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Biology:
life study of
What is Life?
Properties of Life
Cellular Structure: the unit of life, one or many
Metabolism: photosynthesis, respiration, fermentation,
digestion, gas exchange, secretion, excretion,
circulation--processing materials and energy
Growth: cell enlargement, cell number
Movement: intracellular, movement, locomotion
Reproduction: avoid extinction at death
Behavior: short term response to stimuli
Evolution: long term adaptation
http://www.casarioblanco.com/poison-dart-frog.jpg
http://aichlee.files.wordpress.com/2009/02/blue-bird-of-paradise.jpg
Obtaining Food
Heterotrophs need to
feed on other organisms, their byproducts, or their dead bodies to survive
Heterotrophic Organisms
Herbivores: feed directly upon producers
Carnivores: feed directly upon herbivores or other carnivores
Omnivores: feed upon both producers and consumers
Parasites: feed upon living organisms causing disease
Saprobes: feed upon by-products and/or dead bodies (aka detritivore)
Food is required as fuel for respiration:
Cytosolic Glycolysis:
sugars to pyruvate
Mitochondrial Matrix Krebs Cycle:
pyruvate to CO2 and NADH
Mitochondrial Cristae ETS/Oxidative Phosphorylation:
NADH and O2 to H2O and ADP + Pi to ATP
©1996 Norton Presentation Maker, W. W. Norton & Company
Here is an invertebrate animal collecting plant byproducts.
Nectar is a good supply of carbohydrate…not much else
Pollen is a better supply of protein, vitamins, and minerals
Prokaryotes intake small organics from the surrounding medium…
by facilitated diffusion or active transport across cell membrane
Thus digestion
is extracellular
Digestive enzymes
secreted into the
medium convert
macromolecules
into subunits for
uptake
http://library.thinkquest.org/3564/Cells/cell91.gif
saprobe
parasite
©1996 Norton Presentation Maker, W. W. Norton & Company
Here is a fungus body…these penetrate living or dead tissues…
The rhizoids or haustoria digest the material or cells they
penetrate and siphon off small molecules to support the fungal
mycelium. Fungal digestion is basically EXTERNAL:
•Digestive enzymes are secreted into the food
•Subunits are absorbed by diffusion and active transport
These fungi are more “active” in their feeding...
They trap and strangle their nematode prey:
B Arthrobotrys dactyloides
sticky traps
lasso
What is the difference between these two images?
©1996 Norton Presentation Maker, W. W. Norton & Company
Dactylella drechsleri
Two Paramecium and one Pelomyxa
©1996 Norton Presentation Maker, W. W. Norton & Company
engulfing prey by phagocytosis
Paramecium
Pelomyxa
An example of internal digestion
entrapment in
food vacuole for
digestion
The feeding of Paramecium itself is also internal digestion:
oral groove (alveolus)
cytopharynx
(mouth)
cilia movement
capture
contractile
vacuole
waste
endocytosis
elimination
(phagocytosis)
exocytosis
(anal pore)
food
vacuole
contractile
vacuole
enzymatic
digestion
subunit
absorption
micronucleus
macronucleus
Intracellular food digestion:
Golgi
lysosome
enzymes
endoplasmic
reticulum
subunits
waste
exocytosis
phagocytosis
food vacuole
1.
2.
3.
4.
5.
6.
digestive vacuole
phagocytosis of food
food vacuole and lysosome formation
lysosome + food vacuole = digestive vacuole
enzymatic digestion of food
absorption of subunits
exocytosis of waste
Obtaining Food
The origin of animals?
flagellum
(undulipodium)
•Most primitive “animal”?
microvilli
•Parazoa (no true tissues)
–sponges
cell body
•Metazoa (true tissues)
–other animals
•Is there an protozoan that “acts” and “eats” like an
animal?
•Choanoflagellates
•Choanocytes  sponge feeding cells very similar!
Porifera – primitive animal
1.
Incurrent pores: ostia
2.
Body wall: choanocytes for filter feeding
3.
