Transcript Chemistry of Cells: Biochemistry

Chemistry of Life:
Carbon Compounds
Ch. 2
Biology
Ms. Haut
Carbon Compounds
• Organic Compounds
– Contain Carbon
– Derived from living
things
• Carbon atom has four
outer electrons, which
can covalently bond
with an electron from
another atom
http://www.hk-phy.org/articles/laser/c-atom_e.gif
Properties of Carbon
• A carbon atom forms four covalent bonds
– It can join with other carbon atoms to make chains
or rings
ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and Reece, 2007
– The simplest organic compounds are
hydrocarbons.
•
•
These are organic molecules containing only
carbon and hydrogen atoms.
The simplest hydrocarbon is methane.
– Larger hydrocarbons
•
Are the main molecules in the gasoline we burn in
our cars.
– The hydrocarbons of fat molecules provide
energy for our bodies.
http://www.notesandsketches.co.uk/pics/Plastic-Formula.jpg
ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and
Reece, 2007
Macromolecules
• Most of the large molecules
in living things are
macromolecules called
polymers
– Polymers are long
chains of smaller
molecular units called
monomers
– A huge number of
different polymers can
be made from a small
number of monomers
Biology by Miller and Levine, © 2007.
Building Macromolecules
• Cells link monomers to form polymers by
dehydration synthesis
ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and
Reece, 2007
Breaking Down Macromolecules
• Polymers are broken down to monomers by
the reverse process, hydrolysis
ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and
Reece, 2007
Major Groups of Biological
Macromolecules
•
•
•
•
Carbohydrates
Lipids
Nucleic Acids
Proteins
Carbohydrates
• Compounds made up of
carbon, hydrogen, and
oxygen
– 1C:2H:1O
(C6H12O6)
• Monomer units are
monosaccharides
(simple sugars)
• Disaccharides are
made up of 2 simple
sugars
http://www.bio.miami.edu/~cmallery/150/protein/c8.8x13.hydrolysis.sucro
se.jpg
Glucose
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Benjamin Cummings
Glucose
Maltose
Carbohydrates
• Polysaccharides —long chains of simple sugars
• Function as storehouse of energy
– Starches —storage form of glucose in plants
– Glycogen —storage form of glucose in animals
• Cellulose —tough fibers give plant strength and rigidity
(found in wood and paper)
ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and
Reece, 2007
Types of Lipids
• Large nonpolar
molecules, made
mostly of carbon and
hydrogen
–
–
–
–
Fats
Waxes
Phospholipids
Steroids
• Can be used to store energy
– Carbon-hydrogen bond store a lot of energy
• Lipids do not mix with water (hydrophobic)
Fats
• They are also called triglycerides
– One glycerol molecule linked to three fatty acids
Glycerol
Fatty acid
Fats
• Saturated fatty acid —
carbons contain the
maximum number of
hydrogen (animal fats,
butter, lard)
– Solid at room temp.
• Unsaturated fatty acid—
carbons have double
bonds; chains get kinked
(plant oils, some fish oils)
– Liquid at room temp.
Lipids
• Fats store energy efficiently
– Have many more hydrocarbon (high
energy) bonds than carbohydrates
Fats
• Fats perform essential functions in the
human body:
• Energy storage
• Cushioning
• Insulation
Phospholipids
• Make up the lipid bilayer
of cell membranes
• Makes cell membrane
selectively permeable
http://www.mynewsletterbuilder.com/tools/view_news
letter.php?newsletter_id=1409618906
http://www.uic.edu/classes/bios/bios100/lecturesf04am/phospholipid.jpg
Lipids
• Waxes—effective hydrophobic coatings
(insects, plants, even humans)
• Fatty acid linked to alcohol
Beeswax
http://www.pureextracts.us/images/products/BEESWAX.jpg
Waxy cuticle
http://farm4.static.flickr.com/3101/3109866149_2dc2a7083f.jpg
Steroids
• 6 carbon rings; no fatty acid component
• Functions
– Found in cell membranes—keeps fluid at  temps.
– Serve as chemical messengers in the body
(hormones)
– Cholesterol-functions in the digestion of fats and
starting material for hormones
http://www.mansfield.ohiostate.edu/~sabedon/campbl05_files/image013.gif
Nucleic Acids
• Nucleic acids are information-rich
polymers of nucleotides
• Nucleic acids such and DNA and RNA
store and transmit hereditary, or
genetic, information.
