Transcript Honors Biology Module 5 Chemistry of Life Part 2

Honors Biology
Module 5
The Chemistry of Life Part 2
October 22, 2015
Class Challenge
Questions on Homework
Quiz
In Figure 5.2 on Page 137 shows the
difference between Diffusion and Osmosis.
Draw two beakers, one for diffusion and the
other osmosis. Include the membrane,
solvent and solute.
This figure represents the end
stage for Osmosis
--The dividing center line is solid ( ___ ), not
dashed (- - -). A solid line indicates a
semipermeable membrane. (partly
permeable)
--Only a solvent can pass thru a
semipermeable membrane, so the
solvent is attracted to the side of the
membrane that has a higher
concentration of a solute.
In diffusion, both the solute that is in the
high concentration area and the solvent
can pass freely back and forth through the
fully permeable membrane, so the water
level would stay the same on both sides,
but still the concentration of solute
would get evened out in the solvent.
Organic Chemistry
An organic molecule is one that contains only
carbon and any of the following:
hydrogen, oxygen, nitrogen, sulfur, and/or
phosphorous.
If you memorized these last week from Table
5.1, you will easily recognize these six
elements.
Look in your textbook on p. 142 for examples of
organic molecules and some that are not, and
why. Memorize these.
Photosynthesis is an example of
biosynthesis since photosynthesis takes
smaller molecules (water and carbon
dioxide) and makes a larger one (glucose).
6CO2 + 6H2O → C6H12O6 + 6O2
Carbohydrates
Carbohydrates contain only carbon,
hydrogen, and oxygen.
You can see the 'carbo' in the name, for
carbon.
And hydrogen and oxygen make water, thus
'hydrate' in the word carbohydrate.
You may know that carbohydrates give you
energy, and you've learned that glucose is
a simple sugar.
Look at a molecule of glucose:
C6H12O6
You can see there are 6 atoms of carbon, 12 of
hydrogen, and 6 of oxygen.
There are twice as many hydrogen atoms as there
are oxygen.
This is the same ratio as one molecule of water,
H2O.
When a molecule of glucose is drawn in structural
formula, it shows which atoms are linked to
which.
When the atoms are linked in a straight line, we
call it a chain structure. (on the left below)
The chain structure of the glucose molecule below
has a line of Carbon atoms, called a carbon
chain.
But many atoms have more than one structural
formula.
The most commonly accepted form of glucose is
the ring structure.
These diagrams are not drawn exactly like the
ones in the textbook, but if you look closely and
compare to those in your textbook, you can see
these indeed do represent glucose.
In the ring structure on the right below ↓,
CH2OH consists of the same atoms as
drawn in your textbook, and the same as
the chain structure here on the left, where
C links to 2 H's, and to OH.
You will remember in your textbook, in the
chain formation, one oxygen atom had 2
lines linking to a carbon atom.
Here in the chain formation on the left, the
solitary oxygen atom does have 2 links.
If you look carefully and find that same
oxygen atom in the ring formation on the
right, you will again see the oxygen has 2
links linking to carbon.
ETA: You will notice that the Oxygen is
always connected to the Carbon. That is
why in the chain structure here, HO is
written instead of OH.
The chain structure is vertical, so HO must
be written this way so that the O is
connected to the C.
Glucose
http://youtu.be/eeUCWpoVPw0
Isomers (Carbohydrates, cont.)
Isomers are two different molecules that have the
exact same chemical formula.
They are different molecules because of their
different structural formulas.
Glucose and Fructose are isomers. They have the
same atoms (C6H12O6), but in their structural
formula, their atoms are linked together slightly
differently.
This is the reason they taste different.
Carbohydrates
Glucose and fructose are monosaccharides, also
called simple sugars. You may know that the
prefix mono- means one.
Disaccharides are carbohydrates made up of two
monosaccharides. You may remember that
Carbon-Dioxide (CO2) has one atom of carbon
and two atoms of oxygen. Di- means two.
Polysaccharides are made up of more than two
monosaccharides. Poly- means many.
Table sugar is not glucose (a monosaccharide),
but is a disaccharide called sucrose.
Sucrose is formed when glucose and fructose
(which are isomers) chemically react in a
dehydration reaction.
Figure 5.4
When something is dehydrated, water is
removed. So from the combined molecules of
glucose and fructose, H2O is removed, and the
result is sucrose (a dehydration reaction) -C12H22O11
C6H12O6 + C6H12O6 → C12H22O11 + H2O
Remember, sucrose is a disaccharide because it
was formed from two monosaccharides in the
process of dehydration.
When several monosaccharides link together, it is
called a polysaccharide.
Polysaccharides aren't usually sweet. An example is
starch, and is found in most plants.
When a plant has extra monosaccharides, it will store
them as polysaccharides by having many
dehydration reactions that link the monosaccharides
together.
Kind of like when your Mom has a lot of a
apples, she may dehydrate some to use in
baking later, except in a dehydration
reaction, not only do the monosaccharides
lose water, they are actually combined into
polysaccharides.
If the apples are now polysaccharides because they
have lost water, what will the plant do to turn them
back into monosaccharides?
The opposite of dehydration is hydration. The plant
breaks down disaccharides or polysaccharides
back into their monosaccharide components by
adding water.
This is called hydrolysis. (Think of the word
hydrate.)
When humans and animals have excess
carbohydrates, their bodies make a starch called
glycogen.
