Download 4 Types Biological Molecules in plants and animals

Chapter 11
P222
Organic Chemistry – the chemistry of carbon
and carbon compounds
About 65% of the human body is water. Of the
remainder, 91% is only four elements: carbon,
oxygen, nitrogen, and hydrogen. Carbon is the
largest fraction at 53%.
Carbon has four electrons in its outer level, and
can share one or more electrons to make
covalent bonds with itself, or as many as four
other elements.
Carbon molecules come in 3 basic forms:
straight chains, branching chains, and rings.
Valine C5H11NO2
Benzene C6H6
Glucose C6H12O6
Rings and chains can be combined in the same
molecule.
P223: 4 Types Biological Molecules in plants
and animals
Carbohydrates- energy-rich sugars and
starches. Mainly composed of carbon,
hydrogen, and oxygen, in a ratio of 1:2:1
Proteins – large molecules found in animal and
plant tissues. Skin and muscle tissue are
composed mostly of protein. A single protein
may have several thousand atoms
Fats – energy-rich hydrocarbon chain
molecules, nonpolar, does not dissolve in
water. Cholesterol is a fat that is needed by
cells, but high cholesterol may lead to heart
disease.
Nucleic Acids – Biological molecules such as
DNA that have the ability to store the genetic
code. DNA is a huge molecule with millions of
individual atoms.
P224: Carbohydrates
Plant cells use energy from the sun to build
carbohydrates from carbon dioxide and water.
Animal cells consume carbohydrates and
extract the energy by breaking the
carbohydrates into smaller molecules.
Carbohydrates are classified as either sugars or
starches. Sugars break down quickly in the
body, releasing energy within a short time of
being eaten. Glucose is smallest sugar and is
dissolved directly into the bloodstream.
Starches are long chains of simple sugars
joined together to make natural polymers.
Starches are larger molecules, so they are
slower to break down in the body and can
provide energy for a longer time than sugars.
Cellulose is the primary molecule in plant
fibers, including wood. The long-chain
molecules of cellulose are what give wood its
strength. Like starch, cellulose is made from
chains of thousands of glucose molecules.
However, in cellulose, alternate glucose units
are inverted. This is what makes cellulose
strong and difficult for animals to digest.
P225 Photosynthesis
Occurs mostly in plants and some types of
bacteria.
Photosynthesis is the foundation of the food
chain on Earth. Bottom of food chain is
producers, plants that take energy from the
sun and convert it to chemical energy in
glucose. Animals (including humans)
ultimately get energy from photosynthesis
because we eat plants, or eat other animals
that eat plants.
Photosynthesis also produces the oxygen in
our atmosphere. Oxygen is a common
element, but is usually trapped by rocks and
minerals like calcium carbonate (CaCO₃).
P226 Respiration
The digestive system breaks food down into
molecules the body can use. Proteins are split
into amino acids, carbohydrates are reduced to
simple sugars, fats are split into glycerol and
fatty acids. Nutrients are then absorbed into
the blood and transported to all the cells of the
body.
Cellular respiration – the reactions in cells that
release energy from glucose.
This process breaks down glucose into water
and carbon dioxide again, extracting energy in
the process. The glucose and oxygen are used
up, and carbon dioxide and water are
produced – almost the reverse of
photosynthesis.
ATP Cycle – each cell converts the energy in
glucose into chemical energy stored in
molecules of ATP like a battery - then
distributes energy to where it is needed. One
molecule of glucose is used to convert a
maximum of 36 to 38 molecules of ADP to ATP.
Cells use the energy by converting the ATP
back into ADP and the cycle starts over.
Phosphorus is a critical part of the ADP-ATP
cycle.
P227 Water
Liquid water is essential to life. Most chemical
reactions that sustain life only work in solution.
3 important characteristics of water that make
it essential:
Water is a good solvent: In order to have a
chemical reaction, molecules must be able to
move around and contact each other.
Liquid over a wide temperature range: virtually
all living organisms on Earth are most active
between the freezing and boiling point of
water.
High specific heat: takes a lot of energy to raise
the temp a small amount – this helps living
organisms maintain a stable body temp even
when outside temps fluctuate
Macromolecule – really big molecule made up
of thousands or millions of atoms
11.2 p 229 Fats (lipids)
Fats are high-energy molecules that plants and
animals use to store energy in reserve for
longer periods. Oils are fats that are liquid at
room temperature.
Saturated fat – a fat molecule in which each
carbon is bonded with 2 hydrogen atoms.
