Topic 3.5: Genetic Modification and Biotechnology Flashcards
PCR
Artificial method of replicating DNA
Stages of PCR
a) Denaturation
b) Annealing
c) Enlogation
Denaturation
DNA sample is heated to separate it into two single strands.
Annealing
DNA primers attach to the 3’ ends of the target sequence
Elongation
A heat-tolerant DNA polymerase (Taq) binds to the primer and copies the strand
PCR Materials
a) DNA sample
b) Primers
c) Taq polymerase
d) Nucleotides
Gel electrophoresis
Technique that separates proteins or fragments of DNA according to size
Gel electrophoresis process
a) Samples placed in a block of gel and current is applied
b) Smaller samples move faster through the gel (Less resistance)
DNA Separation in Gel Electrophoresis
a) DNA is negatively charged (due to phosphate group)
b) Samples will move towards the positive terminus.
Protein Separation in Gel Electrophoresis
Proteins are treated with an anionic detergent in order to impart a uniform negative charge on all molecules
DNA Profiling
Technique by which individuals can be identified and compared by their genetic sequences
DNA Profiling Process
a) Individuals have different lengths of particular DNA segments called short tandem repeats (STR)
b) These segments are amplified by PCR and then separated by gel electrophoresis for comparison
c) Unique profiles appear when multiple loci are compared
Gene transfer process
a) Isolation of gene and vector (by PCR)
b) Digestion of gene and vector (by restriction enzymes)
c) Ligation of gene and vector (by DNA ligase)
d) Selection and expression of transgenic construct
Benefits of GM Crops
a) Could be used to improve nutritional standards
b) Can grow in a wide range of environments
c) Could reduce farming costs and associated deforestation
d) Can be used to reduce spoilage (longer shelf life)
Risks of GM Crops
a) Could trigger unexpected health issues (e.g. allergies)
b) Patent protections could restrict access (equity issues)
c) Possible cross-pollination with weeds (hard to contain)
d) Could compete with native plants (reduce biodiversity)
Example of GM Crops
a) Bt corn is a transgenic crop that produces an insecticide
b) Bt corn may be impacting survival of monarch butterflies
c) In lab conditions, butterfly mortality is higher when fed plants dusted with Bt pollen
d) There is insufficient field evidence to support this
Clones
Groups of genetically identical organisms, derived from a single original parent cell
Animal cloning
a) Binary fission
b) Budding
c) Fragmentation
d) Parthenogenesis
Binary fission
a) The parental organism divides equally into two clones
b) Occurs in flatworms (also used by bacteria and protists)
Budding
a) Cells split off from parent, generating smaller clones
b) Occurs in Hydra, but is also common to yeast
Fragmentation
a) New organisms grow from separated fragment of parent
b) Common to starfish and some species of annelid worm
Parthenogenesis
a) Embryos formed from an unfertilised (diploid) ova
b) Occurs in some species of fish, insect, reptile, amphibian
Human cloning
Identical twins (monozygotic) are created when a fertilised egg (zygote) splits into two identical cells, each forming an embryo
Plant cloning
a) Plants have the capacity for vegetative propagation, whereby small pieces of plant can be induced to grow independently
b) Adult plants possess totipotent meristematic tissue capable of cellular differentiation
Stem cutting
A separated portion of a plant stem that is used to regrow a new clone via vegetative propagation
Artificial cloning
a) Embryo cloning
b) Adult cloning
Embryo cloning
a) Animals can be cloned from an embryo by separating the embryonic cells into groups
b) As embryonic stem cells are pluripotent, each cell can potentially form a cloned offspring
b) As this method occurs after random fertilization, it is not possible to control the genetic features of potential clones
Adult cloning
a) Adults can be cloned via the process of somatic cell nuclear transfer (SCNT)
b) The nucleus is removed from an adult body cell (diploid) and fused with an enucleated egg cell
c) An electric shock stimulates division of the egg cell and the growing embryo is implanted into a surrogate
