Module 7: Genetic Code & Protein Synthesis Part 2
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78 Terms
What is the Central Dogma of molecular biology?
DNA → RNA → Protein
What is transcription?
Making RNA from DNA.
What is translation?
Making proteins from mRNA.
What enzyme makes RNA during transcription?
RNA polymerase.
What direction is RNA synthesized?
5' to 3'.
What bases are found in DNA?
A T C G.
What bases are found in RNA?
A U C G.
What does mRNA do?
Carries genetic instructions for making proteins.
What are proteins made of?
Amino acids.
How many standard amino acids are there?
20.
What is a ribosome?
A structure that builds proteins from mRNA.
How many subunits make up a ribosome?
Two.
What is tRNA?
RNA that brings amino acids to the ribosome.
What is a codon?
Three nucleotides on mRNA.
What does a codon determine?
Which amino acid is added.
What is an anticodon?
Three bases on tRNA that pair with a codon.
What is the main start codon?
AUG.
What other start codons were mentioned?
GUG UUG and CUG.
How many nucleotides make one codon?
Three.
How many amino acids do five codons encode?
Five.
What bond connects amino acids?
Peptide bond.
What is the primary structure of a protein?
The amino acid sequence.
What is the secondary structure of a protein?
Local folding of the protein chain.
What is the tertiary structure of a protein?
Overall 3D shape of one protein chain.
What is the quaternary structure of a protein?
Multiple protein chains joined together.
What does codon redundancy mean?
Multiple codons can code for the same amino acid.
What is codon bias?
Preference for certain codons over others.
How many total codons exist?
64.
How many codons code for amino acids?
61.
How many codons are stop codons?
Three.
What is an exception to the universal genetic code?
UGA codes for tryptophan in vertebrate mitochondria.
What is the wobble hypothesis?
One tRNA can recognize multiple codons.
Which codon position allows wobble?
Third position.
What do CUU CUC CUA and CUG code for?
Leucine.
What is a mutation?
A change in DNA sequence.
What is a point mutation?
A change involving a single nucleotide.
What is a base substitution?
Replacing one nucleotide with another.
What is a silent mutation?
A mutation that does not change the amino acid.
What is a missense mutation?
A mutation that changes an amino acid.
What is a nonsense mutation?
A mutation that creates an early stop codon.
What is a frameshift mutation?
A mutation that shifts the codon reading frame.
What causes a frameshift mutation?
Insertion or deletion of bases not divisible by three.
What is a reading frame?
The grouping of nucleotides into codons.
What happens if exactly three nucleotides are inserted?
One amino acid is added without shifting the reading frame.
Can inserting three nucleotides still affect a protein?
Yes.
Why are mutations important for evolution?
They create genetic variation.
Who confirmed that the genetic code is a triplet code?
Crick and Brenner.
What did Nirenberg and Matthaei study?
Which codons code for specific amino acids.
What did the Nirenberg and Matthaei experiment use?
Synthetic RNA and E. coli cell extracts.
What amino acid does UUU code for?
Phenylalanine.
What amino acid does AAA code for?
Lysine.
What amino acid does CCC code for?
Proline.
What amino acid does GGG code for?
Glycine.
What does aminoacyl-tRNA synthetase do?
Attaches the correct amino acid to its tRNA.
What energy molecule is required to charge tRNA?
ATP.
What is an aminoacyl-tRNA?
A tRNA with an amino acid attached.
What are the main stages of translation?
Initiation elongation and termination.
What is initiation?
The ribosome binds mRNA to begin translation.
What is the Shine-Dalgarno sequence?
A ribosome binding sequence in prokaryotic mRNA.
What is the Kozak sequence?
A translation initiation sequence in eukaryotic mRNA.
What do initiation factors do?
Help assemble the translation machinery.
What are the three ribosomal tRNA sites?
A P and E.
What happens at the A site?
Incoming charged tRNA binds.
What happens at the P site?
The growing protein chain is held.
What happens at the E site?
Empty tRNA exits the ribosome.
Where does the initiator tRNA bind?
P site.
What do elongation factors do?
Help deliver and move tRNAs through the ribosome.
What forms peptide bonds in the ribosome?
Peptidyl transferase.
What happens during translation termination?
The completed protein is released.
What tells the ribosome to stop translating?
A stop codon.
What enters when a stop codon reaches the A site?
A release factor.
What is the 3' UTR?
An untranslated region that can help with termination.
What is a post-translational modification?
A chemical change made to a protein after translation.
What is phosphorylation?
Adding a phosphate group to a protein.
What is glycosylation?
Adding carbohydrates to a protein.
What is lipidation?
Adding lipids to a protein.
Can transcription and translation happen together in prokaryotes?
Yes.
Why can RNA polymerase pause during bacterial translation?
To stay near ribosomes and help protect mRNA.