Protein Synthesis And Selection Flashcards
(27 cards)
Compare and contrast DNA in prokaryotic and eukaryotic cells
They both have DNA nucleotides with the same structure containing phosphate group, nitrogen containing base and deoxyribose sugar.
They both have nucleotides joined by phoshphodiester bonds
DNA has exons only whereas DNA in eukaryotic has introns and exons
DNA is free in the cytoplasm whereas DNA in enclosed in the nucleus
DNA is not associated with histone whereas DNA is associated with histone
DNA is circular whereas DNA is linear
DNA is shorter than in eukaryotic
Compare and contrast mature DNA and mRNA
Both are polymers made from nucleotides
Both contain nucleotides linked by phosphodiester bonds
DNA is double stranded whereas MRNA is single stranded
DNA is longer whereas mRNA is shorter
Thymine in DNA whereas uracil in MRNA
DNA has introns and exons whereas mrna has exons only
DNA has hydrogen bonds whereas mrna has no hydrogen bonds
Deoxyribose in DNA whereas Ribose in mrna
Compare and contrast MRNA and TRNA
Both are polymers of nucleotides from RNA
Both are single stranded
Both contain nucleotides linked by phosphodiester bonds
Both contain uracil
Mrna has codons whereas trna has anticidons
Mrna has no hydrogen bonds whereas trna has hydrogen bonds
Mrna is linear whereas trna is clover shaped
Mrna is longer
Gene definition
Sequence of DNA nucleotides that code for an polypeptide chain
Describe transcription
DNA helicase breaks hydrogen bonds and one strand acts as an template
Free RNA nucleotides attracted to complementary base pair
Adenine to uracil
Guanine to cytocine
RNA polymerase joins adjacent RNA nucleotides forming a phosphodoester bond by condensation reaction
Pre mrna spliced into mature mrna by removing introns
Introns definition
A triplet/codon that doesn’t code for a sequence of amino acids
Exons definition
A triplet/ codon that codes for a sequence of amino acids
Describe translation
Ribosome binds to codons on mrna and read start codon
Ribosome binds with 2 codons
Trna carrying specific amino acids with complementary anitcodon binds with codon.
Formation of peptide bonds between amino acids by condensation reaction using energy from ATP
Trna released as Ribosome moves along mrna
Ribosomes reads stop codon and releases polypeptide into RER
Proteome definition
The time it takes for a cell to produce a range of protiens
Loci definition
The position of a gene within the chromosome
Allel
Different versions of genes
Where does transcription occur in prokaryotic and eukaryotic cells
Prokaryotic = cytoplasm
Eukaryotic = nucleus
Where does translation occur
In the cytoplasm at a Ribosome
What is a gene mutation
Change in DNA nucleotide base sequence resulting in formation of new allel
Universal definition
All codons code for the same triplets in all organism
Non overlapping definition
Each base is only read once on a triplet
Degenerate
More than one triplet codes for an amino acid
Explain why a mutation may not affect the protein structure?
Genetic code is degenerate so amino acid base sequence not effected and mutation may occur in introns which don’t code for an polypeptide chain
Explain how a mutation can have a positive effect ?
Mutation leads to change in primary then tertiary structure which can positively change the properties resulting in increased reproductive success and increased survival chance
Substitution mutation
Change to a single base in the DNA leading to change in primary structure. But can be a Silent mutation as change can be degenerate
Addition/ deletion mutation
Addition or removal of a singular base causing frameshift leading to change in amino acid base sequence
What is an mutagenic agent?
Increases the rate of spontaneous mutation
Give an example of mutagenic agents
High energy ionisation such as x rays which damage the DNA structure
DNA reactive chemicals such as nitrous oxide which coverts bases
Biological agents such as viruses and bacteria
Chromosomal mutation
This is called chromosome non disjunction whereas one daughter cell get no DNA
