Transcript Lecture 2

Lecture 2
Macromolecules
Carbohydrates
Thanks,
Water!
Yesterday’s Exit Ticket:
Covalent
Bond
Covalent
Bond
O
Hydrogen
Bond
Covalent
Bond
H
O
H
Shared
Electrons
Covalent
Bond
H
https://www.youtube.com/watch?v=QqjcCvzWwww
H
Shared
Electrons
The polarity of water molecules, and the
resulting hydrogen bonds among molecules,
give water properties that support life on Earth
• Cohesion
• Temperature moderation
• Solvent of life
• ??
Key Themes
(2) “Think Like a Biologist”: Understand What Life Is.
“Unity” of life: What are the common features of all life?
• Structure and function of the molecules of life
Organic vs. Inorganic
?
• ORGANIC COMPOUNDS:
– Biologically-derived
– Contain carbon (C) and
often hydrogen (H)
– Involve covalent bonds
• INORGANIC COMPOUNDS:
– Not biologically-derived
– Feature ionic bonds
Blogs.scientificamerican.com; demotix.com
BIOLOGY CRASH COURSE:
(Because I can only talk so much…)
http://www.youtube.com/watch?v=QnQe0xW_JY4&list=EC3EED
4C1D684D3ADF
Another one on water and bonds:
http://www.youtube.com/watch?v=HVT3Y3_gHGg
(1:54-5:07)
Most macromolecules are polymers,
built from monomers
• Three of the four classes of life’s organic molecules are
polymers:
– Carbohydrates
– Proteins
– Nucleic acids
• A polymer is a long molecule consisting of many similar
building blocks
• These small building-block molecules are called
monomers
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings; provocraft.com
Biologically Important
Macromolecules
(large molecules
constructed
from simpler molecules)
Fig. 4.1: Life is based on carbon
1. Carbohydrates (made from simple sugars)
2. Lipids (from fatty acids)
3. Nucleic acids (from nucleotides)
4. Proteins (from amino acids)
The polarity of water molecules, and the
resulting hydrogen bonds among molecules,
give water properties that support life on Earth
• Cohesion
• Temperature moderation
• Solvent of life
• Macromolecule creation and breakdown
Synthesis (formation) of macromolecules
HO
1
Fig. 5.2 (a)
2
3
H
H
HO
H2O
All macromolecules are formed from small building
blocks strung together by removing water:
-H from one end and
-OH from the other
Synthesis (formation) of macromolecules
HO
1
2
3
H
Short polymer
Unlinked monomer
Dehydration removes a water
molecule, forming a new bond
HO
Fig. 5.2 (a)
H2O
2
1
3
Longer polymer
Dehydration synthesis
Single unit = monomer;
macromolecules with many monomers = polymers
H
HO
4
H
Breakdown (digestion) of macromolecules
HO
1
2
3
4
Hydrolysis adds a water
molecule, breaking a bond
Fig. 5.2 (b)
HO
1
Macromolecules are broken down
by adding water (hydrolysis).
2
H
H2O
3
H
HO
H
Synthesis and Breakdown of
Macromolecules
http://www.colorado.edu/ebio/genbio/05_02Polymers_A.html
Today’s Exit Ticket
• Make a chart listing the 4 types of biological
molecules, their monomers, and their
functions
Macromolecule
Monomer or
Types
Function(s)
Key Element(s)
(e.g. carbon)
Carbohydrates
• Carbohydrates are sugars and their polymers
– Monomer: monosaccharides (single sugars)
– Macromolecules: disaccharides & polysaccharides
– Key elements:
• C, H, O
healthtips-sastha.blogspot.com
Lipids
• Lipids do not form polymers
• The unifying feature of lipids is having little or
no affinity for water (hydrophobic)
• Key elements: C, H
• Biologically important lipids:
– Fats
– Phospholipids
– Steroids
Recipes.wiki.com; pictureschat.com;
Lipid Functions
• Fats: Energy storage
• Phospholipids: Cell membranes
• Steroids: Hormones, cholesterol
communication
component of animal cell
membranes,
precursor for hormones
Animals.nationalgeographic.com
Proteins
– Monomer: Amino acids
– Polymer: Polypeptide (aka protein)
– Key Elements: C, H, N, “R” (R varies)
Proteins are:
a) Hydrophobic
b) Hydrophilic
c) Could be either
d) Not sure
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Protein Functions
• Proteins are >50% of the dry mass of most cells
– Structural support
– Storage
– Transport
– Cellular communications
– Movement
– Defense against foreign substances
– ALL enzymes are proteins – chemical reactions
wouldn’t occur in our cells without proteins!
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Nucleic Acids
– Monomer: Nucleotides
– Polymer: Nucleic acids (DNA, RNA)
– Key Elements: Sugar (C, H, O), N, Phosphate (P, O)
– Functions: Stores and transmits hereditary information
Nitrogenous
base
Phosphate
group
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Sugar
Fig. 5-27ab
5' end
5'C
3'C
Nucleoside
Nitrogenous
base
5'C
Phosphate
group
5'C
3'C
(b) Nucleotide
3' end
(a) Polynucleotide, or nucleic acid
3'C
Sugar
(pentose)
Fig. 5-UN2
Real World
Connection:
Human Health
The role of
nutrition in
(physical &
mental) health
Functions of diet
• Energy supply
• Building blocks
• Regulators of metabolism
Guysandgoodhealth.com
Energy supply
Sugars are “burned” for energy gain
with oxygen in cellular respiration
Cellular respiration releases energy:
O2 + Sugar
H2O + Energy + CO2
I
(H-C-OH)n
I
Breaking C-H
bonds releases
energy
Photosynthesis uses solar energy to make sugars:
O2 + Sugar
H2O + Energy + CO2
I
(H-C-OH)n
I
Building C-H
bonds requires
energy
Life’s major energy conversions:
Light energy  Chemical Energy  Cellular Work
Photosynthesis
Makes C-H bonds
(using the sun’s energy)
CHOH
sugar
Respiration
http://www.okgenweb.org/~okmcinto/Midway/classlist/1984.htm
Breaks C-H bonds
(releasing a lot of energy)
5 minute break…
Hexoses (C6H12O6)
Carbohydrate macromolecules
are built from simple sugars
Glucose
Galactose
Simple sugars generally have
several of these units:
I
H - C - OH
(CH2O)n
I
The names of carbohydrates often end in “ose”,
as for hexose sugars (with 6 C) like glucose,
fructose, and galactose.
