Download ch 2 test-energy life and the biosphere

1
Organisms and Energy
Energy and Nutrients
All living things need energy
Energy is the capacity to do work or to cause change
chemical energy: energy stored in the structure of molecules
organisms can use some of this energy as its released during chemical reactions, but most of it is
released as unusable energy
free energy: energy that’s available to do work
examples of free energy- energy plants use for growing and producing food and the energy you
use for exercise and thinking
living cells need a constant source of free energy for chemical, mechanical, and transport work
transport work: involves the movement and concentration of the nutrients needed to make
complex molecules and to increase cellular organization during growth
mechanical work involves movement like muscle contractions that enable you to kick a ball
chemical work involves maintenance of the cell – cells need to manufacture molecules to
replace ones that are used up or damaged
nutrients: a substance that supports the growth and maintenance of an organism
ex: carbs, lipids, proteins
heterotrophs: an organism that obtains its food molecules (carbon compounds) from other organisms
consumers: an organism that feeds on other organisms or on their organic wastes
**heterotrophs = consumers**
ex: animals, fungi (mushrooms and mold), and most bacteria
obtain the nutrient ions from decomposers by eating plants
decomposers: any organism that lives on decaying organic material, from which it obtains energy and
nutrients
ex: bacteria, fungi, mineral ions like potassium, iron, nitrate, and ammonium
complete the breakdown of organic nutrients and return inorganic nutrients to the soil or water, where
they are available for reuse
autotrophs: an organism that forms its own food molecules (carbon compounds) from abiotic materials
producers: any organism that produces its own food
**heterotrophs = consumers**
ex: plants, protists, some bacteria
they absorb the nutrient ions dissolved in soil water from decomposers through their roots
photoautotrophs: use the process of photosynthesis to make their own food
chemoautotrophs use the process of chemosynthesis to capture energy, which is stored as chemical
energy and used for cell work
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photosynthesis: the process where cells use light energy from the sun to make organic compounds
from inorganic compounds
sunlight
CO2 + H2O
chlorophyll
C6H12O6 + O2
Chemical
energy
chlorophyll- allows plants to capture solar energy and change it into chemical energy
photosynthesis converts light energy into chemical energy and creates glucose and oxygen
chemosynthesis: a biological pathway that uses energy from the oxidation of inorganic substances to
drive the formation of organic molecules
cellular respiration: the series of chemical reactions by which a living cell breaks down carbohydrates
and obtains energy from them
cellular respiration changes chemical energy produced by photosynthesis into free energy in the form of
ATP for the cell to use for cell work
it produces carbon dioxide and water as waste products
cells:
90% heat energy
C6H12O6 + O2
enzymes
Chemical
energy
CO2 + H2O + energy
nd
2 law
10% free energy
1st law
1st law of thermodynamics:
1)
2)
3)
4)
5)
6)
reproduce
movement
move materials in and out of cells
chemical reactions
growth
maintenance
Energy can’t be created or destroyed, but it can change forms
2nd law of thermodynamics:
Most of the energy available is converted into unusable energy in the form of heat energy
Systems tend to change in a way that increases the disorder, or entropy, of the system plus its
surroundings
Sunlight is the source of all energy
because only autotrophs can capture energy from inorganic sources, autotrophs directly or indirectly
supply the energy and organic nutrients needed for all heterotrophs
heterotrophs must eat to get energy and nutrients to grow and develop
sunlight
producers
primary consumers
heat
secondary consumers
heat
tertiary consumers
heat
quaternary consumers
heat
this chain can’t continue endlessly because it would run eventually run out of energy
*the 2nd law of thermodynamics*
every time energy travels from level to level, 90% of it is lost as heat: only 10% of the energy
transferred to each level makes it  the amount of energy gets smaller as levels increase and
the world gets more disordered
Energy and nutrients flow from the producers to
consumers to decomposers
tertiary consumers
abiotic factors: nonliving
things in an ecosystem;
referring
to aoverlapping
physical orfood
nonliving
component
of an
Food
web: the
chains
of an ecosystem
secondary consumers
ecosystem
Food chain: each individual track of energy transfer
primary consumers
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Ex of a food chain:
producers
grass  mouse  snake  hawk  eagle
quaternary consumers
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ex: soil, minerals, water, weather, climate,
biotic factors: living things in an ecosystem; referring to a living component of an ecosystem
