B1
- Created by: Inda1
- Created on: 07-02-16 16:46
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- B1
- Genes, chromosomes and DNA
- each chromosome is one very long molecule of DNA That is coiled up
- A gene is a short length of a chromosome
- Genes control the development of characteristics
- Genes exist in different versions
- Each version gives a different from of characteristic
- The different versions of the same gene are called alleles
- Each version gives a different from of characteristic
- Genes are instructions for cells
- each gene is a code for making a certain protein
- some proteins are structural proteins. They are part of things like skin, hair, blood and the cytoplasm
- Other proteins are funtional proteins for example enzymes are proteins that helps with digestion
- An organism's genotype describes the genes It's got
- An organsims genotype is all the genes it has
- Thw charateristics that an organism display are calles its phenotype
- Gnens and varation
- so half a childs chromosomes have come from each parent This means that ....
- Children get some of their alleles from each of their parents
- this is why children look like theor parebts
- Every child will have a new, unique , combinationn of allelles taht why there is no two people in the world except for identcal twins
- so half a childs chromosomes have come from each parent This means that ....
- Inheritance and genetic diagraks
- Allelles are the different version of the same gene
- Homozygous traits are if you have two alleles the same for that particular gene
- Hetrozygous traits are if you have twio different alleles for that paricular gene
- Genetic disorders
- some disorders are inherited- one or both parents carry a faulty allele and pass it on to their children
- cystic fibrosis and huntingtons disease are both caused by a faulty allelle of a single gene
- Cystic fibrosis
- is a ressisive allele
- symptoms include : Thick mucus in air ways, Breathing difficulty, Cheast infection, Difficulty digesting food
- Huntingtons disease
- Is a dominant allele
- This disoder causes shaking, clumsiness, mwemory loss, Rthere is not cure
- The donimnant allele mwans that there is 50% chance of each child inheriting the disorder
- The carrier parent will of course be a sufferer too since it is a dominant allele, The symptoms don't usually appear till about 40 years of age
- Genetic testing
- When embroyos are produced using IVF, doctors can test the embroyos to check if they've got a cetain genetic disorder
- This is known as pre-implantation genetic diagnosis and is especially important if there's concern that one of the parents might carryy alleles for a genetic disorder.
- Doctors can also test fetuses in the womb for genetic disorders by testing the fluid surounding the fetus
- Issues surrounding genetic testing
- The result of genetic testing may not be 100% accurate. There are often errors due tpo misinterpretations and the sample being contaminated
- Like most medical procedures, tests carries out during pregnancy aren't 100% safe for example doing a genetic test on the fluid around the fetus may cause miscarriages
- If the result is positive should other family members be tested, Some people may prefer not to know, but is this fair on any partners or futire children
- Is it right for someone who's at risk of passing on a genetic condition to have children? is it fair to put them under pressure not to, if they decide they want children?
- When embroyos are produced using IVF, doctors can test the embroyos to check if they've got a cetain genetic disorder
- Genes, chromosomes and DNA
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