Excurrent pore: osculum (here huge)
4.
Body wall has mineral spicules
5.
High cellular mobility and totipotency
Photo credit: Mike please provide original source of this image
gland cell secretes digestive enzymes to
disintegrate prey item into smaller particles
and
anus!
a blind
pouch
system
©1996 Norton Presentation Maker, W. W. Norton & Company
Gastrovascular cavity digestion in Cnidarian polyp
digestive cell takes in smaller particles for intracellular digestion
This is a combination of external and internal digestion
There is also a unique prey capture process in cnidarians
Ciliary
Receptor
Receptor Cell
Interstitial
Cell
Cnidocyte
prey capture
Nematocyst
Epidermis
Neuron
Longitudinal
Muscle Fibrils
Mesoglea
Circular
Muscle Fibrils
Gastrodermis
Digestive Cell
Granular
secretions
phagocytosis for
internal digestion
Food Vacuole
Gland cell
Cilia
http://library.thinkquest.org/26153/marine/sketch/597b.jpg
A closer look:
Cnidocil
(modified
cilium)
enzyme secretion for
external digestion
©1996 Norton Presentation Maker, W. W. Norton & Company
Cnidoblasts (cyan) contain nematocysts (yellow and blue)
This feature of cnidarians is perhaps most famous in the
scyphozoans (jellyfish) and hydrozoans (Portuguese-man-o-war)
In flatworms, such as Dugesia, and like cnidarians,
the mouth is also the anus…the digestive system is
a blind pouch.
ocellus
©1996 Norton Presentation Maker, W. W. Norton & Company
What do
these
corrugations
do for
Dugesia?
Increase
the surface
area for
nutrient
absorption.
also serves as the
anus…a blindpouch system
This cartoon shows a longitudinal slice of a chiton with the
three principal parts: foot (locomotion or attachment), visceral
mass (internal organs), and mantle (secretes the valves).
The radula scrapes food from environmental surfaces.
dorsal aorta
gonad
heart
pericardial cavity
(coelom)
ventricle
valve plates
hemocoel
auricle
radula
mantle
mouth
digestive
gland
anus
foot
stomach
nephridium
nephridiopore
ventral
gonopore
nerve cord
(not shown)
…a tubular digestive system
As for most molluscs, chitons use a radula to scrape their
food from environmental surfaces. Below is a radula
removed from a chiton mouth. Bivalve molluscs are filter
feeders, however.
http://www.abc.net.au/quantum/stories/Chiton_teeth_m97943.jpg
http://www.midnightsunschool.com/Katchemak_Bay/graphics/Radula_dia.png
http://www.midnightsunschool.com/Katchemak_Bay/graphics/radula.jpg
Mollusc – Feeding
Photos: Cleveland P. Hickman, Jr.
©1996 Norton Presentation Maker, W. W. Norton & Company
Earthworms also have a tubular digestive system
Earthworms also have a tubular digestive system
subunit
uptake
enzymatic
digestion
intake
muscular grinding
©1996 Norton Presentation Maker, W. W. Norton & Company
waste
elimination
molting animals: shed their exoskeleton to grow
Not a tetrachotomy!
What does this mean?
The parsimonious
dichotomies are still
unknown
http://upload.wikimedia.org/wikipedia/commons/6/62/Cicada_molting_animated-2.gif
Ecdysozoa Phylogeny
LM or SEM?
Chitin
•Hard exoskeleton
•Fungi, Nematodes, Tardigrades
•Arthropods, insects and crustaceans
•Malpighian tubules
•Cyclomorphosis
http://www.impactlab.com/wp-content/uploads/2008/09/tardigradasm.jpg
LM or SEM?
CH3
N-acetyl glucosamine
CH2OH
O
H
O
H
O=C
CH3
CH2OH
O
H
H
NH
H
OH H
O
OH H
H
NH
O=C
H
O
CH2OH
O
O
OH H
H
H
NH
O=C
CH3
http://3.bp.blogspot.com/_Ne3bhx2j74s/SfBVhHkImmI/AAAAAAAAAQI/ft8QPJAteec/s1600-h/tardigradeIMGP8105.jpg
ß 1-4 glycosidic bond
like cellulose, but
includes a nitrogen
atom.
