Gene Expression Flashcards
Allele
Different forms of a gene due to slightly different order of bases e.g. brown eyes and blue eyes
Amino acids
Building blocks of proteins. Carried by the tRNA molecule. There are 20 different types.
Anticodon
A sequence of three nucleotides/bases on a tRNA molecule that complementary bonds with a specific codon on a strand of mRNA during translation.
Block Mutation
A mutation resulting in a change in the number or arrangement of genes on chromosomes.
Chromosome
A threadlike structure made of DNA and (in eukaryotes) associated histone proteins on which the genetic information of an individual is stored.
Codon
A triplet of nucleotides within a molecule of messenger RNA that specifies a particular amino acid during the synthesis of proteins in a cell.
Complementary base pairing rules
These state that the nitrogenous bases Adenine and Thymine will always pair together (Uracil replaces Thymine in RNA) and Cytosine and Guanine will always pair together.
Degeneracy
Degeneracy in the code is that if you change the third position of a triplet you often code for the same amino acid.
Degeneracy leads to redundancy in that two or more codons can specify for the same amino acid. For example, codons GAA and GAG both specify glutamic acid (GLU). Because an amino acid may be coded for by more than one codon, this can buffer the effect of any mutations as a change in one base may not alter the amino acid coded for.
Deletion Mutation
A base is removed from the DNA and this results in a reading frame shift with each triplet after that being different.
DNA
Deoxyribonucleic acid. The genetic material of most living organisms. It plays a central role in the determination of hereditary characteristics by controlling protein synthesis in cells. It has a double helix shape.
Enzymes
A protein that is a biological catalyst that helps increase the rate reactions of the cell.
Exons
Remaining coding sequences on the mRNA strand which are then translated (introns are non-coding and are removed)
Frame Shift
Since mRNA is read in codons (groups of 3 bases) a change in ONE nucleotide by either inserting or deleting will result in a change in the reading frame. The change will affect all the codons, and therefore amino acid sequence from this point onward.
Gametes
A reproductive cell that fuses with another to form a zygote - eg. eggs (ova) and sperm (spermatozoa). Mutations in these cells will be inherited by offspring.
Gene
A length of DNA that codes for a particular polypeptide/protein/enzyme
Genetic code
A triplet code where each 3 bases codes for a specific amino acid
Genotype
The genetic make-up of an organism for a feature
Homologous Chromosomes
Chromosomes that have the same genes at the same location. In diploid cells, one chromosome comes from the female parent, the other from the male parent.
Insertion
A base is inserted into the DNA, resulting in a frame shift and all the other bases move down one
Meiosis
Meiosis is cell division that produces gametes/sex cells with a haploid/ (half the number of chromosomes) as the parent cell / somatic cells