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RNA, DNA,
and Protein
Synthesis
Deoxyribonucleic Acid (DNA)
A double stranded
molecule containing
genetic material that
carries all the
information about an
organism and is
passed from parent
to offspring.
Nucleotides
(building blocks of DNA)
1. Sugar
2. Phosphate group
3. Nitrogenous base
Lll
DNA Nucleotide
Nitrogen Bases
The 4 nitrogen
bases in DNA are:
adenine,
 guanine,
 cytosine, and
 thymine.

The Structure of DNA
Rosalind
Franklin
Used X-Ray
crystallography to
get information
about the
structure of DNA.
Structure of DNA
Using Rosalind
Franklin’s data,
two scientists:
 James Watson
(USA)
 Francis Crick
(GBR)
Proposed that
DNA was a
double-helix.
Watson & Crick along with Maurice Wilkins jointly received
the Nobel Prize in physiology or medicine for their work.
The Double-Helix
A twisted ladder with two long chains of
alternating phosphates and sugars. The
nitrogen bases act as the “rungs” joining
the two strands.
How long is your DNA?
Chromosome Structure:
Chromosomes are
complexes of DNA
wound around proteins
(called histones) residing
in the nucleus of the cell.
Genes are sections of
DNA that code for a
specific protein that
determines a particular
characteristic.
Ribonucleic Acid (RNA)
RNA is similar to DNA in that it is also a nucleic
acid composed of 4 nucleotides.
Ways RNA is different from DNA:
RNA contains
Ribose, a 5-carbon
sugar (instead of
deoxyribose)
2) Uracil replaces
thymine
3) Single-stranded
1)
Messenger RNA (mRNA)
 Copies
a
section of DNA
by matching
bases.
 Contains the
instructions
(recipe) for
producing a
specific protein.
TRANSCRIPTION
 The
process of copying
information from a section of
DNA into mRNA.
 Transcription is like copying
down a recipe. In this case it’s
a recipe for a specific protein.
TRANSLATION
Translation =
reading or
“translating” the
RNA code to form a
chain of amino
acids.
 Results in protein
synthesis
 Occurs in the
cytoplasm.

Transfer RNA (tRNA)
tRNA acts like a
truck to transport
an amino acid to
the ribosome to
make the specific
protein coded by
the mRNA.
 A specific amino
acid is attached to
one end.

The Genetic Code
The genetic code is
responsible for
building all the
proteins in the body
using 20 different
amino acids.
Amino acids
Protein molecule
The genetic code is the “language” that
translates the sequence of nitrogen bases in
DNA (mRNA) into the amino acids of a
protein.
Codon = three nucleotides on DNA or mRNA
 One codon specifies one amino acid
 Some codons are redundant (code for the
same amino acid)
 The genetic code is universal to all
organisms

Codon: A three letter “word”
(sequence of RNA nucleotides)
that specifies an amino acid.
DNA: TAC CTT GTG CAT GGG ATC
mRNA AUG GAA CAC GUA CCC UAG
A.A
MET G.A HIS VAL PRO STOP