6: Biotechnology & Genomics for A-Level Biology (OCR)

Why can a gene from one species be expressed in a different organism?

Due to the universal genetic code.

Codons specify the same amino acids in nearly all organisms, enabling cross-species gene function.

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What type of organism contains DNA from another species following gene transfer?

Transgenic organism

A transgenic organism has been genetically modified to contain foreign DNA.

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Which enzyme synthesises DNA from an mRNA template when producing complementary DNA?

Reverse transcriptase

This enzyme forms cDNA from mRNA, allowing genes without introns to be cloned.

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What DNA copy is produced from mRNA during gene cloning to avoid introns?

Complementary DNA

(cDNA)

cDNA represents only expressed genes because it is synthesised from mature mRNA.

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What type of enzyme cuts DNA at specific recognition sequences to isolate genes?

Restriction endonuclease

These enzymes recognise specific base sequences and cut the DNA backbone.

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What process artificially synthesises a gene in the laboratory using automated equipment?

Gene machine

A gene machine chemically synthesises DNA sequences without needing a template.

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What laboratory technique rapidly amplifies specific DNA fragments in vitro?

Polymerase chain reaction

PCR uses repeated heating and cooling cycles with DNA polymerase to copy DNA.

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What method increases DNA quantity by growing transformed cells containing recombinant DNA?

Culture of transformed host cells

Host cells replicate the inserted DNA as they divide.

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What regulatory DNA sequence must be placed before a gene to allow transcription to begin?

Promoter

RNA polymerase binds to the promoter to start transcription.

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What regulatory sequence signals the end of transcription in a gene construct?

Terminator

Terminator sequences cause RNA polymerase to detach from the DNA.

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What enzyme joins DNA fragments together during the construction of recombinant DNA molecules?

DNA ligase

DNA ligase forms phosphodiester bonds between adjacent DNA fragments.

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What type of DNA carrier is used to transfer inserted genes into host cells?

Vector

Common vectors include plasmids and viruses used to deliver recombinant DNA.

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What process introduces recombinant DNA vectors into host cells?

Transformation

Transformation allows host cells to take up recombinant plasmids or viral DNA.

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True or False:

PCR amplifies DNA by repeatedly cycling through heating and cooling stages.

True

Heating separates strands, cooling allows primers to bind, and DNA polymerase extends new strands.

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True or False:

Restriction enzymes join DNA fragments together to form recombinant molecules.

False

Restriction enzymes cut DNA; ligases join fragments.

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Fill in the blank:

Genes inserted into vectors are often identified using ______ genes that indicate successful genetic modification.

marker

Marker genes allow detection of cells that have taken up recombinant DNA. Examples include antibiotic resistance genes.

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What therapy involves inserting functional genes into human cells to treat genetic disorders?

Gene therapy

Recombinant DNA technology enables therapeutic genes to be introduced into patient cells.

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True or False:

Ethical concerns about recombinant DNA technology can involve environmental impacts and ownership of genetic resources.

True

Debates include GM crops, patents on genes, and ecological effects.

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Short fragments of single-stranded nucleic acid used to find complementary DNA sequences in a sample are known as what?

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DNA probes

They bind to complementary sequences through base pairing, allowing specific genes or alleles to be detected.

What process allows a single-stranded nucleic acid fragment to bind to a complementary DNA sequence?

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DNA hybridisation

Complementary base pairing allows the probe to attach to a matching target DNA sequence.

Why are fluorescent or radioactive tags attached to probes used in genetic testing?

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To make probe binding detectable.

Labels allow scientists to see where the probe has attached to DNA containing the target sequence.

Fill in the blank:

A probe used to detect a specific allele must have a ______ base sequence to the target DNA

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complementary

Complementary base pairing ensures the probe binds only to the correct DNA sequence.

How do labelled probes identify individuals with alleles linked to inherited diseases?

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By screening for specific alleles.

If the probe binds, the allele associated with the condition is present in the DNA sample.

True or False:

Labelled probes can only be used to detect entire genes and cannot identify specific alleles.

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False

Probes can be designed to detect very small sequence differences between alleles.

Using **genetic information** to advise individuals about the risk of passing on **inherited disorders** is known as what?

