22: GENE TECHNOLOGY Flashcards
(40 cards)
What are the three methods used to produce DNA fragments?
- Using restriction endonucleases
- Using a ‘Gene Machine’
- Using reverse transcriptase
These methods are crucial for obtaining specific DNA sequences for various applications in genetic technology.
Define restriction endonucleases.
A group of enzymes that cut DNA at specific sequences of bases, known as recognition sequences.
These enzymes are naturally found in bacteria and are used in molecular biology for DNA manipulation.
What are sticky ends?
Single stranded sections of DNA that form an overhang at the end of a double stranded molecule.
Sticky ends facilitate the binding of complementary DNA sequences.
What is a palindromic sequence in the context of DNA?
A base sequence on one strand is the same as on the other strand, but in reverse (e.g., GAATTC and CTTAAG).
Palindromic sequences are important for the action of restriction enzymes.
What is the advantage of using a ‘Gene Machine’?
It can produce any nucleotide sequence quickly and accurately, and the genes are free of introns.
This makes the genes suitable for expression in prokaryotic cells.
What is reverse transcriptase?
An enzyme that converts RNA into DNA, specifically used by retroviruses.
This enzyme is essential for producing cDNA from mRNA.
Fill in the blank: The DNA produced by reverse transcriptase is known as _______.
cDNA
cDNA is complementary to the original mRNA molecule.
Why must pancreatic cells be used to obtain the gene that codes for insulin?
Only pancreatic cells contain insulin mRNA, which is necessary for gene expression.
Other cells have the insulin gene but do not express it.
What is the purpose of the Polymerase Chain Reaction (PCR)?
To amplify DNA fragments, increasing their quantity for analysis.
PCR is a critical technique in molecular biology for cloning DNA.
What is the optimal temperature for Taq polymerase during PCR?
72°C
This temperature is optimal for the enzyme’s activity in synthesizing new DNA strands.
Describe the process of gel electrophoresis.
A technique used to separate DNA fragments based on length by applying an electric current through a gel.
Shorter DNA fragments move faster and farther than longer ones.
What is a gene probe?
A single stranded, short sequence of DNA nucleotides with a complementary base sequence to the target gene.
Gene probes are used in genetic screening to detect specific alleles.
True or False: Genetic disorders such as cystic fibrosis are caused by dominant alleles.
False
These disorders are typically caused by recessive alleles.
What are variable number tandem repeats (VNTRs)?
Repetitive sequences of DNA bases between genes that vary in number among individuals.
VNTRs are key components in genetic fingerprinting.
List the five main stages of genetic fingerprinting.
- Extraction of DNA
- Digestion with restriction enzymes
- Separation using gel electrophoresis
- Binding of DNA probes
- Visualisation
These stages are essential for analyzing DNA differences between individuals.
Why do closely related individuals have more similar VNTRs?
They inherit DNA from the same ancestors, leading to shared VNTR patterns.
This genetic similarity is useful in determining familial relationships.
Fill in the blank: PCR is used to amplify DNA containing the potential _______.
disease-causing allele
This amplification is crucial for detecting genetic disorders.
What is the role of genetic counselling before genetic screening tests?
To advise couples on the risks of passing genetic disorders to their children.
Genetic counsellors provide support and information based on screening results.
What is the primary use of DNA fingerprinting?
To determine paternity, genetic relationships, and variation
Individuals inherit half of their genetic material from each parent, leading to similarities in DNA fingerprints among closely related individuals.
What do repeated base sequences of different lengths in non-coding regions of DNA result in?
Restriction fragments of different lengths unique to each parent
This uniqueness allows for the differentiation of genetic fingerprints among individuals.
If the restriction bands in a DNA fingerprint do not match those of the parents, what does this indicate?
The individual is not related to the parents
This is used in paternity testing to confirm or deny biological relationships.
What role does DNA fingerprinting play in forensic science?
It helps determine who was present at a crime scene
However, it does not prove that the individual committed the crime.
How can genetic fingerprints assist in diagnosing diseases?
By matching DNA samples from affected individuals with those of known disease profiles
This is particularly useful for diseases like Huntington’s disease.
Why is screening for Huntington’s disease beneficial in families with a history of the disease?
Symptoms usually appear in middle age, and individuals may not be aware of their defective allele
This information is crucial for family planning.
