Download Unit 2: Introduction to Biology – Molecules of Life – Part 1

Unit 2: Introduction to Biology – Molecules of Life – Part 1
Vocabulary Preview
biology
cell
molecule
atom
proton
neutron
electron
model
symbol
compare
contrast
Bohr model
chemical symbol
formula
bond
inorganic
polar
aquahydroorganic
carbon
carbohydrate
protein
amino acid
lipid
nucleic acid
nucleotide
_________________
_________________
_________________
Background:
Biology is the study of life. All living things are made of cells. Cells are made up of molecules.
Molecules are made of atoms. Atoms are made of protons, neutrons, and electrons.
We often represent atoms with idealized models or even symbols to make our study of science
easier.
These 3 pictures are all Bohr models of atoms. Discuss how they are the same (compare). How are
they different (contrast)?
It is ridiculous to think that you would make such a detailed drawing every time you wanted to
represent an atom, so we have simplified these representations even more.
These 3 pictures are all models of a molecule of water. Compare and contrast the models.
Notice in the 3rd model that the atoms are reduced down to just the chemical symbol for the element
(H=hydrogen and O=oxygen). We can simplify this even more by just writing the formula for the
molecule without representing the bonds holding them together at all: H2O
When we write H2O we are literally saying we have 2 hydrogen atoms and 1 oxygen atom (the 1 is
“understood” and not actually written) in every molecule of this stuff we call “water”.
Water is a very important molecule in Biology. We will talk about the role of water in many, many
processes and systems throughout the year.
Here are some key words associated with water:
inorganic – water does not have any carbon atoms in its molecules (if it did the formula would have a
“C” in it) so we describe it as being “inorganic”; the word organic in Biology means that a molecule
contains carbon (we’ll review this soon)
polar – water is a polar molecule; this means that the electrons that oxygen and hydrogen are
supposed to share are not being shared equally – oxygen is an electron hog; this creates a negative
end at oxygen and a positive end at the hydrogens; opposite ends are called “poles”
aqua – prefix referring to water as in aquatic or aquarium
hydro – prefix also meaning water as in hydrolysis or dehydration
Unit 2: Introduction to Biology – Molecules of Life – Part 2
Other molecules of life are much, much bigger than water molecules. These are the molecules that
make up cells and are involved in the chemical reactions that make up the biochemical pathways in
living things (like photosynthesis). These molecules are 4 general types: carbohydrates, proteins,
lipids, and nucleic acids.
These 4 types of molecules are all organic. They all have carbon atoms in their molecules, which we
can see when we look at models of these molecules or their formulas and see the letter “C” for
carbon.
CARBOHYDRATES: Think sugar!
The picture below is a model of a molecule of glucose. Notice the C’s for carbon connected in a ring
that give the molecule its general shape. Sometimes we simplify these models even more. The
second picture is a molecule of glucose, also, but the C’s have not been drawn to simplify it.
Everywhere that 2 lines (bonds) meet represents a carbon atom. They are numbered 1-6 to help you
see them.
Glucose is a monosaccharide. There are many monosaccharides, including fructose (as in “high
fructose corn syrup”). Monosaccharides make up disaccharides, oligosaccharides, and
polysaccharides. Sucrose is a disaccharide we commonly call “table sugar”. Common
polysaccharides include starch, cellulose and glycogen.
PROTEINS: Think amino acids!
Below are 6 molecules called amino acids that make up proteins. Notice they all have C’s for carbon
because they are organic.
Both carbohydrates and proteins, as well as nucleic acids, are molecules classified as polymers. This
means that a carbohydrate or a protein is made up of many of the same type of smaller molecules.
You can think of a polymer as kind of like a bead necklace and the beads as the smaller molecules.
The smaller molecules are called monomers.
Word Parts:
poly – many
mono – one
mere – unit
monomer + monomer + monomer + monomer + monomer + monomer = polymer
The monomers are hooked together by chemical bonds. When the bonds form, water is also
produced. Because a molecule of water (H2O) is formed from the two monomers that are being
linked together, the reaction is called a dehydration synthesis reaction.
Polymers can also be broken back down into their monomers. A molecule of water is needed for
each bond that has to be broken. This kind of reaction is call hydrolysis.
Word Parts:
de – to remove (like the word decapitate means to remove the head)
hydro – water
syn – together
lys – to split
Unit 2: Introduction to Biology – Molecules of Life – Part 3
LIPIDS: Think fats!
Lipids are also organic molecules. There are many kinds of lipids, including fats, oils, waxes,
pigments, and steroids.
Phospholipids are most
commonly found in the
membranes of cells, both
the main cell membrane
and the membranes that
form the organelles like the
nucleus and the
endoplasmic reticulum
Fatty acids are found in fats, oils and waxes,
including the fat in meat, lard, shortening, butter,
milk, cream, yogurt, cheese, candles and crayons.