• They ultimately control the life of a cell
• The monomers of nucleic acids are
nucleotides
• Nucleotides consist of three parts:
• a 5-carbon sugar
• a phosphate group
• a nitrogenous base
Nitrogenous
base (A)
Phosphate
group
Sugar
Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Nucleic Acids
• There are two kinds of
nucleic acids,
ribonucleic acid (RNA)
and deoxyribonucleic
acid (DNA).
– RNA contains the sugar
ribose.
– DNA contains the sugar
deoxyribose.
http://www.phschool.com/science/biology_place/biocoach/images/transcription/dvsrna.gif
• DNA consists of two
polynucleotides
twisted around each
other in a double
helix
• The sequence of the
four kinds of
nitrogenous bases
in DNA carries
genetic information
ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and
Reece, 2007
Deoxyribonucleic acid
• Stretches of a DNA molecule called genes
program the amino acid sequences of
proteins
– DNA information is transcribed into Ribonucleic
acid (RNA), a single-stranded nucleic acid
– RNA is then translated into the primary structure
of proteins
Proteins
• A protein is a polymer constructed from
amino acid monomers.
• Proteins perform most of the tasks the body
needs to function
– cellular structure
– movement
– defense
– transport
– communication
– Enzymes regulate chemical reactions
Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Proteins are made from just 20 kinds of
amino acids
• Proteins are the most structurally and
functionally diverse of life’s molecules
– Their diversity is based on different
arrangements of amino acids
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• Each amino acid contains:
– an amino group
– a carboxyl group
– an R group, which distinguishes each of the 20
different amino acids
Amino
group
Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Carboxyl (acid)
group
• Each amino acid has specific properties
Leucine (Leu)
Serine (Ser)
HYDROPHOBIC
Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Cysteine (Cys)
HYDROPHILIC
Amino acids can be linked by peptide
bonds
• Cells link amino acids together by
dehydration synthesis
• The bonds between amino acid monomers
are called peptide bonds
Overview: A protein’s specific shape
determines its function
• A protein, such as lysozyme, consists of
polypeptide chains folded into a unique
shape
– The shape determines the protein’s function
– A protein loses its specific function when its
polypeptides unravel
Figure 3.14A
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Figure 3.14B
Protein Structure
• Primary structure
•
The specific
sequence of
amino acids in a
protein
• A slight change in
the primary
structure of a
protein affects its
ability to function.
• The substitution of
one amino acid for
another in
hemoglobin causes
sickle-cell disease.
ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and
Reece, 2007
Protein Structure
• Secondary structure is polypeptide coiling or
folding produced by hydrogen bonding
Primary
structure
Amino acid
Secondary
structure
Hydrogen
bond
Pleated sheet
Alpha helix
Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
• Tertiary structure is the overall shape of a
polypeptide
• Quaternary structure is the relationship
among multiple polypeptides of a protein
Tertiary
structure
Polypeptide
(single subunit
of transthyretin)
Quaternary
structure
Transthyretin, with four
identical polypeptide subunits
Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
What Determines Protein
Structure?
•A protein’s shape is
sensitive to the
surrounding
environment.
– Unfavorable
temperature and pH
changes can cause a
protein to unravel and
lose its shape.
– This is called
denaturation.
http://www.yellowtang.org/images/protein_denaturatio_c_la_784.jpg
Acknowledgements
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Unless otherwise noted, illustrations are credited to Prentice Hall and have been
borrowed from Biology by Miller and Levine, © 2007. These images have been
produced from the originals by permission of the publisher. These illustrations
may not be reproduced in any format for any purpose without express written
permission from the publisher.
ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and
Reece, 2007. These images have been produced from the originals by
permission of the publisher. These illustrations may not be reproduced in any
format for any purpose without express written permission from the publisher.
BIOLOGY: CONCEPTS AND CONNECTIONS 4th Edition, by Campbell, Reece,
Mitchell, and Taylor, ©2003. These images have been produced from the
originals by permission of the publisher. These illustrations may not be
reproduced in any format for any purpose without express written permission
from the publisher.
BIOLOGY: CONCEPTS AND CONNECTIONS 4th Edition, by Campbell, Reece,
Mitchell, and Taylor, ©2001. These images have been produced from the
originals by permission of the publisher. These illustrations may not be
reproduced in any format for any purpose without express written permission
from the publisher.