AQA A-LEVEL BIOLOGY CHEAT SHEET
GENETIC INFORMATION,
VARIATION AND
RELATIONSHIPS BETWEEN
ORGANISMS
, DNA IN EUKARYOTES VS PROKARYOTES (PROKARYOTIC DNA IS THE SAME AS D
CHLOROPLAST + MITOCHONDRIAL DNA)
• EUKARYOTIC DNA IS LINEAR, PROKARYOTIC DNA IS CIRCULAR CHRO
• EUKARYOTIC DNA IS LONGER, PROKARYOTIC DNA IS SHORTER & IMPORTANT D
• EUKARYOTIC DNA IS BOUND TO HISTONES, PROKARYOTIC DNA IS NOT (DNA +
HISTONES = CHROMOSOMES)
T
• EUKARYOTIC DNA CONTAINS INTRONS, PROKARYOTIC DNA DOES NOT CONTAIN
• Non-overlapping - each base
INTRONS
• GENES – SEQUENCES OF DNA BASES WHICH CODE FOR THE AMINO ACID SEQUENCE OF • Degenerate– more than 1 trip
A POLYPEPTIDE OR FUNCTIONAL RNA (RRNA, TRNAS) the same, s
BASE SEQUENCES OF DNA IN A TRIPLET DETERMINES THE SEQUENCE OF AMINO ACIDS IN • Universal – the same triplet
A POLYPEPTIDE (PRIMARY SEQUENCE OF AMINO ACIDS DETERMINE TERTIARY STRUCTURE the same amino acid in all li
ETC…)
NONE CODING SEQUENCES MAY BE POSITIONED BETWEEN GENES
• INTRONS – SEQUENCE OF DNA BASES NOT CODING FOR (A SEQUENCE OF) AMINO
ACIDS/POLYPEPTIDES
Why some gene mutatio
• EXONS – TRIPLET SEQUENCE CODING FOR A POLYPEPTIDE (INTRONS FOUND WITHIN •
GENES) 1. Change in base se
• LOCUS – FIXED POSITION OF A GENE ON EACH CHROMOSOME IN A HOMOLOGOUS 2. Results in formation of a new combi
PAIRING 3. Degenerate genetic code, so amino acid s
change // mutation in intron, so AA se
• HOMOLOGOUS CHROMOSOMES ARE OF THE SAME SIZE, SAME GENES, MAY HAVE
DIFFERENT ALLELES
4. New allele recessive so does not influ
• ALLELE – ALTERNATIVE FORM/VERSION OF A GENE 5. Results in change in polypeptide that
• TRIPLET – SEQUENCE OF 3 DNA BASES
pr
6. May change amino acid but not its t
• MUTAGENIC AGENT – A FACTOR THAT INCREASES THE RATE OF MUTATIONS
• PROTEOME – FULL RANGE OF DIFFERENT PROTEINS A CELL CAN PRODUCE
• GENOME – COMPLETE SET OF GENES IN A CELL
GENETIC INFORMATION,
VARIATION AND
RELATIONSHIPS BETWEEN
ORGANISMS
, DNA IN EUKARYOTES VS PROKARYOTES (PROKARYOTIC DNA IS THE SAME AS D
CHLOROPLAST + MITOCHONDRIAL DNA)
• EUKARYOTIC DNA IS LINEAR, PROKARYOTIC DNA IS CIRCULAR CHRO
• EUKARYOTIC DNA IS LONGER, PROKARYOTIC DNA IS SHORTER & IMPORTANT D
• EUKARYOTIC DNA IS BOUND TO HISTONES, PROKARYOTIC DNA IS NOT (DNA +
HISTONES = CHROMOSOMES)
T
• EUKARYOTIC DNA CONTAINS INTRONS, PROKARYOTIC DNA DOES NOT CONTAIN
• Non-overlapping - each base
INTRONS
• GENES – SEQUENCES OF DNA BASES WHICH CODE FOR THE AMINO ACID SEQUENCE OF • Degenerate– more than 1 trip
A POLYPEPTIDE OR FUNCTIONAL RNA (RRNA, TRNAS) the same, s
BASE SEQUENCES OF DNA IN A TRIPLET DETERMINES THE SEQUENCE OF AMINO ACIDS IN • Universal – the same triplet
A POLYPEPTIDE (PRIMARY SEQUENCE OF AMINO ACIDS DETERMINE TERTIARY STRUCTURE the same amino acid in all li
ETC…)
NONE CODING SEQUENCES MAY BE POSITIONED BETWEEN GENES
• INTRONS – SEQUENCE OF DNA BASES NOT CODING FOR (A SEQUENCE OF) AMINO
ACIDS/POLYPEPTIDES
Why some gene mutatio
• EXONS – TRIPLET SEQUENCE CODING FOR A POLYPEPTIDE (INTRONS FOUND WITHIN •
GENES) 1. Change in base se
• LOCUS – FIXED POSITION OF A GENE ON EACH CHROMOSOME IN A HOMOLOGOUS 2. Results in formation of a new combi
PAIRING 3. Degenerate genetic code, so amino acid s
change // mutation in intron, so AA se
• HOMOLOGOUS CHROMOSOMES ARE OF THE SAME SIZE, SAME GENES, MAY HAVE
DIFFERENT ALLELES
4. New allele recessive so does not influ
• ALLELE – ALTERNATIVE FORM/VERSION OF A GENE 5. Results in change in polypeptide that
• TRIPLET – SEQUENCE OF 3 DNA BASES
pr
6. May change amino acid but not its t
• MUTAGENIC AGENT – A FACTOR THAT INCREASES THE RATE OF MUTATIONS
• PROTEOME – FULL RANGE OF DIFFERENT PROTEINS A CELL CAN PRODUCE
• GENOME – COMPLETE SET OF GENES IN A CELL