Unsaturated fat – a fat molecule that has less
hydrogen atoms than a saturated fat.
Chemical processing of some food adds some
hydrogen to unsaturated fats in a process
called hydrogenation. Partially hydrogenated
fats have a longer shelf-life, however, research
is showing they are unhealthy.
P230 Proteins – basic building blocks of cells
and all parts of animals: muscle, skin, blood,
internal organs
Amino acids – organic molecules that are the
building blocks of proteins.
Virtually all proteins found in animals are made
from only 20 different amino acids. Many fit
together like a lock and key. This is one reason
why proteins that do the same function in one
organism do not work in another organism.
Food supplies new proteins that a body needs
to live and grow. Digestion breaks down
protein into amino acids. Cells reassemble the
amino acids into new proteins suitable for the
body’s needs.
P231 Enzymes – special proteins that are
catalysts for chemical reactions in living things.
Thousands of chemical reactions are going on
in your body EACH SECOND.
Sugar does not turn into water and carbon
dioxide by itself. Outside the body, this
reaction would need a flame. How does the
body do this at a lower temperature?
Enzymes allow your body to initiate chemical
reactions at low temperature and to control
the rate of reactions.
Catalyst – a chemical that allows a reaction to
have a much lower activation energy than it
normally would
The body controls the rate of reactions by
regulating the amount of enzymes produced.
When a cell needs more energy, it produces
more enzymes to break down glucose.
Without those enzymes, glucose molecules
stay together and store their energy.
P234 Vitamins – Most chemicals required for
life can be synthesized by your own body.
However, there are certain chemicals
necessary for life that the human body does
not make.
Vitamin C – ascorbic acid is required for your
brain and nervous system, and to transfer
energy (ADP/ATP). It must be supplied daily
through food.
Vitamin D – calciferols – not a true vitamin
since it can be made by your skin when
cholesterol reacts with ultraviolet light.
Sunscreens block UV rays from the skin and
can result in vitamin D deficiency, so it is added
to foods such as milk. A severe deficiency
softens bones (rickets or osteomalacia)
B Vitamins – must be obtained from food.
They work to maintain healthy skin and
muscle, nervous system, cell growth and
division
B-1: thiamine
B-2: riboflavin (aka vitamin G)
B-3: niacin (aka vitamin P)
B-5: pantothenic acid
B-6: pyridoxine
B-7: biotin (aka vitamin H)
B-9: folic acid (aka vitamin M)
B-12: cyanocobalamin
Folate: especially important during periods of
rapid cell division and growth, such as infancy,
needed to make DNA and RNA, and to make
red blood cells.
------------------------------------------------------------P 232 DNA and nucleic acids
Protein synthesis – using the information in
DNA to assemble proteins from amino acids
Cells must continually create the proteins they
need from amino acids. DNA molecule is put
together like a twisted ladder (double helix)
Each side of the ladder is made of 5-carbon
sugars called deoxyribose and phosphate
groups. The nitrogen bases are paired in the
center of the ladder.
4 Nitrogen Bases:
Adenine pairs with Thymine
Guanine pairs with Cytosine
The assembly instructions for building a
protein are coded in the sequence of nitrogen
bases ON ONE SIDE of the ladder
Example:
TAA – GCT – AGG – GCT – GGG – GGC – TAA
Start – alanine – argenine – alanine – glycine – glycine – stop
(5 amino acids)
TTT – phenylalanine
TTA - Leucine
ATG – Methioine
TAA – start/stop
GCT – Alanine
CCC – Proline
GTT – Valine
ACA - Threonine
GGT – Glycine
GGC – Glycine
AGG – Argenine
ACT - Serine
P233 DNA
Mutation – change in the sequence of base
pairs in DNA that may be passed on to
successive generations
The DNA molecule is able to make exact
replicas of itself. Enzymes split the DNA
molecule down the center. Each half of the
molecule contains a complementary code of
nitrogen bases. Since guanine only pairs with
cytosine, and adenine only pairs with thymine,
each half of the molecule contains the
complete genetic info for how to make
proteins.
Enzymes called polymerases move along the
unzipped DNA molecule rebuilding the
nitrogen bases on each side. More enzymes
rebuild the sugar and phosphate backbone on
top of the completed nitrogen bases.
Another set of enzymes compares the old and
new DNA strands for errors and corrects them
by replacing nitrogen bases where necessary.
There is less than one error out of every billion
base pairs.