Unit 4 - Gene Expression Flashcards
RNA is ____ stranded
single stranded
Where is RNA found?
In the nucleus and cytoplasm of the cell
What are the three types of RNA?
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
What is mRNA and what does it do?
Messenger RNA, carries the genetic code from the nucleus to the cytoplasm
What is tRNA and what does it do?
Transfer RNA, carries amino acids to the ribosome for translation
What is rRNA and what does it do?
Ribosomal RNA, produced in the nucleolus. Combines with proteins to form ribosomes
What is transcription?
The transfer of the genetic code from DNA to messenger RNA (mRNA)
(creation of mRNA from a DNA template)
What are the 5 steps of transcription?
First three are the same as DNA replication 1. DNA Unzips 2. Complimentary base pairing 3. Formation of phosphate-sugar backbone Different: 4. RNA separates from DNA 5. Removal of introns
What is translation?
Process whereby amino acids are assembled according to the order specified by DNA as transcribed in mRNA. (tRNA caries the amino acids to the ribosome for translation)
Where does translation take place?
Takes place on ribosomes which are composed of rRNA in association with proteins
What’s a codon?
Each set of 3 mRNA nucleotides that codes for one amino acid
What are the three steps of translation?
- Initiation
- Elongation
- Termination
Describe the Initiation step of translation
Ribosome attaches to the mRNA, reads start codon (AUG), anticodon of the tRNA carrying methionine pairs with its complimentary codon.
Describe the Elongation step of translation
Peptide chain grows as subsequent amino acids are brought in added.
Describe the Termination step of translation
Ribosome encounters a stop codon, ribosome and mRNA fall apart, polypeptide is complete.
