Lecture notes BHCS2003 - Genetics

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The central dogma,
transcription and regulation of
gene expression
The central dogma of biology




What is RNA

Similar structure to DNA but has ribonucleotides instead of deoxyribose acids

RNA is able to base pair with itself and DNA

Bases are: A, U, C, and G

RNA is generally shorter than DNA and is less stable

Functions:
-Carrying genetic information (some viruses use RNA instead of DNA as their



The central dogma, transcription and regulation of gene expression 1

, genome)
-Acting as a messenger between DNA and proteins (mRNA)
-Helping build proteins (tRNA and rRNA)

Regulating gene expression (e.g. miRNA, siRNA)




Transcription

Transcription is the process of copying or transcribing DNA

Transcription and RNA processing occurs in the nucleus, translation occurs in
the cytoplasm

Transcription is performed by RNA polymerase

RNA polymerase copies DNA in a 5’ to 3’ direction




The central dogma, transcription and regulation of gene expression 2

, Initiation

Genetic elements are required for initiation of transcription

Different RNA polymerases have different core promoters

Most protein coding genes contain a TATA box upstream of the the TTS, a
“weak” TTS sequence and upstream elements such as DPE




The central dogma, transcription and regulation of gene expression 3