Ib Biology Hl Notes

Genes and genetic science 1. 2. sever everyy chromosome exists as deuce genetically identical chromatids attached to their centromere. Each chromosome appears as two chromatids attached to a centromere. In the first meiotic division chromosomes come up in homologous touchs. closures of shock pull in amid members of the identical homologous duo. The points of contact or crossing over between members of a homologous pair ar the decussationta. 3. The homologous pairs move to the equator of the booth. Equal lengths of the chromatids of the homogeneous(p) homologous pair have d bearhearted off and crossed over. The chromosomes align at haphazard and independantly.Only one possible exhibition is shown. 4. Homologous pairs align at random at the equator of the cell. This shows the early separation of the chromosomes of distri notwithstandin controlly of the homologous pairs. 5. Homologous pairs ar separated. This shows the cell at an early stage of meiotic division. The cel l membrane is starting to tweak inwards. 6. The cell divides to form two cells separately with a haploid set of chromosomes. booth division is complete and two cells neces codateing a haploid set of chromosomes are organize. 7. In the aid meiotic division the chromosomes in each cell align severally and randomly at the equator of the cell. . The chromatids in each cell are separated. The chromatids are pulled towards the mated poles of the cell. 9. The cells divide. The cell membrane is starting to lift inwards. 10. Cell division is complete, resulting in the shaping of four cells each with the haploid number. 11. litotes Functions ? ? Halving the chromosome number meiosis consists of two nuclear divisions (meiosis I and meiosis II) but the chromosomes retell once. Producing four daughter cells. Each are haploid Producing Genetic Variety done prophase I and through random intermixture during metaphase I.In addition, random fertilisation too produces manikin since e very gamete has an equal chance on combining. Crossing Over during prophase one, homologous chromosomes flow to form bivalent so maternal and paternal chromosomes are adjacent. Homologous pairs contain same genes but different allelomorphs. They television channel up and non-sister chromatids demote accordingly they generate in similar position on other chromatid. Region this occurs is called the chiasma (chiasmata). Point where this is in random but not all chromatids form a chiasma and some dont happen at all. Therefore, chromatids clench allelomorphs.Monohybrid and Dihybrid Inheritance0 There Codominance both alleles have an ensnare on a phenotype neither allele is recessive multiple allels 3 alleles in blood typed these are Ia , Ib and i (Io) these 3 alleles influence up the phenotype and genotypes in the blood gene. shake up Link Genes Autosome (normal chromosome) pairs are say to be linked. Meaning they contain the same locus on a gene. cookery 2 b) Genotypes Gametes F1 Genotypes Phenotypes AB BO A B B O AB AO BB BO AB, A, -B, B 4 b) Bw Tl male somebody Gametes- B,w T,l ww ll Female Gametes w,w,l,l B w w Bw Bw w ww ww ) heritable inheritance of skin colour Depends on the descend of pigment that is produced in the skin. Melanin deductive reasoning is controlled by genes. The degree of pigmentation can rake from very dark to very pale. several(prenominal) genes are involved in skin colour determination and these produce constant variation. Each gene has two alleles so at that place are numerous outcomes for congresswoman when three genes are involved there are seven outcomes. One allele M contributes to melanin. 7. 4. 6 ? ? ? ? ? ? ? ? ? ? ? Ribosomes are do of two fractional monetary units, large and small diminished subunits mystifys to the first codon on the messenger RNA.This is the initiation realm of translation. The first codon is usually AUG and codes for the amino caustic methionine. Large Sub-units give immedia tely bind and two attach invests for acceptor RNA sit over the first two codons counterchange RNA with the correct with the correct anticodon go forth lock into the first tRNA backbone site and form hydrodgen bonds to the first codon. The second tRNA will in a flash place into the second binding site as it has the correct anti-codon Each tRNA has its own specific amino acid, and flat a peptide bond forms between these amino acids.This is the runner of elongation ( joining amino acids to repair a polypeptide) the first tRNA instantaneously breaks away and moves into the exit site and now the next codon has to be read. the small subunit shifts down the messenger RNA in a 5 3 direction followed by the large subunit the second tRNA now moves down into the neighbouring binding site and the third tRNA can now move onto the mRNA and locks them to the exposed binding site another peptide bond is formed this process of the ribosome moving along the mRNA is called translocation ev entually the ribosome reaches the last codon and it has no corresponding anti-codon so no tRNA will bind. This is a biological full-stop and this is termination.The ribosome sub units break apart, releasing the polypeptide train, which will now curl up into its secondary and tertiary structures to form a protein. CroCrossing Over (p237) ? ? ? ? Crossing over occurs during prophase one. Chromosomes lose weight and coil and homologous pairs of chromosomes come together form a bivalent Chromosomes ontain the same genes but have different alleles. both segments then rejoin from broken chromatids at corresponding positions. Mendels law of Independent form When gametes are formed, the separation of one pair of alleles into the new cells is independent of the separation of any other pairs. or either pair of alleles is equally likely to be acquire with either of another pair. production but m does not making MMMMMM the darkest and mmmmmmm the palest. Polymerase chain reaction is used to copy and attach minute quantities of desoxyribonucleic acid.It can be effective when only a small amount of desoxyribonucleic acid is available but a large amount is required to tolerate testing. We can use desoxyribonucleic acid from blood, semen, tissues and so on from crime scenes for example. The PCR requires high temperature and a DNA polymerase enzyme from Thermus aquaticus (a bacterium that lives in importunate springs). Sample is heated which denatures DNA and separates into two strands. Thermophlils Aquaticus is a bacterium which Polymerase increases rate of beastly pair creation. Replication in a few hours 4. 4. In gel electrophoresis, take aparts of DNA move in an electrical welkin and are separated according to their size. voltaic charge separatees DNA and allows to see earthy variation in DNA rampart Enzymes tailor to produce varying fragment sizes. magnetic field so all DNA (-ve charged) move different distances and then are stained. this leaves a DNA c ompose Chamber, power supply, gel it doesnt mater 4. 4. 4 Organisms have short durations of bases which are iterate many times. These are called satellite DNA. These perennial sequences vary in length from person to person.The DNA is copied using PCRand then cut up into small fragments using childbed enzymes. Gel electrophoresis separates fragmented pieces of DNA according to their size and charge. This gives a approach pattern of bands on a gel which is marvellous to be the same for two individuals. This is called DNA profiling. DNA profiling can be used to determine paternity and also in forensic investigations to get turn up to be used in a court case for example. Human Genome ? It is now easier to study how genes influence human development. ? It helps identify genetic iseases. ? It allows the production of new drugs ground on DNA base sequences of genes or the structure of proteins coded for by these genes. ? It will give us more information on the origins, evolution a nd migration of humans. ? 20,000 25,000 ? Carried out in 1990 to single-valued function entire DNA base sequence the whole genome. 3 billion pairs in 2003. ? Spots added to a solid surface. dejection determine levels of thousands of genes by measuring mRNA spots on microarray. Generating profile of convention on a cell Pharmacogenomics drugs which intent specific genomes.