Nutrition Exam 1 Flashcards
If you were giving a presentation to third grade students on nutrition, how would you define nutrition?
Nutrition is the way food is broken down in a chemical and physical sense to get the necessary things, like nutrients from the food eaten, to help with growth, health and maintenance.
What are the four major processes involved in nutrition?
Ingestion
Digestion
Absorption
Metabolism
What are the major classes of nutrients?
Carbohydrates Protein Lipids Vitamins Minerals Water
True or False. Energy is a nutrient.
False - energy is a property of it
Nutrients are any substance(s) in food that a living organism uses to obtain ___________, synthesize ____________, or regulate ____________ processes.
Obtain Energy
Synthesize Tissue
Regulate Metabolic Processes
List two examples of nutrients that cannot be replaced by other nutrients.
Minerals
Vitamins
What makes a nutrient an essential nutrient?
a nutrient that has to be from the diet and can’t be synthesized by body or in proper amounts
What makes a nutrient a nonessential nutrient?
a nutrient not needed in the diet and can be synthesized by body in proper amoutns
List four macro-nutrients.
Carbohydrates
Proteins
Lipids
Water
List two micro-nutrients.
Vitamins
Minerals
Define Herbivores
plant eaters
Define Carnivores
meat eaters
Define Omnivores
plant and meat eaters
List two examples of autoenzymatic digesters
Pandas
Pigs
Cats
List two examples of alloenzymatic digesters each.
Cattle
Deer
Sheep
Name three of the digestive tract accessory organs?
Pancreas
Liver
Salivary Glands
The stomach, small intestine, and large intestine all have these layers of tissue, including: epithelium, lamina propria, and muscularis mucosa. Collectively these three tissues are known as the __________.
Mucosa
Pancreatic _____ cells produce ____________ and pancreatic __________ cells make _____________.
duct cells produce bicarbonate and pancreatic acinar cells produce enzymes
What transports absorbed nutrients to the liver?
Liver Lobules
Illustrate or describe the difference between the apical brush boarder and basolateral brush boarder membranes of the epithelial cell.
Apical Brush Border is the surface of the villi covered in microvilli that contains tight junctions that connect cells to one another. The Basolateral Brush Border is the bottom part that has Intracellulor Spaces that are wider with the Sodium pump located there.
Name the accessory digestive tract organ that has the ability to make its own glucose when necessary.
Liver
The pancreas has endocrine and exocrine function. What are the main products of the endocrine pancreas and exocrine pancreas?
Endocrine = cells that make hormones that enter blood Exocrine = pancreatic asinar cells that produce enzymes
The absorptive cells for the small and large intestines are different. What are those cells called?
SI = Enterocyte LI = Colonocyte
Both the small and large intestines have cells that produce mucus, what is this cell called?
Goblet Cell
List the stomach cell type that produces hydrochloric acid.
Parietal Cell
Differentiate between a holoenzyme and apoenzyme.
Apoenzyme: catalytically inactive protein part without the cofactors
Holoenzyme: catalytically active
What are enzyme cofactors?
inorganic ions
Give a specific example of a cofactor.
metals = Magnesium
Give a specific example of a coenzyme.
organic molecules = NAD/NADH
here are six classes of enzymes. Name and describe the action of each enzyme class.
Oxidoreductases = oxidation reduction reaction Transferases = transfer of functional groups Hydrolases = hydrolysis reaction Lyases = group elimination to form double bonds or addition to double bonds Isomerases = isomerization of substrate Ligases = bond formation coupled with ATP hydrolysis to provide energy
What is an active site?
where biochemical reactions are catalyzed
In general, how does an enzyme influence the substrate and the rate of the reaction and product formation? (Why are enzymes catalyst for reactions?)
The enzyme brings the substrate and catalytic sites together and holds it in a specific way that allows the two to be catalyzed where the energy barrier is lowered
Compare and contrast absolute and relative enzyme specificity.
Absolute Specificity = action on only one substrate
Relative Specificity = action on a group of substrates
Describe the two active site models.
Lock and Key model = for absolute specificity
Induced Fit model = flexible active site that molds to substrate shape
True or False. If a substrate has chirality, an enzyme can use both chiral isomers for the reaction.
