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amylopectin
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A homopolysaccharide. Glucose that has a alpha (1->4) and beta (1->6) linkage and is branched.
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glycogen
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carbohydrate energy storage for animals. It’s a homopolysaccharide. Glucose is alpha (1->4) and is branched.
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cellulose
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structural carbohydrate for plants. It a homopolysaccharide. Glucose with a beta (1->4) linkage and is unbranched
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cellulose
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It’s the major component of rigid cell walls of many plant cells. It is insoluble in water. Mammals cannot digest this compound because they lack the enzyme to digest the beta linkage.
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chitin
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structural carbohydrate for animals. It is a homopolysaccharide. Glucose with a beta (1->4) linkage and is unbranched
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fungi
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chitin is present in the cell walls of ____

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