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BIOLOGY 1 BASIC

We have 46 chromosomes (23 pairs). The bands on the chromosomes show different GENES- genes come in pairs
1. Chromosomes are made out of DNA- double helix - shows how organism should be constructed, how each cell should function
  1. Genes are sections of DNA, genes control development of diff characteristics- issues instruction to cell- carries this out by producing proteins.
    1. Structural protein- structure in the body eg collagen in ligaments. Functional- how the body works eg enzymes
      1. Sex cells contain single chromosomes eg 23 chromosomes. 23-sex determining gene.
Differences between individuals of same species- variation. Can be caused by genes: eye colour and dimples or environment:scars, dyed hair or both: height, weight.
GENETIC MODIFICATION
1. All organisms have DNA- possible to introduce genetic information from one organisms to another. Produces a new combination of genes and characteristics.
GENETIC VARIATION & INFORMATION.
ALLELES
1. Genes have different versions- alleles eg eye colour B and b- inherit one from each parent.
  1. Dominant- controls characteristics. Recessive need 2. Heterozygous- 2 different alleles eg Bb. Homozygous 2 of same allele eg BB or bb.
    1. Female- XX lack of Y produce ovaries. Male- Xy- produce testes & androgens
Poor diet can lead to disease eg fatty can lead to heart disease. Possible to limit certain diseases by making LIFESTYLE CHOICES.
Huntington's Disease- 1 dominant allele- disease. Affects CNS 4th chromosome faulty allele. SYMPTOMS- involuntary movements, forgetfulness.
1. Cystic fibrosis- affects cell membranes- thick mucus round lung, guts. SYMPTOMS- chest infections, salty sweat, weight loss. HAVE 2 HAVE 2 RECESSIVE ALLELES TO HAVE IT. Ff- carrier FF NO ff have
  1. GENETIC DISORDERS
GENETIC TESTING
1. Amniocentesis- needle into uterus amniotic fluid carrying cells from fetus. 14-16 weeks- 0.5% miscarriage. Chorionic villus- 8-10 weeks. Forceps through cervix- placenta- which holds chorionic villi fetal cells. 2% miscarriage.
  1. False positive- don't have disease tests says you do, false negatively etc
    1. Implications- right to interfere with nature? what can be done/should be done. Could be used to have info: your ethnicity, susceptible to certain conditions. Babies should be screened at birth: tailor healthcare problems, stop g disorders being passed on.
      1. Less money- less suffering on treatment. Other hand, diseases are natural wrong to eliminate. Storing genetic information questions confidentiality eg discrimination turned down for jobs if higher risk of illness.
Embryo selection
1. Other way of preventing babies having genetic disorders- IVF 1/ ova harvested from mother and feritilised 2. embroys tested for faulty allele. 3/ healthy implanted in uterus
2. Pre implantation genetic diagnosis- 1/ after fertlisation embryo allowed divide to 8 cell before single cell is removed fro each one- testing.2/ testing if carry alleles for specific g disorder.
3. CONTROVERSIAL- unnatural- concerns that ppl could select characteristics- reduce variation eg blue eye, brown eye disappear.
Gene therapy - potential treatment for genetic disorders, involves healthy genes inserted. Genes inserted into modified virus infecting patient becoming part of cells correcting faulty allele.
1. Raises questions: is it safe?- potential risks and side effects. some can't be answered by science- right to manipulate genes?, can we decide for future generations. Address same ethical issue- is it acceptable?- based on if benefit majority.
  1. ARGUMENTS FOR: 1/ Acceptable procedure vs vaccination not invasive. 2/ people with g conditions need lifetime of treatment. It improves lives & free up resources. 3/ Some conditions reduce life expectancy- allows normal life.
    1. ARGUMENTS AGAINST: 1/ It's unnatural and morally wrong to change people's genes & DNA. 2/ Experimental don't know long term effects. 3/ Need to be tested on humans- not safe- side effects?
ASEXUAL REP
1. Bacteria & single cell organisms can reproduce dividing individuals- clones (genetically identical to parent). - plants&animals reproduce like this. Variation in organisms that reproduce asexually ONLY caused by environment.
2. Clones can occur naturally: cells embryo separate, 2 new embryos- identical twins. Produced artificially: animal- nucleus from adult body cell transferred to empty egg cell (without nucleus) into a surrogate animal- same genetics as donor.
  1. CELL DIVISION- 1/ Parental cell with 2 pairs of chromosomes. 2/ Each chromosome replicates itself. 3/ Copies are pulled apart. Cell divides for only times. 4/ Each daughter cell has same number of chromosomes & contain same genes as parental cell.
STEM CELLS
1. Most organisms made up of various specialised cells- different structures. In early stages of development, cells aren't specialised= stem cells.
  1. They have potential develop into any cells. Can be used to replace damaged tissues eg Parkinson's. Clone embryos- enough cells. Collected at 8 cell stage- cells are unspecialised- 16 cell specialisation begins. Possible to use up to 150 cell stage- not effective.
2. ETHICS OF STEM CELLS- is it right to clone embryos & s cells- are they seen as people? IVF disused embryo? - acceptable to use parental consent.
  1. Could be cloned from patient's cells- reproductive cloning (new individ identical to donor) illegal UK.
    1. GOVERNMENTS made laws on issues special advisory committees explore ethics of procedures such as cloning & stem cell use.

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BIOLOGY 1 BASIC

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	Created by Laura Platt about 8 years ago