Introduction to Transcription and Translation Flashcards
What are genes?
Short segments/sequences of DNA that contain genetic instructions that specify the AA sequences of proteins
What acts as the bridge between genetic information (DNA) and a protein?
Ribonucleic acid
How does RNA acts a bridge between DNA and a protein?
2
RNA copies a short segment of DNA by using it as a template
This is then used in the synthesis of the protein
Which happens first translation or transcription?
Transcription first then translation
List the order of the flow of genetic information.
5
DNA
Transcription
mRNA
Translation
Protein
Define transcription
A portion of DNA nucleotide sequence (gene) is copied into a RNA nucleotide sequence
Where does transcription occur in eukaryotes?
Occurs in the nucleus
Where does transcription occur in prokaryotes?
Occurs in the cytoplasm
Define translation.
2
The synthesis of polypeptide under direction of RNA
Formation of amino acid chains - proteins
Where does translation occur?
Cytoplasm
Why does transcription occur in the nucleus of eukaryotic cells?
Because the DNA of eukaryotes is protected by the nucleus
What must be cut out of eukaryotic DNA before translation?
Non-coding DNA must be cut out
What is non-coding DNA also called?
Introns
What is coding DNA also called?
Exons
What must be done between transcription and translation in eukaryotic cells?
mRNA processing is required
What are the two main differences between RNA and DNA?
2
RNA is single stranded and a short polymer
DNA is double stranded and a long polymer
What is messenger RNA?
RNA molecules copied from genes which direct synthesis of proteins
Give three examples of RNAs
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
Small nuclear RNA (snRNA)
How does transcription begin?
It begins with opening and unwinding of a small portion of DNA to expose the bases on each DNA strand
How does DNA replication differ from transcription?
4
The RNA strand does not remain hydrogen bonded to it’s DNA template
The DNA helix reforms and displaces the RNA chain
RNA copies only from a limited region of DNA
RNA polymerases are used instead of DNA polymerases
Why does RNA copies only from a limited region of DNA?
This is because RNA molecules are much shorter than DNA
What does RNA polymerase do?
It catalyses the formation of the phosphodiester bonds that link nucleotides together and form the sugar-phosphate backbone of the RNA chain
