Key Area 1.3 Gene expression Flashcards
What is gene expression?
the activation of only certain genes in a cell to produce a particular protein
How many types of RNA are there?
3
Name the 3 types of RNA.
mRNA- Messanger
rRNA- Ribosomal
tRNA- Transfer
What does mRNA do?
copies the code from the DNA molecule and carries it to the ribosomes
What does tRNA do?
binds to specific amino acids and transports them to the ribosomes
Where is tRNA found?
in the cytoplasm
What does rRNA do?
forms a complex with protein molecules to make the ribosome
What are the 3 differences between RNA and DNA?
DNA has deoxyribose sugar- RNA has ribose sugar
DNA has thymine (base) - RNA has uracil (base)
DNA is double stranded- RNA is single stranded
What makes up an RNA nucleotide?
phosphate, base, ribose sugar
What are the 2 stages of Gene Expression (Protein Synthesis) called?
transcription and translation
Where does transcription take place?
in the nucleus
Where does translation take place?
in the ribosomes
What is stage 1 called?
transcription
What enzyme is used in Gene Expression?
RNA polymerase
What happens during transcription?
RNA polymerase unwinds DNA into 2 strands breaking the hydrogen bonds.
RNA polymerase joins RNA nucleotides with their complimentary bases.
A primary transcript is formed.
What is RNA splicing?
When exons (coding regions) are spliced together and introns (non-coding regions) are removed from the primary transcript to form the mature mRNA transcript
What pairs with adenine during Gene Expression?
Uracil
What is stage 2 of Gene Expression called?
Translation
What happens during translation?
The tRNA anticodon is complimentary to mRNA codon. The tRNA binds to a specific amino acid at its attachment site and carries it to the ribosomes.
Stop and start codons make translation stop and start. Peptide bonds form between the amino acids making a polypeptide chain.
What do tRNA molecules have?
Anticodon and amino acid attachment site
What do rRNA molecules have?
Codon
What is alternative RNA splicing?
When different axons are spliced together to code for a different protein. Different mature transcripts are made from the same primary transcript.
What bonds form between the amino acids?
peptide bonds
What is phenotype?
phenotype is determined by the portions produced as a result of gene expression, it is the outwards appearance of a molecule
What is a string of amino acids called?
Polypeptide chain
