Transcript Chemical digestion

Symbols
Symbols
Atomic Number- No.
of protons
Atomic Mass – No. of
protons and neutrons
(electron mass
negligible)
Chemical symbols
found on Periodic
table
Definitions
• Element- Substance consisting of one type of
atom.
• Isotope – Atom of an element with different
number of neutrons.
• Molecule – Smallest unit of substance. Retains
chemical & physical properties of substance.
Compose of 2 atoms held together by a bond.
Atoms may be of same/different elements.
• Compound- Substance composed by chemical
combination of two or more elements in definite
proportions.
Relationships
• Work in groups of 4 and respond to the following
questions.
• Are N2, H2, and O2 elements or compounds?
• Are N2, H2, and O2 atoms or elements?
• Is C an atom or element?
• Is H20 a molecule or a compound?
Elements of Life
Organic Compounds
• Carbohydrates (sugars) : Carbon, Oxygen,
Hydrogen
• Lipids (fats): Carbon, Oxygen, Hydrogen, and
Phosphorus
• Proteins: Carbon, Oxygen, Hydrogen,
Nitrogen, and Sulfur
• Nucleic Acids (DNA, RNA): Carbon, Oxygen,
Hydrogen, Nitrogen, Phosphorus
Isotopes have a different # of neutrons.
Isotopes have the same number of electrons and behave the
same way chemically.
Radioisotopes
• Valuable research tools.
• Unstable nucleus; over time gives off
subatomic particles & energy; results in stable
nucleus.
• Decay of radioisotopes occurs at constant rate
called half life.
• Use carbon isotopes to date fossils and
minerals.
• Use other radioisotopes in medical tests.
Isotopes
Why is the atomic mass not exactly double the
atomic number?
Periodic Table
Bonding
• Atoms – held together by chemical bonds.
• Two types – Ionic bond and covalent bond.
• Ionic bond – one or more electrons
transferred from one atom to another.
• Covalent bond – electrons shared between
atoms.
• Van der Waals Forces – Weak attractive force
between molecules.
Bonding
•
•
•
•
Compounds are held together by chemical bonds.
Electrons are involved in chemical bonding.
The outer shell (orbital) of atom is called valence shell.
Electrons in this shell are valence electrons.
Bonding
•Atoms with unfilled
valence shells are
chemically reactive.
•Atoms seek to fill
valence shell.
•Bonding fills valence
shell with electrons.
Ionic Bond
Covalent Bond
Bond Strength
• Covalent bonds are strongest bond. Takes
more energy to break bond.
• Ionic bonds are weaker than covalent.
• Van der Waals forces are weak attractions.
Assignment:
Create a graphic organizer. Compare and
contrast ionic and covalent bonds. Work with
a partner.
Properties of Water
• Only substance on Earth found as solid, liquid,
and gas. Solid less dense than liquid state.
• Polarity
• Cohesion
• Adhesion
• Capillary Action
Polarity
Water is polar- uneven
distribution of electrons
between hydrogen and
oxygen atoms.
Hydrogen bondsAttraction between +
charged H and –
charged O. One atom
forms multiple H bonds.
H bonds give water
special properties.
Cohesion
• Attraction between
molecules of the
same substance.
• Surface tension –
tension at surface
of water is related
to cohesion
Adhesion
• Attraction between
molecules of different
substances.
Capillary Action
Capillary action is
responsible for water
moving through a plant.
Adhesion- water is
attracted to roots, stems,
and leaves.
Cohesion – water column
is held together as it
rises.
Review
1. What do the numbers 11 and 23 near the sodium symbol
represent?
2. Use the Bohr model on the right. How many
a. How many valence electrons are available?
b. What is the atomic mass of this element?
c. Is this element an isotope? Why?
3. What elements are present in a protein?
4. What type of bond is occurring between the Mg and Cl?
a. Which of the two elements has a higher
electro-negativity?
b. What would happen to this compound in an
aqueous solution?
5. On the left is a drop of water. Why does
water make drops?
Mixture/Solutions/Suspensions
• Mixture: Two or more elements/compounds
physically mixed but not chemically mixed.
• Solution: Homogeneous mixture in which one
substance is dissolved (solute) in another
(solvent) usually water.
• Suspension: Mixture of water and non
dissolved substance.
Solution
• NaCl dissolves in
water.
• NaCl is the solute;
water is the solvent.
• Water surrounds
the Na + and Cl-.
Suspensions
• Blood is an example of a
suspension.
• Red blood cells are suspended
in a liquid called plasma.
pH
• A molecule of water can form ions
• 1 molecule in 550 million will react to form ions.
• Water has the same number of H+ and OH-; it is
neutral.
• Solutions that have a higher concentration of
H+ than water are acidic.
