A revision summary of OCR A level Biology Manipulating Genomes 6.1.3
Made by a student who achieved A* in A level Biology.
Covers all the points within the OCR Biology Specification.
Condenses 3 OCR specification books and class notes.
Manipulating Genomes
Genome – all the genetic material within an organisms (incl. DNA & Polymerase Chain Reaction (PCR) - Amplifies DNA sample.
mitochondria) 1. DNA mixed with
- Exons – code for proteins (only 2% of DNA) - Primer - short single stranded sequence of DNA,
- Introns – non-coding regions (98% of DNA) - DNA polymerase & excess nucleotides
Bioinformatics – development of software to collect & comprehend biological 2. Denaturation
data - mixture placed in thermal cylinder and heated to 95°
- Access to large volumes of data on DNA and proteins which is universal. - H bonds broken & DNA strands separate
- Comparison of sequences to identify genetic disease. 3. Annealing
- Identify source of outbreak, mutations in outbreak, prediction of future - Mixture cooled to 50°
mutations, identify vulnerable populations & which to give vaccine to. - Primers can bind to complementary base pairs of DNA.
Computational biology- sequencing data to build (computational) theoretical This marks the start of sequence to be synthesised.
models of biological systems, to predict what will happen in circumstances. 4. Extension
- Analyse pathogen – sequencing can determine the genetic code of disease - Mixture heated to 72°
and the antigen proteins it codes for. Helping make vaccines. - Optimum temp for DNA polymerase to add free
- Evolutionary relationships – comparison of genomes confirms or leads to complementary nucleotides to primers
reclassification of evolutionary relationships. - form sugar phosphate backbone
- Proteomics – the study of amino acid sequencing, the sequence of bases Applications
codes for an amino acid. 3 bases code for one amino acid. - Detecting viral infections e.g. COVID19 PCR tests
o We can identify which alleles are associated with disease - Detecting mutations of virus e.g. COVID19
o Identify spliceosomes – the idea a single gene can code for multiple - Forensic – amplifies small quantities of DNA from crime
proteins. Exons can be joined in different ways = different proteins. scene
Synthetic biology – design & construct artificial biological pathways & - Monitoring spread of infectious disease
organisms. - Amplifies DNA of extinct organisms
- Genetic engineering e.g., gene modification - Tissue typing – matches donor & recipient DNA to
↓rejection
DNA Sequencing – process of determining the precise order of nucleotides within a DNA molecule
Fred Sanger – replicated single stranded DNA by interrupted PCR
1. DNA is mixed with primer, DNA polymerase, excess nucleotides,
2. dNTPs added – known modified bases with radioactive isotope. Joining stops formation of sugar phosphate backbone & sequence is
terminated.
3. Denaturation process (explain…)
4. Annealing process (explain…)
5. Extension process (explain…)
6. Each time DNA polymerase randomly synthesises dNTP’s sequence is terminated. This forms many DNA fragments of different lengths. After
high repetitions, DNA chains are produced with terminator base in every possible position.
7. End base pair of each DNA fragment is known (by colour of radioactive isotope). Sequence of radioactive dNTPs used to determine DNA
sequence.
8. Capillary flow sequencing - DNA sample drawn through capillary tubes. Fluorescent markers on dNTPs read by laser beam and placed in
sequence.
Order of bases in capillary tube show sequence of complementary strand to original DNA.
(modern tech) uses High Throughput sequencing e.g. Next Generation Sequencing – millions of fragments of DNA can be sequenced
simultaneously
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