Transcript protein synthesis - Jannali

By: Shelley Quirk
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42 toothpicks
18 milk bottles cut in half (36 halves)
– sugar
18 raspberry lollies cut in halfphosphate
25 jelly beans cut in half (5 of each 5
colours)- bases:
Adenosine- orange
Thymine- purple
Cytosine- pink
Guanine- green
Uracil- blue
4 jelly snake, aprox. 6cm long,
different colours
A4 white paper representing a cell
Colored paper circle, 6cm diametera ribosome
Clean sharp knife
Cutting board
Gloves
Scissors
Marking pen
Heinemann Biology textbook
Equipment
DNA is a double stranded helix molecule made of
subunits called nucleotides.
 Each nucleotide contains a sugar (deoxyribose), a
phosphate, and a base.
 There are four bases (adenosine, thymine, cytosine and
guanine).
 Alternate sugar and phosphates form the sides with
bases connected to the sugars making “rungs” like a
ladder.

The information about the number, type and sequence of amino
acids, needed to make a protein molecule, is found as a code in DNA.
The code- a sequence of bases.
One gene sequence codes for one polypeptide (a single chain of
many amino acids)
A set of 3 bases (a codon) codes for one amino acid of a
polypeptide.
A protein is one or more polypeptides.
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a gene length of DNA unwinds in the nucleus
RNA polymerase enzyme moves along the exposed single DNA strand
linking complementary RNA nucleotides together to form a messenger
RNA strand.
RNA contains the base uracil where thymine is found in DNA.
The mRNA strand is then modified so that it only consists of the
base sequence that will code for the protein. It removes the
non-coding regions, introns, while still in the nucleus by splicing
the coding regions, exons, together.
 The modified mRNA then moves from the nucleus into the
cytoplasm
 The start codon (AUG) and a stop codon control the length of
the mRNA strand.
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In the cytoplasm, an enzyme attaches amino acids to tRNA molecules.
Each type of amino acid is attached to its specific tRNA.
The modified mRNA moves out of the nucleus into the cytoplasm.
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The start codon (AUG) end of the mRNA strand binds onto a ribosome. A tRNA
carrying the amino acid methionine at one end and anticodon (UAC) at the other,
binds to the mRNA start codon within the ribosome.
DNA strand
Amino acid
forming
polypeptide
bond (jelly
snakes)
Ribosome
mRNA
strand
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A second tRNA binds to the next codon. Its amino acid links to the polypeptide
bond of the first amino acid.
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The first tRNA is released from the ribosome. The ribosome moves along
the mRNA strand one codon at a time. Two tRNAs at a time are
temporarily bound within the ribosome and their amino acids linked
together
DNA strand
Amino acid
forming
polypeptide
bond (jelly
snakes)
Ribosome
mRNA
strand
A polypeptide chain
forms (jelly snakes)
When a ‘stop’ codon is
reached the polypeptide
chain is released into the
cytoplasm