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Berg • Tymoczko • Stryer
Biochemistry
Sixth Edition
Chapter 1:
Biochemistry: An Evolving Science
Tips on note taking...
• Remember copies of my lectures are
available on my webpage
– If you forget to print them out before class, or if
you don’t want to print them out due to the new
copying policy, I suggest the following…
I am more interested in your listening and
involvement in our discussion….take notes
on that
• try this format:
• slide 1: ………notes…….
– Later, compare notes for slide 1 with slide 1
Perspective of this Course
• This course is taught as pure science
• emphasis on evolution
– from molecular evolution to organismal
evolution
• This is a purely-scientific explanation of the
development of life on earth and our
understanding of the biochemical principles
that sustain it.
Outline
• DNA illustrates the Relation between
Form and Function
• Biochemical Unity Underlies Biological
Diversity
• Chemical Bonds in Biochemistry
• Biochemistry and Human Biology
On Life and Chemistry...
1. Living things are composed of lifeless
molecules
2. Chemistry is the logic basis of biological
phenomena
Hierarchy in Biology
• The top of the list depends on lower levels!
• Order: Ecosystems, communities, populations,
organisms, organs systems, organs, tissues,
CELLS, (these are the living components)
• organelles, MOLECULES, atoms, subatomic
particles. (these are nonliving components)
Properties of Life
Who’s this guy?
Form Follows Function…
Molecules act Like Organisms
• Subjected to Evolutionary pressures
• A molecule’s Form determines its
functions
DNA is a good example…
• James Watson and Francis Crick…
• 1953…hypothesized about the structure (the
form) of DNA.
• With the molecule’s form established…its
function could be supported.
I wonder How this works?
~1953
~2003
DNA is a 2-stranded Molecule
The building blocks of DNA
• The nucleotides
• These are the nitrogen bases
Nucleotides are joined together
to form one strand…
(a nucleic acid)
DNA is made from a “polyester linkage” between nucleotides
Rather, its called a
NOT THAT KIND OF
Phosphodiester linkage…
POLYESTER…
These bonds hold all
Nucleic acids together.!
Can you draw an ester?
Can you draw a diester?
Can you draw a phosphodiester?
A phosphate containing polyester
AKA the sugar phosphate backbone.
One nucleotide is chemically bonded to the next.
The two strands are held together to
form the DNA double helix!
• Again…form eludes to function…
• The nitrogen bases’ shape suggested how they
might work to hold the double helix together.
DNA can replicate because of its
form…
Because of its shape…DNA is the
long term storage molecule for
Genetic Information
• Another nucleic acid helps the process
though…
• RNA
• RNA is chemically different from DNA
– Different sugar used…a ribose sugar
– Different base is used…uracil
RNA has a Different shape than
DNA
• RNA is a SINGLE STRANDED
molecule…not a double helix.
• It can twist into many different shapes..
• With many different possible shapes…
• You have many different….?
RNA functions
•
•
•
Genetic info access (transcription)
Ancient genetic info storage ?
Catalytic functions
– Ribozymes
•
New functions…
– Aptamers.
The type of molecule with the
greatest repertoire of Functions…
(that we’re currently aware of)
•
•
The proteins
A linear arrangement of their building
blocks
– Amino acids
•
•
The arrangement of amino acids in the
proteins determines the shape of the
protein (a process called protein folding)
And also its function.
Protein folding
Dysfunctional proteins..
• Come from anything that changes the shape
of the protein
• Genetic mutations
• Environmental factors.
– If you restore the shape, you restore the
function.
1.2 Biochemical Unity underlies
Biological Diversity
• Many different types of Life on earth
• All with different morphologies….
Though Biologically Diverse…All
life has Biochemical Unity
• All life is made out of the same stuff
– Atoms and molecules
• All life uses DNA as a genetic storage
molecule
• All life uses similar metabolic pathways to
power living processes.
– Glycolysis
• A common ancestor for all life?
Phylogenetic Tree of life
(using molecular evolution data)
Chemical Bonds in Biochemistry
• The important “molecules of life” are organic
compounds
• They can be composed of many thousands of
atoms chemically joined together.
• Even though they are huge…the atoms that
comprise them follow the same chemistry as
their smaller molecular relatives
Biomolecules: The Molecules
of Life
H, O, C and N make up 99+% of atoms in the human
body
ELEMENT
Oxygen
Hydrogen
Carbon
Nitrogen
PERCENTAGE
63
25.2
9.5
1.4
Biomolecules: The Molecules
of Life
• What property unites H, O, C and N and
renders these atoms so appropriate to the
chemistry of life?
• Answer: Their ability to form covalent
bonds by electron-pair sharing.