DNA & RNA Basics
What sugar is found in DNA but NOT RNA?
Deoxyribose
What process uses DNA as a template to produce an RNA molecule?
Transcription
What type of RNA brings amino acids to a ribosome?
tRNA
What are the three RNA bases in the start codon?
AUG
What is a change in the nucleotide sequence of DNA called?
Mutation
Which nitrogen base is found in RNA instead of thymine?
Uracil
Where does protein synthesis (translation) occur in the cell?
Ribosome
What type of RNA is a major structural and functional component of ribosomes?
rRNA
What amino acid is coded for by the start codon?
Methionine
What type of mutation occurs when one nucleotide is replaced by a different nucleotide?
Substitution
What is the name of a segment of DNA that contains instructions for making a protein?
Gene
What molecule carries the genetic instructions from DNA to a ribosome?
mRNA
What is a group of three nucleotides on mRNA called?
Codon
If the DNA template strand reads TAC–GGA, what is the complementary mRNA sequence?
AUG–CCU
What type of mutation occurs when an extra nucleotide is added to a DNA sequence?
Insertion
Which type of nucleic acid is usually double-stranded and remains in the nucleus?
DNA
What is the correct sequence of information flow from DNA to a finished protein?
DNA → RNA → Protein
What is the name of the three-base sequence on tRNA that pairs with an mRNA codon?
Anticodon
Using a codon chart, what amino acids are coded for by the mRNA sequence AUG–GCU–UUU?
Methionine–Alanine–Phenylalanine
Why can inserting one nucleotide into a gene change many amino acids in the resulting protein?
It causes a frameshift, changing how the following codons are read.
Put these structures in order from smallest to largest: chromosome, nucleotide, gene.
Nucleotide → Gene → Chromosome
A cell produces mRNA, but the mRNA never reaches a ribosome. Which stage of protein synthesis cannot occur?
Translation
If an mRNA codon is GCU, what is its complementary tRNA anticodon?
CGA
A DNA template sequence is TAC–AAA–CGT. What mRNA sequence would be produced?
AUG–UUU–GCA
A mutation changes the mRNA codon GAA to GAG. Both codons code for glutamic acid. What effect would this mutation have on the amino acid sequence?
No change; it is a silent mutation.
If DNA and RNA both contain adenine, cytosine, and guanine, what TWO structural differences could you use to identify them?
Their sugar (deoxyribose vs. ribose) and DNA is usually double-stranded while RNA is usually single-stranded.
A student claims that transcription and translation both directly use DNA to make their products. Explain why this is incorrect.
Transcription uses DNA to make RNA, while translation uses mRNA to build a protein.
During translation, what determines the order in which amino acids are added to a growing protein?
The order of codons in the mRNA.
A DNA template strand reads TAC–CTT–AAA–ACT. Transcribe it and determine the resulting amino acid chain.
mRNA: AUG–GAA–UUU–UGA. Amino acids: Methionine–Glutamic acid–Phenylalanine–STOP.
A mutation changes the shape of a protein responsible for transporting oxygen in red blood cells. Explain how this could affect the organism.
The altered protein may function improperly, affecting red blood cell shape and reducing efficient oxygen transport.