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Transcription and Translation
How DNA Controls the Cell
DNA and Control of the Cell
I. DNA controls the cells by coding for
A. Proteins are used
1. in cell construction
2. as enzymes - catalysts that control
II. Protein structure
A. Consists of a chain of
2. The order of the amino acids in the chain
determine the type of
that is created
3. Every three base pairs in DNA ( ) codes
for one
Transcription
I. Transcription is the process of copying one
strand of DNA to
II. RNA is the working molecule
A. DNA stays in the so it is protected
B. is the copy of DNA that is functional
B. RNA has a Single Strand
1. Only has a single
*Thymine is replaced by Uracil (Uracil pairs with
Use this DNA template to create a
strand of RNA
T
A
C
C
*Divide up your strand into codons
T
A
A
C
G
Use this chart to discover what amino
acids your codons code for… write
them under each codon
Translation
Once the mRNA leaves the nucleus it travels to
a ribosome that will help translate the
mRNA into an amino acid chain.
Where are ribosomes
found in the cell?
*If the protein is going to
be used inside the cell it is
made at a
*If the protein is going to
be packaged for use
outside the cell, it will be
made on a ribosome
attached to the
Translation
I. The ribosome matches up the codons of
mRNA with “anitcodons” of transfer RNA
(tRNA) by matching up the bases.
*Label a
codon,
anticodon,
mRNA, tRNA
and amino
acid on this
image
Translation
I. Each tRNA unit has an amino acid attached
to it
II. When two units of tRNA are in the ribosome
the amino acids are linked to each other
Translation
III. The ribosome ejects the first tRNA unit and moves
down, accepts another tRNA unit and links the
amino acids.
IV. This continues and the amino acid chain grows.
Translation
V. The ribosome reaches a “stop” codon and
the ribosome and protein releases from the
mRNA
http://www.stolaf.edu/people/giannini/flashan
imat/molgenetics/translation.swf
VI. Based on the order of amino acids, the
protein folds up into a particular shape that
does a particular function in the body:
–
–
Hemoglobin: delivers oxygen to the body
Insulin: regulates blood sugar
Proteins
• Come in two basic categories:
• Fibrous:
Fig. 1: Image
of a collagen
protein
responsible
for building
connective
tissue
– Structure is long chains
– Function is that they’re typically are a structural protein that
help build tissues in the body
• Globular:
– Structure is more like a sphere shape
– Functions are typically enzymes and transport proteins
Fig. 2: Representation of a hemoglobin protein responsible
for transportation of oxygen in the blood stream