ex: the organisms in an ecosystem
ecosystem: a community of living things and its abiotic environment
made up by its abiotic and biotic factors
has lots of factors in common
ex: ocean, marshes, coral reefs, desert, rainforest, pond, prairie, forest
habitats: type of place where particular organisms live
ex: in a pond- some organisms are bottom-dwellers and others live along the shore (these are different
habitats)
biosphere: the outer portion- air, water, and soil- where life is found
ex: our earth
all ecosystems combined to make up earth’s biosphere
Energy and Entropy
entropy: how much energy in a system has become so dispersed that it’s no longer available to do work
organisms must be well organized to remain alive and to grow
a key to maintaining organization of all living systems is energy
in ecosystems, light or chemical energy flows from the environment (from the sun or inorganic
compounds) to producers to consumers to decomposers
producers don’t use all the energy they absorb in photosynthesis- most is released as heat energy
same with consumers- some of the chemical energy is converted into free energy for cell work, but most
is released as heat energy
as energy flows through food webs, it escapes into the surroundings in the form of heat energy
so there’s only a one-way flow of energy through food webs
living systems overcome the tendency toward entropy by constantly obtaining energy from their
surroundings
organisms stay organized and can function and grow only as the entropy of their surrounding increase
so: energy isn’t created or destroyed so the total energy of the universe remains the same (1st law) and
it’s dispersed as heat energy which increases the entropy of the universe (2nd law)
Enzymes and Energy
To release chemical energy to perform work, cells must have a way to break and form chemical bonds
Chemical reactions in most organisms take place within a narrow range of temperatures
Those temperatures aren’t high enough to supply the activation energy to start a reaction
Many organic compounds are sources of energy for the cells of living organisms – 3 most important
energy sources are monosaccharides, disaccharides, and polysaccharides
The first step in releasing chemical energy from organic compounds is to break them down into their
building blocks: glucose, amino acids, fatty acids and glycerol
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This chemical energy released from organic compounds is obtained by breaking chemical and then
forming new chemical bonds
One indication that organisms release and use energy is that all organisms give off heat. Some like
fireflies, also give off light
Energy will be released in a chemical reaction if the chemical bonds that are broken hold more energy
that the new ones that are formed
What are Enzymes?
enzymes: proteins- tertiary level  globular or spherical
they speed up chemical reactions by lowering activation energy
activation energy: the amount of energy needed to start a reaction
any chemical reaction requires the input of energy called activation energy
enzymes are catalysts
catalysts: chemicals that lower activation energies
chemical reactions would otherwise be too slow to sustain life
mixing reactants won’t produce a product – the only way they can be changed is by a biochemical
reaction, again requiring the action of an enzyme
each enzyme only catalyzes specific reactions
the specific reaction catalyzed by an enzyme depends on a small area of its tertiary structure called the
enzyme’s active site
active site: the indent or groove where the substrate binds with the enzyme
the active site’s shape must match the shape of the substrate
substrate: the starting molecules
the close fit of the active site and substrate brings the enzyme and substrate close together which
lowers the activation energy with allows the chemical reaction from the substrate to the product to
happen
the fit of the enzyme and substrate is called the enzyme-substrate complex
denatured: doesn’t work anymore because the shape of the active site is changed
because the shape of the active site is changed, it doesn’t match the shape of the substrate anymore, so
the enzyme and substrate can’t combine to form an enzyme-substrate complex
two things denature enzymes:
1. temperature (like in the seed lab)
2. pH (like in the digestive system)
enzymes aren’t rigid so sometimes the shape of the substrate causes it to adjust its shape slightly for a
better fit between the enzyme and substrate
the reactions don’t consume the enzymes, so they are reusable and remain unchanged
once the chemical reaction occurs, the new product molecules break away, leaving the enzyme the
same as it was before the reaction so they can be reused
these enzyme-catalyzed reactions are reversible-- it can build substrates into a product or break a
product into substrates  enzymes can speed up chemical reactions in both directions
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How do Enzymes affect Chemical Reactions?
