Genes and Gene Expression

gene

functional unit of heredity

heredity

the transmission of genetic traits from parent to offspring

gene expression

the production of RNA and/or proteins from the info stored in DNA; transcription and translation

transcription

occurs in nucleus; info stored in a segment of DNA is used to produce a complementary RNA molecule called mRNA

translation

occurs in cytoplasm; the nucleotide sequence of the mRNA is used to determine the composition of a polypeptide chain, a precursor to a protein; tRNA is used to carry specific amino acids to the ribosomes

transcription pairing

A with U, C with G

terminator

sequence that transcription ends with and RNA is released

gene complexity

the region of DNA between the promoter and the termination of transcription

introns

regions of the gene that are not part of the code for a protein

exons

regions of the gene that are part of the code for a protein

pre-mRNA

the mRNA with the introns

spliceosomes

remove introns from pre-mRNA then join the remaining pieces of exons to become functional mRNA

alternative splicing

when various combinations of exons are joined into mRNA that allows for different proteins to be made from the same gene

genetic code

the info contained in mRNA and relates to the nucleotide sequence of mRNA to the amino acid sequence of a protein

codons

three nucleotide sequences that mRNA is arranged into, each of which specifies an amino acid during translation

start codon

AUG, codes for methionine

stop codons

UAA, UGA, and UAG, do not code for any amino acid

translation

process that occurs on ribosomes, turns mRNA into a polypeptide, involves rRNA, tRNA, and mRNA; tRNA anticodons are complements of mRNA codons, and the rRNA catalyzes the formation of a peptide bond between the amino acids at the opposite end of the tRNA