Protein synthesis Flashcards
Protein synthesis in eukaryotes
- Transcription: DNA is copied on single-stranded mRNA.
- mRNA processing: a) Non-coding sections removed. b) Caps and tails are added.
- Translation: Ribosomes make proteins.
Transcription
RNA Polymerase
Breaks H-bonds on DNA and complimentary base pairs RNA nucleotides in 5’-3’ directions.
Codon
- Segments of 3 nucleotides on mRNA.
- Codes for start, stop, and amino acids.
mRNA processing: RNA splicing.
What are introns and exons?
Introns: non-coding segments on mRNA that are removed by spliceosomes.
Exons: coding sequences are joined
mRNA processing: adding caps and tails.
What is the purpose of adding caps and tails?
- Protects mRNA from damage during transfer into cytoplasm.
- Anchors mRNA to ribosome.
mRNA processing: adding caps and tails.
What is 5’ cap and Poly (A) tail?
5’ cap: guanine added to 5’ end of mRNA.
Poly (A) tail: sequence of adenine added to 3’ end.
Translation
Enzymes involved
rRNA, tRNA.
Translation
Anticodons
Nucleotide sequence located at one end of tRNA.
Matches complementary codon in mRNA sequence.
Translation
Role of rRNA
- rRNA matches codon with complementary anticodon.
- rRNA helps speed up formation of peptide bond between amino acids by orienting them in the correct placement.
Translation
tRNA structure and function
L-shaped enzyme that delivers amino acids to ribosomes.
Has complimentary anticodon on one end.
Translation
Role of ribosomes
Ribosomes attach to 5’ cap of mRNA.
Eukaryotic cells
- Have true nucleus with nuclear envelope.
Prokaryotic cells
- Have no nucleus
Protein synthesis in prokaryotes
- Transcription and translation: ribosomes attach to mRNA as it’s being transcribed.
- mRNA processing: a) no caps or tails needed. b) no RNA splicing bc no introns exist.