1) speeds up reactions
2) allows reactions to occur at lower temperatures
ex: we burn glucose, but we aren’t 350º
3) can build up or break down substrates
4) enzymes have specificity – each substrate has a specific enzyme
ex: the enzyme in saliva is amylase and it breaks down the substrate amylose
5) enzymes must fit the substrate at the active site
6) enzymes’ active site can be altered by changes in pH and temperature which means the enzyme
becomes denatured
denatured: doesn’t work anymore
7) have an “-ase” ending
Chemical Reactions in Organisms
chemical reactions occur continuously in all organisms
metabolism: consists of all the chemical activities and changes that take place in a cell or organism
there are two types of metabolism (and they all involve enzymes):
synthesis – “building up” reactions
decomposition – “breaking down” reactions
synthesis reactions:
include biosynthesis reactions that form larger, more complex molecules from small, less complex ones
ex: glucose forming starch, nucleotides forming DNA, amino acids forming proteins
proteins building tissues, like blood and muscle
photosynthesis building sugars from carbon dioxide and water
biosynthesis requires free energy, because the products are more ordered and contain more chemical
energy than the simpler, less ordered reactants  since the reactants added together make the product
and the reactants have less energy than the products, free energy needs to be added to the reactants to
complete the product
biosynthesis also enables organisms to grow and maintain their structure
decomposition reactions:
large molecules break down into smaller molecules
ex: glycogen breaking into glucose in muscle cell
glucose breaking down into carbon dioxide and water during cellular respiration
the energy stored in the glucose becomes available to the muscle cell or for other biosynthesis reactions
decomposition releases free energy and some heat energy in the form of ATP and used by the cell
because they produce simple molecules from complex molecules, which increases entropy
cells use some of the free energy and simple molecules released during decomposition for biosynthesis
of other macromolecules
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so synthesis and decomposition reactions in the cell are coupled to energy flow and the cycling of
matter
Energy Transfer and ATP
Through a process of decomposition called oxidation, certain bonds are broken and rearranged
oxidation: the removal of electrons from a molecule
some of the energy of the original molecule is released as heat energy and free energy
the free energy follows a series of electron transfers and ends up as ATP
What is ATP?
Adenosine triphosphate
ATP stores energy that can be transferred to other molecules
drives the reactions of biosynthesis
connects many energy-conversion reactions during metabolism
has been called the “energy currency” of living cells
just like people have to pay a fee to exchange foreign currency to our currency:
cells exchange chemical energy for ATP—the “fee” is the energy lost as heat energy
ATP than pays most of the energy “debts” inside a cell
ATP is a nucleotide consisting of 3 parts: adenine, ribose, and 3 phosphate groups
the structure of ATP makes it an efficient and useful energy-transfer molecule in cells
ATP supplies much of the energy for the transport and mechanical work needed by cells
when an ATP is involved in a chemical reaction, the bond between the 2nd and 3rd phosphate groups
break and free energy is released
high energy!
