Transcript The Structure and Function of Macromolecules

The Molecules of Life:
Structure and Function
Objective
To understand the structure and function of biomacromolecules and to be able to identify them
based on their characteristics.
Essential Question: What are the molecules of life, what
are their general structures, and functions?
Polymers

What is a polymer?




Poly = many
Mer = part
A polymer is a large molecule consisting of many
smaller sub-units bonded together.
What is a monomer?

A monomer is a sub-unit (single unit) of a polymer.
Making and Breaking Polymers

How are bonds between monomers formed
in the creation of organic polymers?


Dehydration Synthesis reactions (“condensation”)
Monomers bond to one another through the
removal of water.
Dehydration Synthesis
Hydrolysis

Polymers are broken down into monomers.



hydro = water
lysis = to break/lyse, “loosening”
Water is added and the lysis of the polymer
occurs.
What do you notice?
The 4 classes of
Biomacromolecules:




Carbohydrates
Lipids
Proteins
Nucleic Acids*
* = save for later!
Carbohydrates

Sugars





carbo = carbon
hydrate = water
Molecular formula (CH2O)n
Store energy in chemical structure
Glucose:


most common monosaccharide
produced by photosynthetic autotrophs
Structure of Monosaccharides


An OH group is attached to each carbon except one,
which is double bonded to an oxygen (carbonyl).
Each “carbon” is surrounded by a “hydrate” (water)

Carbohydrates are classified according to the size of
their carbon chains, varies from 3 to 7 carbons
Triose = 3 carbons
Pentose = 5 carbons
Hexose = 6 carbons

In aqueous solutions many monosaccharides
form rings:
Structure of Disaccharides


Double sugar that consists of 2 monosaccharides,
joined by a glycosidic linkage.
What reaction forms the glycosidic linkage?

dehydration synthesis
Examples of Disaccharides:
Lactose = glucose + galactose
Sucrose = glucose + fructose
Polysaccharides


Structure: Polymers of a few hundred or a few thousand
monosaccharides.
Functions: energy storage molecules or for structural support
Examples of Carbohydrates






Starch = a plant storage from of energy, easily
hydrolyzed to glucose units
Cellulose = a fiber-like structural material - tough and
insoluble - used in plant cell walls
Glycogen = a highly branched chain used by animals to
store energy in muscles and the liver.
Chitin = a polysaccharide used as a structural material in
arthropod exoskeleton and fungal cell walls.
Lactose = a simple sugar found in milk and dairy
products
Glucose = simplest sugar; a monosaccharide; feeds
brain
Lipids

Structure:


Greasy or oily nonpolar compounds
Functions:






Energy storage
membrane structure
Protecting against desiccation (drying out).
Insulating against cold.
Absorbing shock
Regulating cell activities by hormone actions.
Structure of Fatty Acids


Long chains of mostly carbon and hydrogen atoms with
a -COOH group at one end.
When they are part of lipids, the fatty acids resemble
long flexible tails.
Saturated and Unsaturated Fats

Unsaturated fats :




liquid at room temp
one or more -C=C- (double bonds) between carbons in the
fatty acids allows for “kinks” in the tails
most plant fats
Saturated fats:




solid at room temp
have only single C-C bonds in fatty acid tails
all Carbon atoms fully surrounded (“saturated” by H’s)
most animal fats
Saturated or Unsaturated? That is the question
Saturated
fatty acid
Unsaturated
fatty acid
Structure of Triglycerides



1 glycerol + 3 fatty acids
3 linkages are formed between the –OH group of the
glycerol and a –H of the fatty acid.
Fatty acids and glycerol bound together by ester bonds.
Phospholipids


Structure: 1 glycerol + 2 fatty acids + phosphate group.
Function: Main structural component of membranes, where they
arrange in bilayers.
Phospholipids in Water
Waxes

Lipids that serve as coatings for plant parts and as
animal coverings.
Steroids


Structure: Four carbon rings with no fatty acid tails
Functions:


