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What happens during transcription?
the information in a DNA sequence that is copied into a complementary RNA sequence.
What happens during translation?
the RNA sequence is used to create the amino acid sequence of a polypeptide.
What is a promoter?
a special sequence of DNA to which the RNA polymerase binds very tightly.
What does the promoter do?
They 'tell' RNA polymerase where to start transcription and which strand of DNA to transcribe.
What is the initiation site?
Where the transcription begins.
What are the start codons?
AUG, which codes for methionine.
What are the stop codons?
UAA, UAG, UGA
What are introns?
Noncoding base sequences.
What are exons?
Coding base sequences.
What is pre-mRNA?
It is the primary mRNA sequence that has the introns and exons on it.
What is the Probe?
A segment of single stranded nucleic acid used to identify the DNA complementary sequence.
What is RNA splicing?
The removal of the introns and binding or splicing of the exons together.
What are the functions of the tRNA molecule?
- It associates with mRNA.
- It interacts with ribosomes.
- It binds to an amino acid and is 'charged' as it carries the amino acid.
What are the three steps of Translation?
Initiation- formation of the initiation complex that creates the start codon. AUG
Elongation- The formation of polypeptide bonds between amino acids elongates the polypeptide chain, and is catalyzed by rRNA.
Termination- The translation stops when a stop codon reaches the A site. UAA UAG UGA
What is the A site?
- The amino acid site.
- Where the charged tRNA anticodon binds to the mRNA codon.
What is the P site?
The polypeptide site is where the tRNA adds its amino acid to the polypeptide chain.
How does RNA differ from DNA?
- It contains uracil instead of thymine.
- Uses ribose sugar instead of deoxyribose.
- It is single-stranded.
What are the three types of RNA that participate in protein synthesis?
- mRNA- carries a copy of a gene sequence in DNA to the site of protein synthesis at the ribosome (the cytosol). Transcription.
- tRNA- carries amino acid to the ribosome for assembly into polypeptides. Translation.
- rRNA- catalyzes peptide bond formation and provides a structural framework for the ribosome. Translation.
What is transcription?
Copies the information in the DNA sequence into a complementary DNA sequence.
What is translation?
When the RNA sequence is used to create the amino acid sequence of a polypeptide.
What is the Central Dogma?
Describes information from from DNA to RNA into polypeptides.
What is reverse transcription?
Synthesis from RNA to DNA. (retroviruses)
What does both prokaryotic and eukaryotic transcription require?
- A DNA template for complementary base pairing
- Nucleoside triphosphates to act as substrates
- RNA polymerase enzyme
Transcription happens in what three steps?
- Initiation- Unwinds DNA strand.
- Requires a promoter that tells RNA polymerase where to start transcription (initiation site) and which strand of DNA to transcribe.
Elongation- DNA polymerase unwinds the DNA. DNA polymerase reads DNA template strand from 3' to 5' and produces the RNA transcript by adding nucleotides 5' to 3'. Does not require a primer.
Termination- RNA polymerase reaches its termination site, the RNA transcript is set free from the template.
What are the differences between Eukaryotic and Prokaryotic gene expression?
Eukaryotic genes have non-coding sequences (exons and introns).
Eukaryotic gene transcripts are processed before translation and go through modification at both ends. RNA splicing occurs to remove introns then spliceosomes reconnect the exons.
tRNA molecules have what three functions?
They bind amino acids. When this happens, they are 'charged'.
It associates with mRNA.
It interacts with ribosomes.
What happens to polypeptides after translation?
Signal sequences of amino acids direct polypeptides to their cellular destinations.