O- O- OO – P –– P –– P ––
O
O
O
*the oxygens repel each other  lots energy are in the bonds to
hold them  when these bonds are broken, lots of energy explodes
*single covalent bonds
*when this bond is broken (the 2nd bond), lots of energy explodes
ATP is continually synthesized and broken down in cells
ATP  ADP + P + energy
(decomposition)
a high amount of energy is released when the bond holding the last phosphate is broken
this is the reason that ATP makes energy
this energy is free energy and provides energy for cell work
if the bond between the 1st two phosphate bonds is broken, less energy is released than breaking the
bond between the 2nd and 3rd phosphate groups
ADP + P + energy  ATP
(synthesis)
To form ATP again, ADP must be combined with one phosphate group which requires free energy
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produced (synthesized) from glucose
decomposed into ADP (adenosine diphosphate)
90% heat energy
Glucose
enzyme
synthesis
glucose-6-phosphate + O2
energy
ATP
decomposition
ADP
CO2 + H2O + energy for cell cork
1.
2.
3.
movement
growth
reproduction
when a phosphate is transferred to glucose, glucose-6-phosphate is formed
this molecule is easily converted by cells into energy
to form glucose-6-phosphate, the synthesis reaction of glucose must be coupled with decomposition
reaction of ATP for energy
ATP was decomposed to form ADP + P + energy
At the same time, glucose was being synthesized
Before glucose can be completely synthesized, it has to accept the phosphate group and free
energy from the decomposition ATP
The phosphate group from the decomposition of ATP attaches to the 6th carbon in glucose and
the free energy activates the reaction
the product is glucose-6-phosphate
It’s called glucose-6-phosphate because the phosphate group from the decomposition of ATP attaches
to the 6th carbon in glucose
Cells can use the free energy stored in ATP to supply activation energy or start reactions
1 glucose molecule can be converted into approximately 36-38 ATP molecules
you will eventually run out of ATP if you don’t eat or have oxygen
ex: when you run and run, you’ll eventually have to stop due to lactic acid which makes your
muscles burn and the fact that you need oxygen for ATP
Digestion
Digestion Inside and Outside Cells
only small molecules can pass through membranes and into cells, where energy release takes place
however, most food particles that animals ingest are too large
so they must break them down into macromolecules like carbs, proteins, and lipids, and then break
them down even further
digestion: the processes that break down food
the smallest products of digestion:
o carbs: glucose
o lipids: fatty acids and glycerol
o proteins: amino acids
physical digestion: the breakdown of large pieces of food into smaller ones
ex: chewing and grinding
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increases the surface area of food, making the chemical digestion part easier because the large surface
area allows enzymes more access to the food particles
chemical digestion: involves the breakdown of complex food molecules into simpler ones
ex: starch becoming glucose
enzymes in the various organs of the digestive tract control these chemical reactions
without chemical digestion, nutrients obtained from large food molecules couldn’t be absorbed and
used by the organism
extracellular digestion: digestion that takes place outside of cells
most animals, including humans, rely on this type of digestion
most animals secrete digestive enzymes into a digestive cavity, where chemical digestion yields
the simpler molecules that are then absorbed by the cells
intracellular digestion: the digestion that takes place inside of cells with the foods the organisms made
themselves
plants digest food this way
digestive enzymes break down the food into small molecules that the cell can use
some plants have the ability to capture insects and digest them in special cavities formed by the leaves
 after the insect is trapped, the leaf cells secrete enzymes that digest it
many organisms produce enzymes that digest food outside the organism itself and then absorb the
nutrients into the cells
ex: most fungi digest materials from dead plants and animals, like bread mold
bread mold is a fungus that secretes enzymes that diffuse out of the cells and digest bread. The
mold then absorbs the products of digestion into its cells.