So the reverse of the dehydration of fructose and
glucose to form sucrose, would be hydrolysis of
sucrose to make glucose and fructose.
This chemical reaction is achieved by honeybees
when they make honey.
Organic Acids and Bases
• Acids usually taste sour, while bases tend
to taste bitter. Fruit juice contains acid,
and many cleaning products contain
bases.
• If acids and bases react together, they
usually form water and another class of
molecule called "salts."
• Table salt is one example.
• Organic acids contain a certain pattern
of atoms bonded together: Oxygen has a
double bond with Carbon, indicated by 2
lines, and the Carbon has a bond with
OH. (O=C-OH)
This pattern is called an acid group. →
(In the chain structure of glucose on p. 143
(top of page), you see a double bond of C
with O, but that same C does not bond
directly with OH, that molecule does not
contain an acid group, and therefore is
not an organic acid.)
When you see this grouping within a
molecule, you will know the molecule is
an organic acid.
This special grouping is NOT a molecule by
itself; it is a grouping that can be IN a
molecule.
This molecule has an acid group in it, so
the whole molecule is an organic acid.
O=C - OH
Organic bases have a group of atoms in
common called the amine group, but in
this chapter, organic bases are just
mentioned and not discussed.
If you have a pool, you know that you must
use pool strips to check the pH of the
water to keep it from turning green!
Keeping the pH balanced is necessary for
clean water.
The pH of substances other than water can
also be measured.
The pH scale runs from 0-14. For solutions
measuring lower pH than 7, the lower the pH,
the more acid.
For solutions having a pH higher than 7, the
higher the pH, the more like a base the
solution becomes.
These are said to be alkaline.
Look at the chart on p. 147 to see which
substances are acids or bases, and which are
neutral.
Lipids
Lipids (or fats) link to glycerol in a
dehydration reaction.
One glycerol molecule and 3 fatty acid
molecules have a dehydration reaction to
make 1 lipid molecule and 3 water
molecules.
Lipids cannot be dissolved in water. An
example is cooking oil.
Lipids are said to be hydrophobic.
This does not mean it is afraid of water,
haha, but that is a good way to remember
it. =)
Animals can convert excess carbohydrates
into glycogen, but lipids can actually store
twice as much energy for when food is
scarce.
Saturated fats are called "saturated"
because they have all the hydrogens it can
take. It is "saturated" with hydrogen.
These saturated fats have no double bonds
between carbons.
Unsaturated fats have at least one double
bond between carbon atoms.
Lipids
https://youtu.be/VGHD9e3yRIU
Proteins and Enzymes
Proteins come in many different shapes and sizes
and are very complex. Their basic building blocks
are amino acids.
When amino acids link up using a dehydration
reaction, a peptide bond forms.
The structural formula for a protein very complex.
An average amino acid has about 20-40 atoms, and
the most simple protein has 124 amino acids. But
an average protein has several thousand amino
acids!
The Ribonuclease Protein-Simple or Not?
• http://youtu.be/WL4TizC5qG4
Enzymes are a special class of proteins that
act as catalysts.
For animals, these catalysts speed up the
breaking down process of polysaccharides
and disaccharides.
Most enzymes do their job based on the
shape that the enzyme molecule has.
Cellular Metabolism, Enzymes
http://youtu.be/cbZsXjgPDLQ
Remember, lactose is a disaccharide. If the
particular enzyme in someone's body that
is specifically designed for the lactose
disaccharide is unable to work properly, a
person will not be able to digest the
lactose that is in milk.
There are medicines to help this.
• Why is it when you are making a Jell-O mold
they caution you not to add pineapple.
• Fresh Pineapple contains an enzyme that stops
the reaction which causes Jell-O not to gel. As
is the case with most enzymes, this enzyme is
very fragile. In Experiment 5.3, you are asked to
add heat to the pulpy part of the pineapple and
then the jell-o did congeal. The heat destroyed
the enzyme.
Most food enzymes are very fragile, so that any
food processing destroys them.
That is why it is important to eat foods that are
closest to their natural state as possible so that
your body will digest these enzymes.
For some people though, when they eat pineapple
their gums bleed. The pineapple enzymes break
down the tissues in their gums.
Deoxyribonucleic Acid - DNA
In Figure 5.10 as you read the text, learning the parts of a
DNA strand. DNA, or deoxyribonucleic acid, is
formed in a double chain. These two chains are made
up of three basic parts:
1.
Deoxyribose (a simple sugar that contains 5 carbons)
2.
A phosphate group (an arrangement of 3
things: phosphorous, hydrogen, and oxygen atoms see the picture on the right of Figure 5.10 in your
textbook)
A nucleotide base
3.
The nucleotide's base can be one of four different
types: adenine, thymine, guanine, or
cytosine.
Notice which pairs are consistently linked together
in this image.
The phosphate groups link to the deoxyribose
units, which is what the outer "rails" of the DNA
strand is made of.
DNA Structure
http://youtu.be/qy8dk5iS1f0
DNA Double Helix Structure
http://youtu.be/VegLVn_1oCE
What is DNA
http://youtu.be/q6PP-C4udkA
Experiment 5.C: The pH Scale
See Figure 5.6 on page 147
Litmus paper :
Substance
pH Reading
Acid/Base?
1. Vinegar
2. Milk
3. Ammonia
4. Water
5. Salt Water
6. Unknown
lower pH than 7, the lower the pH, the more acid.
pH higher than 7, the higher the pH, the more like a base
(alkaline)