Week 14 Quiz

Which sequence states the central dogma in order, with the place where each step happens in a eukaryotic cell?

Select one.

• DNA → protein (translation, in the nucleus) → mRNA (transcription, at a ribosome)
• DNA → mRNA (transcription, in the nucleus) → protein (translation, at a ribosome in the cytoplasm)
• DNA → mRNA (translation, in the nucleus) → protein (transcription, at a ribosome in the cytoplasm)
• DNA → mRNA (transcription, at a ribosome) → protein (translation, in the nucleus)

Translation, the step that joins amino acids into a chain, takes place inside the nucleus.

True or false.

• True
• False

RNA polymerase reads the template strand 3′-TAC CGA ATA ACT-5′. Which mRNA does it build?

Select one.

• 5′-ATG GCT TAT TGA-3′
• 5′-UAC CGA AUA ACU-3′
• 5′-AUG GCU UAU UGA-3′
• 5′-AUG GCT UAU UGA-3′

The genetic code has 64 codons, and 3 of them are stop codons. How many codons code for amino acids?

Select one.

• 20
• 64
• 3
• 61

An mRNA reads 5′-AUG UUU CCC UAG-3′. Codon table: AUG = Met (start); UUU = Phe; CCC = Pro; GCU = Ala; UAU = Tyr; UAA, UAG, UGA = stop. Which chain of amino acids does a ribosome build from it?

Select one.

• Met–Phe–Pro
• Phe–Pro
• Met–Phe–Pro–Ala
• Met–Pro–Phe

During translation, a three-base anticodon pairs with a codon. Which molecule carries the anticodon?

Select one.

• The mRNA
• The tRNA
• The DNA template strand
• The release factor

Select every codon that is a stop codon in the standard genetic code.

Select every option that applies.

• UAA
• AUG
• UAG
• GUG
• UGA

In the gene for the beta chain of hemoglobin, the codon GAG codes for glutamic acid (Glu). In sickle cell disease that codon is GUG, which codes for valine (Val). Which statement describes the change?

Select one.

• Two bases change, and two amino acids change
• One base changes, but the amino acid stays Glu
• One base changes, and Glu is replaced by Val
• No base changes; only the protein's fold changes

Asked to transcribe the template 3′-TAC GGA CCT ACT-5′, a chatbot writes the mRNA 5′-AUG CCT GGA UGA-3′. What is the error?

Select one.

• The first codon should be UAC, copied straight from the template
• The last codon UGA should be read as an amino acid
• Reading should begin at the second base, not at AUG
• The second codon carries a T; the template GGA pairs to CCU

GCU and GCC both code for alanine (Ala). A change in a gene turns one codon GCU into GCC. What happens to the protein at that position?

Select one.

• It still has Ala, because the code has more than one codon for alanine
• It loses an amino acid, because GCC is a stop codon
• It gains Val, because any base change swaps the amino acid
• Translation stops early, because the reading frame shifts