amino acids, sugars, minerals, water, and oxygen can diffuse into cells, but large molecules can’t diffuse
into cells and are absorbed by other means
complex multicellular animals digest food in specialized cavities or digestive tubes with two openings 
food enters the mouth at one end of the tube, and material that can’t be digested passes out of the
anus at the other end of the tube  the result is one-way movement of food and waste
ex: earthworms
cellulose from plants, which makes up grass, is so difficult to digest because cellulose is made of beta
linkages, which most animals can’t digest because they don’t have the enzymes to digest it
however, there are special adaptations that allow animals to digest cellulose
-goats and cows have 4-chambered stomachs
-horses and rabbit’s stomachs have special side pockets where microorganisms live and help
digest cellulose
carnivores can’t digest cellulose and consume mostly meat, which is more easily digested than grass, so
they have shorter digestive tracts
ex: lions have shorter digestive tracts than zebras because lions are carnivores and eat meat and
zebras eat grass which is made of cellulose
An Overview of Human Digestion
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ingestion: the process of taking food into the digestive tract
ingestion starts in the oral cavity, or mouth
is mostly water
pH is almost neutral (6.8-7.2)
two structures in the mouth physically digest food:
- teeth: chewing action which increases the surface area  able to be broken down faster
surface area does this because…
for example: imagine how long it would take to burn a piece of paper if you lit the corner
now imagine if you tore up the paper into many pieces and lit each piece’s
corner
-the highly muscular tongue: allows food to come in contact with the saliva; moves food around
carbohydrate digestion begins here:
salivary glands: a watery secretion containing digestive enzymes that begins chemical digestion
saliva: water + amylase
salivary amylase: an enzyme that digests the substrate amylase (starch) to shorter polysaccharides and
maltose (*starch isn’t fully broken down yet – it needs to be broken into glucose!)
this is why when you keep food like a cracker in your mouth for a long time, it starts to taste sweet – the
starch begins to break down into sugars
when you swallow food, it passes over the epiglottis
epiglottis: a trapdoor-like tissue that normally prevents food and liquids from entering the larynx or
trachea (or airway)
food then enters the esophagus
esophagus: a muscular tube connecting the mouth to the stomach
made of smooth muscle
carries food to the stomach through peristalsis
peristalsis: wavelike contractions that move food from the mouth to the stomach
food then passes through the cardiac sphincter
cardiac sphincter: the structure that regulates the movement of food from the esophagus into the
stomach; its a ring-like muscle that acts like a valve relaxes, releasing small amounts of partially digested
food into the stomach
the food then reaches the stomach
made of smooth muscle
pH is really low- 2-3
denatures the salivary amylase (it no longer fits the substrate)
infolding or ridges in the stomach called rugi
-increases surface tension  more gastric glands
-leaves room for expansion
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digestion of proteins:
the enzymes that break down large protein molecules in the stomach require a strongly acidic
environment
this acidic condition is provided by the stomach glands that secrete HCl
the acid is so concentrated that it could destroy living tissue
the cells of the stomach lining aren’t harmed because some of them secrete a thick, protective coat of
mucus
scientists now know that ulcers are caused by bacterium, not acid, and can be treated with antibiotics
food stays in the stomach—presence of food secretes gastrin which secretes HCl which secretes pepsin
Come
gastrin: secretes HCl
from
HCl: makes the stomach really acidic which means carbs can’t be digested here; secretes pepsin
gastric
pepsin: breaks peptide bonds – takes polypeptide chains and breaks then into amino acids
glands
contractions of muscles lining the stomach wall thoroughly break up and mix food with secretions from
stomach glands
these secretions called gastric juices are composed of enzymes, mucus, and acid
as a result of their action, the contents of the stomach soon become souplike
after an average meal, the stomach usually empties in approximately 4 hours
food then passes through the pyloric sphincter
pyloric sphincter: the structure that allows food out of the stomach and into the small intestine
like toothpaste coming out
Accessory organs provide digestive material to break down substances even though
they aren’t part of the digestive tract
are organs that aren’t a part of the digestive tract but are important in secreting chemicals that help to
digest food and contribute digestive juices to the small intestine through ducts:
-liver (secretions enter gallbladder)
lipids: bile – emulsifies fats – large fat droplets broken down into smaller fat droplets
(*lipids aren’t completely digested yet!)
