Bradford VTS Online Resources:
- autosomal recessive inheritance.doc
- basic human genetics.pdf
- case scenarios in genetics (TEACHING RESOURCE).doc
- case study genetics – jane and john (TEACHING RESOURCE).doc
- case study genetics – more (TEACHING RESOURCE).doc
- case study genetics – samina (TEACHING RESOURCE.doc
- familial breast cancer – primary care pathway.pdf
- familial breast cancer – summary for GPs.docx
- familial breast cancer guidelines.doc
- familial breast or ovarian cancer guidelines.pdf
- genetic cancer screening.doc
- genetics by jude hayward.ppt
- genomics – top tips 2019.pdf
- screening in pregnancy.pdf
- should i be tested for thalassemia and sickle cell.pdf
If you have files you would like me to host on here and share with others, OR if you would like to help develop these pages further, then please email me.
Basic genetic terminology
- Gene: basic unit of genetic information.
- It is made up of a DNA.
- DNA helps makes an RNA product that is either directly functional or makes a protein.
- Chromosomes – the protein strands around which DNA (and hence genes) is anchored.
- Each human cell contains 23 pairs of homologous (identical) chromosomes.
- So, human somatic cells contain 46 chromosomes, i.e., 46 DNA molecules, of various lengths, which form 23 pairs of homologous chromosomes.
- 1 of these 23 pairs is ONE pair of sex chromosome – which consists of either 2 X chromosomes (female genotype) or one X and one Y chromosome (male genotype)
- A chromosome pair contains one chromosome inherited from each parent.
- Germ cells (sperm cells/ova) only contain 23 SINGLE chromosomes (no chromosome pairs!)
- In other words, they are a haploid chromosome set with only one copy of each chromosome. (NB every other cell in the body has a diploid set of chromosomes)
- When a couple have a baby, one part of the pair of each of the 23 chromosomes comes from each parent.
- This enables diversity as population generations progress.
- Expressivity is the extent of expression of a given genotype at the phenotypic level. In other words, to what extent does the abnormal gene express and manifests itself as a disease? Patients with Marfan syndrome present with highly variable manifestations of the disease. Some have mild Marfan’s (arachnodactyly) to a whole variety of presentations including the severe life-threatening (aortic aneurysm) form.
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