False : only one
How are enzymes activity controlled and regulated?
Substrate Concentration
Allosteric Control
Covalent Modification
Environmental factors
You purchased in July, 2019 a sack of β-glucanase enzyme to feed to pigs that are being fed corn. Due to a shipping mishap the order was delivered to you in Las Cruces on a Saturday and you were gone for the weekend. The purchase sat on your unshaded doorstep for the weekend. Do you have any reason to suspect the activity of the enzyme and why?
Yes, because enzyme catabollyc rate are affected by the temperature of the environment which would have lead to being out in the sun and heat constantly.
Describe allosteric effects and how they influence enzyme activity.
there are allosteric activators and inhibitors that can affect the binding of a molecule at one site while also affecting the binding of a molecule at another
Explain enzyme inhibition and the different types of inhibitors.
Competitive = one that resembles the substrates and binds instead preventing bonding Non-competitive = reduces activity by bonding enzyme even if already bound Uncomptetitve = (RARE) binds after enzyme and stops the reaction
There are three types of inhibitors. Two of the inhibitors have an inhibitor site on the enzyme. What are those two inhibitors called?
Non-competitive and Uncompetitive
How does covalent modification regulate enzymes? Include at least two examples of covalent modification in your answer.
when covalent bonds are broken on a protein or when a functional group is added/removed
ex; methylation and phosphorylation
Why is it important that enzymes are produced in an inactive form and which organ would be in immediate danger if enzymes were produced in an active form?
must be inactive form so that they do not digest the pancreas
What stimulates the digestive glands to secrete gastrointestinal juice and enzymes?
nerves and hormones
Define hormone.
biological messenger that is transported into tissue fluids to stimulate specific cells/tissue
How do hormones work?
alter function of cells by binding to specific receptor proteins in target cells
List three gastrointestinal hormones that are crucial to digestion.
Gastrin
Cholecystokinin
Secretin
Gastrin is secreted from the __-______ in the gastric pits of the stomach.
G - Cells
Briefly diagram or describe what causes gastrin secretion. What stimulates gastrin release?
when food is put in the mouth and to the stomach then neurological and chemical signals cause release of gastrin
Where is somatostatin produced (hint: there is more than one)?
D-Cells in gastric pits of pyloris
Secreted by Pancreas and Central Nervous System
Somatostatin inhibits other hormones. Name the hormones somatostatin inhibits.
Inhibits gastrin, insulin and glucagon
Where is secretin produced?
S-cells in crypts of Lieberkuhn
What stimulates cholecystokinin release?
chyme rich in AA, triglycerides and fatty acids enter the small inestine
Compare and contrast the regulatory phases of gastrointestinal secretions.
Gastric Inhibitory Peptide = from K-cells when rich chyme enters SI it inhibits gastric acid secretion, releases insulin by pancreatic beta cells and lipogenesis by adipose tissue
Vasoactive Intestinal Peptide = from Enteroendocrine cells in SI crypts of lieberkuhn when chyme enters SI and stimulates secretion of electrolytes, water and bicarbonate
Classify the following sugars as either an aldopentose, aldohexose, or ketohexose
accordingly. D-Xylose, D-glucose, D-fructose, and L-Arabinose. Then circle the sugar(s) that
are structural carbohydrates.
D-Xylose = Aldopentose D-glucose = Aldohexose D-fructose = Ketohexose L-Arabinose = Aldopentose
What are the products in the digestion of maltose, sucrose, lactose, starch, and
raffinose?
Maltose = alpha 1.4 glucose-glucose Sucrose = alpha 1,2 beta glucose-fructose Lactose = beta 1,4 galactose-glucose Raffinose = galactose-glucose fructose
Name three volatile fatty acids in the order from most carbon to least carbon.
Pollysaccharides
Oligosaccharides
Monosaccharides
List two homoglycans and two heteroglycans.
Homoglycans = Arabinan and Xylan Heteroglycans = Hemicellulose and Pectin
Discuss the advantages and disadvantages to non-ruminants consuming fiber.
