Transcript Unit 2 The Chemistry of Life

Unit 2
The Chemistry of Life
How can this plant
digest a frog?
Like other carnivores, the Venus
flytrap eats animals to get nutrients
that it needs to make molecules such
as proteins and nucleic acids. Other
chemical compounds made by plant’s
cells enable the Venus flytrap to digest
the animals that it eats. These
chemicals are similar to the chemicals
that allow you to digest the food that
you eat.
????????
If plants can make their own
food through photosynthesis,
why would a plant species
evolve a mechanism to
capture and eat animals?
The animal must be
supplying nutrients that
the plant cannot get from
other sources.
Venus fly traps grow in
swampy areas that have
nitrogen poor soil. These
plants get the nitrogen
they need for survival by
trapping and digesting
animals.
Video
http://www.youtube.com/watch?v=ymnLpQNyI6g
What does your backpack,
shoes, and ipod all have in
common?
They are all made up of
ATOMS-> Smallest basic
unit of matter.
Atoms are made up of:
Protons-> positively charged
particles and dense
Neutrons-> neutral charge / no
charge
Electrons-> negatively charged
particles and small
Protons and neutrons live in the
nucleus (center of the cell)
Electrons are in the outer levels=
electron cloud
Draw and label the atom
Element
A type of atom that cannot be
broken down into simpler
substances.
Can also be a group of atoms of
the same type.
Ex-> gases such as hydrogen and
oxygen. Metals= aluminum and
gold.
Atoms are made up of the
same types of particles, so
what makes one element
different from another?
 Different elements differ in the number
of protons they have.
Atomic number=
number of
protons
Atomic Mass
How many protons does
hydrogen have? Oxygen?
Hydrogen= 1
Oxygen= 8
Energy levels
Different energy levels can hold a
different number of electrons.
1st energy level= hold 2 electrons
2nd level= hold 8 electrons
Stable atoms have a full outermost
energy level
91 elements
4 that make up 96 % of your
body= carbon, oxygen, nitrogen,
and hydrogen
The other 4% are called trace
elements because they are found
in little amounts but we need them
to survive-> like calcium, iron,
potassium
Compounds
 Atoms of elements found in organisms are
usually linked or bonded to other atoms=
compound.
 Common compounds= water (H2O), carbon
dioxide (CO2)
Ion
 Atom that has gained or lost one or more
electrons.
 Forms because an atom is more stable when its
outermost energy level is full. The gain or lose
results in a full outer level.
 Either positive or negative
 Atoms with few electrons= lose electrons and
becomes more positive
 Gains electrons= more negative.
NaCl
 Transfers electron from
sodium atom to chlorine
atom
 When sodium loses electron
it becomes positive-> full
charged because it has a
filled outermost energy
level.
 The electron lost goes to
the chlorine ion, causing
the chlorine to become
more negative and have a
full energy level.
 End product is an ionic bond-> bond
that forms when two oppositely
charged particles exchange electrical
forces.
 Opposites attract (+ / -)
What determines whether
an atom becomes a
positive ion or a negative
ion?
 Atoms with few outer electrons tend to lose
electrons and form positive ions; atoms with
almost full outer energy levels tend to gain
electrons and form negative ions.
Covalent Bonds
 Form when atoms share a pair of
electrons.
 Need 4 electrons to fill its outermost
energy level
CO2= Carbon Dioxide
O
C
O
 An oxygen atom needs 2 electrons to fill its
outer energy level. In Carbon dioxide, carbon
makes a double bond, or shares two pairs of
electrons with each oxygen atom.
Molecule
Two or more atoms held
together by covalent bonds.
Properties of
Water!!!!!
Waters unique
properties allow life
to exist on Earth.
Polar vs. Nonpolar
 Polar: Water and
some gases
 Uneven distribution
of electrons
 Nonpolar= liquids,
CO2, Oxygen, oils,
fats
 electrons are
distributed more
evenly around the
outer shell.
They both tend to remain separate that is why
they say “oil and water don’t mix.”
Life depends on hydrogen
bonds
 Water is polar-> act the
same way as the
magnetic poles. Have
regions with a slight
positive and slight
negative charge.
 Waters oxygen atoms
are slightly negative
and hydrogen is slightly
positive= HYDROGEN
BOND
Where else can we find
hydrogen bonds?
 DNA
 Proteins
Properties of Hydrogen Bonds
 Weakest of the bonds
 High specific heat= water resists changes
in temperature, therefore water must
absorb more heat energy to increase
temperature.
Very important with cells because our cells
release a lot of heat and water absorbs that
heat which allows us to regulate cell
temperatures.
Properties Continue
 Cohesion-> attraction
among molecules of a
substance.
Makes water molecules
stick together.
Ex- beads on a car
when it is washed
Spider walking on top
of the water.
Properties Cont.
 Adhesion-> attraction
among molecules of
different substances.
 Water molecules stick to
other things.
 Ex- upward curve of the
surface of the water->
graduated cylinder
 Ex- plants transport water
up their roots to their
leaves.
