Introduction to
Biochemistry
Biochemistry

Chemistry of living organisms.
 The study of biology at the molecular level.
Elements
• Make up all matter.
• 92 occur in nature.
• Identified by names or chemical symbols
(abbreviations of modern or Latin names).
• Identified by number (based on structure of
subunits or atoms).
• Described and organized in periodic table.
Periodic Table
Atoms
• Subunits of elements.
• Smallest complete units of matter.
• Cannot be broken down or changed by
ordinary chemical and physical means.
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Atomic Structure

Nucleus
– Positively charged protons.
– Neutrally charged neutrons.
– Surrounded by negatively charged electrons.
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Molecules and Compounds
Molecules
• Formed when two or more atoms unite on
the basis of their electron structures
• Can be made of like atoms or atoms of
different elements
Compounds
• Composed of two or more elements
Biomolecules

Carbohydrates
 Lipids
 Proteins
 Nucleic acid
Carbohydrates

Composed of carbon, hydrogen, and oxygen.
 Sugars
 Monosaccharides
– Ex. Glucose

Disaccharides
– Ex. Sucrose

Polysaccharides
– Ex. Glycogen, Peptidoglycan
Carbohydrate - Glucose
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Carbohydrate - Sucrose
www.chm.bris.ac.uk
Carbohydrate - Peptidoglycan
www.biologie.uni-hamburg.de
Carbohydrate - Glycogen
www.elmhurst.edu
Lipids

Fatty Acids
– The building
blocks of
lipids.
biology.clc.uc.edu
courses.cm.utexas.edu
Lipids

Examples are:
– Waxes
– Fats and oils
– Phospholipids
– Steroids
Phospholipid Cell Membrane.
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Proteins

Made up of polymers
of amino acids.
 “beads on a string.”
 20 primary amino
acids exist.
 A polymer of 3 or
more amino acids
forms a polypeptide.
Proteins

Primary Structure
– Linear sequence of amino acids.

Secondary Structure
– Form helices or sheets due to their structure.

Tertiary Structure
– A folded protein.

Quaternary Structure
– 2 or more polypeptide chains bonded together.
Protein Structure
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Enzymes

Are proteins.
 Are considered
biological catalysts.
– Speed up a chemical
reaction without being
altered.

Names often end in “ase.”
– Ex. Lipase,
carbohydrase.

Act on a substrate.
 Proteins, including
enzymes, can be
denatured.
Nucleic Acids

DNA and RNA.
– (DNA - deoxyribonucleic acid,
RNA - ribonucleic acid).
Is the “hereditary molecule.”
 Contains genes that code for a certain
product.
 DNA is translated into RNA which is used
to produce a protein or other product.

Nucleic Acid Structure

DNA nucleotides
– Building blocks of DNA.

RNA nucleotides
– Building blocks of RNA.
Nucleic Acid Structure

DNA
– Nitrogenous base
– Deoxyribose
– Phosphate group

RNA
– Nitrogenous base
– Ribose
– Phosphate group
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Nitrogenous Bases

Adenine (A)
 Guanine (G)
DNA and RNA
 Cytosine (C)
 Thymine (T) – only DNA
 Uracil (U) – only RNA
Nitrogenous Bases

A and G
– Purines (double-
ring structures)

C, T, and U
– Pyrimidines
(single-ring
structures)
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DNA Structure

Nucleotides bond between
sugar and phosphate groups
to form long polymers.
 Double-stranded DNA
 - The two nucleotide
polymers bind
at the nitrogenous
bases.
– Bonding forces cause the
double-stranded polymer
to form a double helix.
www.genome.gov
DNA Structure

James Watson (left) and Francis Crick
(right) discovered the double-helix structure
of DNA and its process of replication in the
1950s.
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DNA Replication

Occurs during cell division.
 Both strands of the double-helix unwind
and replicate a complimentary strand.
 The parent strand and new daughter strand
form a new double-helix.
 DNA polymerase is one enzyme used in
replication process.
DNA Replication –
Semiconservative Replication
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Gene Expression

A gene contains the instructions for making
a gene product.
 The genetic code is based on the sequence
of the nitrogenous bases (A, T, C, and G).
 The gene product is usually a protein but
may be different types of RNA.
The Central Dogma

Proposed by Francis Crick in 1957.
 Explains the flow of genetic information
within a cell.
 DNA
RNA
Protein
The Central Dogma

1. Genetic information contained in one
gene of DNA molecule is used to make one
molecule of mRNA by a process called
transcription.
– mRNA (messenger RNA) is one of 3 types of RNA
used in protein synthesis.

2. The genetic information in the mRNA
molecule is used to make a protein in a
process called translation.
Transcription

The genetic code from the DNA molecule is
transcribed to produce an mRNA molecule.
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Translation

The process of translating the mRNA
sequence, which directs the proper sequence
of amino acids to produce a particular
protein or product.
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The End