Difficult to digest.
Chitinase/cellulase
only produced in
certain organisms.
http://www.ua.es/dpto/dcarn/fitopatologia/Images/Celegans1.jpg
http://creatures.ifas.ufl.edu/nematode/nem_fig1.jpg
Nematode Tubular Digestive System
Stylet
Esophagus
Digestive
glands
Anus
Intestine
http://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematodexssm.gif
Nematode Diseases of Humans
Thread Worm
Whipworm
Pinworm
Trichinosis
Hookworm
Filarial worms (elephantiasis, filariasis)
Spider Anatomy: Not that different from a mollusc in many ways… but are
not in Phylum Mollusca…They are Phylum Arthropoda but not Class Insecta.
• Fang injects venom with digestive enzymes into prey
• The chelicera support tube as stomach sucks in liquified prey tissues
• Food passes through intestines for complete digestion/absorption
• Waste eliminated from anus
octopod
Sub-Phylum: Chelicerata Class: Arachnida
http://www.rochedalss.eq.edu.au/spider/spideran.gif
Spinnerets
extrude silk
fibers organized
to capture prey
to be food.
Insecta: the largest class of Arthropods
Out-numbers all other animals combined!
Found in just about every environment…except marine!
Entomology: the study of insects
Evolved in Devonian period 400 MYBP
smelling food
seeing food
hexapod
http://www.anselm.edu/homepage/jpitocch/genbios/33-33-InsectAnatomy-L.gif
A look inside the digestive system:
• Mandibles chop food sideways
• Stomach holds food, grinds food
• Digestive gland injects enzymes
• Intestine absorbs subunits
• Rectum dehydrates wastes
• Anus ejects fecal pellet
http://www.life.umd.edu/entm/shultzlab/snodgrass/Lecture1/Figure1-8.gif
Rectum
Digestive Gland
Stomach
Intestine
(hindgut)
http://www.anselm.edu/homepage/jpitocch/genbios/33-33-InsectAnatomy-L.gif
http://www.scubainstr.com/sitebuildercontent/sitebuilderpic
tures/JKPhotoGlry/Lobster-SideView.jpg
http://www.letsgodigital.org/html/review/underwaterphotography/p
anasoniclumixtz3/photography/lobster.jpg
decapod
1.
2.
3.
4.
5.
6.
7.
Brain: Sensing Food
Cardiac stomach
Pyloric stomach
Heart
Intestine
Digestive gland hepatopancreas
Anus
http://www.osl.gc.ca/homard/en/espece.html
jointed mouthparts
for grasping, tearing
food
http://library.thinkquest.org/26153/marine/sketch/729c.jpg
Photo credit: Mike please provide original source
of this image…is this a maxilliped?
Cycliophoran attached to lobster
mouthparts. May be several species
on a single animal. Discovery 1995!
http://content.answers.com/main/content/img/McGrawHill/Encyclopedia/images/CE757536FG0010.gif
She has a diverticulum to hold
the blood meal for later use.
She lives for 4-5 days on this
one blood meal.
The blood protein is used for
laying a “raft” of eggs in water.
piercing stylet
This female mosquito has sensory
organs to locate the victim animal
(thermal, CO2) and it’s blood
vessels (octenol).
She also has a stylet to pierce into
an animal’s circulation system.
©1996 Norton Presentation Maker, W. W. Norton & Company
http://www.cynical-c.com/archives/bloggraphics/aedes.jpg
Most birds
have a crop
for holding
food to feed
offspring.
The gizzard
assists in
mechanical
grinding of
food.
