M6 - Genetic change Flashcards
explain how a range of mutagens operate
External causes of mutations are called mutagens, these include:
Electromagnetic radiations - eg. UV radiation
Chemicals - eg. nicotine, Agent Orange
Naturally occurring - as a result of biological reactions eg. hydrogen peroxide
compare the causes, processes and effects of different types of mutation
point mutations - involves alterations to one (or more) bases or one or more bases being inserted or deleted from a DNA strand at a single point.
causes
- can be spontaneous (natural) or be induced (unnatural).
- Spontaneous mutation deals with errors in normal DNA replication that are not repaired by enzymes resulting in insertion or deletion of a nitrogenous base from DNA sequence.
- Induced mutation can be due to the exposure to environmental agents such as ionising radiation, chemicals or naturally occurring substances.
types
silent - no change to the amino acid sequence in polypeptide
missense - change to one amino acid
nonsense - premature stop codon, shortens polypeptide, results in non functioning polypeptide
chromosomal mutations - involves changes to entire chromosomes or significant parts of a chromosome. It can also include deletion of an entire chromosome, or sections of a chromosome duplicating, being deleted, inverting or moving location (translocation)
types
numerical abnormalities - extra or missing chromosome
structural abnormalities - chromosomes having chunks deleted, duplicated, or translocated from one chromosome to another, or them being inverted
distinguish between somatic mutations and germ-line mutations and their effect on an organism
Somatic mutations - occurs in a body cell and cannot be inherited by an offspring, can have significant impact eg. cancer
Germ-line mutations - occurs in a gamete (egg or sperm cell) and can be inherited by offspring, do not impact the individual but can give rise to new variations in the population
assess the significance of ‘coding’ and ‘non-coding’ DNA segments in the process of mutation
Coding
DNA sequence in the coding regions of DNA is responsible for the mRNA sequence during transcription. Then, the mRNA codons each specify an amino acid, resulting in an amino acid sequence of a polypeptide chain during translation. Polypeptide chains can be folded to make proteins. Therefore the mutation in the coding regions will affect the mRNA sequence, amino acid sequence and, thus, the structure & function of the resulting protein.
Non Coding
Can affect regulating the gene activity, which lead to increased or decreased production of the protein. They control the action of regulatory proteins (they act on genes and regulate their functions) meaning mutation in the non- coding segments may result an unwanted proteins being expressed.
investigate the causes of genetic variation relating to the processes of fertilisation, meiosis and mutation
compare the processes and outcomes of reproductive technologies
Artificial insemination:
Medical option used for fertility treatment and involves placing male semen into the vagina or uterus of a suitable female.
Process
An AI technician collects semen from the desired bull using an artificial vagina
The bull’s semen is kept frozen until ready for use
The farmer contacts an AI technician when his cow is in heat
The AI tech uses an insemination rod to place the semen directly into the cow’s uterus
Outcomes
Reduces risk of injury or disease transmission that is associated with traditional cattle mating
Increase genetic variation in their herd and to introduce specific desired traits into their herd
Artificial pollination
The process of manually fertilising flowers.
Process
They use a brush to collect pollen from Plant B
Then the pollen collected is placed onto Plant A
Outcomes
Results in fewer offsprings
analysing single nucleotide polymorphism (SNP)
When an SNV (single nucleotide variants) occurs in 1% or more of the population, it is then an SNP. They are located within any region of DNA - coding or non coding. To be classified as an SNP, two or more versions of the DNA sequence must occur in at least 1% of the population. The frequency of DNA variations between individuals is determined by international collaboration to share DNA sequencing data. Computer analysis and mathematical modelling allow the frequency of a valiant to be determined.
investigate and assess the effectiveness cloning, including but not limited to:
- whole organism cloning
- gene cloning
whole organism cloning
animals
- cloned using a technique called somatic cell nuclear transfer (SCNT).
- this results in a clone of the organism that contributed the nucleus.
plants
- cloned using techniques such as cutting and grafting
- only certain combinations of plants will successfully grow together using grafting
Gene cloning
- an exact copy of a single gene
- uses PCR, when a DNA sample is extracted from a cellular source,
- then sample is heated to unwind the double stranded DNA
- then it is cooled to allow primers (short, custom built sequences of DNA) to attach to the target DNA
- then DNA polymerase (proteins that assist in copying DNA) attach to the single-stranded DNA after each primer to facilitates the additional of complementary nucleotides
- this cycle repeats, allowing target DNA sequence to be copied many times
- results in billions of copies
describe techniques and applications used in recombinant DNA technology
Recombinant DNA (rDNA) is defined as the DNA that results from moving a section of DNA from its normal location and inserting it into another site. It can occur naturally or it can occur by using biotechnology.
Methods of inserting recombinant DNA include
- Using a virus as a vector to insert DNA into a host cell
- “cutting and pasting” the DNA from the original organism into s bacterial plasmid
- Injecting DNA directly into the cell nucleus of host eg. using a gene gun to blast the gene in or using a sharp micropipette to perform microinjection
Gene Cloning using rDNA
- involves creating a transgenic bacterium with the desired gene inserted into its plasmid, along with the appropriate gene regulators
- this bacterium then undergoes fission to reproduce, leading to more transgenic bacteria with the desired gene being produced
- hence each offspring bacterium has a clone of the gene and so can produce the gene product
investigate the use of technologies to determine inheritance patterns in population
DNA sequencing - determining the order of nucleotide bases in a stretch of DNA.
DNA profiling - identifies individuals using specific sites known to have variation between individuals such as STRs (short tandem repeats) - varies in length due to different number of repeats
