mod 6 Flashcards
1
Q
Electromagnetic radiation mutagen
A
- Ionising radiation is radiation with enough energy to remove electrons from atoms.
- Causation of mutations
- X-rays, gamma rays, alpha and beta particles.
- Directly cause mutations by causing ionisation within DNA, breaking sugar-phosphate backbone or hydrogen bonds between nitrogenous bases.
- Indirectly by ionising other molecules in the cell, which can produce free radicals that can interact with other molecules to form compounds that harm DNA.
2
Q
Chemicals mutagen
A
- Changing bases in DNA, such as reactive oxygen species, free radicals, heavy metals and deaminating agents.
Deaminating agents can remove an amino group from a base, turning it into another base.
3
Q
Naturally occurring mutagens
A
- appear through natural processes and are derived from natural processes such as microbes, plants, animals or the sun.
- biological include various toxins produced by living organisms, such as mycotoxins formed by fungi.
Non biological include heavy metals such as arsenic and lead or chemicals in charred food like burnt toast.
4
Q
point mutations
A
- mutations in a single base of DNA that can alter the function of the protein encoded by the gene
- Single change in a base can alter an amino acid leading to change in protein shape, altering produced protein.
- Mostly occurs in non coding DNA regions (introns) and dont affect DNA sequence as it isnt translated during protein synthesis.
- silent mutations, missense nonsense, missense substitution, insertion, deletion.
5
Q
chromosomal mutations
A
- occur in large regions of a chromosome and often involve many genes. more detrimental then point mutations
- deletion of a section of a chromosome often most detrimental
- duplication
- inversion; sections of the same chromatid being replaced by each other.
- translocation when sections of sister chromatids replace each other
- nondisjunction is the failure of a homologous pair of chromosomes to segregate during meiosis resulting in the duplication of a chromosome
6
Q
germline mutations vs somatic mutations
A
- germline are those which occur in gametes or cells that divide to give rise to gametes while somatic occur in any cell other then reproductive cells
- somatic cell mutations can potentially have no or significant effect such as tumour suppressing genes being changed, leading to cancer or excessive exposure to the Sun’s UV rays leading to skin cancer.
- As germline mutations occur in reproductive cells, they can be passed onto offspring. In many cases the gene is passed on but not phenotypically expressed, due to recessive mutations. However throughout generations an individual with two copies of the recessive allele will emerge
7
Q
coding and non coding DNA segments
A
- coding regions exons and non coding regions introns
- exons responsible for gene expression through protein synthesis and introns not responsible for gene expression as via RNA splicing introns in mRNA are removed and thus can’t be translated. Most of the DNA in a cell is non-coding DNA hence most mutations have no effect due to being in introns.
- RNA splicing is involved in the termination step of transcription. FIrstly a 5-cap and a poly-A-tail is attached to the ends of the pre-mRNA to stabilise it. Specific locuses being the introns are recognised and removed by the spliceosome, a protein catalyst. Then the pre-messenger RNA becomes mRNA.
8
Q
Causes of genetic variation
A
- When a germline mutation occurs in exons, the changed gene produces a new allele.
- Thus starts with germline mutations
- Fertilization shuffles the DNA of each parent through sexual reproduction, emerging offspring with a combination of genetic material from each parent, increasing genetic variation.
- During meiosis and metaphase I, independent assortment of homologous chromosomes resulting in new combinations of alleles by shuffling parent alleles. Homologous chromosomes line up randomly at equator, shuffling paternal and maternal chromosomes.
- crossing over is during prophase I, where alleles of non-sister chromatids of homologous chromosomes are reshuffled, producing new alleles.
9
Q
effect of mutation, genetic drift and gene flow on gene pool
A
- arising of alleles via mutation create the gene pool of a population which is the total of all the alleles of all genes in a population of species at a particular time. natural selection dependent on genetic phenotypic variation, thus without mutation evolution can not ensue.
- gene flow is the transfer of genetic material across all populations, typically via migration. can directly introduce new alleles to a population or change the frequency of alleles directly affecting gene pool.