The intestine
does:
•enzymatic
digestion
•subunit
uptake
esophagus
intestine gizzard stomach
crop
rectum
cloaca
http://i.pbase.com/u49/wangi/upload/40767363.P1150275small.jpg
The rectum holds and partially dehydrates waste
The cloaca is a single passage area for:
digestive, urinary, and reproductive systems
©1996 Norton Presentation Maker, W. W. Norton & Company
Blue whales and other baleen whales are filter feeders
You can see the baleen (teeth) of this whale that filter out krill
In most vertebrates, digestion begins with mastication using teeth
connective
tissue
bone
Infection of
the gums
(periodontitis)
is associated
with
endocarditis!
In humans, tools (knives, blender, cooking pots) are used
to initiate food preparation externally!
©1996 Norton Presentation Maker, W. W. Norton & Company
Human Molar l.s.
Dentition may include cutting, tearing, and grinding teeth
cutting
grinding
Juvenile teeth may be
replaced by adult teeth
Human dentition indicates we are omnivores!
©1996 Norton Presentation Maker, W. W. Norton & Company
tearing
Among vertebrates the dentition has functional significance:
beaver
Huge indeterminate incisors
slash into young tree trunks,
molars grind plant material
deer
muscular lips tear off leaves,
molars grind them
dog
©1996 Norton Presentation Maker, W. W. Norton & Company
snake
grasping and angled
back for swallowing
prey whole
large canine teeth and
pointed molars (more like
canines), designed for
tearing animal flesh…minimal
grinding of tissue
Not shown:
ventilation system
connects at glottis in
throat (pharynx)
amylase
peristalsis
©1996 Norton Presentation Maker, W. W. Norton & Company
The human digestive system:
©1996 Norton Presentation Maker, W. W. Norton & Company
The movement of food in the digestive tube is by peristalsis
amylase
acidic
portion
bile (emulsifier)
bacterial culture
unknown
pepsin, HCl
trypsin, amylase,
H2CO3 (alk),
lipase
water reabsorption
subunit absorption
waste holding,
elimination
alkaline
portion
©1996 Norton Presentation Maker, W. W. Norton & Company
The human digestive system:
circular
muscles
for
peristalsis
©1996 Norton Presentation Maker, W. W. Norton & Company
An intestinal cross section reveals the increased surface area:
villi
©1996 Norton Presentation Maker, W. W. Norton & Company
To increase the surface area of the absorptive regions of
the intestine, the lining is corrugated and lined with villi
sugars,
amino acids,
nucleotides
Notice how the villus is coated with microvilli…for more area!
©1996 Norton Presentation Maker, W. W. Norton & Company
The villi of the intestine have good blood supply for nutrient uptake
microvilli
villus
©1996 Norton Presentation Maker, W. W. Norton & Company
Here you can see the microvilli from a single villus
©1996 Norton Presentation Maker, W. W. Norton & Company
The adult (frog) has
a shorter digestive
system…
…than the larva
(tadpole)
Can you
speculate why
this might
have evolved?
What evidence would you gather to
test your hypothesis?
Horses cannot digest much of their food. Microbes are only in the
caecum. Horse manure makes good compost and food for fungi.
Equus caballus
Why did the Franklin
Mushroom Farm move to PA?
http://upload.wikimedia.org/wikipedia/commons/thumb/6/64/Frisian_horse.jpg/800px-Frisian_horse.jpg
Because their microbes are in their caecum too, rabbits
pass material through their digestive system twice.
Recent meals pass as cecotropes, which the rabbit eats
to re-digest the materials that the microbes liberate. As
cecotropes pass through the second time, they are
dehydrated as the familiar rabbit pellets.
Oryctolagus cuniculus
http://www.dcn.davis.ca.us/go/pmartin/photos/vodka.jpg
In ruminants, the
microbe culture is
mixed with masticated
food in the rumen.
The mixture is
masticated repeatedly
(chewing the cud)
from this rumen to
assist fermentation…
especially hydrolysis
of cellulose.
Then the mixture
passes to the rest of
the digestive system.
