Protein Synthesis Flashcards
differences between DNA and RNA
- Rna has Ribose sugar, Dna has Deoxyribose Sugar
- DNA has thymine (T), RNA has Uracil (U)
- RNA is single stranded, DNA is double stranded
Types of RNA
mRna
tRNA
rRNA
What is mRNA +function
Messenger RNA: Copy of a gene, Carries information to make proteins from the nucleus to the cytoplasm
What is tRNA +function
Transfer RNA: brings amino acids to ribosomes during protein synthesis
Composed of:
-a site for amino acids to attach
- a site called anticodon that determines which of the 20 AAs is attached to the tRNA
What is rRNA +function
Ribosomal Dna: component of the Ribosomes, translate the sequence of amino acids to their corresponding protein
Composed of: Large subunit, small subunit
Similarities between RNA and DNA
- both have 5-carbon sugar
- Both are polymers of nucleotides
- DNA/RNA have the same structure
Steps of Protein Synthesis
- Transcription
- RNA processing
- Translation
What is transcription
the process of making RNA from DNA.
What is translation
the process of building a sequence of amino acids to form a protein based on the information carried by the mRNA
What is RNA processing
the process of making mature mRNA out of precursor mRNA
Ribosome structure (rRNA)
3 binding sites:
1. (large subunit)
A (attachment): where tRNA initially binds
P(parking): where the amino acid is transferred from its growing polypeptide chain and held
E(end): where the ‘empty’ tNA sits before being released
2. Small subunit
Steps of translation
- initiation
- elongation
- termination
What are Exons and Introns
Exons: section of genes that contain information to make a protein (coding regions)
Introns: non-coding sections of genes
How is mature mRNA made (RNA SPLICING/PROCESSING)
- During transcription, pre-cursor mRNA is created by copying a gene
- Pre mRNA has exons and introns
- during RNA splicing, introns are spliced to create mature mRNA with only exons
Steps of transcription
- initiation
- elongation
- termination
When does transcription start (initiation)
- RNA polymerase +transcription factors attaches to the 5’ end (PROMOTER REGION)
- they start to unwind the gene
what is RNA polymerase
the enzyme that synthesizes the RNA Molecules
what transcription factors
assemble at the promoter region and recruit the RNA polymerase
What happens during elongation (TRANSCRIPTION)
-addition of nucleotides
- RNA polymerase zooms down the gene in a 5’-3’ direction
- anti-sense strand used as a template to create mRNA molecule
- transcribes antisense template, using corresponding nucleotides (base-pairing rule) (only replacing Thymine with Uracil) making an exact copy of the sense strand
- DNA rewinds as RNA polymerase zooms down
What happens during termination (TRANSCRIPTION)
when the RNA polymerase reaches the TERMINATOR region, detaches and releases the pre-mRNA
What is the genetic code
code of the genes, uses 4 nucleotides (GUANINE, ADENINE, THYMINE, CYTOSINE)
-read in triplets
Translation (INITIATION)
- the first tRNA (with METHIONINE), the ribosome and the mRNA come together
- the small ribosomal subunit binds to the mRNA +slides to start codon
- first tRNA binds to AUG (start codon) in A site
- amino acid moves along to P site
Translation (ELONGATION)
- second tRNA approaches, if complementary, it binds to A site
- first peptide bond forms between amino acid in A site and amino site in P site
- tRNA in P site is released
- ribosomal unit slides down the mRNA to next codon (P site). First tRNA moves to E site and is released
- A site is empty for next codon to attach and for new peptide bond to form
Translation (TERMINATION)
- A stop codon enters A site
- no corresponding amino acids
- polypetide chain is released
