Ms. Sastry
AP Biology
Leigh High School
No Chapter 4 - Functional Groups Hunt – Biomolecules Review
As mentioned (in class), generally “plain” hydrocarbons are not found in living cells. There are
usually other groups of atoms attached somewhere on the molecule. There are certain groups of
atoms that are frequently attached to the organic molecules we will be studying, and these are
called functional groups. These are things like hydroxyl groups which form alcohols,
carbonyl groups which form aldehydes or ketones, carboxyl groups which form carboxylic
acids, and amino groups which form amines. These groups tend to act the same and have
similar properties no matter where on a carbon backbone molecule they’re stuck. Additionally, a
molecule may have more than one functional group and/or more than one type of functional
group attached.
Go to http://www.phschool.com/science/biology_place/biocoach/biokit/intro.html
Complete reading all sections – focus on the sections with functional groups (concept 6) and
isomers (concept 4). Take the self quiz.
Identify the functional groups in the following molecules:
Functional group:
Write the Symbol Used below:
Alcohol (Hydroxyl Group)
Aldehyde (Carbonyl Group)
Ketone (Carbonyl Group)
Carboxylic Acid (Carboxyl Group)
Amine (Amino Group)
Amino Acid (Amino Group + Carboxyl Group)
Phosphate group
Sulfhydrl group
-OH
Biomolecules:
ATP or Adenosine Triphosphate – The ENERGY molecule of your cells
Ms. Sastry
AP Biology
Leigh High School
Glucose –ring form
Cysteine – an amino acid
Cocaine
Also Glucose!
Glutamine – also
an amino acid
Aspirin
Find 5 examples of biomolecules from your text that have functional groups and
draw/print them – identify the functional group/s they carry. Use chapter 5 for this
activity.
Ms. Sastry
AP Biology
Leigh High School
An antifungal medication
Ms. Sastry
AP Biology
Leigh High School
Chp 5 – Macromolecules- In class follow along lecture notes
I. Carbon skeletons
A. Isomers
1. Structural isomers - differ in the arrangement of their atoms
2. Geometric isomers - differ in the arrangement of atoms around a double bond
3. Enantiomers
a. molecules that are mirror images of each other
b cells can tell the two apart
c usually one is biologically active while the other is not
B. Polymers
1. Large molecules made by linking many individual building blocks together in long chains.
Four types – carbohydrates, lipids, proteins, nucleic acids
2. The building block subunits are called monomers.
3. Subunits are linked by a reaction called dehydration synthesis and can be cleaved/broken
down into monomers by a reaction called hydrolysis.
Give examples of these 2 reactions and know their biological significance
II. Carbohydrates (p. 64) - the most important energy source for cells and include sugars and
their polymers
A. Nomenclature
1. Monosaccharides (Fig. 5.3) - single sugar units - note the -ose suffix in the names.
Classification: Can be ketose/aldose sugar based on functional groups. Know examples of
aldose sugar and ketose sugar. Number of Carbons can change. Know examples of C3, C5,
C6 sugars. Can form ring structures (Fig. 5.4). Know to identify the structures of glucose,
ribose, fructose – linear and ring structures by sight!
2. Disaccharides (Fig. 5.5) - formed by linking two monosaccharides by dehydration synthesis.
Bond between monosaccharides = glycosidic linkage. Know the structures of sucrose,
lactose, and maltose
3. Polysaccharides (Fig. 5.6)-formed by linking many sugar units together
Ms. Sastry
AP Biology
Leigh High School
-general examples - starch, glycogen, and cellulose are the three common polysaccharides
A. Storage Polysaccharides (Fig. 5.6)
1. Starch - the storage carbohydrate in plants - formed by linking many glucose units using
dehydration synthesis; Starch is made using linkages between monomers of glucose. Know how
to identify the structure of starch
a amylose - straight chain carbohydrate - up to 1000 glucose
b. amylopectin - branches of 24-36 glucose off main chain (β 1-6 linkage); 1000-6000 glucose
2.Glycogen - the storage carbohydrate in animals; glycogen is more extensively branched than
amylopectin to increase the efficiency of storage. Why?; Glycogen is stored in liver and muscle;
humans store enough glycogen for about 1 day; the levels of blood glucose and glycogen are
controlled by insulin and glucagon. Insulin promotes the storage of glucose while glucagon
promotes its release.
C. Structural Polysaccharides (p. 68). Know the structure of cellulose (Fig. 5.8)
1.Cellulose - the structural component of the plant cell wall; about 50% all organic carbon in
biosphere is tied up in cellulose. Globally plants produce 1011 tons cellulose per year. It is
formed from glucose monomers connected by dehydration synthesis; tends not to coil. Enzymes
which digest starch cannot digest cellulose. Cellulose is called fiber or roughage in our diet.
Why is cellulose an important part of a healthy diet?
2.Chitin - the structural component in the exoskeleton of arthropods. It is found in the fungal cell
wall rather than cellulose as in plants.
III.Lipids (p. 70) - nonpolar (hydrophobic) compounds that are insoluble in water.
A.Fats
1. Many fats are triglycerides made by dehydration synthesis of glycerol and 3 fatty acids (Fig.
5.10). Know how to recognize a fat (ester linkage + hydrocarbon chain)
2. The C-H bonds in the tails are the reason fats are hydrophobic.
3. The main purpose is energy storage; lipids store >2x energy per gram as carbohydrate; Why
did fat evolve?
a. Saturated lipids (called fats) - contain the maximum possible hydrogen atoms; no double
bonds; “straight” chains; most animal fats are saturated; solid at room temperature; e.g., bacon
grease, lard, butter (Fig 5.11)
Ms. Sastry
AP Biology
Leigh High School
b. Unsaturated lipids (called oils) - missing one or more hydrogen atoms, resulting in double
bonds which cause the chains to “kink” or “bend”; plant fats and those of fish are unsaturated;
liquid at room temperature because kinks prevent close packing of molecules; e.g., canola oil,
peanut oil. Why are most plant oils found in the seeds of the plant? If peanut butter is made
from peanuts (a plant) why is it solid rather than liquid?
