Transcript The Make-up of Life(K)

The Make-Up of Life
Tree of Life by Gustav Klimt
Biology 392 Chapter 2
Mrs. Gallagher
2-1 The Nature of Matter
What is everything made of?
• Anything that has mass and takes of space
is called MATTER.
Is there anything that is not matter?
• The smallest unit that an element can be
broken down to and still have the
properties of that element is called an
ATOM.
Organization of Matter
• Atoms usually do not occur alone, but
exist with other atoms as:
–Elements (all of the same atoms)
–Molecules or Compounds
• Same or different atoms bonded
MATTER: anything that has mass &
takes up space
Protons
Neutrons
Electrons
ATOMS
Molecules or
Compounds
Organic
C-C, C-H bond
LIFE!
bonded
Inorganic
Does not contain
C-C bonds
pure
Elements:
Shown in
Periodic Table
Atomic Number
# of protons
(and also # of
electrons)
Chemical
symbol
6
C
Name of
Element
Carbon
12.011
Atomic Mass
The weight
Of carbon
atom or
average
weight of
all isotopes
Elements
• A substance which cannot be split into simpler
substances by a chemical reaction
• A grouping of the same type of atoms
– ORDER MATTERS!
• More than 100 elements exist (shown in the periodic
table)
• Carbon Elements:
Elements found in Living Organisms
PINK: CHNOPS!
BLUE: lesser elements
GREEN: trace elements
About 97% of the compounds present in organisms contain only six
elements: CHNOPS
Source: Dept. of Chemistry, University of Florida
BONDING
• Atoms need to bond together to make
molecules or compounds
– “Molecule”is often used to refer to an
individual grouping. “singular”
– “Compound”- larger conglomerate of
bonded molecules.
• Molecules and compounds are written out
in a chemical formula: example- C6H12O6
Why do atoms bond?
• An atom wants to have a complete outer
shell (called valence level) of electrons.
To do this, it can…
• Share electrons with another atom
• Give away its electron(s) in this level
• Receive electrons from another atom
*Remember: an atom is  when its outer
orbital is filled
TYPES OF BONDS
1. IONIC - One atom (very unstable) gives 1, 2 or 3 electrons away
to another atom. The atom that loses electrons becomes positively
charged. The atom that gains the electrons becomes negatively
charged. The opposite charges cause the atoms to “bond” together
(opposites attract).
2. COVALENT- atoms share a pair of electrons (sometimes share
2 (double bond) or 3 (triple bond) pairs)
3. VAN DER WAALS-Attraction between oppositely charged
areas of adjacent molecules
4. HYDROGEN- (will be discussed in detail in next section)
Example of Ionic Bonding-NaCl
Na (sodium) is very unstable because it only has one
e- in its outer orbital. Cl’s (chlorine) outer orbital is
almost filled. Na gives its lonely e- to Cl.
Na become Na+
Cl becomes Cl-
Their opposite charges cause them to be attracted
to one another- This is an ionic bond.
Electrolytes
• A solution that conducts electricity.
• Term for salts, specifically ions.
• Main electrolytes in the body:
Na+, K+, Ca2+, Mg2+ , Cl−
• Why are they important in your body?
– Role in regulating hydration of the body as well
as blood pH
– Critical for nerve and muscle function
Example of Covalent Bonding- Water
Example of a Covalent Bond
Van der Waals forces
• Attraction between oppositely charged
areas of adjacent molecules
*weaker than covalent bonds and ionic bonds
Learning Checkpoint
What is an ion?
Why is it important that atoms bond?
What causes atoms to bond?
Explain the difference between an ionic
bond and a covalent bond.
• What are Van der Waals forces?
•
•
•
•
2-2 Properties of Water
Water!
• What is the chemical formula for
water?
• How much water covers the Earth?
• How much of your body is water?
• Is there water in food?
• How long could you live without
water?
•
•
•
•
•
H2 O
75%
60-70%
Yes!
3 days
Properties of Water
• Phases: Solid, Liquid, Gas
• Polarity
• Hydrogen bonds
– Adhesion
– Cohesion
• Making Mixtures
– Solutions
– Suspensions
• Making Acids and Bases
Water Density
• Ice is less dense than liquid water
• When water freezes it forms a rigid
structure that makes the cube spread- it
becomes larger and less dense
• Benefits:
– Fish and plant life can survive in liquid layers
of water under ice
PHASE CHANGES:
the closeness and speed of the compounds
Polarity
Hydrogen ends
become slightly
positive
• Water is polar
• Although the
compound is
neutral
overall there
is a shift of
charge within
the compound
The much larger atom, Oxygen,
pulls more on the shared eThis end of the compound becomes slightly
more negative.