Genetic counselling ## Footnote Counselling may involve explaining risks, testing options and possible medical decisions.

What **medical approach** uses a person’s **genetic information** to guide treatment decisions such as drug choice or dosage?

Personalised medicine ## Footnote Genetic variation can influence drug metabolism and effectiveness.

# True or False: **Genetic screening using probes** can identify individuals who may respond differently to certain drugs.

True ## Footnote Some genetic variants affect how drugs are metabolised or how effective they are.

# Fill in the blank: The process of analysing many individuals to identify those with **genetic variants** linked to disease risk is called genetic \_\_\_\_\_\_.

screening ## Footnote Screening programmes may identify carriers, at-risk individuals, or people likely to benefit from preventative treatment.

What kind of repeated DNA sequence varies in number between individuals and is used in **genetic fingerprinting**?

VNTRs ## Footnote Variable number tandem repeats are short sequences repeated a different number of times in different people.

Why is a **DNA profile** unique to an individual?

Different VNTR patterns ## Footnote The number of repeats at multiple VNTR loci varies, making chance matches unlikely.

What is the first major step used to make many copies of selected DNA regions before producing a **DNA profile**?

PCR ## Footnote PCR amplifies target DNA so there is enough material to analyse.

After **PCR** has amplified DNA fragments, what laboratory method separates them by size?

Gel electrophoresis ## Footnote DNA fragments move through a gel; smaller fragments travel further.

# Fill in the blank: In **gel electrophoresis**, the \_\_\_\_\_\_ DNA fragments move furthest through the gel.

smaller ## Footnote Separation depends on fragment length because shorter fragments pass more easily through the gel matrix.

What feature of DNA causes fragments to move towards the **positive electrode** during electrophoresis?

Negative phosphate groups ## Footnote DNA is negatively charged because of its phosphate backbone.

What visible result is compared between samples to decide whether **DNA profiles** match?

Banding pattern ## Footnote Matching individuals show bands in the same positions on the gel.

# True or False: Two unrelated individuals are very likely to have identical **VNTR patterns**.

False ## Footnote The chance is very low, which is why DNA profiling is useful for identification.

How can **genetic fingerprinting** be used in forensic science?

Match crime scene DNA. ## Footnote Investigators compare DNA from a sample such as blood or hair with suspects’ DNA profiles.

How can **genetic fingerprinting** help determine genetic relationships?

Compare inherited bands. ## Footnote Closely related individuals share more DNA fragments because some alleles are inherited from common parents.

Why might doctors use **genetic fingerprinting** in medical diagnosis?

To identify disease-linked alleles. ## Footnote It can help detect whether a person carries or has inherited particular genetic variants.

# True or False: **Genetic fingerprinting** can be used to estimate genetic variability within a population.

True ## Footnote More variation in DNA profiles suggests greater genetic diversity in the population.

Why is **genetic variability** important for breeding programs?

Select desirable individuals to enhance traits. ## Footnote Breeders identify relatedness and choose parents with useful characteristics while managing diversity.

# Fill in the blank: In a **parent–child DNA profile** comparison, some bands in the child must match the \_\_\_\_\_\_.

parents ## Footnote A child inherits alleles from both parents, so every band should come from one or the other.

Why is **PCR** especially useful when analysing forensic samples?

Tiny samples can be amplified. ## Footnote Crime scene DNA is often present in very small amounts, so amplification is needed before analysis.

# True or False: **Gel electrophoresis** separates DNA fragments according to base sequence rather than fragment length.

False ## Footnote In this context, fragments are separated mainly by size, not by their exact nucleotide order.

What does a larger number of **shared bands** usually suggest when comparing two DNA fingerprints?

Closer genetic relationship ## Footnote Relatives tend to have more bands in common than unrelated individuals.

Why might **genetic fingerprinting** be useful in animal and plant breeding beyond selecting traits?

To identify genetic relatedness and avoid inbreeding. ## Footnote DNA profiles can reveal relatedness, helping breeders reduce mating between closely related individuals.

6: Biotechnology & Genomics Flashcards

Explain applications of genome sequencing and gene technologies. (46 cards)