Topic 8: DNA, Genes, Protein Synthesis Flashcards
What is a gene
A gene is a base sequence of DNA that codes for:
- the amino acid sequence of a polypeptide
- a functional RNA
What do you call the fixed position of the gene on a DNA molecule
Locus
Where is DNA found
Mostly in nucleus
(also in mitochondria as mitochondial dna)
What are the 4 bases of DNA
- Adenine
- Thymine
- Cytosine
- Guanine
What is a codon
A sequence of three bases that codes for a single amino acid
How many amino acids are coded for in protein synthesis
20 amino acids
(because some have multiple codes)
What does it meanby the genetic code being degenerate
several code words have the same meaning (amino acid)
What are stop codes
When the codon does not code for an amino acid, but for the ribosome to stop the polypepetide chain
What is always the start codon
Methionine
(AUG)
What does it mean by the code is non-overlapping
Each base is only read once, and the triplets are read in the same direction
What does it mean by the code being universal
The genetic code is the same in almost every living being, with a few specific exceptions.
What do you call a sequence that does not code for an amino acid
Introns
What do you call a sequence that codes for an amino acid
Exons
What happens to the introns
They are removed by splicing before the final mRNA reach the ribosomes.
What do you call the proteins associated with DNS
Histones
What forms a chromosone
DNA molecule and its associated proteins (histones)
When the cell is not dividing, what are the chromosones like?
- not visible
- uncoiled
- loosely found throughout nucleus