Hydrogen Bonding
• Due to polarity, water compounds attract
to one another
• Slightly negative oxygen attracts slightly
positive hydrogen from another compound
• This attraction among water is
COHESION.
• Water is also attracted to other materials.
This is ADHESION.
COHESION
Water compounds attract
To one anothercauses water to “bead”
ADHESION
Water compounds attract
To glass molecules
And form a meniscus
Capillary Action!
• Water “climbs” up plant veins by attracting to the
sides (adhesion) and attracting to each other
(cohesion)
The greatest solvent on Earth!
• Water’s polarity allows it to break ionic
bonds of other compounds…creating free
ions.
Mixtures
Two or more elements physically mixed
together but not chemically combined (not
bonded)
1.
SOLUTIONS- a solute is dissolved into a solvent
– Distributes evenly
– “Like dissolves Like”
– Ex: Koolaid, salt water
2. SUSPENSIONS- added substance does not
dissolve but breaks into small enough pieces that
it remains suspended in the water and does not
settle out.
- Ex: blood
Learning Checkpoint
• Why does ice float on a lake?
• Explain the polarity of water – how are the
charges distributed?
• What is the difference between adhesion
and cohesion?
• Explain the difference between a solution
and a suspension.
Water Dissociation
Water can break apart on its own into 2 charged
ions
Acids and Bases
Water can react to form individual ions:
H2O
H+ + OH-
• In pure water this occurs naturally but
the amount of H+ is always = to the
amount of OH- so water remains neutral
pH scale: “the power of Hydrogen”
• Some solutions made with water become acidic
or basic. This is determined by the amount of
H+ (hydrogen ions) in the solution
• pH = - log [H+]
• Because it’s logarithmic, each pH unit
represents a tenfold difference in
concentration of H+ ions. This means
something with a pH of 4 is 10 times more
acidic than something with a pH of 5.
ACID: Any compound that forms H+ ions in solution
BASE: Any compound that forms 0H- ions in
solution
pH and Living Things
• pH values in living cells are usually kept
between 6.5 and 7.5
– Optimal pH for chemical reactions to take
place in the body
– Any switch in pH could cause serious/fatal
problems
2-3 Carbon Compounds
• Why Carbon?
– Carbon can from 4 covalent bonds (can create many
different compounds)
– Carbons can bond to one another forming large
chains or rings
• Linking of carbons can form very large molecules
called Macromolecules
• Each individual unit is called a monomer.
When they are linked together they are called a
polymer.
• 4 macromolecules necessary for life:
carbohydrates, lipids, protein, nucleic acids
Nucleic Acid
• Contain hydrogen, oxygen, nitrogen, carbon
and phosphorus
• Monomer- nucleotide
• Polymer- DNA or RNA
• Store or transmit genetic information
*Nucleic Acids will be studied in greater detail
when we study genetics
Carbohydrates
• Made of carbon, hydrogen and oxygen (ratio of
1:2:1)
• Monomer- monosaccharides (simple sugars):
glucose, galactose and fructose
– Disaccharides- 2 sugars linked together: sucrose,
maltose, lactose
• Polymer- polysaccharides: glycogen (animals),
starch and cellulose (plants)
• Main source of energy
Lipids
• Made mostly of carbon and hydrogen and
some oxygen
• Not soluble in water: fats, oils and waxes
• Monomer: all lipids have an end called
glycerol in which fatty acid chains attach
• Polymer- lipid
• Used to store energy, also for membrane
structure
Saturated vs. unsaturated fats
Saturated- no double bonds
between carbons, all
possible hydrogens
Unsaturated- at least
one double bond,
less hydrogen, can bend
Saturated vs. Unsaturated
• All single bonds
connect C
• Solid at room temp
• Ex: butter, lard
• “Straight, stackable”
• Contain double
bonds
• Liquid at room temp
• Ex: olive oil, corn oil
• Typically plantbased
What are trans-fats?
• “Trans” double bonds are not naturally found in
biological systems
• When unsat. fats are “hydrogenated” to become
sat. fat (easier to store, ship, use), the H’s can
rearrange and ‘straighten out’ the molecule
• Trans fat is bad (?) b/c it is not recognized by our
body’s enzymes (?)