The molecule to the left is chlorophyll, the green pigment
found in plants. Notice that it looks like a flower 
The molecule to the right is a steroid hormone. Steroid
hormones are made from cholesterol. Cholesterol and
steroid hormones have the 4 rings you see in common.
NUCLEIC ACIDS: Think DNA!
The last group of organic molecules we’re going to study is the nucleic acids. The two nucleic acids
we study that are nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). These
are HUGE molecules made up of molecules called nucleotides. Below is a picture of a nucleotide.
The nucleic acids are found in the nucleus of eukaryotic cells.
DNA never leaves the nucleus because it is protected from
chemicals that would damage or destroy it inside of this
important cell structure.
Nucleic acids are also polymers made up of monomers
called nucleotides. The nucleotides are hooked together
in dehydration synthesis reactions. Nucleic acids can be
broken down by hydrolysis.
We are going to refer to these 4 types of organic molecules ALL YEAR, as well as the inorganic
molecule water. First, we are going to get a little more background on all of them, then we are going
to study each of them in detail. It will take us the entire first semester to get a good understanding
of these molecules and to be able to compare their structures and their functions.
To get started on this process, we are going to complete an activity called “Pattern Matching:
Organic Molecules”.
Name ______________________________
Date __________________
Period _______
Unit 2: Introduction to Biology – Molecules of Life
Homework – Part 1
Tomorrow we will turn in this assignment at the beginning of the period. It is worth 5 daily grade extra credit
points. After we have passed it up, we are going to go over it as a class and you will have the opportunity to ask
questions about what you do not understand. Then, we are going to take a quiz over the same material. The quiz is
worth 100 daily grade points (no extra credit).
Use your notes and the discussion in class to complete the questions below. If you need help, raise your hand or
come in to tutorials.
1. In this class, Biology, we are going to study __________________.
2. Living things are made up of __________________.
3. Put these words in order from “biggest” to “smallest”: atom, cell, molecule ________________
__________________ __________________
4. Think carefully! Atoms have a nucleus made up of protons and neutrons. Cells have something
called a nucleus, too, but it is made up of __________________, which are in turn made of atoms.
5. How do we represent atoms in science? _____________________________________________
6. Why do we use letters to represent atoms? ___________________________________________
7. The formula for carbon dioxide is CO2. What does this formula tell you? ____________________
__________________________________________________________________________________
8. Formulas in general always tell you __________________________________________________
9. Why is water described as inorganic? ________________________________________________
10. What are the two prefixes that mean water? _________________________________________
(please continue on the back)
Understanding Models Practice
One of the biggest challenges for many students is looking at and understanding what is being shown in a diagram,
particularly a diagram of a complicated molecule. Below are some initial exercises to make you better at this important
science skill.
11. Use your notes as a reference and a PENCIL to draw a Bohr model of a carbon atom using the
symbols given below. The two rings are the energy levels; the space in the middle is for you
to draw the nucleus.
proton
+
neutron
electron
-
12. Draw a molecule of water using the symbols for the elements (letters) to represent the atoms
and lines to represent the bonds between the atoms.
Name ______________________________
Date __________________
Period _______
Unit 2: Introduction to Biology – Molecules of Life
Homework – Part 2
Tomorrow we will turn in this assignment at the beginning of the period. It is worth 5 daily grade
extra credit points. After we have passed it up, we are going to go over it as a class and you will
have the opportunity to ask questions about what you do not understand. Then, we are going to
take a quiz over the same material. The quiz is worth 100 daily grade points (no extra credit).
Use your notes and the discussion in class to complete the questions below. If you need help, raise
your hand or come in to tutorials.
1. Name the 4 general types of organic compounds. _____________________________________
__________________________________________________________________________________
2. Why are these molecules called organic? ____________________________________________
3. When you look at a model of a molecule, what element (kind of atom) is understood to be where
two lines (bonds) meet? _______________________
4. From the discussion in class, if you had teeny tiny itsy bitsy hands, could you hold on to a bond
between two atoms in a molecule like you can hold on to a bar holding together two things? ______
Explain. __________________________________________________________________________
5. What are molecules monomers) that make up proteins called? (do not answer organic)
________________ ________________
6. What are the three glucose polymers listed in your notes? ______________________,
___________________, and _____________________
7. What does the prefix or word part “hydro” mean? ____________________
8. What does the prefix or word part “aqua” mean? _____________________
9. What does “mono” mean? _________________
10. What does “poly” mean? _________________
11. Proteins are different when compared to the other 3 types of organic compounds because they
always contain the letter _________ in their formula or a diagram of a molecule which represents the
element ________________.
Name ______________________________
Date __________________
Period _______
Unit 2: Introduction to Biology – Molecules of Life
Homework – Part 3
Tomorrow we will turn in this assignment at the beginning of the period. It is worth 5 daily grade extra credit points.
