Protein Structure And Function Flashcards
What are the stop codon bases
AUU
AUC
What is mRNA used for
To determine the amino acids sequence of proteins that are synthesises in the cytoplasm
What is a codon
The sequence of 3 bases on mRNA that code for a single amino acid
What the the RNA bases
Adenine
Guanine
Cytosine
Uracil
Describe the process of transcription
DNA helicase breaks hydrogen bonds, 2 strands separate
Free nucleotides join complementary bases on the strand
RNA polymerase enzyme allows this
RNA polymerase recognises stop triplet code so detaches
Describe what happens in splicing
Introns interfere with polypeptide synthesis
So
Splicing removes introns
Exons recombine
Different between exons and introns
Introns don’t code so non-functional
Exons code for protein
Describe translation
Ribosome attaches to starting codon on mRNA
tRNA carries amino acid
tRNA has complementary anticodon
Ribosome move along mRNA
2 tRNA pairs with 2 codons on mRNA
Enzyme + ATP used to form peptide bonds between amino acids
Ribosome moves to next codon
tRNA released from amino acid earlier
Process continues until ribosome reaches stop codon
What changes if there’s a DNA mutation in base sequence
mRNA base sequence changes mRNA codon changes Amino acid sequence of protein changes Protein structure changes Protein function changes Cell function changes
What is substitution
Base replaced
What is deletion
Base removes
What is insertion
Base added
What happens when deletion occurs
Frame shift So sequence read differently Likely amino acids change Only causes harm depending on where Ie more harmful at end of sequence
Name the types of substitution mutations
Nonsense
Mis-sense
Silent
What happens in nonsense mutation
If change in base results in stop codon being produced
Polypeptide stopped prematurely
What happens in mis-sense mutation
Different amino acid coded for
Polypeptide produced different by 1 amino acid
Significance depends on role of amino acid
Important if it helps form structure of final protein (would lead to not functioning properly)
What happens if silent mutation
Still codes for same amino acid as before
Due to degenerate nature
Explain why the genetic code is describes as universal
Codon codes same amino acid in all organisms
Explain why the genetic code is described as degenerate
Amino acids have more than one codon
Explain why the genetic code is describes as non-overlapping
Bases only read once
How do you distinguish between a codon and an anticodon
Anticodon only on tRNA
Condone on DNA or mRNA
What are single strands and contain ribose sugar
mRNA and tRNA
How many nucleotides made tRNA
Around 80
What outside factors increase the chance of mutations
High energy radiation
Certain chemicals
What are mutagenic agents or mutagens
Things that increase the chances of mutation occurring
Eg high energy radiation or certain chemicals
How can mutations be positive
They create variation and genetic diversity
Name the 2 genes that control cell division
Proto-oncogenes
Tumour suppressor genes
What do proto-oncogenes do?
Stimulate cell division
What do tumour suppressor genes do
Slow cell division
List the key word stages of protein synthesis
Helicase Unzipping Nucleotides Complementary Polymerase Splicing mRNA Cytoplasm Ribosomes Codons tRNA Peptide bonds Polypeptide chain
