Translation: read a codon table to build a protein
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Read this first
DNA template strand (model, not to scale), 3′ to 5′, 17 bases
CGTACCTTTGGGAAATC. The mRNA pairs with it base by base: A with U, T with A, C with G, G with C. Table excerpt of the standard genetic code: AUG, methionine; GAA, glutamic acid; ACC, threonine; CUU, leucine; UAG, stop; AAA, lysine; UUU, phenylalanine.
Pia makes mRNA from this DNA template strand. The ribosome begins at the first AUG. Which amino acid is last in the chain?
- stop, from the codon UAG at the end
- lysine, from the template triplet AAA
- leucine, from the codon CUU before the stop
- phenylalanine, from cutting groups from the first base
DNA coding strand (model, not to scale), 5′ to 3′, 14 bases
ATGTGGGACTAGCC. The mRNA has the same letters as this strand, with U in place of T. Table excerpt of the standard genetic code: AUG, methionine; UGG, tryptophan; GAC, aspartic acid; UAG, stop; UAC, tyrosine; ACC, threonine; CUG, leucine; AUC, isoleucine.
Ren has only the DNA coding strand. The ribosome begins at the first AUG of the mRNA. Which chain results?
- methionine, tryptophan, aspartic acid, stop
- tryptophan, aspartic acid
- methionine, tryptophan, aspartic acid
- tyrosine, threonine, leucine, isoleucine
Rate card (textbook rate, model length)
item value unit time to add one amino acid 0.05 seconds coding part from AUG to the end of the stop codon 120 bases Tala reads a rate card for a model mRNA in a bacterium. At that rate, how long does the ribosome take to build the chain?
- 3 seconds, counting each pair of the 120 bases
- 6 seconds, counting each of the 120 bases
- 1.95 seconds, for 39 amino acids
- 2 seconds, counting 40 codons as amino acids
Comparison card (model data)
mRNA bases before AUG bases from AUG to the end of the stop codon bases after the stop codon P 9 48 12 Q 3 51 3 R 0 45 30 Ari compares three model mRNAs on a card. The ribosome begins at AUG and ends at the stop codon. Which mRNA builds the longest chain?
- R, with the longest whole mRNA of 75 bases
- P, with the longest start region of 9 bases
- Q, with 16 amino acids once the stop is not counted
- Q, with 17 amino acids, counting the stop codon
Use this
Notebook (model data), 4 rows. Columns: line, what it says. 1, A codon is a group of three mRNA bases. 2, The ribosome begins at AUG and reads codons in order. 3, The stop codon UAA adds one last amino acid, then ends the chain. 4, A tRNA anticodon pairs with its codon, base for base.
Bo reviews a classmate's notebook on translation. Exactly one line is wrong. Which line, and why?
- Line 4, because the anticodon has the same letters as the codon
- Line 2, because the ribosome begins at the first base
- Line 1, because a codon is a group of two bases
- Line 3, because a stop codon adds no amino acid
Use this
Notebook (model data), 4 rows. Columns: line, what it says. 1, The standard code has 64 codons. 2, Three of the codons are stop codons. 3, Each amino acid has only one codon, so 20 codons are used. 4, Nearly all living things use this same code.
Esme reviews a classmate's notebook on the genetic code. Exactly one line is wrong. Which line, and why?
- Line 1, because the code has 16 codons from pairs of bases
- Line 3, because one amino acid can have several codons
- Line 2, because each stop codon adds one amino acid
- Line 4, because each species has its own code
Notebook (model data)
line what it says 1 The start codon AUG codes for methionine 2 The second codon GGC codes for glycine 3 The tRNA that pairs with the third codon CAU has the anticodon CAU 4 The chain has three amino acids Jun reviews a classmate's notebook on the message AUG GGC CAU UAG. Exactly one line is wrong. Which line, and why?
- Line 3, because the anticodon pairs with CAU, so it is GUA
- Line 2, because glycine has just one codon
- Line 1, because the ribosome begins at the first base
- Line 4, because the stop codon adds a fourth amino acid
Use this
Message card (model data), 2 rows. Columns: message, codons. M, AUG GCU CUU UAA. N, AUG GCC CUC UAA. Table excerpt of the standard genetic code: AUG, methionine; GCU, alanine; GCC, alanine; CUU, leucine; CUC, leucine; UAA, stop.
Kira asks whether two different model mRNAs can build the same chain. Which claim and reason go together?
- No, because N has more bases than M and so builds a longer chain
- Yes, because both messages begin with AUG and end with UAA
- No, because each amino acid has one codon and N uses new codons
- Yes, because one amino acid can have several codons
Model mRNA (not to scale), 5′ to 3′, cut into codons
AUG GGC UUU UAA. A plant cell and a bacterium cell each read it. Table excerpt of the standard genetic code: AUG, methionine; GGC, glycine; UUU, phenylalanine; UAA, stop.
Luz imagines a model mRNA moved from a plant cell into a bacterium cell. Which claim and reason go together?
- Different amino acids, because a bacterium reads codons as two bases
- The same amino acids, because the code is identical across species with no exception
- Different amino acids, because each species has its own table
- The same amino acids, because the code is nearly universal
AUG CCU UAA GGA. Table excerpt of the standard genetic code: AUG, methionine; CCU, proline; UAA, stop; GGA, glycine. Milo asks why the ribosome stops at UAA. Which claim and reason go together?
- The ribosome reads past UAA to GGA, because stop codons are ignored
- The chain ends at UAA, because a tRNA with the anticodon UAA fits and ends it
- A last amino acid is added at UAA, because each codon has a tRNA
- The chain ends at UAA, because no tRNA pairs with a stop codon