Biology - dna and gene technologies Flashcards
how is dna contained in eukaryotic cells
contained in nucleus in long, thread-like structures called chromosomes
what is dna
large polymer made up of smaller monomers
what are the monomers of dna made up of
monomer is a nucleotide, made of three components, a sugar (ribose), a phosphate and a nitrogenous base
there are 4 bases: adenine, cytosine, guanine, thymine
nucleotide bases
complementary base pairing
bases bond by hydrogen bonding
structure of dna
made up of 2 polynucleotide chains (strands) that are twisted around each other to form a double helix
protein synthesis
- chromosome consists of millions of bases of dna
- gene is a section of chromosome which codes for a specific protein
- code is read as triplets and each triplet codes for a single amino acid
- there are some triplets that code for the same amino acid
- the sequence of amino acids produces the protein
what is a mutation
change in dna sequence
harmful mutations
- mutations can be harmful if it changes a triplet, which will then code for a different amino acid and therefore change the structure of the protein
- if a mutation occurs within an enzyme, the active site may no longer be complementary to the substrate
what are silent mutations
- large sections of dna do not code for proteins
- mutations are unlikely to affect phenotype
- could happen if a change in a triplet occurs but the new triplet still codes for the same amino acid
what is genetic engineering
- modification of organism’s genetic material
- involves taking a copy of a gene from one organism and inserting that gene into another organism’s dna
- creates GMO or GENETICALLY MODIFIED ORGANISM, which is also called TRANSGENIC
what are the steps of genetically engineering bacterial cells
- useful gene cut from dna using RESTRICTION ENZYME (enzyme cuts dna in staggered way, creates sticky ends)
- BACTERIAL PLASMID DNA cut open using SAME RESTRICTION ENZYME, also creating sticky ends (unpaired bases on ends of plasmids are complementary)
- useful gene and plasmid dna are mixed and gene is inserted into plasmid through hydrogen bonds that form complementary bases in sticky ends
- DNA LIGASE is used to join the plasmid DNA and gene together, creating RECOMBINANT PLASMID
- recombinant plasmid is then inserted into bacterial cell - plasmid acts as a VECTOR, as it carries the gene into the bacterial cell
- bacterial cell can be cultured through cloning, so multiple GENETICALLY MODIFIED bacteria containing recombinant plasmid will be made
examples of proteins produced by genetically engineering bacterial cells and their uses
- hormones e.g. insulin to treat diabetes
- enzymes e.g. rennin for producing cheese
- blood clotting factors e.g. factor VIII in order to treat haemophilia
- antibiotics e.g. penicillin
genetically engineering of plants
- plants dont have plasmids
- plants have bacteria AGROBACTERIUM TUMEFACIENS used to make GM plants (these have Ti PLASMID that is able to enter plant cells and genome when bacteria infect plant)
- plant cells grown in culture and then develop into new plants thatt contain useful gene
examples of GM plants
pest resistance in Bt cotton
disease resistance in bananas
adding nutrients to avoid malnutrition in countries e.g. golden rice infused with carotene to prevent vitamin A deficiency
genetic engineering in producing medicine
e.g. insulin, blood clotting factors
- can produce larger quantities of medicine
- fewer side effects as human proteins
- however, there are concerns about unknown long-term consequences as relatively recent technology
