Definitions Flashcards
What is a chromosome?
DNA and histones are organised into structures that are called chromosomes
What is a gene?
A sequence of DNA bases that codes for the specific amino acid sequence of a polypeptide
What is a homologous pair of chromosomes?
Carries the same genes in the same loci but not necessarily the same alleles
Consist of a maternal and paternal chromosome
What is a locus?
The fixed position that a gene occupies on a particular DNA molecule or chromosome
What is an allele?
Different forms of a gene
What are histones?
The proteins that DNA is wrapped around in eukaryotes
What is a base triplet?
A sequence of three nucleotide bases that codes for a specific amino acid
What are codons?
Base triplets in mRNA
What does degenerate mean?
Different triplets or codons coding for the same amino acid
What are stop codes?
Indicate the end of the code for a specific polypeptide
What is a start code?
Indicate the start of the code for a specific polypeptide
What does non-overlapping mean?
Each base is only read once as part of a specific triplet
What does universal mean?
The same triplets code for the same amino acids in all organisms
What does reading mRNA mean?
When the ribosome moves along the mRNA reading codons
What are introns?
Base sequences present WITHIN genes but DO NOT code for amino acids.
What are exons?
The base sequence in genes that DO code for amino acids.
What are multiple repeats?
Some of the base sequences present BETWEEN genes
What are anticodons?
3 unattached tRNA nucleotide bases
What is a genome?
The complete set of genes (and non-coding DNA)in a cell
What is a proteome?
The full range of proteins that a cell is able to produce
What is pre-mRNA?
The mRNA formed during transcription using DNA containing both exons and introns
What is genetic diversity?
The number of different alleles in a population
What are genetic mutations?
Change in the base sequence caused by errors in DNA replication
What is chromosome mutations?
Change in number/structure of chromosomes caused by errors in cell division
What is a mutagenic agent?
A factor that increases mutation rate, it makes spontaneous mutations more likely
What is substitution?
The replacement of one or more bases by one or more different bases
What is deletion?
The removal of one or more bases
What is addition?
The adding of one or more bases
What is duplication?
Where one or more bases is repeated
What is inversion?
Where a sequence of bases is reversed?
What is translocation? (Mutations)
Where a sequences of bases is moved from one location in the DNA molecule to another part of the genome
What is a frame shift?
The alteration in all the triplets from the point of mutation
What is a diploid cell?
A cell with the full number of chromosomes
What is a haploid cell?
A cell with half the number of chromosomes. One from each homologous pair
What is meiosis?
A type of nuclear division that produces cells that are genetically different