Component of animal cell membranes
Modified to form sex hormones
Example Lipids




Triglycerides = found in food; energy source
Phospholipids = cell membranes; regulation
Waxes = plant and animal coating; candles
Steroids = components of membranes and for
hormones
Proteins

Structure:



Polypeptide (“many peptide”) chains
Consist of peptide bonds between 20 possible
amino acid monomers
Have a 3 dimensional globular shape
Structure of Amino Acid Monomers

Consist of an asymmetric carbon covalently bonded to:




Hydrogen
Amino group
Carboxyl (acid) group
Variable R group specific to each amino acid
Properties of Amino Acids

Grouped by polarity

Variable R groups (side chains) confer different properties to
each amino acid:

polar, water soluble.

non-polar, water insoluble

positively charged

negatively charged
Structure of Proteins

Dehydration synthesis reactions form the peptide bonds
between amino acids
Functions of Proteins

Enzymes = accelerate specific chemical reactions
up to 10 billion times faster than they would
spontaneously occur.

Structural materials


keratin - found in hair and nails

collagen - found in connective tissue
Contraction

actin and myosin fibers that interact in muscle tissue.

Specific binding



antibodies that bind specifically to foreign substances to
identify them to the body's immune system.
Specific carriers

membrane transport proteins - move substances across cell
membranes

blood proteins (hemoglobin), that carry oxygen, iron, and
other substances through the body.
Signaling

hormones such as insulin that regulate sugar levels in blood.
Recap

Carbohydrate Functions:



Lipid Functions:



Examples include:
How?
Examples include:
How?
Protein Functions:


Examples include:
How?


http://www.youtube.com/watch?v=Oz2x_yx
PXww&feature=related&safety_mode=true
&persist_safety_mode=1&safe=active
http://www.youtube.com/watch?v=lijQ3a8y
UYQ&safety_mode=true&persist_safety_m
ode=1&safe=active
Primary Structure


Unique sequence of amino acids in a protein
How? Dehydration synthesis between amino acids
Modeling Primary Structure:
Salivary Amylase

What do the different
colors represent?

How do you think
they would interact?

GFCWAQYSSNDCR
Secondary Structure



Repeated folding of protein’s polypeptide backbone
How? H bonds form between atoms in backbone
2 types: a-helix, b-pleated sheets
Let’s model Secondary Structure

Look at your string of amino acids.



What do the different colors represent?
Note the order of colors.
Take the “backbone” and create some a-helices
and some b-pleated sheets.
Tertiary Structure



Globular folding!
How? Bonding between R groups
http://www.youtube.com/watch?NR=1&v=ysPt1lIllcs&safety_mode=true&persist_
safety_mode=1&safe=active
Let’s model Tertiary Structure

Note the colors on your polypeptide.





White = hydrophilic
Yellow = hydrophobic
Blue = “negatively charged”
Red = “positively charged”
Green = “sulfur R-group” (bonds only Cysteines)
Quaternary Structure


2 or more polypeptides bonded together
How? Attraction between backbones and R groups of
neighboring globs
Let’s model Quaternary Structure

Find a neighbor, and attach R groups that
might be attracted to each other. What types
would?
Good image of protein folding

http://www.umass.edu/molvis/workshop/im
gs/protein-structure2.png
Factors That Determine Protein Conformation





Depends on physical conditions of environment
 pH, temperature, salinity, etc.
Change in environment may lead to denaturation of protein
Denatured protein is biologically inactive
Can renature if primary structure is not lost
What happens when protein folding goes wrong?


http://www.youtube.com/watch?NR=1&v=H2Ouxl_GNjA&safety_mode=true&persist_safety_mode=1&safe=active
http://www.youtube.com/watch?v=RNIwwLdDLnI&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
Your Tasks

Protein Activity Wrap Up



Stamps for journal activity (models)
Draw your last diagram!
Enzyme Activity is now extra credit!


“Due” tomorrow for 3 stamps – directions are linked to website
There will be a general enzyme question on the test, so know
their functions