-gallbladder (secretions enter small intestine)
- pancreas (secretions enter small intestine)
pH of 7-8
carb, lipid, and protein digestion are all completed here!
carbs: amylase – breaks down amylose into glucose
lipids: lipase – breaks lipids into 1 glycerol and 3 fatty acids
proteins: trypsin – breaks down small polypeptides into amino acids
food then enters the small intestine
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small intestine: a tube approximately 6 m long where chemical digestion is completed and food
molecules are absorbed
pH of 7-8
1st third involved in chemical digestion of carbs, lipids, and proteins
2nd third is involved in absorption of nutrients
villi- dramatically increase the surface area to absorb nutrients
food molecules are absorbed through the intestinal walls into the bloodstream
the blood carries the molecules to all the cells where they are used in metabolism
any undigested material eventually passes to the large intestine, where bacteria help
produce several vitamins, gases, and other compounds
reabsorbs water
collects undigested wastes
the vitamins and much of the water that was mixed with the food are absorbed through the walls of the
large intestine
these absorption partly dries out the wastes, called feces
the feces are then eliminated through the anus
feces: poop
fiber, found in fruits and vegetables, helps with the elimination of wastes from the large intestine
Carbohydrates, Proteins, Fats, and Absorption
Carbohydrate Digestion
begins in the mouth with the action of salivary amylase and is completed in the small intestine
salivary amylase: an enzyme that digests the substrate amylase (starch) to shorter polysaccharides and
maltose by breaking the chemical bonds in starch molecules and adding water molecules to the
products of this breakdown
salivary
amylase
amylose + H2O
maltose
saliva has a pH between 6-7.4, so salivary amylase functions best in that pH range
but the stomach has a very low pH of 2-3 so carbohydrates can’t be digested in the stomach
carbohydrate digestion is completed in the small intestine with pancreatic amylase
the pancreas delivers pancreatic juices that convert the acidic food mixture to a basic pH again
the maltose produced by salivary amylase is further broken down into glucoses by pancreatic amylase
final result: glucose – done with carb digestion!
Protein Digestion
occurs in the stomach and in the small intestine
first in the stomach:
the presence of food causes cells to release a hormone called gastrin which enters the bloodstream
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gastrin secretes HCl which secretes pepsin in an inactive form called pepsinogen
HCl changes pepsinogen to active pepsin
pepsin: the active protein digesting enzyme in the stomach; it breaks large protein molecules into
smaller polypeptides
then further digestion in the small intestine:
breaks these smaller polypeptides into amino acids
trypsin is the intestinal enzyme that completes protein digestion by breaking peptide bonds, producing
amino acids from those smaller polypeptides
a basic pH activates trypsin and other intestinal chemicals
a basic pH is necessary for the intestinal enzymes to function  when food enters the small intestine,
pancreatic juice enters the small intestine through the pancreatic duct and shifts the pH from acidic to
basic
final result: amino acids – done with protein digestion!
Fat Digestion
occurs in the small intestine
fats don’t mix with water
enzymes can digest only the fat molecules on the surface of the fat droplets
fats are prepared for digestion by bile in the liver
bile is a substance secreted by the liver and stored in the gallbladder
bile emulsifies, or physically breaks down, large fat droplets into small fat droplets, increasing the
surface area of the droplets available to the fat-digesting pancreatic enzymes
bile doesn’t contain digestive enzymes
lipase is the fat-digesting enzyme secreted in the pancreatic and intestinal juices and splits fats into 3
fatty acids and 1 glycerol
final result: glycerol and fatty acids – done with lipid digestion!