Fructose
Fig. 5.3
Sugars
• Monosaccharides: molecular formulas in multiples of CH2O
– Glucose (C6H12O6) is a common monosaccharide
– Classified by the number of carbons in the carbon skeleton (hexose = 6
Cs)
– Major fuel for cells and as
raw material for building molecules
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
ET1
Sugars exist as rings in the cell.
Monosaccharides
Glucose
Fructose
Disaccharide
Sucrose
Fig. 5.5
Dehydration reaction (-H2O) in the synthesis of sucrose
Fig. 5-5
Disaccharides
Glucose
Glucose
(a) Dehydration reaction in the synthesis of maltose
Maltose
Fig. 5-5
Disaccharides
Glucose
Glucose
Maltose
(a) Dehydration reaction in the synthesis of maltose
Glucose
Fructose
(b) Dehydration reaction in the synthesis of sucrose
Sucrose
A disaccharide is formed when a dehydration
reaction (-H2O) joins two monosaccharides
http://www.colorado.edu/ebio/genbio/05_05Disaccharides_A.html
Important Monosaccharides
Glucose, fructose, galactose
•
•
Foodnsport.com
Fuel for cells
Raw material for building larger
molecules
Important Disaccharides
Table sugar (transport sugar in plants) = sucrose
(1 glucose + 1 fructose)
Topnews.in; cals.ncsu.edu
Important Disaccharides
Processing
and bleaching
+ Molasses
Table sugar (transport sugar in plants) = sucrose
(1 glucose + 1 fructose)
Meijer.com; thenibble.com
Predict the formula for a disaccharide made from two hexoses.
A) C2H4O2
B) C6H12O6
C) C12H24O12
D) C12H22O11
Think-Pair-Share
Deduce answer by combining pieces you already know.
Hexose has 6 carbons
I
Carbohydrates have general formula of H-C-OH or (CH2O)n
C6H12O6 for a hexose
I
When two hexoses are connected, one H2O molecule comes out: C6H12O6 + C6H12O6
= [C12H24O12 - H2O] = C12H22O11
Important Disaccharides
Milk sugar = lactose (1 glucose + 1 galactose)
Farmboy24.flickr.com; thedailygreen.com
Lactose intolerance
Role of genetic background
(Nutrigenomics)
Different from allergy to milk
Uneeda-audio.com
Polysaccharides
• Polysaccharides are the polymers of sugars
– Are more than 2 monosaccharides together
– Have storage and structural roles
•
•
•
•
Glycogen (energy storage in animals)
Starch (energy storage in plants)
Cellulose (cell wall structure in plants)
Chitin (cell wall structure in fungi; exoskeleton
structure in arthropods
[insects/crustaceans])
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Energy storage polysaccharides:
Starch and glycogen are BOTH made from glucose
Chloroplast
Starch
Mitochondria
Glycogen granules
0.5 µm
1 µm
Fig. 5.6
Amylose
Amylopectin
Starch - mostly in plants
Glycogen - mostly in animals
Structural Polysaccharides
• Chitin
– Exoskeleton of arthropods
– Structural support for the cell walls of many fungi
Chitin forms the
exoskeleton of
arthropods.
Chitin is used to make
a strong and flexible
surgical thread.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Cellulose makes up the tightly-packed fiber structure of plant cell walls
Cellulose
microfibrils
in a plant
cell wall Microfibril
Cell walls
10 µm
0.5 µm
Many organisms have enzymes that
break bonds in starch.
Only a few microbes have enzymes to
break bond in cellulose. Animals
cannot break cellulose bond, but some
- cows and termites - use microbial
symbionts that can.
Cellulose
molecules
Fig. 5.8
 Glucose
monomer
Fig. 5.9
Human Appendix – Biological Remnant?
Extension.umn.edu
Functions of diet
Energy storage capacity:
• Carbohydrates = 4 kcal/gram
• Proteins = 4 kcal/gram
• Fats = 9 kcal/gram
I
H - C - OH
I
“Carb”
(CHOH)n
(CH”R”)n
(CH2)n
I
H-C-H
I
Fat
Gram-for-gram, fats store twice as much energy
as carbohydrates and proteins
Glycogen
•Quickly mobilized & quickly exhausted
•Good for sprint/mental tasks
Fat
•Slowly mobilized & more lasting
•Good for extended exercise/marathon
On “Atkins Diet” (low carbohydrate diet), glycogen
stores shrink and can result in “low energy”
Today’s Exit Ticket
• Make a chart listing the 4 types of biological molecules,
their monomers, and their functions
Macromolecule
Monomer or
Types
Function(s)
Key Element(s)
(e.g. carbon)
• What element(s) (i.e. atom types) do all 4 molecules have
in common?