• Solutions that have a lower concentration of H+
that water are basic (or greater OH -)
pH Scale
7 = Neutral pH
Below 7 = acidic pH
Above 7 = basic pH
Each pH change represents a
10 fold change in the level of
H+.
EX: pH of 4 has 10x more H+
than pH of 5
EX: pH of 5 has 10x less H+ than
pH of 4
Organic Molecules
• Are made of carbon.
• Can be very small like CO2 to very large like a
protein.
• Living organisms are made of and use organic
molecules.
Carbon
• Is tetravalent; can form 4 bonds.
• Bonds with many types of elements:
H,N,O,P,S
• Can form many types of structures.
Macromolecules
• Macromolecule – Giant molecule made from
smaller molecules.
• Polymer- Large molecule consisting of similar
or identical molecules linked together.
• Monomer – Subunit of polymer.
• Polymerization - Process of polymer creation
Polymerization
Figure 5.2 The synthesis and breakdown of polymers
Organic Molecules
• Carbohydrates, proteins, and nucleic acids are
polymers (and macromolecules).
• Lipids are macromolecules (but not polymers)
• All are biomolecules.
Carbohydrates
• Made of C, H, O in 1:2:1 ratio;
(CH2O)
• Used for energy by all
organisms, plants & some
animals use them for
structures.
• Monosaccharides- single
sugar (monomer)
• Glucose is a monosaccharide
used for energy.
Carbohydrates
• Disaccharides - Two sugars
• Table sugar sucrose is a disaccharide
composed of two monosaccharides glucose
and fructose (fruit sugar).
Carbohydrates
• Polysaccharides are
polymers made of many
monosaccharides.
• Examples:
- Plant starch – used to
store energy
- Glycogen (animal starch)
– used to strore energy.
- Cellulose – used by
plants for structure.
Cellulose
Lipids
• Made from C, H mostly.
• Used to store energy, for cell membranes,
water proof coverings, some hormones.
• Three types of lipids
- Triglycerides
- Phospholipids
- Cholesterol
Triglycerides
• Made of 2
components
- glycerol
- fatty acid chains
(3)
• Used to store
energy (2x energy
in a
polysaccharide)
Saturated vs. Unsaturated
Saturated Lipid•Single bonds between Cs in
carbon skeleton.
•Each C single bonded to H. (i.e.
saturated with H)
•Chain straight / pack tightly
/solids at RT.
Unsaturated Lipid –
•Some Cs double bonded
• Makes kink in chain
• Chains can’t pack as tightly/
oils at RT.
Figure 5.11 Examples of saturated and unsaturated fats and fatty acids
Saturated vs. Unsaturated
• Saturated fats
- Animal fats
- Raise LDL or bad cholesterol levels.
• Unsaturated fats
-Vegetable fats
- either help to raise HDL or good
cholesterol levels or decrease LDL levels.
Phospholipids
•Phospholipidsglycerol,
2 fatty acid chains, &
phosphate group.
•Function – to make
up cell membranes.
Cholesterol
Steroids- lipids with 4
fused carbon rings.
Cholesterol is a steroid.
Function- component of
animal cell membranes.
Precursor from which other
steroids are made including
hormones.
High levels contribute to
atherosclerosis
Nucleic Acids
• Made of C, H, O, N, P
• Used to store and transmit genetic
information.
• Two types: DNA & RNA
• Monomer: Nucleotide
Nucleotides
Nucleotides
-Nitrogenous base
-Pentose (5C) sugar/
Deoxyribose in DNA
Ribose in RNA
-Phosphate group
DNA
DNA (polymer) is made by
bonding nucleotides
together.
Phosphate of one
nucleotide is bonded to
sugar of the next
nucleotide.
Proteins
• Made of C, H, O, N
• Have many functions:
- Control chemical reaction rates – Enzymes
- Form bones and muscles – Structural
- Hemoglobin carries oxygen – Transport
- Fight disease - Antibodies
Proteins
• Are
structurally
diverse
consistent
with their
many
functions.
Proteins
• Amino Acids –
Monomer
• There are 20 amino
acids.
• Proteins are made by
the bonding of some
configuration of the 20
amino acids
Figure 5.16 Making a polypeptide chain
• There are 4 levels
of protein structure:
•Primary
•Secondary
•Tertiary
•Quaternary
Chemical Reaction
• Changes one set of chemicals into another set of chemicals.
• Reactants- enter into chemical reaction
• Products – produced by chemical reaction
• Involves breaking and making of chemical bonds.
Energy
• Energy is released when chemical bonds are broken; reactions occur spontaneously.
• Energy is absorbed when chemical bonds are formed; reactions require additional
energy.
• Living organisms carry out both types of chemical reactions to sustain life ;
metabolism.
Enzymes
• Are catalysts; speed up rate of chemical
reaction.
• Are proteins; biological catalysts.
• Speed up reaction rates by lowering activation
energy.
