DNA Structure
What shape is the DNA molecule
Double helix
What is a codon?
A sequence of 3 bases in mRNA that codes for one amino acid
What is a mutation?
A change in the DNA sequence
What are the two main stages of protein synthesis?
Transcription and translation
What does DNA stand for?
Deoxyribonucleic acid
What are the four bases found in DNA?
Adenine, Thymine, Cytosine, Guanine
Which molecule carries codons
mRNA
What type of mutation replaces one base with another?
Substitution
Where does transcription occur in a cell?
In the nucleus
What do we call a full set of an organism's DNA?
Genome
Which two parts make up the DNA backbone
Sugar and phosphate
What is the role of tRNA in translation
Brings the correct amino acid to the ribosome
Which type of mutation has the biggest impact on the protein: substitution or frameshift
Frameshift
What is produced at the end of translation?
A polypeptide (protein)
What is a ribosome?
An organelle that acts as a 'Protein Factory'. Where the second part of protein synthesis takes place.
What type of bond holds the base pairs together
Hydrogen bonds
Why is DNA considered 'highly conserved'?
Because it's core sequences and functions are remarkably similar across diverse living organisms.
Name one possible effect of a silent mutation
No change to the amino acid sequence
What is the role of the ribosome?
It reads mRNA and joins amino acids together
Which enzyme builds mRNA during transcription?
RNA polymerase
Explain how the structure of DNA enables it to be copied accurately during replication
Complementary base pairing (A-T, C-G) allows each strand to act as a template. DNA polymerase adds matching nucleotides, producing identical copies.
Describe how the genetic code ensures the correct sequence of amino acids in a protein
Each mRNA codon matches a specific tRNA anticodon with a linked amino acid. The sequence of codons determines the order of amino acids joined in the ribosome
Explain how a mutation in a DNA base sequence could lead to a non-functional protein.
A change in the base sequence may alter a codon, changing the amino acid. This can affect the protein’s folding or active site, making it non-functional.
Outline the steps from DNA to a finished protein, naming the key molecules involved.
DNA is transcribed to mRNA in the nucleus. mRNA exits to the cytoplasm and attaches to a ribosome. tRNA molecules bring amino acids to the ribosome, where codons are matched and a polypeptide is formed.
Spell out loud the full name for DNA. No looking at your notes!!
D-E-O-X-Y-R-I-B-O-N-U-C-L-E-I-C A-C-I-D