After we have passed it up, we are going to go over it as a class and you will have the opportunity to ask questions about
what you do not understand. Then, we are going to take a quiz over the same material. The quiz is worth 100 daily
grade points (no extra credit).
Use your notes and the discussion in class to complete the questions below. If you need help, raise your hand or come in
to tutorials.
1. Look at the diagram of the saturated fatty acid and the unsaturated fatty acid. What is different about the
unsaturated fatty acid that makes it all “bendy”? _________________________________
2. Where did your teacher tell you phospholipids are found in cells? _________________________
3. Draw the simplest symbol for a phospholipid that we generally use. _______________________
4. What are the molecules that make up DNA and RNA called? _____________________________
5. The prefix “de-“ means “to remove”—like “detachable” means “removable”. What do you think has been removed
(what element) from ribonucleic acid to make it deoxyribonucleic acid. ________
Understanding Models Practice
One of the biggest challenges for many students is looking at and understanding what is being shown in a diagram,
particularly a diagram of a complicated molecule. Below are some initial exercises to make you better at this important
science skill.
6. Below are several diagrams of molecules that you saw in your notes. Use your notes to write the type of organic
molecule for each one (carbohydrate, protein, lipid, or nucleic acid)in the first blank, then a more specific term
from the list below in the second blank.
amino acid (3 times)
cholesterol
DNA
fatty acid
glucose (2 times)
nucleotide (2 times)
phospholipid
________________________
_____________________
_____________________
________________________
_____________________
_____________________
_________________________________
______________________________
_________________________________
_______________________________
______________________________________
______________________________________
___________________________________________
___________________________________________
_____________________________
_______________________________
_____________________________
________________________________
___________________________________
___________________________________
___________________________
___________________________
Name ______________________________
Date __________________
Period _______
Unit 2: Introduction to Biology – Molecules of Life
HW QUIZ - 1
Match the following definitions with the correct term. Put a printed, CAPITAL letter in the blank.
_______ 1. The study of life
_______ 2. Used to represent abstract things
like atoms to make science easier to study
_______ 3. Letters and numbers used to
represent the number of atoms of each
element in a molecule
_______ 4. Does not contain carbon
_______ 5. Hydrolysis means to split with
____________
_______ 6. Element represented where two
lines meet in a drawing of a molecule
_______ 7. Force that holds two atoms
together represented by a line between two
letters or other symbol in a drawing of a
molecule
_______ 8. Molecules that make up proteins
_______ 9. Molecules that make up nucleic
acids
_______ 10. One of the simplest
carbohydrates
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
amino acids
Biology
bond
carbon
formula
glucose
inorganic
model
nucleotides
water
Q 11-15: Put the following terms in order from BIGGEST to smallest. Either number them in the blanks
provided with number 1 being the biggest and 5 the smallest or you can rewrite them in the long
blank provided.
_____atoms
_____cell
_____living thing
_____molecules
_____proton
____________________________________________
Q 16-21. The formula for glucose is C6H12O6. Explain what this formula tells you about the number
and type of each atom in one molecule of glucose. ________________________________________
__________________________________________________________________________________
Name ______________________________
Date __________________
Period _______
Unit 2: Introduction to Biology – Molecules of Life
HW QUIZ - 2
Which of these molecules are organic and which are inorganic? Indicate your answers by writing an
O or an I in each blank.
1. _____ H2S
2. _____ CH3COOH
3. _____H2O
4. _____ CH3CH2OH
5. _____
6. If –aria/ -arium refers to “a place”, then the word aquarium literally means a place where
_________ is.
7. A hydroplane is an airplane that takes off and lands on ___________________
8. The word dehydration means to remove _____________
9. The word hydrolysis means to split with _____________
10. Glucose is a monomer of several polymers including ____________________,
_________________ and ________________.
11. Proteins are polymers of the monomer ______________ _____________.
12. When compared to the other types of organic compounds (polymers), which type of organic
compound (polymer) always contains the element nitrogen, represented by an ‘N’ in the formula or
diagram of the molecule? ____________________
Name ______________________________
Date __________________
Period _______
Unit 2: Introduction to Biology – Molecules of Life
HW QUIZ - 3
Match the following structures to the type of molecule they represent. Write a printed CAPITAL letter
in the blank.
_______ 1.
A.
B.
C.
D.
_______ 2.
_______ 3.
_______ 4.
lipid/fatty acid
lipid/steroid
nucleotide
amino acid
5. What letter do you look for in a diagram (model) of an organic molecule or the formula of an
organic molecule? __________, which represents the element ___________________.
6. Which diagram (on the front) is a monomer of a protein (just write the number)? ___________
7. Which diagram (on the front) is a monomer of a nucleic acid (just write the number)? ________
8. Three of the four types of organic compounds are represented by the diagrams on the front.
Which type of organic compound is NOT represented on the front? ___________________________
9. Which type of organic compound always has a ‘P’ in its formula or diagram of a molecule, showing
that phosphorus is in the molecule? ____________________ ___________________