Transcript Cells Lecture V

Cell Unit Lecture V
Enzymes and
Macromolecules
Biology Standards Covered


1b ~ students know enzymes are proteins that
catalyze biochemical reactions without altering the
reaction equilibrium and the activities of enzymes
depend on temperature, ionic conditions, and the
pH of the surroundings
1h ~ students know most macromolecules
(polysaccharides, nucleic acids, proteins, and lipids)
in cells and organisms are synthesized from a small
collection of simple precursors (monomers &
polymers)
Standards translated


1b ~ an enzyme is a specialized protein that
makes a reaction happen or increases the rate
of a reaction. Enzymes are affected by pH
(acidity), temperature, and salty conditions.
1h ~ Most macromolecules (polymers) are
made in cells from a small collection of simple
molecules (monomers)

This is like a Lego house (polymer) made up of
individual Legos (monomers)
Carbon Based Molecules



All living things are made up of a collection of
atoms and molecules that work together to support
life
Nearly all living things on planet Earth are
supported by one atom, an atom of Carbon
There are Four primary Carbon Based Molecules
supporting all life on our planet:
Carbohydrates ~ sugars
 Lipids ~ fats
 Proteins ~ amino acid chain (polypeptide)
 Nucleic acids ~ DNA, RNA, & ATP

Carbon Based Molecules

Carbon is the most
important element in
living systems

It has:
6 Protons
 6 electrons
 6 Neutrons
 Mass of 12.011 amu


It bonds in four
directions and can form
double bonds
Carbon Based Molecules



Carbon based molecules can
be small and they can be very
large.
The smallest are called
monomers and usually consist
of one carbon ring or molecule
Larger carbon based molecules
are made up of many
monomers to form a polymer
Mono = one
 Poly = many

Carbon Based Molecules

Carbohydrates as carbon based molecules
 Also
known as “sugars”
 Made up of three elements
 Carbon
 Hydrogen
 Oxygen
A
couple of the simplest carbohydrates are
fructose and glucose
 These
are single carbon ring molecules that provide
energy for cellular respiration
Carbon Based Molecules


Carbohydrates can be a
simple sugar like Glucose
or many Glucose
monomers linked together
A Disaccharide is a sugar
that has two Glucose
monomers

The most common
disaccharide is sucrose
Carbon Based Molecules

Polysaccharides are many
Glucose monomers linked
together

Starch ~ a polysaccharide sugar
made by plants to store energy
Cellulose ~ a polysaccharide
made by plants to form cell walls
Glycogen ~ a polysaccharide
made by animals to store sugar
for energy (usually in the liver)


Good Carbs & Bad Carbs
Carbon Based Molecules



Lipids are an important carbon
based molecule that can be broken
down into energy for the cell and
function as part of the cell’s
structure
They include fats, oils, and
cholesterol
They are non-polar and repel polar
substances like water
Carbon Based Molecules


A phospholipid having a
phosphate head and two fattyacid tails is a monomer of the
polymer known as the cell
membrane
The phosphate head of the
phospholipid attracts water
because it is polar while the
fatty-acid tails repel it as it
passes through the membrane
Carbon Based Molecules



Lipids store a huge amount
of energy in their fatty-acid
tails
A lipid is saturated if the
Carbon chain is loaded with
Hydrogen atoms
A lipid is unsaturated if
there are a few or more
double bonds between
Carbons making it “kink”
Carbon Based Molecules


Proteins are another
important carbon-based
molecule made up of several
dozen to thousands of amino
acids
An amino acid chain is also
known as a polypeptide
chain because of its many
peptide bonds holding the
amino acids together
Carbon Based Molecules

Each amino acid is made up of
the same functional groups
except for one R – Group
Amino group
 Carboxyl group
 Hydrogen & base Carbon
 Unique R Group


Amino acids are monomers
while a protein is the polymer
Carbon Based Molecules



Nucleic acids are the fourth
Carbon based molecule
They are all made up of
monomers called nucleotides
DNA, RNA, and ATP are
nucleic acids that are found in
all living organisms

ATP pictured here has 3
phosphates bonded to a 5Carbon sugar and a Nitrogen
base
Carbon Based Molecules
Enzymes the special protein


An enzyme is a protein polymer that is made up
of many amino acid monomers
Cells use enzymes to catalyze biochemical reactions
To “make them happen”
 To “speed up reactions”



An enzyme has a unique 3-dimensional shape that
defines the role/job that it performs
An enzymes shape is maintained by being in the
right temperature, pH (acidity), and ionic
conditions
Enzymes the special protein

Chemical Reactions
 Reactants  Products


Water + Carbon Dioxide  Glucose + Oxygen + Water
Activation energy is the “energy required to start a
chemical reaction”
Think of pushing a ball to the top of a small hill so that
it can roll down a very steep slope on the other side
 The energy it took to push the ball to the top of the hill
is the activation energy


Enzymes often lower activation energies
Enzymes the special protein

When enzymes are
present, the
breakdown of
Glucose happens
easier 
Enzymes the special protein

pH is the “percent
Hydrogen” of a solution


Also known as “acidity”
The scale is based on
Powers of 10 and goes
from 0  14 with Zero
being the MOST Acidic
and 14 being the MOST
Basic
Enzymes the special protein


An enzyme protein
has an active site
where a substrate
molecule attaches
This makes it
possible for a
chemical reaction to
occur and the
enzyme acts as a
catalyst
Enzymes the special protein


Enzymes are often
referred to as
having a “lock and
key” model
Enzymes are
affected by
temperature and as
temp. increases,
enzyme activity
increases