Genome projects and gene technologies Flashcards
What is the genome?
All the genes in an organism.
What is the proteome?
All the proteins produced by an organism.
Why is determining the proteome of prokaryotes easier than eukaryotes?
Prokaryotes don’t have introns, so their genome directly codes for proteins.
What is recombinant DNA technology?
Transferring DNA fragments from one organism to another to produce proteins.
Why is recombinant DNA possible across species?
The genetic code is universal, and transcription/translation mechanisms are conserved.
What are transgenic organisms?
Organisms containing DNA from a different species.
How does reverse transcriptase help in producing DNA fragments?
It converts mRNA into complementary DNA (cDNA), useful because mRNA is more abundant.
What does a reverse transcriptase reaction contain?
mRNA, reverse transcriptase enzyme, and free DNA nucleotides.
What do restriction endonucleases do?
Cut DNA at specific palindromic sequences, creating sticky ends.
What are sticky ends?
Short single-stranded sequences at the end of DNA fragments that can base-pair with complementary sequences.
What is a gene machine?
A device that synthesizes DNA fragments from scratch without needing a template.
What is in vivo amplification?
Copying DNA inside living organisms, usually via transformation.
Step 1 of in vivo cloning – how is the DNA fragment inserted into a vector?
Both vector and DNA fragment are cut with the same restriction enzyme; ligase seals them via phosphodiester bonds.
Step 2 – how is DNA transferred to host cells?
Via transformation using plasmids (cell membranes made permeable) or bacteriophages (inject DNA directly).
Step 3 – how are transformed cells identified?
Marker genes (e.g. fluorescent) are used; only cells with the new DNA glow under UV light.
Why are promoter and terminator regions needed in vectors?
So RNA polymerase knows where to start and stop transcription.
What is in vitro amplification?
Copying DNA outside living organisms using polymerase chain reaction (PCR).
What are primers?
Short DNA strands complementary to the start of the DNA fragment.
Outline the steps of PCR.
Heat to 95°C – separates DNA strands.
Cool to 50°C – primers anneal.
Heat to 72°C – DNA polymerase adds nucleotides.
Repeat – DNA amount doubles each cycle.
What is gene therapy?
Treating genetic disorders by inserting functional alleles into cells.
What is somatic gene therapy?
Alters body cells; effects not inherited.
What is germline gene therapy?
Alters sex cells; effects passed to offspring. It is currently illegal in humans.
What are DNA probes used for?
To locate specific alleles or mutated genes.
What is a DNA probe made of?
A short single-stranded DNA with a fluorescent or radioactive label.
How is a probe used to identify alleles?
DNA is digested, separated by electrophoresis, transferred to membrane, and incubated with probe; bound probe fluoresces under UV.
What is a DNA microarray?
A slide with many DNA probes to detect multiple genes/alleles in a single test.
What are variable number tandem repeats (VNTRs)?
Short, repeating non-coding DNA sequences that vary between individuals.
What is genetic fingerprinting?
Comparing the number/position of VNTR repeats in different individuals’ DNA.
What is electrophoresis used for?
Separating DNA fragments by size using an electric field.
How is a genetic fingerprint made?
DNA sample is amplified via PCR (targeting VNTRs).
Fragments are tagged and separated by electrophoresis.
Bands are visualised under UV and compared.
How can genetic fingerprinting be used?
Determine genetic relationships (e.g. paternity).
Assess genetic diversity in a population.
Forensic identification.