Protein
• Contain nitrogen, carbon, hydrogen and
oxygen (amino group and carboxyl group)
• Monomer- amino acid
• Polymer- polypeptide or protein
• Control reactions, regulate cell processes,
form bones and muscles, transport and
help fight disease
Protein Structure
Hydrogen bonds and Van der Waals forces hold the
protein shape together.
Why is protein structure so important?
2-4 Chemical reactions
• Process that changes one set of chemicals
(reactants) into another set of chemicals
(products) by making and/or breaking bonds
• Bonds are the storage place of energy in
molecules / compounds
– Break a bond  RELEASE energy
– Make a bond  REQUIRES energy
Energy in Reactions
• EXERGONIC (E exiting)
• Chemical reactions that release energy
• Often spontaneous (occur on their own)
– But often need a “push” to get started
• ENDERGONIC (E needing)
• Chemical reactions that absorb energy
• Need energy input to occur
• Activation energy
-“The starting push” of chemical reactions
-The minimal amount of energy required to get a
chemical reaction started
Types of Reactions
• Hydrolysis
– Break apart monomers
– by the addition of water.
– An H is added to one monomer & an OH is added to
the other monomer.
• Dehydration Synthesis ( or Condensation)
–
–
–
–
Join monomers
One monomer loses a H+ and the other loses an OHWater is removed
Covalent bond is formed
Dehydration Synthesis
Enzymes
• Proteins that lower the activation energy required and
allow reactions to happen at the normal temperature
of cells.
• Each enzyme is specific (only works on one
particular reaction)
• Can be used over and over again for that reaction
• The reactant that the enzyme helps is called the
substrate. The enzyme is usually named after the
substrate with the ending –ase added to it.
• Coenzymes are non-protein helper molecules that
sometimes assist enzymes with their job.
What can affect the rate of
Enzymes function?
• Each enzyme will only do one specific reaction.
Enzymes are never used up or changed in the
reaction.
• Increasing the substrate concentration and/or
enzyme concentration can speed up the rate of
reaction.
• Enzymes are picky about the temperature, and
pH. If either is not ideal the enzyme rate will
slow and possibly stop. An enzyme will
denature if temp. or pH are not right.
Learning Checkpoint
• What are the 4 carbon compounds
necessary for life?
• What is the main function of
carbohydrates?
• What are some of the functions of protein
in the body?
• What is the easiest way to distinguish a
lipid from a carbohydrate?
• What is a monomer and a polymer?
Practice Questions:
The diagram shows a reaction that forms a
polymer from two monomers. What is this
type of reaction called?
a)
b)
c)
d)
Glycolysis
Hydrolysis
Photosynthesis
Dehydration synthesis
Which statement best describes an effect of
the low density of frozen water in a lake?
a) When water freezes, it contracts, decreasing the
water level in a lake
b) Water in a lake freezes from the bottom up,
killing most aquatic organisms
c) When water in a lake freezes, it floats, providing
insulation for organisms below.
d) Water removes thermal energy from the land
around a lake, causing the lake to freeze
Which statement correctly describes how
carbon’s ability to form four bonds makes
it uniquely suited to form
macromolecules?
a) It forms short, simple carbon chains
b) It forms large, complex, diverse molecules
c) It forms covalent bonds with other carbon
atoms
d) It forms covalent bonds that can exist in a
single plane
Carbohydrates and proteins are two types of
macromolecules . which functional
characteristic of proteins distinguishes
them from carbohydrates?
a)
b)
c)
d)
Large amount of stored information
Ability to catalyze biochemical reactions
Efficient storage of usable chemical eergy
Tendency to make cell membranes hydrophobic
Substance A is converted to substance B in a
metabolic reaction. Which statement best
describes the role of an enzyme during this
reaction?
a)
b)
c)
d)
It adjusts the pH of the reaction medium
It provides energy to carry out the reaction
It dissolves substance A in the reaction medium
It speeds up the reaction without being
consumed
A scientist observes that, when the pH of an
environment surrounding an enzyme is
changed, the rate the enzyme catalyzes a
reaction greatly decreases. Which
statement best describes how a change in
pH can affect an enzyme?
a) A pH change can cause the enzyme to change its shape
b) A pH change can remove energy necessary to activate an
enzyme
c) A pH change can add new molecules to the structure of
an enzyme
d) A pH change can cause an enzyme to react to a different
substrate