Terminology: learn these definitions!
Gene: region/s of DNA that are made up of nucleotides; the molecular unit of heredity.
Genes include: ‘coding’ regions of DNA (exons) and ‘noncoding’ regions of DNA.
Genome: all the genetic material in the chromosomes of an organism, including its genes and DNA sequences.
Coding regions
Known as exons, and are the part of the gene that codes for a protein.
Noncoding regions
These regions are sequences are components of an organism’s DNA that do not encode protein sequences. They used to be called junk DNA, but this is no longer acceptable! You also need to remember that many functions of non-coding DNA are yet to be determined.
Noncoding sequences include:
-A variety of regulatory elements that control transcription of nearby genes such as promoters, etc (these are called cis-regulatory elements).
-Instructions to make certain types of functional RNA (i.e. tRNA, rRNA, regulatory RNAs, microRNAS).
-Centromeres – where sister chromatids are attached.
-Telomeres – caps on the end of DNA that prolong the life of chromosome.
-Introns – non-coding parts of genes that are transcribed into mRNA, but then removed by RNA splicing before transcription. .
Transfer RNA (tRNA) is a type of molecule that helps decode a messenger RNA sequence into a protein. From this information, identify which group tRNA belongs to.
A. Exons
B. Introns
C. Noncoding RNA
D. Noncoding DNA