• Activation energy; the amount of energy
needed to get a chemical reaction started.
• Lowering activation energy makes the reaction
happen faster.
Enzymes
Enzymes
• Enzymes provide site where reactants are
brought together.
• Reactants = substrate
• Substrate binds to active site of enzyme;
enzyme substrate complex
• Reaction occurs.
• Product released; enzyme freed for another
reaction.
Enzymes
Enzymes
• Enzymes are specific; enter into one type of
reaction.
• Enzymes are biological molecules; can be
damaged by changes in pH and temperature
Digestion
• Nutrient – substance that supplies energy and raw
material for growth, maintenance, and repair.
- water for all of life’s activities
-carbohydrates for energy
- fats (lipids) for cell membranes, hormones
- proteins for enzymes, structures, transport
- vitamins for working with enzymes to regulate body
processes
- minerals such as calcium/bones, iron/hemoglobin,
sodium & potassium/nerve function
Figure 6.11 Example of an enzyme-catalyzed reaction: Hydrolysis of sucrose
Figure 6.12 Energy profile of an exergonic reaction
Figure 6.13 Enzymes lower the barrier of activation energy
Figure 6.14 The induced fit between an enzyme and its substrate
Figure 6.15 The catalytic cycle of an enzyme
Figure 6.16 Environmental factors affecting enzyme activity
Figure 6.17 Inhibition of enzyme activity
Calorie
• When food is burned, energy is converted to
heat.
• Calorie= amt. of heat to raise the
temperature of 1 g of H2O 1 degree Celsius
• c = 1 calorie C= 1,000 calories = kilocalorie
Digestion
• To break down food into simple molecules
that can be used by body.
• Two types of digestion:
- Physical digestion: Breaking down of food
into smaller pieces.
- Chemical digestion: Breaking down of
macromolecules, polymers into smaller
molecules.
Digestion-Anatomy
Identify
Digestion
• Mouth
- Teeth tear apart food
(physical digestion)
- Saliva has an enzyme
amylase to break down
starches to complex
sugars. (chemical
digestion)
Digestion
• Esophagus moves food
from mouth to stomach.
• Smooth muscles
contract to swallow food.
• Contractions known as
peristalsis.
Digestion
• Stomach continues
mechanical and chemical
digestion.
• Mechanical – Stomach
muscles contract; mix &
churn food; produce chyme.
• Chemical – HCl and pepsin
(enzyme) work together to
break down proteins into
polypeptides.
Digestion
Accessory Digestive
Structures
• Pancreas- produces
hormones to regulate
blood sugar; produces
enzymes to breakdown
carbohydrates, lipids,
proteins. (chemical)
• Liver produces bile
which breaks down lipids
(fats) to smaller
molecules.
• Gallbladder stores bile.
Digestion
• Small Intestine – 2 functions: complete
chemical digestion and absorption of food
molecules.
• Has 3 parts: duodenum, jejunum, ileum
• Chemical digestion: All molecules broken
down to smallest component glucose, amino
acids, fatty acids, glycerol
Complete
Mechanical Digestion
Mouth
Esophagus
Stomach
Small Intestine
Chemical Digestion
Digestion
Absorption of glucose and amino acids occurs at the villi
(finger like projections). Absorbed by blood.
Absorption of fats occurs at the villi; absorbed into lymph
system.
Digestion
• Large intestine functions: Remove water from
undigested material; make vitamin K; expel
waste from body.
Enzyme Lab
•
Investigating Enzyme Activity
•
Introduction: Enzymes are Biological catalysts (usually proteins) that speed up the
rates of chemical reactions that take place within cells. In this investigation, you
and your group will study how temperature or pH affects the activity of enzymes.
The specific enzyme you will use is catalase, which is present in most cells and
found in large concentrations in liver and blood cells. You will use liver
homogenate as the source of catalase. Catalase promotes the decomposition of
hydrogen peroxide (H2O2) in the following reaction:
2 H2O2
•

2 H2O
+
O2
Hydrogen peroxide is formed as a by-product of chemical reactions in cells. It is
toxic and soon would kill cells if not immediately removed or broken down.
(Hydrogen peroxide is also used as an antiseptic. It is not a good antiseptic for
open wounds, however, as it is quickly broken down by the enzyme catalase,
which is present in human cells.)
Enzyme Lab
Your assignment is to design an experiment which tests the affect of
temperature/pH on the action of catalase.
There are pieces of equipment available in the classroom. In the
course of designing the experiment decide which of the equipment/
glassware you will use and how many. Write this down.
1. State the purpose of the lab.
2. What is the experimental hypothesis? (remember to use an “If….,
then…” statement)
3. Write out in detail, and sketch out if necessary, the final procedure
(method) your group will follow to test your above hypothesis.
3. Have your procedure approved by the teacher.