Title Booklet-2026.pdf ✅

1 Mr. Ali BITAR Biology Teacher - Diploid and haploid cells - DNA mutation - The karyotype - Exercises Toward Grade 12- LS Seniors 2026 Follow me on Instagram @3alibitar

3 Mr. Ali B I T A R I- Diploid cells and haploid cells Diploid cells, noted as 2n, contain two copies of each chromosome: one inherited from the father and one from the mother. These chromosomes can each be made up of either one or two chromatids. This applies to the majority of the body's cells, called somatic cells. For example, in humans, all skin, muscle, liver, brain cells, etc., are diploid and contain 46 chromosomes (2n = 46). Haploid cells, noted as n, contain only one copy of each chromosome, which can also consist of either one or two chromatids. They are found only among the reproductive cells, also known as sex cells or gametes. In humans, sperm cells and egg cells are haploid and each contain 23 chromosomes (n = 23). Diploid cell 2n / 2 chromatids Diploid cell 2n / 1 chromatid Haploid cell n / 2 chromatids Haploid cell n / 1 chhromatid Follow me on Instagram @3alibitar
4 Mr. Ali B I T A R II- DNA mutation 1- Definition of mutation: A mutation is a permanent alteration in the nucleotide sequence of DNA, involving changes in the order of nitrogenous bases (adenine, thymine, cytosine, and guanine) that constitute a gene. 2- Types of point mutations : Deletion, insertion, substitution. 3- Effect/consequence of the mutation : - Missense : an amino acid is modified in the protein. - Silent : no change in the protein. - Nonsense : the protein is incomplete (because of the stop codon). - Frameshift : (in case of deletion and insertion mutations). 4- STOP codons : UAA – UAG – UGA. Follow me on Instagram @3alibitar