Lecture 1 Flashcards
(17 cards)
What is DNA composed of?
DNA is a very large molecule made up of smaller units called nucleotides. Each nucleotide has three parts: a sugar (ribose), a phosphate molecule, and a nitrogenous base.
What are the four nitrogenous bases found in DNA?
Adenine, cytosine, guanine, and thymine.
Define a gene.
A gene is a stretch of DNA that codes for a type of protein that has a function in an organism.
What is the difference between exons and introns?
Exons are the coding regions of a gene, while introns are the non-coding regions that are removed during splicing.
What is a genome?
The genome is the complete set of genetic material of an organism, including all of its genes, as represented in its DNA.
What is recombinant DNA (rDNA)?
Recombinant DNA (rDNA) molecules are DNA molecules formed by laboratory methods of genetic recombination to bring together genetic material from multiple sources, creating sequences that would not naturally occur.
Why is recombinant DNA technology possible?
It is possible because DNA molecules from all organisms share the same chemical structure, differing only in their nucleotide sequence.
What is a palindromic sequence in the context of DNA, and why is it important in R-DNA technology?
A palindromic sequence is a nucleic acid sequence in a double-stranded DNA molecule where reading in the 5’ to 3’ direction on one strand is identical to the sequence in the same direction on the complementary strand. It is important because R-DNA technology uses palindromic sequences and leads to the production of sticky and blunt ends.
List the first three basic steps in obtaining recombinant DNA.
- Isolate the DNA fragment containing the gene to be cloned (insert).
- Cut the DNA.
- Join DNA fragments.
What happens after DNA fragments are joined and what is the role of a vector?
The DNA fragments are inserted into a host cell using a vector. The rDNA molecules are then generated when the vector self-replicates in the host cell. These molecules are transferred into an appropriate host cell, and host cells carrying the rDNA molecule are selected using a marker.
What are commonly used vectors in rDNA technology?
Bacterial plasmids are commonly used vectors.
What are restriction enzymes and what do they do?
Restriction enzymes cut DNA molecules at specific sequences.
What enzyme is used to join DNA fragments?
Ligase enzyme.
How is vector DNA typically introduced into E. coli cells when using a plasmid vector?
The vector is added to an E. coli culture, calcium ions are added, followed by a brief heat shock. This makes the E. coli cell surface membrane permeable to DNA, allowing plasmids to enter.
Name three medical applications of genetic engineering.
- Treatment of genetic diseases (gene therapy), e.g., SCID.
- Production of medically useful biologicals (e.g., insulin, human growth hormone).
- Vaccine production.
- Pharmacogenomics.
How is recombinant DNA technology used to produce insulin?
The DNA for insulin is isolated, a plasmid is removed from a bacterial cell and cut open with a restriction enzyme. The insulin gene, with complementary sticky ends, is added to the plasmid to create a recombinant plasmid. This is inserted into transgenic bacteria, which are grown in culture to produce insulin, which is then extracted.
Describe one negative effect of Recombinant DNA Technology.
Negative effects include extensive erosion and genetic destruction of plant germplasm, ecological imbalance, production of ‘monsters,’ production of dangerous toxic chemicals, and the production of highly lethal microbes for microbiological warfare.
