click below
click below
Normal Size Small Size show me how
Intro to Genetics
Genetics, Monohybride Crosses, Key terms.
Question | Answer |
---|---|
Gene: | A basic unit of inheritance consisting of a length of DNA on a Chromosome. |
Allele: | Different forms of a Gene inherited from Parents. |
Genotype: | The genetic make up of an organism. |
Phenotype: | The physical and chemical characteristics of an Organism. |
Recessive Allele: | Alleles whose phenotype will only be displayed if the organism is Homozygous for that Allele. |
Dominant Allele: | Alleles whose Phenotype will be apparent whenever it is present, in both Homozygous and Heterozygous situations. |
Homozygous: | An organism that has the same Allele of a Gene. (E.g Both recessive Alleles for Cystic Fibrosis). |
Heterozygous: | An organism that had two different types of Allele for a Gene (e.g a Pea with Gg). |
Monohybrid Inheritance: | The inheritance of a gene from two Homozygous parents that have different alleles. |
Somatic Gene Therapy: | Gene Therapy in which the Therapeutic Genes are transferred to the cells of the body. The treatment is limited to the individual and is not hereditary. |
Germline Gene Therapy: | Gene Therapy in which the Therapeutic genes modify the Germ (sex) cells, thus making the treatment Hereditary. |
Gene Therapy: | The process of replacing defective Genes with Therapeutic Genes which code for the correct protein. |
Name the types of Genetic Screening: | |
What are the issues with Germline Gene Therapy? | Altering the DNA of an embryo in early stages could cause unwanted side effects. Also, where would the line be drawn? What is okay to change and what isn't? |
Name the four types of Genetic Screening: | Preimplantation Genetic Testing (done in IVF), Identification of Carries (done on parents before conception), Amniocentesis and Chorionic Sampling. |
Amniocentesis and disadvantages: | Samples of the Amniotic fluid taken at 16+ weeks, cells analysed for genetic disorders. Disadvantages include 1% chance of spontaneous abortion, late testing so termination difficult and long testing time. |
Chorionic Sampling and disadvantages: | Samples of the Embryonic tissues taken at 8-10 weeks, cells are actively dividing so quicker results. Disadvantages include, 2-4% chance of spontaneous abortion, no sex linked diagnostic as X chromosome inactive. |
Preimplantation Genetic Screening: | This is done during IVF, cells are taken from embryos that are 8 -10 cells big and the DNA is screened for genetic disorders, the parents then may choose which embryos are implanted. Playing god? |
Identification of Carries: | Potential parents may be screened for genetic diseases (such as CF) and if both are carriers they may alter their perception on having children. |
What is prenatal screening? | The screening of pregnancies to determine if the embryo has any genetic diseases. |