Dis = causes bloating, gas and decrease in nutrient digestion Ad = increase mucus secretion, production of VFAs, hypocholesterolmeia, glucose tolerance effect, fecal bulking effect
What is the function of salivary α-amylase?
cleaves alpha 1,4 glycosidic linkages
cleaves amylose to maltose
minor role in time food is in mouth
alpha 1,4-endoglycosidase
Circle which species has salivary α-amylase: ruminants, horse, human, dog, cat, pig.
man
pig (weak)
What is the difference between salivary and pancreatic α-amylase?
Salivary: secreted by parotid salivary glands
Pancreatic: secreted by pancreatic acinar cells and cleaves amylose to maltose AND maltotriose
What is the enzyme called that can digest amylopectin’s alpha1,6 bonds?
isomaltase
. Describe the role of brush border enzymes in the digestion of carbohydrates. Do all
species have the same brush border enzymes?
all have maltase, and isomaltase
ruminants don’t have sucrase: breaks glucose and fructose
poultry don’t have lactase: breaks lactose ad galactose
How is carbohydrate digestion different in ruminant versus non-ruminant herbivores?
Which one utilizes nutrients better?
Nutrient supply depend on the sequence of mammalian versus microbial digestion
Ruminants are better because use microbial metabolism endproducts better
What attributes make the rumen a good fermentation vat?
minimal oxygen
constant temp 37-42 C
pH regulated at 5.5-7.2
How does the symbiotic relationship between host animal and anaerobic microbes
work?
Anaerobic enzymes provide enzymes capable of digesting structural carbohydrates
Nutrients for host: energy, protein, vitamins
What happens to excess hydrogens that are a by-product of microbial fermentation?
Methanogenesis
What types of ruminal microbes are involved in the digestion of carbohydrates?
Bacteria
Protozoa
Fungi
Name a rumen bacterium (spelled correctly) that degrades plant fiber and the
fermentation end products that result
Ruminococcus flavefaciens
Name a rumen bacterium that degrades starch and the fermentation end products that
result
Strepticoccus bovis
Name a rumen bacterium that degrades starch and the fermentation end products that
result
Strepticoccus bovis
How do the proportions of VFAs differ with diet?
Forage diet = greater acetate to propionate
Grain diet = lower acetate to propionate
Describe absorption of VFAs in the ruminant.
Passive diffusion absorbs from rumen to portal blood
How much energy is provided to a ruminant from VFAs?
70%
What is the primary site of VFA absorption in ruminants?
small intestine
Define passive transport.
facilitated diffusion going down the concentration gradient
Discuss why the Na+K+ATPase pump is important to nutrient absorption. Include information on where the Na+K+ATPase pump is found and action. Be specific.
found in basolateral membrane of absoprtion cells found in intestinal epithelium and links energy to absorb/secretion process
Creates electro-chemical gradient and transports 3Na+ out and 2K- in causing the inside of the cell to be negative and have a low count of Na
Define SGLUT1
sodium dependent glucose transport = active
Define GLUT5.
glucose transport 5 transports fructose not glucose lumen into the cell
Define GLUT2.
glucose transport 2 transmembrane carrier protein that allows protein facilitated glucose movement across cell membranes
. GLUT2 is found in the basolateral membrane of the enterocyte and several other
tissues throughout the body. Name 2 other tissues where GLUT2 is found.
kidney cells
pancreatic
intestinal
Does VFA absorption, in the ruminant, remain unchanged? If not, how can VFA absorption change (increase/decrease)?
If a ruminant on high plan of nutrition with abundant VFAs then they have a long papillae
Why are butyrate concentration very low in the blood?
80% of the butyrate absorbed transfomrs into 5-hydroxybutyrate that goes into the blood
Volatile fatty acids are produced in the rumen due to fermentation. Name the 3
predominant VFAs produced and how are they used in the body.
Acetate
Propionate
Butyrate
Differentiate between glycolysis and gluconeogenesis
glycolysis: breaks down glucose into pyruvate, ATP and NADH
gluconeogenesis: breakdown of glycogen into glucose
What is the major purpose of the pentose phosphate pathway?
produces ribose-5-phosphate to make RNA and DNA
produces NADPH to help build other molecules
