4.1 DNA, Genes And Chromsomes Flashcards
Define locus
The position of a gene on a chromosome
Define allele
Different form of the same gene
Define mutation
Change in a base sequence of a gene resulting in a different allele or amino acid
What is a sequence of three DNA bases called?
What does it do?
A codon
Codes for a specific amino acid
What 3 things describes the genetic code?
It is degenerate - different combinations of code which code for the same amino acid because there are 64 codons and 20 amino acids. The base sequence also contains start and stop codons
Non overlapping
Universal
Define genome
Complete set of genes in a cell
Define proteome
Full range of proteins that a cell is able to produce
What are introns?
What happens to them?
They are non coding sections of DNA
They are removed from the base sequence during protein synthesis before the polypeptide is produced
Define extrons
Coding sections of DNA that are transcribed and translated into a polypeptide
What other area, other than introns, contain DNA that do not code for an amino acid?
Non-coding multiple repeats
Define homologous pair
Pair of matching chromosomes
Describe the structure of DNA in prokaryotic cells
Where else is this form of DNA found?
DNA molecules are short, circular and not associated with proteins
In the mitochondria and chloroplasts of eukaryotic cells
Describe the structure of DNA in the nucleus of eukaryotic cells
DNA molecules are long, linear and associated with proteins called histones. DNA and histones from a chromosome
Define gene
A gene is a section of DNA that contains the sequence of bases of DNA that contains the information for making polypeptides and functional RNA
Describe a homologous chromosome
A pair of matching chromosomes in a pair that are the same size and contain the same genes but with different alleles found at the same locus
