Genetic Disorders
Overzicht
Most of what your genes do passes unnoticed. Occasionally a single faulty instruction, or one chromosome too many, produces an effect large enough to shape a whole life. These are the genetic disorders, and they are among the few places in biology where a family diagram, a fraction and a set of symptoms all describe the same thing. Learn to move between those three descriptions and this topic becomes arithmetic rather than memory.
In this lesson you will meet the three inherited conditions the specification names by example, and you will see why one of them shows up in every generation of a family while another can hide for decades in people who feel completely well. You will then look at a different kind of cause altogether, where nothing is wrong with any individual allele and the problem is simply that a cell finished up with the wrong number of chromosomes. This is also the topic where the two tiers of this course ask for genuinely different things, so the lesson marks that boundary as it goes and shows you the plain wording that scores full marks on the Core Tier paper.
Doelstellingen
- Some disorders are inherited. Students should be able to interpret data relating to genetic disorders such as polydactyly, cystic fibrosis and sickle cell anaemia.
- Some inherited conditions are caused by inheritance of abnormal numbers of chromosomes, eg Down’s Syndrome is caused by the presence of an extra chromosome.
Mindmap
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Lesnotitie
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Lesevaluatie
Gefeliciteerd met het voltooien van de les op Genetic Disorders. Nu je de sleutelconcepten en ideeën, het is tijd om uw kennis op de proef te stellen. Deze sectie biedt een verscheidenheid aan oefeningen vragen die bedoeld zijn om uw begrip te vergroten en u te helpen uw begrip van de stof te peilen.
Je zult een mix van vraagtypen tegenkomen, waaronder meerkeuzevragen, korte antwoordvragen en essayvragen. Elke vraag is zorgvuldig samengesteld om verschillende aspecten van je kennis en kritisch denkvermogen te beoordelen.
Gebruik dit evaluatiegedeelte als een kans om je begrip van het onderwerp te versterken en om gebieden te identificeren waar je mogelijk extra studie nodig hebt. Laat je niet ontmoedigen door eventuele uitdagingen die je tegenkomt; beschouw ze in plaats daarvan als kansen voor groei en verbetering.
- Cystic fibrosis is caused by a recessive allele f. The working allele is F. Which pair of alleles is carried by a carrier of cystic fibrosis? A. FF B. Ff C. ff D. A carrier has no alleles for this gene Answer: B
- Polydactyly is caused by a dominant allele. Which statement is correct? A. A person needs two copies of the allele to have the condition B. A person with one copy of the allele has the condition C. The condition always skips a generation D. Only females can have the condition Answer: B
- How many chromosomes are found in a body cell of a person with Down's syndrome? A. 23 B. 45 C. 46 D. 47 Answer: D
- Two carriers of cystic fibrosis have a child. What is the percentage chance that the child has cystic fibrosis? A. 0% B. 25% C. 50% D. 75% Answer: B
- Which of the following describes the event that leads to Down's syndrome? A. A dominant allele is inherited from one parent B. A recessive allele is inherited from both parents C. A pair of chromosomes fails to separate during meiosis D. A chromosome is lost during mitosis in the adult Answer: C
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