- genetic drift refers to random changes in allele frequencies of a population. Founder effect is the formation of a new population by a small group of an existing parent population, where the genetic makeup of this population is not representative of the existing population. this results in a different allele frequency as the original population, hence new alleles may emerge be maintained or removed, affecting gene pool. The genetic bottleneck effect is the occurrence of a population on the brink of extinction growing in number again, changing allele frequency as surviving individuals give rise to a genetically distinct population. new alleles can emerge, they can be maintained or removed, affecting gene pool.
10
Q
biotechnology meaning
A
- defined as the exploitation of living organisms or their products to improve human health and the environment
11
Q
genetic technologies meaning
A
- refers to a range of activities concerned with understanding gene expression, exploiting genetic variation ,modifying genes and transferring genes to new hosts.
12
Q
Artificial insemination
A
- refers to the direct injection of semen from a male with desired traits into the uterus of a female to induce pregnancy. Hence offspring will most likely have the desired traits
- Advantages: sperm can be stored away thus artifical insemination can occur at the right time, allows for farmers to keep a herd of cows without the need for bulls. Continual production of desired animals maintains an excellent genetic stock improving herd and economically benefitting farmers
Disadvantages: Decrease in genetic variation, leaving populations more susceptible to extinction by disease. Ethical concerns such as the question if it is morally acceptable to interfere in the reproduction process, expression of desired trait not guaranteed
13
Q
Artificial pollination
A
- refers to the process of transferring pollen from the anthers of a plant with a desired trait to the stigma of another flower
- Advantages: Produced offspring with desired traits, enables horticulturists to select and breed plants with desirable characteristics to improve quality or yield of a crop.
- disadvantages: decrease in genetic variation leaving populations more susceptible to extinction by disease, expression of desired trait not guaranteed, requires excessive time and labor
14
Q
Whole organism cloning
A
- Creates an identical copy of an entire multicellular organism through somatic cell nuclear transfer (SCNT). Firstly extracting somatic cell from desired organism and nucleus is extracted. Another female’s egg is denucleated to remove genetic material and the nucleus from the somatic cell is inserted into the egg and the resulting embryo is placed into another surrogate mother who will birth the cloned individual.
- Very ineffective, success rate is very low, however it does occur such as in Dolly, the first cloned organism being a Finn-dorset sheep.
- advantages: if cloned organism succeeds in arising, it will produce guaranteed desired organism
- disadvantages: very ineffective, rarely successful. reduces genetic variation. Major ethical concerns regarding longevity and health of cloned organism, such as Dolly living for approximately half of the expected lif duration for Finn-dorset sheeps. Not fully known why. but research suggests the telomeres of the chromosomes from the somatic cell are already shortened, essentially the cloned organism isnt born at the age of 0. Immoral in society due to religious beliefs and social values about human dignity.
15
Q
Gene cloning
A
- refers to the process of incorporating a gene into a plasmid, which when introduced into a suitable host self replicates and creates large number of identical copies of the gene. used to gain information about the nucleotide sequence of a specific gene, or to use the specific gene for curative purposes.
- restriction enzyme used to cut either side of the human gene at interest, as well as to cut a specially selected plasmid. this makes them have the same complementary sticky ends. In some cases the desired gene will be incorporated into a plasmid, being the recombinant plasmid. Bacteria are made competent to take up plasmids, so the bacteria are grown on an agar plate containing the antibiotic, and bacteria that have not taken up a plasmid will lack the gene for resistance to the antibiotic and will not grow. Bacteria that have taken up a recombinant plasmid will not glow in the dark. Bacteria with recombinant plasmid will be transferred to another nutrient medium to grow, and all the resulting bacteria will contain the recombinant plasmids. other vectors can be used such as BACS.
- relatively little issues regarding effectiveness and ethical concerns. proven effective in biopharmaceuticals such as being used to produce human insulin curing diabetes and used in creating copies of CTFR gene to cure cystic fibrosis.
