Mutation - a change in the arrangement of bases in an indivdual gene or structure of a chromosone. some mutations are caused by the micopying of just one or a small number of nucleotides. this is called point mutation.
chromosomal mutations involve changes in the position of genes within a chromosone. whole chromosone mutations is where an entire chromosone is lost during meosis or duplicated by errors in process. mutations occurs commonly when DNA is copied for cell division. most damaging mutations occur when its happens with the gametes because this is passed onto future offspring. there is also: gene deletion, translocation and inversion.
cystic fibrosis occurs when a mutation is found in the gene CFTR. can be several different mutations. the role of CTFR is to transport chloride ions, in cystc fibrosis the CTFR channel does not work. so the chloride ions build up in the cells instead of moving through the channels, so water does not move out either. and the mucus cannot be diluted - becomes thick and sticky.
The inferior vena cava collects blood (low in oxygen) while the superior vena cava recieves blood from parts of the body.
the right atrium >> right ventricle >> pulmonary arteries (deoxgenated blood) >> (semilunar valves prevent backflow) >> pulmonary veins >> returns left atrium >> left ventricle (backflow prevented by bicuspid valve) >> aorta.
contraction of the heart : systole | atrial systole | ventricular systole| .. when the atria's contracts forces blood into ventricles. when the ventricles contract force blood into the pulmonary artery and the aorta. ..... semilunar valves open and atrioventricular valves closed.
relaxation of the heart: diastole| the heart is relaxed and fills with blood. semilunar valves closed. atrioventricular valves open.
the purine bases: adenine and guanine .... the pyrimidines bases: cystosine and thymine. a nucleotide or mononucleotide is composed of phosphate, sugar, and base. the bases are held together by hydrogen bonds, forming the double helix.
transcription: dna replication. 1) the double helix unwinds, this happens because of the enzyme helicase and the hydrogen bonds are broken. 2) the strands act as templates. the exposed act attract new bases. 3) DNA polymerase and ligase 4) MRNA is formed.
Gene therapy is when a faulty allele is replaced with a healthy allele. germ line threapy can be passed on to future generations, could lead to designer babies,