Examples
 http://www.youtube.com/watch?v=OuD
P9-TA7dg
 http://www.youtube.com/watch?v=tv4J
rc06yLA&feature=related
 http://www.youtube.com/watch?v=45y
abrnryXk
Many compounds dissolve in
water
 Molecules and ions can’t take part in chemical
processes inside cells unless they dissolve in
water.
 Materials such as sugar and oxygen cannot
be transported from one part of an organism
to another unless they are dissolved in blood,
plant sap, or water based fluids.
Solution= mixture of substances that is
the same throughout= homogeneous
mixture
 Solvent-> substance
 Solute-> substance
that is present in the
that dissolves.
greatest amount,
 Example= kool aid
and is the substance
powder
that dissolves
solutes.
 Example= Water
Example / Scenario
 Your plasma (liquid  Why do the solutes such
as proteins and sugars
part of your blood)
is 95% water. Which dissolve in the water of
blood plasma?
is the solvent and
 Answer-> polar= because
solute?
the attraction between the
 Solvent= water;
water molecules and the
Solute is the other
solute molecules is
5% which is made
greater than the attraction
up of proteins,
among the molecules of
sugars.
the solutes.
1.
What is the most
comment solvent in
everyday life?
1.
2.
3.
4.
A. carbon containing
chemicals
B. ethanol
C. water
D. All of the above
3. What is solubility?
a. The ability of a given
substance(solute) to
dissolve into a
solvent.
b. The ability of a given
substance(solvent) to
dissolve into a
solute.
2. In a solution (which is a
mixture of a solute and a
solvent) which do you
typically have more of?
a. Solute
b. Solvent
c. Same amount of both
4. How does temperature
affect solubility?
a. Solubility is not affected by
temperature.
b. Solubility decreases with
an increase in
temperature.
c. Solubility increases with
an increase in
temperature.
5. How does a solute dissolve into a solvent?
a. Polar solvent molecules separate the
molecules of other polar substances.
b. Polar solvent molecules separate the
molecules of other non-polar substances.
c. Non-polar solvent molecules separate the
molecules of other non-polar substances.
6. What are the main factors that affect solubility?
a. Temperature
b. Pressure
c. Nature of solute and solvent
d. All of the above
Answers
 1. C- Water
 2. B
 3. A
 4. C
 5. A
 6. D
Acids and Bases
 Acids
 Releases a hydrogen
ion (H+) when it
dissolves in water.
 0 to 7= acids
Strong
Acid
 Bases
 Removes H+ ions
from a solution
 7-14= basic
Weak
base
Weak
Acid
Strong
Base
Ph of 7=Neutral-> neither acidic or basic
Ph Scale (Potential
Hydrogen)
How is Ph regulated in our
bodies?
 Through buffers-> compounds that can bind
to H+ ion when the H+ concentration
increases and can release an H+ ion when
the H+ ion decreases.
 Buffer “locks up or stops” the H+ ions in
order for our bodies to maintain homeostasis.
 Example-> normal Ph of blood is 7.35-7.45
(slightly basic), therefore a small change in
this could really disrupt your cells and can be
fatal.
Carbon Based
Molecules
Carbons unique bonding
properties
 Building blocks of life because they are the
basis of most molecules that make up living
things.
 Keep organisms alive! Yay :)
 Unique atomic structure because it has four
unpaired electrons on the outer energy level
and can form covalent bonds with up to four
other atoms!!!!!!
Three types of molecular
structures
 Straight Chain
 Branched Chain
 Ring
Monomer / Polymer
Polymer= molecule that contains many
Monomers bonded together.
Monomer=
small
molecular
subunit
How many monomers are above?
Four Carbon Based
Molecules in Living Things
/ Macromolecules
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids
Carbohydrates
 Fruits, grains, sugars, starches
 Made up of carbon, oxygen, and hydrogen when
broken down they provide a source of usable
chemical energy for cells
 Major part of plant cell structure too!!!
 Most basic= simple sugars or monosaccharides
Six carbon sugar in fruits= fructose
Six carbon sugar= glucose
 two sugars bonded= table sugar
Many glucose molecules bonded together form
polysaccharides which are polymers of
monosaccharides
Polysaccharides
 What are they?
 Polymers-> cellulose and starches
Lipids
 Nonpolar molecules such as fats, oils, and
cholesterol
 Carbon chains bonded to oxygen and hydrogen
 Some are broken down for cell use and others are
parts of cell structures.
 Olive oil, meat, butter-> have a molecule called
glycerol which are bonded to molecules called fatty
acids.
 Two types of fatty acids-> saturated and
unsaturated
Lipids cont.
 Many contain three fatty acids bonded to
glycerol= triglycerides
 Saturated fats= maximum number of hydrogen
atoms possible.
 Unsaturated fats= fatty acids are not saturated
with hydrogen atoms.
 Cell membrane-> made up of a phospholipid
bilayer with polar heads and nonpolar tails.