Bos taurus
to
fresh food
mixed with
microbes
including
methanogens
fermentation breaks
down cellulose
fresh food
bolus enters
rechew
fermented
cud
finish stomach
digestion
©1996 Norton Presentation Maker, W. W. Norton & Company
Ruminant animals use bacteria and archaeons to assist digestion
but early in the pathway…
©1996 Norton Presentation Maker, W. W. Norton & Company
The herbivorous
tropical bird, the
hoatzin, uses a
muscular crop for its
fermentation vat.
It can represent 20%
of the bird’s total
weight!
It is a poor flier.
Its young falling, into
swamps below, crawl
back up into the nest
using claws on the
wings (like dinosaurs).
Opisthocomus hoazin
Digestion of polysaccharides
amylase
glu
Starch
amylase
glu
Glucose Glucose
-1,4 glycosidic bond
glu
amylase
glu
Maltose
maltase
glu
glu
Maltose
maltase
Glucose Glucose Glucose Glucose Glucose Glucose
These monosaccharides are ready for
absorption from the digestive system.
Proteins are polymers of some 22 different amino acids
Enzymes cleave the peptide bond during…
Protein digestion in mammals:
Stomach
pepsin
amino end His
Glu
Tyr
pepsin
recognize phenolic AA, cleave amino side
Thr
Lys
His
Glu
Ser
Arg
Asp
Trp
Thr
Phe
carboxyl end
recognize phenolic AA, cleave carboxyl side
Pancreas
chymotrypsin trypsin recognize basic AA, trypsin
chymotrypsin
cleave carboxyl side
His
Glu
Tyr
Thr
Lys
His
Glu
Ser
Arg
Asp
Trp
Thr
Phe
Thr
Phe
cleave AA from amino end cleave AA from carboxyl end
terminal AA removers
His
Glu
aminopeptidase carboxypeptidase
Tyr
Thr
Lys
His
Glu
Ser
Arg
Asp
Trp
dipeptide splitter
recognize dipeptide, cleave peptide bond
dipeptidase
dipeptidase
dipeptidase
dipeptidase
His
Glu
Tyr
Thr
Lys
His
Glu
Ser
Arg
Asp
Trp
Thr
Phe
His
Glu
Tyr
Thr
Lys
His
Glu
Ser
Arg
Asp
Trp
Thr
Phe
Individual Amino Acids For Absorption in Small Intestine
How do you make digestive enzymes without digesting yourself?
Chymotrypsinogen conversion into chymotrypsin
Finished chymotrypsin
with active site
Activation by acidic recognizing Tyr, Trp
and Phe
pepsin cleavage
©1996 Norton Presentation Maker, W. W. Norton & Company
Chymotrypsinogen from
pancreas is inactive
Summary of macromolecule digestion into subunits
Polysaccharides
Disaccharides
Monosaccharides
starch
(amylose)
salivary amylase
pancreatic amylase
Proteins
maltose
sucrose
lactose
Peptides
Endopeptidases:
stomach pepsin
pancreatic trypsin
pancreatic chymotrypsin
intestinal
maltase
sucrase
lactase
gluose
frucose
galactose
Amino Acids
Exopeptidases:
pancreatic
intestinal
monoglycerides
Fats (triglycerides)
Emulsified fats pancreatic lipase fatty acids
liver bile
glycerol
lactose
lactase
glucose + galactose
In normal human genotypes, adult lactase production is shut down.
Fermentation of milk-based food only occurs by bacteria in the large
intestine. This results in cramps, gas, and diarrhea! Lactose intolerance.
Having mutation in adult shutdown of lactase production
>75% Dutch, Swedes, Danes, Swiss, US Whites,
Germans, Slavs, Northern French, Northern
Italians, Tutsi, Fulani (milk traditionally in adult diet)
<60% Indian, Southern Italians, Saami, US Hispanics,
Balkans, Mexicans, Maasai, Southern French,
Greeks, South Americans, African Americans,
Lebanese
<20% Central Asians, Eskimo, Australian Aborigines,
Bantu, Chinese, Southeast Asians, Native
Americans (no milk in traditional adult diet)