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BIOL 103 Study Guide - Final Guide: Antigen, Atmospheric Pressure, Factor Ix

Course Code
BIOL 103
Virginia K Walker
Study Guide

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Bio 103 Exam Study Notes
Virginia Walker’s lab projects on the genetic mechanisms of resistance
- Resistance to chemicals: chemo causes birth defects, developed system so
that we don’t need to test on mammals (flies)
- Resistance to environmental stresses: freeze and freeze-thaw resistance in
plants, invertebrates and microbes (hydrate control)
- Effects of pollutants on organisms (nanoparticles)
Nutrition and Digestion
Autotrophs: harvest light or chemical energy
Heterotrophs: eat other organisms
Fungi can be parasitic or predatory
- Can be parasites, get nutrients from living animals (athlete’s foot, dactylella
dreschsleri, arthrobotrys dactyloides)
Intracellular Digestion
- Protozoa
- Phagocytosis (85 different proteins involved, cell eating)

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- Endocytosis (cell drinking)
Extracellular digestion
- Digested food products are phagocytosed directly into the cells that line the
gastrovascular cavity- further digested intracellularly
- Wastes are excrete out of the mouth
- One opening for entry and exit of food
- Cellulose cellulase via microorganisms
- Caecum: developed during the evolution of plant eating animals, beginning of
large intestine
- Rabbits eat their own poop so that the small intestine can have another
chance at digesting food
- Ruminant: mammal that chews cud regurgitated from its rumen
- Digestive tract- mouth, esophagus, forestomach (rumen, reticulum, omasum),
abomasums, intestines
- Steven Chu- use termites to convert cellulose into ethanol= green energy
- Digestion= complex organic molecules simpler molecules digestion
Digestive enzymes
1. Oral cavity: teeth, salivary glands
- Purpose of saliva is to moisten and digest food, defense functions, produce
1000mL per day, contains amylase
- Starch (polysaccharide)----(amylase, hydrolysis reaction)- maltose (2
glucose units)
2. The stomach
- When food enters our stomach gastric juice (HCl, pepsin) is secreted
- Pepsin is a protease (member of an enzyme family that is important for the
hydrolysis of proteins)

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- How does the stomach lining avoid getting hydrolyzed by pepsin and
damaged by HCl?
a) Gastric glands in the chief cells lining the stomach produce pepsin in an
inactive form, pepsinogen (inactive enzymes are called zymogens and
the pepsin zymogen= pepsinogen)
b) Goblet cells that line the stomach produce a viscous mucous layer with a
pH ~6
c) The parietal cells that produce the HCl don’t accumulate the acid. It forms
in the stomach after secretion of H+ and Cl- ions. (Note: the parietal cells
are signaled to produce HCl by a peptide hormone).
d) Cells lining the stomach have particularly resistant membranes
- Ulcers are caused by bacteria (helicobacter pylori), can be treated with
antibiotics, gastin stimulated the growth of the bacteria
- Crop: a pouch like expanded part of the oesophagus of birds, in which food is
stored or partially digested before passing on to the gizzard
- Gizzard: contains tiny pebbles that help pulverize food
- Stomach: secretes HCl and pepsinogen
3. Small intestine
- The contents of the stomach (=acid chyme) then pass on to the small
intestine where there is a large number of digestive enzymes produced by
a) Intestinal glands (maltase: takes maltose and hydrolyzes it to glucose,
b) Pancreas (restores pH to approximately neutral pH 7, proteases)
c) Liver (digestion of fats)
- Proteases
o Endoproteases: hydrolysis of peptide bonds within a polypeptide (e.g.
pepsin, trypsin, enterokinase, chymotrypsin, elastase)
o Exoproteases: hydrolysis of terminal peptide bonds (e.g.
aminopeptidase, dipeptidase, carboxypeptidase)
- Digestion in the small intestine
o Intestinal glands: maltase + proteases enterokinase,
aminopeptidase, dipeptidase
o Pancreas: proteases carboxylpeptidase, trypsin, chymotrypsin,
Pancreatic amylase (starch maltose)
Lipase (fats fatty acids + monoglycerides)
Nuclease (nucleic acids nucleotides)
Sodium bicarbonate
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