MGD Week 1
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15 questions
| 🇬🇧 | 🇬🇧 |
| How are mitosis and meiosis clinically significant | Mitosis - regeneration of tissues - manipulation of stem cells Meiosis - Consequences of faulty meiosis - e.g.) infertility, retardation |
| Difference between RNA and DNA | RNA - Single stranded, ribose sugar, uracil DNA- Double stranded, 2-deoxyribose sugar, thymine |
| Describe the formation of visible chromosomes (under light microscopes) from the double helix structure | In the nucleus - double helix structure of DNA is wrapped around histones to form nucleosomes, which form 'beads on a string DNA' - Nucleosomes tightly packs into solenoid structure, forming 30nm fibres - Fibres are compacted into several hierarchical loops to create highly condensed structure which is visible |
| Describe what happens in each stages of cell cycle | G1 - Cell content replication - lysosomes, mitochondria etc. doubled - APART from chromosomes S - DNA replication - each of 46 chromosomes are doubled G2 - Cell division preparation - double check of duplicated chromosomes and repair Mitosis - cell division Cytokinesis - division of cytoplasm - parent cell becomes 2 daughter cells with identical genetic information |
| Describe the stages of mitosis Prophase, prometaphase, metaphase, anaphase, telophase | Prophase - breakdown of nuclear membranes - chromosomes condense Prometaphase - Spindle fibres attach to chromosomes Metaphase - chromosomes align at the middle Anaphase - chromosomes divide and sister chromatids move to opposite poles Telophase - Nuclear membranes form - chromosome decondense - spindle fibre disappears |
| Give out the purpose of checkpoint 1 and 2 in the cell cycle Also, indicate where they are in the cell cycle | Checkpoint 1 - in between G1 and S - checking process before entering S phase - signifies cells to enter S phase Checkpoint 2 - in between G2 and mitosis - waits for signal to enter mitosis - Checks if everything has been replicated, and if DNA and chromosomes are fully intact |
| Name the catalyst used in DNA replication and how it catalyzes | DNA polymerase - utilises deoxyribonucleoside triphosphate (dNTP) and joins new nucleotides onto template strand - while the helicase unwind the DNA helicase and primase is removed |
| What does DNA ligase do | Joins okazaki fragments together on the opposite site of the double helix during elongation - this is because the the helix runs in opposite directions (3' to 5') *note that DNA polymerase acts on a normally running strand (5' to 3') on the oppposite side |
| Name drugs which may inhibit DNA replication | Cisplatin and BCNU - treat cancer and leukaemia - elongation inhibited Arac and 6-MP - treat acute leukaemia - termination inhibited |
| How does genetic diversity arise from meiosis | Independent assortment of chromosomes - meiosis I Crossing over |
| At which stage does crossing over happen? Also describe what happens in that stage in order for crossing over to happen | Prophase I - disintegration of nuclear envelope - formation of tetrad from pair of chromosomes |
| Difference between meiosis I and meiosis II | Meiosis I - homologous chromosome pair divided Meiosis II - chromatids of each chromosome divided |
| As gametes are haploid, genetic information must be halved during spermatogenesis and oogenesis. Describe the process of each | Spermatogenesis - spermatogonium->primary spermatocyte-> spermatids-> mature sperm - 48 days Oogenesis - Oogonium, primary oocyte-> polar bodies -> mature ovum - age 12 to 50 |
| How are mitosis and meiosis clinically significant | Mitosis - regeneration of tissues - manipulation of stem cells Meiosis - Consequences of faulty meiosis - e.g.) infertility, retardation |
| Define genotype and phenotype | Genotype - genetic composition of individual Phenotype - physical appearance of the gene |