Nutrition and Digestion Flashcards
enzymes
biological catalysts made of protein , lower the energy of activation for a reaction- make it more likely- join to the substrate at the active site to form an enzyme- substrate complex
synthesize
reactions can put molecules together
hydrolyze
reactions can take molecules apart
factors effecting enzyme reactions
pH- many enzymes have an optimal pH
substrate concentration- increasing substrate concentration increases enzyme activity until all of the active sites are occupied
temperature- enzymes have an optimal temperature, when outside the optimal range they become denatured (no longer function)
cofactors
are molecules or atoms that aid enzyme function, often metals, bind to enzyme or substrate
coenzymes
most vitamins are organic coenzymes
also attach to enzymes- aid in binding with substrate
competitive inhibitors
molecules that have a shape similar to the substrate and bind to the active site of an enzyme to prevent the desired reaction
ex) CO ci to the binding of oxygen to red blood cells
ex) cyanide blocks enzymes in mitochondria
noncompetitive inhibitors
bind to enzyme but not at active site, instead at an allosteric site
changes the shape of active site so the sunstrate can not bind
ex) penicillion blocks enzymes in bacteria
feedback inhibition
the inhibition of an enzyme by the final product in the metabolic pathway 2
precursor activity
is the activation of the last enzyme in a metabolic pathway by the initial substrate
allosteric activity
is the change in an enzyme caused by the binding of a molecule- this may promote or prevent enzyme activity
catabolic reactions
breaking down substances in metabolism
anabolic reactions
building complex substances in metabolism
polymers
compunds made up of 3 or more subunits, which are joined by dehydration synthesis (removing water to make a bond)
monomers
compounds made up of single subunits which can be produced by the hydrolysis of polymers
carbohydrates
the most important energy source
made of carbon, hydrogen, and oxygen
all sugar molecules made up of either 6 ring hexose base or 5 ring pentose base
ex) glucose, sucrose, fructose
monosaccharides
simple single sugars compounds composed of single sugar units- carbohydrate
disaccharides
2 monomers joined together by dehydration synthesis reaction- carbohydrate
polysaccharides
when many subunits join together to form a long chain- stored glucose for plants, found in cell walls of plants, stored glucose for animals- carbohydrate
benedicts test
test for carbs- detects reducing sugars- turns from blue to orange when reducing sugars are present
starch test
test for carbs- detects the presence of complex carbohydrates or starch- iodine is added and creates a blue black iodine starch complex
lipids
water insouluble
composed of glycerol and fatty acids- combined by dehydration synthesis
carbohydrates are converted to fat
store energy
key component of cell membranes
insulator
triglycerides
lipid- made from glycerol and three fatty acids ex) saturated- fats from animals, all single C-C, unsaturated- oils from plants, double or triple C=C
phospholipids
lipids- phosphate molecule attached to the glycerol, cell membranes
waxes
long fatty acid chains, insoluble in water so ideal for water proofing
translucense test
lipid- lipids cause brown paper bag to become translucent, non-lipids do not
sudan IV test
lipids- lipids dissolve in the sudan IV indicator, turning it from black granular to a pink or red paste
proteins
essential for building and repairing cell structures, antibodies and enzymes are proteins
polymers made up of combinations of 20 different amino acid joined together by dehydration synthesis- amino acids held together by peptide bonds
4 types of protein
1) primary protein- amino acids are in a linear structure
2) secondary protein- helical or folded sheet
3) tertiary protein- further folding of polypeptide creates a small globular structure
4) Quaternary structure- a large globular structure
coagulation
a protein may be denatured if exposed to heat, radiation or differnt pH
coagulation is a permanent change in protein shape ex) boiling an egg
biuret test
proteins- when the blue biuret is added to proteins, the peptide bonds turn the biuret a purple colour.
digestion order
ingestion: taking substances into the body
digestion: breaking down food to release nutrients
absorbtion: absorbing nutrients into the bloodstream
egestion: causing substance to leave the body
types of digestion
mechanical: breaking food into smaller particles - no chemical change
chemical: breaks bonds in molecules- allows molecules across cell membranes
the mouth
teesth- mastication (chewing)
mechanical digestion to increase surface area of food
salivary glands
three on each side
contains: water, mucous, anylase
amylase
starts the digestion of starch
chemical digestion
bolus- food and saliva
pharynx
common area at the back of the throat that divides into two tubes: esophagus- food tube
trachea- windpipe
epiglottis
a valve that blocks entrance to lungs when swallowing
esophagus
moves food down to the stomach
uses muscular contractions called peristalsis
stomach
entrance and exit controlled by spintchers
- cardiac/esophageal spintcher- between esophagus and stomach
pyloric- between stomach and intestine
stomach secretions
food and gastric jucies combine to make chyme. Rugae- folds in mucosa to increase surface area
gastric pits- have cells at the bottom to secrete hcl, pesinogen, mucous
hcl- kills bacteria, mechanically digests, activate pepsin
pepsin- activated upon exposure to acids, breaks proteins into polypeptides
ulcers
if mucous linning breaks down, acid and pepsin can digest mucousa- may be due to bacteria in stomach
small intestine
duodenum, ileum, jejnum- 80% of digestion and absorbtion occurs here- 6 meters long
villi
intestinal lining covered with villi and micro villi, to increase surface area for absolution, enzymes attach to surface
1) capillary bed- absorbs sugars and amino acids
2) lacteal (lymph vessels) absorb fats
small intestine enzymes
trypsinogen- axctivated by small intestial enzyme to become trypsin- breaks long chain peptides into shorter chains.
erepsin- breaks peptides into amino acids
sucrase, maltase, lactase- break dissacharrides into monosaccharides
amylase- breks starch into maltose and glucose. lipase- breaks fats into glycerol and fatty acids bile- emulsifies fats
the pancreas
pancreatic duct connects pancreas to duodenum - secretes pancreatic jucies to the small intetine which contain- bicarbonate solution (netralizes stomach acid), trypsinogen, erepsin, lipase, amylase, lactase, sucrase
the liver
- deamination of amino acids
-stores glucose as glycogen, stores vitamins
-destroys old red blood cells
-hemoglobinin rbcs converted to bilirubin
-synthesizes bile
gallbladder
stores bile until fat enters small intestine, then goes to the small intestine- can become blocked with gallstones-made of cholesterol
hepatic portal system
blood flows directly from small intestine to liver through the portal vein- allow for detoxification before entering general circulation
large intestine
1.5 meters, colon
reabsorbs water, vitamins, salt
contains bacteria ecoli - produces vitamin b and k
caecum
pouch at the beginning, appendix attached
humans cannot digest cellulose- caecum is nonfunctional
rectum
stores feces, anal sphincters- voluntary control
hemeroids, diarrhea, constipation
