Transcript Kids Building Bricks - Johnston County Schools

Protein Synthesis
How a cell uses the DNA code to build proteins!
Protein Synthesis:
Basics
• Amino acids are the building blocks of
proteins
• Amino acids are determined by the
sequence of nucleotides
Protein Synthesis:
Basics
• What you need to build proteins:
–Instructions (DNA)
–Parts (amino acids)
–Workers (RNA)
Protein Synthesis:
Basics
• 3 types of RNA:
1.mRNA = messenger
• DNA message from nucleus to
ribosome
2.tRNA = transfer
• Transports amino acids to ribosome
3.rRNA = ribosomal
Protein Synthesis:
Basics
DNA
• Deoxyribose sugar
• Double sided
• A, T, C, G
RNA
• Ribose sugar
• Single sided
• A, U, C, G
In RNA: Uracil, not Thymine,
pairs w/ Adenine!
Protein Synthesis:
Transcription
• From DNA to mRNA
• Occurs in the nucleus
• Enzymes make a RNA copy of a
segment of DNA
–Just like DNA replication except A
pairs with U, not with T
Protein Synthesis:
Transcription
1. DNA =
TACGCATGA
mRNA =
AUGCGUACU
2. DNA =
TACACGATT
mRNA =
AU G U G C UAA
Protein Synthesis:
Translation
• From mRNA to protein
• Occurs at a ribosome
Protein Synthesis:
Translation
• There is a total of 20 amino acids, but
there are only 4 nitrogen bases…
• So, how many bases must be grouped
together for at least 20 possible
combinations?
–1 base = 41 = 4
–2 bases = 42 = 16
–3 bases = 43 = 64
Protein Synthesis:
Translation
• Three nucleotides of mRNA code for
one amino acid
• Codon = 3 nucleotides of mRNA
• For example:
AAA codes for lysine
–AAA is the mRNA codon
–Lysine is the amino acid
Protein Synthesis:
Translation
• Use the table on p. 292 to identify the
correct amino acid from the following
mRNA codons:
mRNA
1. UCC
2. GCG
3. GGA
4. CUU
Amino acid
1. Serine
2. Alanine
3. Glycine
4. Leucine
Protein Synthesis:
Translation
• Key codons:
–AUG = start (methionine)
–UAA, UGA, & UAG = stop
Protein Synthesis:
Translation
• tRNA brings aa’s to the ribosome
• Each tRNA attaches to only one type of
amino acid, but how does it know which
one is needed?
• Each tRNA has a sequence of 3
nucleotides (anticodon)
• tRNA anticodon pairs w/ the
mRNA codon
Protein Synthesis:
Translation
• Identify the tRNA anticodon:
codon
1. ACU
2. UGC
3. GUA
4. UGU
anticodon
1. UGA
2. ACG
3. CAU
4. ACA
Protein Synthesis:
Translation
• tRNA structure:
Protein Synthesis:
Translation
Protein Synthesis:
Translation
1. Start codon (AUG)
attaches to ribosome
2. tRNA anticodon
(UAC) pairs w/
mRNA codon
transporting Met- to
the ribosome
Protein Synthesis:
Translation
3. Ribosome slides
along mRNA to next
codon
• This process
continues until
STOP codon
Protein Synthesis:
Translation
• Amino acids joined by peptide bonds
• This long string of amino acids is now a
protein!
Protein Synthesis: Recap
Protein Synthesis: Recap
1. DNA =
TACCCCATT
mRNA =
AU G G G G UAA
codons =
(AUG) (GGG) (UAA)
aa’s =
Met - Gly - Stop
anticodon = (UAC) (CCC) (AUU)
Protein Synthesis: Recap
2. DNA =
TACGTGACT
mRNA =
AUGCACUGA
codons =
(AUG) (CAC) (UGA)
aa’s =
Met - His - Stop
anticodon = (UAC) (GUG) (ACU)
Translation Game: How to Play
Goal = build a protein by connecting the
proper sequence of amino acids!
1. Transcribe the DNA strand to mRNA
2. Use p. 292 to translate the mRNA into
a chain of amino acids
Translation Game: How to Play
• Only one person out of seat per team
• You are finished when every member of
your team is seated with a hand raised
Translation Game: Scoring
1st Place = 6 pts
2nd Place = 5 pts
3rd Place = 4 pts
4th Place = 3 pts
5th Place = 2 pts
6th Place = 1 pt
*0 pts if your team doesn’t finish.