 Head is made up of glycerol, two fatty acids, and
a phosphate group (hydrophilic= water loving).
Tail= fatty acids (hydrophobic= water fearing).
Proteins
 Most varied- apart of everything from moving your
leg to digesting your pizza.
 Protein is the polymer made up of monomers called
amino acids.
 Amino acids are referred to as the “building blocks”
of proteins.
 We use 20 different amino acids to build proteins in
our bodies.
 Your body makes 12 and the others need to be
ingested through meat, beans, and nuts.
 All have similar structures: hydrogen atom, an
amino group (NH2), and a carboxyl group (COOH).
Proteins Cont.
 Covalent bonds called peptide bonds.
Peptide bond
Polypeptide is a chain of precisely
ordered amino acids linked by peptide
Bonds. A protein is made up of one or
more polypeptides.
Nucleic Acids
 Detailed instructions that build proteins and are
stored in extremely long carbon based molecules.
 Nucleic acid = polymer
 Nucleotides = monomer
 Nucleotides are made up of: sugar, phosphate
group, and a nitrogen base.
 Two types= DNA and RNA
 ONE FUNCTION!!!!!-> DNA and RNA work together
to make proteins.
 DNA stores information for putting amino
acids together to make proteins, and RNA
helps to build proteins.
 DNA is the basis of genes and heredity.
Chemical Reactions
 When substances are changed into
different substances by breaking and
forming chemical bonds.
 What do your cells need to breathe?
 How do they get it?
 Cellular Respiration
Reactants vs. Products
Reactants
Products
What causes bonds in oxygen
and glucose molecules to
break?
 Energy is added that causes the bonds
to break into oxygen and glucose.
 Each bond requires a different amount
of energy= Bond Energy
What happens when new
bonds form in carbon dioxide
and water?
 When new bonds form, energy is
released and this energy that is
released is equal to the amount of
energy that breaks the same bond.
 Sometimes bonds can form a chemical
equilibrium, meaning they are reversible
and the same on both sides of the
equation.
Example of Equilibrium
 Blood cells and
plasma transport
materials throughout
the body. Carbonic
acid dissolves in the
blood so that carbon
dioxide can be
transported to the
lungs.
Chemical reactions release or
absorb energy
 Energy added = breaks chemical bonds
 Energy released= new bonds form
 Energy is released or absorbed and in
different amounts.
Activation energy
Amount of energy that needs to
be absorbed for a chemical
reaction to start.
Ex.- the energy you would need
to push a rock up a hill.
Exothermic
Releases more energy than it absorbs
Excess energy is typically given off in
heat or light
Reactants have more energy than
products
Ex- firefly squid, fireflies, cellular
respiration (releases usable energy as
well as keep your body warm).
Endothermic
Absorbs more energy than it
releases
Products have more energy than
reactants
Example- photosynthesis-> plants
absorb energy from the sun and
use that energy to make simple
and complex carbs.
Enzymes
How did the Venus Flytrap
digest the frog?
Enzymes-> type of protein
that help to start and run
chemical reactions in living
things.
Break down food into smaller
molecules that the body can
use.
What is activation energy?
 The energy needed to get things
started
 Most of the time the activation energy for a
chemical reaction comes from an increase in
temperature-> sometimes the process is
very slow.
 In order to speed the process up substances
called catalysts decrease the activation
energy needed to start the chemical reaction
-> in the end increases the chemical
reaction.
 When a catalyst (ex- enzymes) is present
less energy is needed and products form a
lot faster.
What are two functions of
catalysts in chemical reactions?
1. Decrease activation
energy
2. Increase reaction time.
Enzymes
 Definition= catalysts for chemical reactions in
living things
 Reactants are usually found at very low
concentrations in the body, but really need to
occur quickly.
 Almost all are proteins= long chains of amino
acids
 Each one depends on its structure to function
 Temperature and ph can affect the shape,
function, and activity of the enzyme.
 Work best at normal body temperature
 If temperature is a little elevated then the
hydrogen bonds will fall apart, enzymes
structure will change, and its ability to
function will be lost.
 This is the reason why a high
temperature / fever is very dangerous to
a person.
Examples of enzymes in action
 Amylase is an enzyme in saliva that breaks
down starches into simpler sugars. Without
amylase it would take a million times slower.
 Blood cell engulfing a pathogen
 The structure is so important because each
enzyme’s shape is specific to a certain
reactant= allows them to fit perfectly
together just like a key fits into a lock
 Specific reactant an enzyme acts on are
called substrates
 The sites where substrates bind to enzymes
are called active sites.
 Enzymes bring substrate molecules close
together, then they decrease activation
energy, substrates attach together and their
bonds are weakened, and then the catalyzed
reaction forms a product that is released
from the enzyme.
Reflection
 On a sheet of paper, review the three
parts of the lock and key model and write
a paragraph (3-5 sentences) describing
the analogy. Consider why the model is
described as a lock and key. Also identify
the different parts and what happens to
each part after the reaction is complete.
You may use your notes