Absorption
the end products of digestion are amino acids, simple sugars, fatty acids, and glycerol
cells can absorb these small molecules through their cell membranes and use them for free energy and
as raw materials for building cellular structures
these small molecules pass through the cells lining the small intestine
villi are the structures in the small intestine are responsible for absorbing the digested food
villi: small fingerlike projections that increases the surface area of the intestinal lining
each villus contains capillaries
capillaries: tiny, thin-walled blood vessels that serve as entry points to the bloodstream
simple sugars, amino acids, fatty acids, and some glycerol, minerals, and vitamins pass through the cells
of the villi and enter the bloodstream through capillaries
the blood carries the products of digestion to the cells
inside the cells, the molecules are either broken down further to yield energy or used to synthesize
substances the organism needs for growth and repair
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Nutrients
glucose is the one nutrient in almost all foods
food that comes from animals has cholesterol
food that comes from plants doesn’t have cholesterol (bun, fries, cookies, sprite, etc….)
lots of calories come from fat
to add fiber to your meal: add fruit and vegetables
soft drinks aren’t a good nutritional choice because they are mostly made of lots of calories and
different sugars – they don’t have any other nutrients
Seeds
plant seeds can germinate in the dark because they break down amylose stored in the seed and can
therefore carry out the process of cellular respiration
how energy growth can come from a seed:
enzymes
amylose + H2O
hydrolysis
ATP
enzymes
glucoses + O2
H2O + CO2 + heat energy + free energy
usable energy
for cell work
cellular respiration
it’s important for germinating seeds to have water because water is needed for the seeds to use the
process of hydrolysis which is needed to break down amylose. The seed can then carry out cellular
respiration
boiling the seeds would denature the enzymes of the seeds so they wouldn’t work  the seed couldn’t
grow
planting the seeds in freezing soil or warm soil would also denature the enzymes so they wouldn’t work
 the seed couldn’t grow
so:
1st and 2nd laws of therodynamics
plants capture solar energy from the sun and transfer it into chemical energy through the process of
photosynthesis
photosynthesis produces chemical energy in the form of glucose and oxygen
this chemical energy is converted into free energy available to do work in the form of the molecule ATP
however, only 10% is converted to free energy – 90% of the energy that is converted from chemical to
free energy is lost as heat energy which increases the entropy of the universe
pancreatic amylase- enzyme that helps digests carbs
breaks starch into polysaccharides, maltose, and glucoses
trypsin- enzyme that helps digests proteins
breaks polypeptide bonds, producing amino acids from those polypeptides
lipase- enzyme that helps digests fats
breaks fats into fatty acids and glycerol
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The Digestive System
mouth
-teeth
-tongue
-salivary glands
esophagus
stomach
*liver, gallbladder, and pancreas
small intestine
large intestine
anus
* = the two accessory organs
Function
Mouth
-mostly water
(oral cavity)
-pH is almost neutral
Teeth and
tongue
-physical digestion
What is secreted
It acts on:
It produces:
salivary amylase
Amylose
smaller
polysaccharides
or maltose
Proteins
polypeptides
-teeth: chewing
-tongue: allows saliva to come in
contact with food; moves food around
Salivary glands
-chemical digestion
-salivary amylase: begins breakdown of
starch
Esophagus
-carries food to stomach
None!
Stomach
-really low pH
-gastrin
-protein digestion
-HCl
-regulation of gastrin, HCl, and pepsin
secretion
-pepsin
-secretion
bile salts
large fat droplets
small fat
droplets
-trypsin
-polypeptides
-amino acids
Liver (secretions
to gallbladder)
Gallbladder
-storage
(secretions to
small intestine)
-transport of bile
Pancreas
-completes digestion of carbs, lipids,
(secretions to
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small intestine)
proteins
-lipase
-fats
-amylase
-carbs
-fatty acids and
glycerol
-maltose
Small intestine
- 1/3 digestion of proteins, fats and
carbs
-proteinases
-peptides
-amino acids
-lipases
-fats
-fatty acids and
glycerol hi
-2/3 absorption (villi)
-secretin
-regulation of pancreatic secretions
- glucose
-carbohydrases
Large intestine
-complex sugars
-reabsorption of water
-collection of undigested wastes
Anus
-waste exit
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