Genetic and Protein Synthesis Flashcards
What is a gene?
A DNA base sequence that codes for the amino acid sequence of a polypeptide or a fully functional RNA molecule.
What is an allele?
A different version of a gene.
What is meant by the genetic code?
A sequence of bases that code for a specific amino acid sequence.
What are codons?
A triplet of bases that code for a specific amino acid.
What are introns?
Sections of DNA that do not code for amino acids.
What are exons?
Sections of DNA that do code for amino acids.
What is a locus?
The fixed position of a gene within a chromosome.
What is the genome?
The complete set of genes within a cell.
What is a proteome?
The complete set of proteins a cell can make.
Why is the genetic code described as degenerate?
More than one base triplet can code for the same amino acid.
Why is the genetic code described as universal?
The same base triplet will code for the same amino acid in multiple different organisms.
Why is the genetic code described as non-overlapping?
A base triplet will only be read once and does not share its bases with any adjacent base triplets.
What is the structure of mRNA?
A single, linear polynucleotide chain. The base sequence of mRNA is complementary to the DNA base sequence and contains codons which are a set of three bases that code for a specific amino acid. It is small enough that it can leave the nucleus.
What is the structure of tRNA?
A single polynucleotide chain folded into a clover-like shape by the formation of hydrogen bonds. It has an anticodon which is complementary to a specific codon on the mRNA and attached to its amino acid binding site is an amino acid.
What are the main stages of protein synthesis?
- Transcription.
- Splicing.
- Translation.
What happens during transcription to produce pre-mRNA from DNA?
- The RNA nucleotides are attracted ro exposed bases due to to the complementary base pairing rule.
How is pre-mRNA modified to make mRNA?
What happens in translation to form a polypeptide?
- The mRNA attaches to the ribosome and the ribosome moves to the start codon.
- A tRNA molecule brings a specific amino acid to the ribosome.
- The anticodon on the tRNA molecule binds to the codon on the mRNA via complementary base pairing.
- This happens on the next codon.
- Peptide bonds form between the amino acids attached to the two tRNA molecules using energy from ATP.
- the first tRNA molecule is released, and the ribosome moves on to the next codon.
- This repeats until a codon is reached and the polypeptide deattaches from the ribosome.
What is the role of ATP in translation?
It provides the energy needed to make peptide bonds.
What is a stop codon?
It is a codon that stops translation and causes the polypeptide chains to detach from the ribosome and fold into its functional tertiary structure.
What is the role of RNA polymerase during transcription?
It joins nucleotides together to form mRNA, by forming phosphodiester bonds between them.
