Transcript Chemistry of Life

Chemistry of Life
G.Burgess
2012
In a nut shell
 All matter is made of atoms; cells are
matter; cells are made of atoms
 Atoms have shape
 Atoms interact chemically and physically
making compounds
 The interaction of compounds shapes life
 three major compounds found in cells are;
proteins, lipids and carbohydrates
 Each type differes in composition and shape.
Lipids
 composed of C,H,and O
 (ie. C57H110O6)
 Produced by both plants and animals as cell
membranes, fats, oils, waxes and steriods.
 Used for prompting chemical reactions of
homeostasis, protection from environment,
and storing excess energy.
 Lipids are hydrophobic; they repell water
Saturated, Unsaturated and Transfats

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Note, both
saturated fats
and transfats
are linear and
unsaturated
have a bend
Saturated and
transfats are
solid at room
temperature
Unsaturated
fats are liquid
at room
temperature
Cell Membrane
 Keeps the cell separate from the external environment and
regulates materials that are able to enter and leave the cell.
 Fluid mosaic model:
 Composed of lipids held together by cholesterols, and
proteins
 Lipids: act as barrier to water
 Cholesterols: add strength to lipid membrane
 Proteins: enable ions and water soluble materials to
enter the cell, give the cell identity and may act as
attachment sites for other cells or macromolecules.
Phospholipid

Note the
polar
head
and fatty
acid tails
are
connecdt
ed by a
glycerol
Cell Membrane
https://encryptedtbn1.gstatic.com/images?q=tbn:ANd9GcTD_hYpU
l6E5TneNniP9ixk_zYQs_6ioHOB4auF44dx4ZO6_GZrg, accessed Sept.6 2013.
https://encryptedtbn0.gstatic.com/images?q=tbn:ANd9GcQkZmwhsfzPah80
ov8CA9T9laWv3UlpMZk2eQbr1NZ_lNA-aL9P, accessed
September 6 2013.
Carbohydrates
 composed of C,H, and O (ratio of 2H to 1O)
 Sugars are made of keytones or aldehydes
combined with carboxyl groups.
 primary source of molecular energy.
 produced by plants in the form of simple
sugars and polysaccharides.
 Simple sugars C6H12O6 are called
monosaccharides
 Simple sugars; gluose, galactose, fructose
 Two simple sugars form a disaccharide more
than two molecules joined make a
polysaccharide.
Glucose, Fructose and Galactose
 Note the
chemical
formula is
the same,
but the
shapes
and
structures
are
different
Glucose
Galactose
Fructose
Proteins

composed of C, H, O and N
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(nitrogen is a necessary element for forming amino acids, the
building blocks of proteins)
a single protein may be formed from 100’s of amino acids
two amino acids make a dipeptide; more make up a
polypeptide
RNA, DNA and hormones are examples of polypeptides.
The type of polypeptide formed depends on the number and
sequence of the amino acids that make it.
there are 20 different amino acid groups.

These acids form the code that controls an organisms basic
behavior and appearance.
Amino Acid Groups
 These are just a
few.
 Each has a
different
composition and
shape.
http://www.healthknot.com/body_protein.html, accessed August 2012
RNA, DNA Structure
 Note both
are made
of nitrogen
bases
 RNA has
ribose
sugar
 DNA has
deoxyribos
e sugar
http://www.proprofs.com/flashcards/cardshowall.php?title=exam-5-review, accessed August 2012
Transport Mechanisms
 Materials need to be transported through out an
organism or cell.
 Hemoglobin is an example of a transport molecule. It
transports oxygen from the lungs to tissues in the body.
 Cells use transport molecules to allow materials to cross
through the cell membrane.
 Either by passive or active transport.
Passive transport

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1.
2.
Molecules enter a cell without the need for ATP.
Always from area of high concentration to area of low
concentration
Diffusion: transport of lipid soluble materials across the
cell membrane (ie. Vitamin A, K, alcohols, some metal
compounds)
Facilitated transport: transport of water soluble
materials with the help of transport proteins.
Diffusion
 The passing of materials from the fluid environment
across the cell membrane to the cytoplasm
 Does not require ATP
 Materials cross the membrane with out the need of
transport proteins
Facilitated Transport
 Passive transport that moves water soluble materials
across the cell membrane

ie. water molecules, glucose, cations, and anions
 Why transport Proteins?



Enable the cell to maintain and regain needed chemical
components for metabolism and cell function.
Help cell to maintain concentrations of chemicals and water
To get rid of excess materials without interfering with continual cell
processes.
Channel Protein
Channel Proteins: form a
hole through which
materials may pass.
Carrier Protein
Carrier proteins: capture
molecules and ions, change
shape and release materials
into cytoplasm
Gate Protein
Gate proteins: open when
signal molecule attaches
‘opening the gate’ to allow
materials to pass into the
cytoplasm.
Cellular Homeostasis and water
concentrations
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Three basic types of cellular environments;
1. Isotonic solutions: these solutions have the
same or similar amounts of dissolved materials as
the cytoplasm of a cell
2. Hypotonic solutions: have a greater
concentration of water than what is present in the
cell
3. Hypertonic solutions: have greater amounts of
dissolved materials than what is present inside
the cell.
Each of the solutions describe have an effect on the
cell’s ability to survive.
Cellular Homeostasis and water
concentrations
 Isotonic Solutions: do not have an effect on a cell, as
they mimic the cell’s inner solution. Ie. saline solution for
eyes.
 Hypotonic Solutions: will cause a cell to enlarge or
break. Since the concentration of water is greater
outside the cell, the water will flow into the cell until
equilibrium is found.
 Hypertonic Solutions: will cause a cell to shrink or
collapse. Since the environment has a greater
concentration of dissolved materials, water from the cell
will move to the environment until the environment has
the same concentration of water as the cell.
Active Transport Proteins
 These proteins, called pumps, move molecules and ions
against concentration gradients.
 They move materials from areas of low concentration to
high concentration.
 To do this they require ATP.
 The Na-K pump (sodium potassium pump) is an example
of an active transport protein.
Digestion and Synthesis of organic
molecules
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Digestion refers to the breakdown of organic molecules into
smaller/ simpler pieces.
Synthesis refers to the formation or joining of simple organic
pieces into larger more complex ones.
These processes are completed by condensation reactions and
hydrolysis reactions.
 Condensation reaction: dehydration reactions occur when a
hydroxyl is removed from one molecule and a hydronium is
removed from another as the two molecules form a larger
molecule. The combining of hydroxyl and hydronium forms
water
 Hydrolysis: water is added to a reaction separating the
hydronium and hydroxyl forming two smaller molecules.
**Hydroxyl and hydronium groups serve to complete the
molecular charges of the smaller molecules.
Digestion and Synthesis Processes
Condensation Reaction
C6H12O6 + C6H12O6  C12H22O11 + H2O
Hydrolysis Reaction
C12H22O11 + H2O  C6H12O6 + C6H12O6
The body uses these reactions to form needed structural and
chemical components.
Interesting Links
 Robert Horvitz's Work on Cell Death,
http://www.dnalc.org/nobel2002.html, Horvitz, B. and
M.Hengartner, Gene accessed Feb.2, 2007.