B.Phospholipids - in a triglyceride, one fatty acid is replaced with a phosphate. The negative
charge(s) of the phosphate makes the “head” of the phospholipid hydrophilic. The long,
hydrocarbon tail is non-polar and, therefore, hydrophobic (Fig 5.12) Know how to recognize
the structure of a phospholipid
C. Waxes - long chain lipids joined to an alcohol or carbon ring; function in waterproofing; e.g.,
plant cuticle, feathers.
D.Steroids - display characteristic 4 interconnected rings; cholesterol is the precursor for most
steroids and is an important component in the cell membrane (Fig 5.14)
IV.Proteins - (p. 73) the primary structural and functional components of cells; 50% of dry
weight of cell; What are some important dietary sources of protein? If you eat plenty of
chicken, why don’t you turn into a chicken?
A. Uses (Table 5.1)
1.Support - collagen, elastin, keratin
2. Storage of amino acids - ovalbumin, casein
3.Transport - hemoblobin
4.Communication
a hormones - insulin
b neurotransmitters - dopamine
5. Receptors - cell membrane proteins
6. Movement - actin, myosin
7. Defense - antibodies
8. Reactions - enzymes
B. Formation
Ms. Sastry
AP Biology
Leigh High School
1. Proteins are made from linking together long chains (sound familiar?) of amino acid building
blocks (Fig 5.15); dehydration synthesis forms a peptide bond between two adjacent amino
acids; many amino acids linked together is called a polypeptide. Is a polypeptide the same as a
protein? Know the general structure of amino acids and how to recognize a peptide bond
2. Amino acids differ from each other only by a variable part of the molecule called the R group.
Based on the R group, amino acids are categorized into three types. Each type has characteristics
which cause the amino acid to behave differently in different environments. This is important for
the formation of the three dimensional shape of proteins. The shape of the protein is important
for its specific function.
a polar - the R group contains poalr O-H or N-H bonds
b non-polar - the R group contains nonpolar C-H bonds
c charged - the R group contains either a charged carboxyl or amino group
C. Structure - (p. 77) a polypeptide folds spontaneously into a specific shape; the shape is
determined by the amino acid sequence and is reinforced by interactions between R groups
1. Primary structure (Fig. 5.18) - the specific sequence of amino acids; Does every protein
have a unique amino acid sequence? Know how to recognize an amino acid chain
2. Secondary structure - H-bonds cause segments of the protein to be coiled or folded (Fig
5.20). Where are the secondary structure ‘bonds’ that hold these conformaions? This is very
importnt to know! Also, be able to recognize these following structures:
a α-helix
b pleated sheet
3. Tertiary structure - results from interactions between amino acid side chains (Fig. 5.22)
a hydrophobic/hydrophilic - a polar amino acid will “prefer” to be in a polar environment. For
example, imagine a protein in an aqueous environment (i.e., polar) which has a series of nonpolar amino acids as part of its primary structure. This section of the polypeptide will be found
inside the protein away from the polar environment. This contributes to its overall shape.
b electrostatic - segments of the polypeptide can be held together by ionic bonds using amino
acids of opposite charge.
c disulfide bridges - very strong chemical bonds formed between the -SH groups of two
cysteine monomers. Know how to recognize this in a structure
d H-bonds - weak interactions which can be used to reinforce sections of three dimensional
shape.
Ms. Sastry
AP Biology
Leigh High School
4. Quaternary structure (Fig. 5.23) - 2 or more polypeptide chains associate to form the
complete protein
D. Denaturation - disrupting native (or natural) conformation; if denaturation not too great the
protein may return to its native conformation; proteins can be denatured in several ways. How
could each of them disrupt the protein conformation?
1. pH
2. salt
3. heat
4. different solvent
5. chemical treatment
E. Protein folding
1. In order to fold proteins into such complex shapes, several steps are required.
2. Chaperone proteins function as temporary braces to hold parts of the polypeptide in place as
interactions between R groups are formed.
V. Nucleic Acids - (p. 83) DNA and RNA are polymers formed by linking together long chains
(here we go again) of nucleotide monomers. A nucleotide is formed from a 5 carbon sugar, a
phosphate and a nitrogen base. Know how to recognize the 3 parts of a nucleotide
A. Nucleic acids and evolution (Table 5.2) - just as your DNA is more similar to your siblings
than to your neighbour, so the DNA of two closely related species is more similar than two
distantly related species. We can use DNA similarities to establish evolutionary
Ms. Sastry
AP Biology
Leigh High School
Macromolecules Review:
Name the following macromolecules and identify the monomeric subunits. State what
helped you figure out the identity of the macromolecule.
2) and 3)
1)
4) Identify the macromolecule below:
6)
5) What is the importance of this ?
9),and 10)
9)
7)
8)
Ms. Sastry
AP Biology
Leigh High School
11)
12)
13)
What is the name of the sugar, and
the base? Therefore what is the name
of this nucleotide?
14)
15) What is this reaction and what bond is being formed?
Take a quiz online: Click here to connect to online macromolecule quiz
Ms. Sastry
AP Biology
Leigh High School