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Summary NUTRITION 445 - Exam 1 Study Guide.
- Course
- NUTRITION 445
- Institution
- Pennsylvania State University - All Campuses
NUTRITION 445 - Exam 1 Study Guide.
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Nutrition 445Exam 1 Study Guide
1.What are the functional categories of proteins?
a.Catalysts - they change the rate of rxns occurring in the body
b.Messengers - some proteins are hormones; hormones act as chemical messengers
c.Structural elements- several proteins have structural roles in the body. i.Contractile proteins : actin and myosin (found in cardiac, skeletal, and smooth muscle)
ii.Fibrous proteins: collagen, elastin, and keratin (bone, teeth, skin, etc.)
d.Buffers- help to regulate acid-base balance. A buffer is a compound that ameliorates a change in pH e.Fluid Balancers- proteins help attract and keep water inside an area to contribute to osmotic pressure.
f.Immunoprotectors- immunoproteins (immunoglobins and antibodies) are Y-shaped, polypeptide chains. Ig function by binding to antigens and creating Ip, then get destroyed thru rxns.
g.Transporters- transport proteins carry substances such as vit, minerals, nutrients thru blood in/out of cells. h.Acute-phase responders- made in liver in response to acute, critical illnesses (sepsis, injury/trauma). 2.What are the types of cellular proteins and what do they do?
a.Receptors- modify cell’s response to environment
b.Transport proteins- regulate flow of materials into & out of cell
c.Structural Proteins- provide scaffolding or infrastructure
d.Catalyic Proteins or Enzymes- catalysts for biological reactions
3.How do we regulate the function of enzymes? Name the regulation mechanisms and describe how they work. Regulation of Enzymatic Function a.Substrate Availability- Substrates (reactants) bind to enzymes with a characteristic affinity (how tight the substrate binds to enzyme) and a kinetic parameter called Km.
b.Product Inhibition- Inhibition of the pathway
c.Allosteric Regulation- Regulation of an enzyme by binding an effector molecule at a site other than the enzyme's active site.
d.Covalent Modification- Regulation of enzyme activity by covalent modification of the
enzyme (usually addition or removal of phosphate groups)
e.Change in pH or Temperature- Change of pH can impact the function of enzymes. Think of digestion and the regulatory process of bringing chyme from the stomach to the small intestine.
i.STOMACH: A lower pH in the stomach will activate enzymes for protein digestion (for example) ii.SI: A buffer (sodium bicarb) must be secreted so that the enzymes in the SI can further digest and absorb macronutrients
f.Induction or Repression- Activating or blocking gene expression – controlling transcription and translation (regulating at the level of gene expression) 4.What is the difference between inducible and constitutive enzymes? a.Constitutive: enzyme production is at constant rate b.Inductive: concentration increases to meet demand
5.Describe enzyme kinetics and any relevant terms.
Vmax: enzyme velocity at substrate saturation
High Km value means more substrate required to saturate = low affinity of substrate.
Reversibility: glycolysis & gluconeogensesis
Functionality depends on protein & non-protein groups
6.What are the 6 enzyme categories and what are their main functions?
a.Oxidoreductase: One compound is oxidized and another reduced (reductases, dehydrogenases, oxidases, etc.)
b.Transferase: Transfer one functional group to another (transaminase)
c.Hydrolase: Catalyze cleavage of bonds between C-C by adding water d.Lyase: Catalyze cleavage of C-C, C-S, C-N bonds without hydrolysis
e.Isomerase: catalyze the interconversion of geometric isomers f.Ligase: catalyzes the formation of bonds between carbon, oxygen, sulfur, nitrogen and needs ATP (acetyl CoA carboxylase)
7.How are the inherent kinetic characteristics of an enzyme related to regulation of a metabolic pathway/ process?
a.Regulation of metabolic pathways includes regulation of an enzyme in a pathway by increasing or decreasing its response to signals . Control involves monitoring the effects that these changes in an enzyme's activity have on the overall rate of the pathway.
8.What are the criteria for enzymes to have diagnostic capability?
a.Enzyme’s degree of organ/tissue specificity
b.Steep concentration gradient of enzyme activity between cell and surroundings
c.Enzyme must function in cytoplasm
d.Enzyme must be stable
9.What is the difference between diffusion, facilitated diffusion (aka carrier-mediated), active transport, and endocytosis?
a.Diffusion is the movement of molecules from an area where the molecule is in high concentration to an area where the molecule is in lower concentration. b.Facilitated diffusion is the movement of a molecule from an area of high concentration to an area of lower concentration with the help of a protein channel or carrier. c.Osmosis is the diffusion of water through a semi-permeable membrane. Water moves from an area of high-water molecule concentration (and lower solute concentration) to an area of lower
water molecule concentration (and higher solute concentration). Water molecules can be transported in this way but can also diffuse directly through the membrane lipid bilayer.
d.Active transport is the movement of molecules from areas of low concentration to areas where the molecule is found in higher concentration. This movement is not spontaneous and requires ATP energy and a protein carrier. The ATP is used to drive conformational changes in the protein to pump molecules against their concentration gradient. This process occurs continuously in nerve cell membranes with sodium-potassium pumps.
10.Understand energy release and consumption in chemical reactions.
a.Chemical reactions that release energy are called exothermic. In exothermic reactions, more energy is released when the bonds are formed in the products than is used to break the bonds in the reactants. b.Chemical reactions that absorb (or use) energy overall are called endothermic.
11.Know the common units of energy.
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