Cellular Control Flashcards
Define Gene
A length of DNA that codes for one (or more) polypeptides
Define Polypeptide
A polymer consisting of a chain of amino acid residues joined by peptide bonds
Define Genome
The entire DNA sequence of that organism. This consists of about 3 billion nucleotide base pairs.
Define Protein
A large polypeptide - usually 100 or more amino acids. Some proteins consist of one polypeptide chain and some consist of more than one polypeptide chain.
Define Transcription
The creation of a single stranded mRNA copy of the DNA coding strand.
What is a triplet code?
It is a sequence of 3 nucleotide bases which codes of one amino acid.
What is meant by the genetic code being a degenerate code?
All amino acids, except methionine have more than one code that codes for them.
How does the gene sequence stop the transcription of amino acids?
Certain codes do not code for amino acid but indicate the sequence to stop so the polypeptide stops being made.
Where are proteins assembled?
In the cytoplasm at ribosomes
What is the first stage of protein sysnthesis?
Transcription
What are the steps in transcription?
A strand of DNA is used as a template (the template strand).
This strand unwinds and unzips by dipping into the nucleolus where the hydrogen bonds break.
Activated RNA nucleotides bind to the exposed template strand (catalysed by the enzyme RNA polymerase).
What are the steps in transcription?
A strand of DNA is used as a template (the template strand).
This strand unwinds and unzips by dipping into the nucleolus where the hydrogen bonds break.
Activated RNA nucleotides bind to the exposed template strand (catalysed by the enzyme RNA polymerase).
This mRNA strand is therefore a copy of the coding strand (the strand that used to be attached to the template strand).
The mRNA passes out of the nucleus through a pore in the nuclear envelope.
Define Translation
The assembly of polypeptides (proteins) at ribosomes.
Define Translation
The assembly of polypeptides (proteins) at ribosomes.
What is the primary structure of a protein?
It is the order of the amino acids in the length of the chain. This is determined by the order of bases on the mRNA.