bio transcription

central dogma

DNA → RNA → Protein

DNA → RNA =

Transcription

RNA → Protein =

Translation

Prokaryotes Transcription occurs in

cytoplasm

Prokaryotes Translation occurs in

cytoplasm (happens at the same time)

Eukaryotes Transcription occurs in

nucleus

Eukaryotes Translation occurs in

cytoplasm (ribosomes)

gene

is a sequence of DNA that contains instructions

protein

is the functional product made from that gene

DNA sequence → mRNA →

amino acid sequence → protein

Sugar-phosphate backbone of nucleic acid

Alternating sugar and phosphate groups forming the “sides” of DNA/RNA

nucleic acid Base attachment

Nitrogenous base attached to 1’ carbon of ribose/deoxyribose

At 2’ carbon

DNA=

H

At 2’ carbon RNA=

OH

nucleic acid Energy source

Comes from nucleotide triphosphates (ATP, GTP, etc.)

DNA strands run

antiparallel

Complementary base pairing

DNA

A–T (2 H bonds), G–C (3 H bonds)

Complementary base pairing RNA

A–U, G–C

% composition

If A = 15% → T = 15%

Remaining 70% → G = 35%, C = 35%

Prokaryotic gene

Promoter → coding region → terminator

No introns

Eukaryotic gene

Promoter (TATA box)

Exons (coding)

Introns (non-coding)

5’ and 3’ UTRs (untranslated regions)

Gene DNA

exons + introns + promoter

pre-mRNA

exons + introns (initial transcript)

final mRNA

exons only + cap + poly-A tail

Coding strand:

same sequence as mRNA (except T → U)

Template strand:

used by RNA polymerase

pre-mRNA:

unprocessed

mRNA

capped, tailed, spliced

Prokaryotic Transcription

No nucleus

No mRNA processing

Transcription + translation occur together

Eukaryotic Transcription

Occurs in nucleus

Requires processing

Separate from translation

Exon:

coding sequence

intron

non-coding sequence