Protein Synthesis Flashcards
Compare eukaryotic and prokaryotic DNA.
Eukaryotic linear WHEAREAS prokaryotic circular
Eukaryotic associated w/ histone proteins WHEREAS prokaryotic not
Eukaryotic contains introns WHEREAS prokaryotic doesn’t
Eukaryotic longER WHEREAS prokaryotic shortER
Both have base pairs
Both have hydrogen bonds
Compare mRNA and tRNA.
mRNA single stranded, tRNA clover-leaf shaped
mRNA no hydrogen bonds, tRNA has hydrogen bonds
mRNA no specific amino acid site, tRNA has specific amino acid site
mRNA codons, tRNA anti-codons
both have base pairs
both synthesised
Compare structure of mRNA and DNA.
mRNA shortER, DNA longER
mRNA single stranded, DNA double stranded,
mRNA no introns, DNA has intons
mRNA uracil, DNA thymine
Both have adenine, guanine and cytosine
Both phosphodiester bonds
Process of transcription.
- DNA helicase breaks hydrogen bonds between complimentary base pairs
- One strand used as template
- free RNA nucleotides associate with exposed DNA via base pairs
- uracil instead of thymine
- RNA polymerase forms phospodiester bonds between nucleotides through condensation reaction
- forms pre-mRNA
- introns spliced - mature mRNA
- leaves DNA through pores to ribosome
Process of translation.
- mRNA binds to ribosome
- ribosome finds start codon
- tRNA with complimentary anticodons, to mRNA codons and specific amino acid associates with codon
- second tRNA with specific amino acid
- amino acids form peptide bond through condensation reaction using ATP
- tRNA releases
- ribosome continues until stop codon
- polypeptide formed and released
Genome is…
Complete set of genes in a cell
Proteome is…
Full range of proteins that a cell is able to produce
Loci is…
The position of a gene within a chromosome
Allele is…
A different form of a gene
A gene is…
DNA base sequence that codes for a sequence of amino acids in a polypeptide
Genetic code is…
Universal
Non-overlapping
Degenerate
Universal is…
The same codons/triplets code for the same amino acids in all organisms
Non-overlapping is when…
Each base is only part of 1 codon/triplet
Degenerate is…
When more than on triplet/codon codes for an amino acid
Consequences of mutations.
Alter secondary structure - changes position of hydrogen bonds
Alter tertiary structure - changes position of hydrogen, ionic and disulphide bonds
What mutations can occurs during DNA replication.
Substitution
Deletion
Addition
Describe the term exon.
Base sequence coding for polypeptide of amino acids
How does selection occur in living organisms?
- Variation due to mutation
- Different environmental pressures
- Selection for advantageous alleles
- Differential reproductive success
- Change in allele frequency
- Occurs over a long period of time
How can a mutation lead to a non-functional enzyme.
- change in base sequence
- change in amino acid sequence
- change in hydrogen/disulphide/ionic bonds
- change in tertiary structure
- substrate not complimentary so no ESC
Not all mutations cause a change. Explain why.
- triplets code for same amino acid
- mutation occurs in introns
- new allele is recessive so does not affect phenotype
- results in formation of new allele
How can a gene mutation have a positive effect.
- change in polypeptide positively changes the properties
- may result in increased reproductive success
What is a silent mutation?
- no change in amino acid
- no effect on polypeptide chain
What are some mutagenic agents?
- increases rate of spontaneous mutation
- high energy ionising radiation = chemicals alter DNA structure
- biological agents = e.g. viruses and bacteria
- DNA reactive chemicals = e.g. nitrous acid can remove NH2 groups from cytosine and convert it to uracil
What is an inversion mutation?
Segment of bases reversed end to end
