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Protein Synthesis
Levels of Genetic Organization
Macromolecules of Evolution
Nucleic acids are the instructions for making proteins, proteins make up traits,
and traits that are best fit for the environment are passed on.
Nucleic Acids - DNA and RNA
• universal code (blueprints) for making proteins
• inherited genetic information
Macromolecules of Evolution
Nucleic acids are the instructions for making proteins, proteins make up traits,
and traits that are best fit for the environment are passed on.
Proteins - determine physical traits
• structure - materials for building cells
• function a. carry substances throughout the body, in & out of
cells
b. trigger muscle movements
c. assist with all chemical reactions
in the body
d. protect the body against disease
Nucleic Acids
Nucleotides are the building blocks of nucleic acids.

Nucleic Acids
Nucleotides bond together to form nucleic acids
• a phosphate group of one nucleotide attaches to the
sugar of another nucleotide (covalent bond)
• bases bond with complimentary bases (hydrogen bond)
DNA Replication
• A half of the DNA ladder is a template to make a copy of
the whole
• Occurs before cell division
– mitosis or meiosis
DNA Replication
• DNA Synthesis
 The DNA bases on each
strand act as a template to
synthesize a complementary
strand
• Recall that Adenine (A)
pairs with thymine (T)
and guanine (G) pairs
with cytosine (C)
 The process is
semiconservative because
each new double-stranded
DNA contains one old
strand (template) and one
newly-synthesized
complementary strand
AT
GC
CG
TA
GC
AT
GC
AT
CG
TA
CG
GC
GC
TA
GC
DNA Replication
3’ end has a free deoxyribose
5’ end has a free phosphate
DNA polymerase:
 can only build the new strand in
the 5’ to 3’ direction
 Thus scans the template strand in
3’ to 5’ direction
DNA Replication
Initiation
• Primase (a type of RNA polymerase) builds an RNA primer
(5-10 ribonucleotides long)
• DNA polymerase attaches onto the 3’ end of the RNA primer
DNA polymerase
DNA Replication
Elongation
• DNA polymerase uses each strand as a template in the 3’ to 5’
direction to build a complementary strand in the 5’ to 3’ direction
 results in a leading strand and a lagging strand
DNA Replication
Determine the sequence of the developing DNA strand!
Template DNA Strand Sequence:
G T C T A C T T G
Complementary DNA Strand Sequence:
C A G A T G AA C
DNA replication video….
….and another video
…and another for good measure.
OK, fine. One more
There are more on my website under Resources
2. RNA Overview
1.
2.
3.
4.
RNA is the other type of nucleic acid.
RNA stands for ribonucleic acid
Its structure is a single strand of nucleotides
RNA’s function is to decode genes within the DNA to
make proteins
5. Like DNA, it has 4 nitrogenous bases –
guanine and cytosine
adenine and uracil
2. RNA Overview
6. There are 3 types of RNA: messenger, transfer, and
ribosomal
Differences Between DNA & RNA
A. Sugars
B. Number
of strands
C. Bases
D. Location
in the
nucleus
1. DNA
deoxyribose
sugar
doublestranded
A-T
G-C
2. RNA
ribose sugar
singlestranded
A-U
G-C
in nucleus,
cytoplasm &
ribosome
Protein Synthesis Overview
DNA
RNA
protein
transcription
translation
traits
Protein Synthesis
DNA  RNA  Protein  Trait
Transcription
1. In the first step of protein synthesis, a gene is copied
2. A half of the DNA helix is used as a template to create
messenger RNA (mRNA)
3. This occurs in the nucleus of the cell
Transcription
Determine the sequence of the developing messenger RNA strand!
Template DNA Strand Sequence:
G T C T A C T T G
Messenger RNA Sequence:
C A G A U G AA C
Translation
1. mRNA leaves the nucleus and travels to the ribosome
Translation
2. Transfer RNAs (tRNA) meets mRNA at the ribosome with
the appropriate amino acids (building blocks of proteins)
3. Amino acids attach together (peptide bond) to form a
polypeptide chain
Translation
4. a 3-base sequence of
mRNA called a codon
codes for a specific
amino acid
5. a 3-base sequence of
tRNA called an anticodon bonds with a
corresponding codon,
delivering its amino
acid
Translation
Glu
Met
Asp
peptide bond
Use the codon chart to determine
the amino acid sequence of the
developing polypeptide chain!
Proteins
1. Amino acids bond together to make
proteins.
2. Proteins differ due to the number, kind,
sequence and arrangement of amino
acids.
3. Amino acids are attached to one another
by peptide bonds to form polypeptide
chains.
4. The 3D form of the protein determines
its function.
Levels of Protein Structure
5. Polypeptide chains spontaneously arrange themselves
into 3-dimensional structures to form functional
6. There are four levels of arrangement from primary,
the straight chain of amino acids, to quaternary,
several polypeptide chains bonded together.
1º - a straight chain
of amino acids
2º - chains bend and
twist
3º - twisted chain folds
even more; bonds
form to hold the 3dimensional shape
4º - Several polypeptide
chains in the tertiary structure
come together. This is a
functional protein!
Human Genes & Proteins
46 Chromosomes (23 pairs)
approximately 25,000 genes =
approximately 25,000 proteins
1 protein = approx. 500 amino acids
1 amino acid = 3 nucleotides
25,000 proteins x 1500 nucleotides = 37,500,000 nucleotides
If there are approx. 3,000,000,000 DNA base pairs on all 46 chromosomes, then…
How much of our DNA codes for proteins?
What do they call the rest of the DNA that does not code for proteins?