Causes of Genetic Disease A gene can affect a phenotype of an organism A gene codes for a single polypeptide The polypeptide affects the phenotype through a particular mechanism The phenotype of an...
Constructing Punnett Grids A monohybrid trait is one that is controlled by only one gene Generally, we consider that such a gene has two alleles Either: one allele is dominant and the other is rece...
Segregation of Alleles Meiosis is a form of nuclear division that results in the production of haploid cells from diploid cells During meiosis a diploid cell will divide twice to form four haploid ...
Mendel's Experiments Gregor Mendel was an Austrian monk He was trained in mathematics and natural history at the University of Vienna In the mid-19th century, Mendel carried out breeding experiment...
Drawing the Stages of Meiosis Cells undergoing meiosis can be observed and photographed using specialized microscopes The different stages of meiosis have distinctive characteristics meaning they c...
Non-disjunction Non-disjunction occurs when chromosomes fail to separate correctly during meiosis This can occur in either anaphase I or anaphase II, leading to gametes forming with an abnormal num...
Genetic Variation & Meiosis Crossing over and random orientation promote genetic variation Having genetically different offspring can be advantageous for natural selection and therefore increas...
DNA Replication before Meiosis Before meiosis occurs, all of the DNA inside the nucleus of the 'parent' cell is replicated This occurs during a period of the cell cycle known as interphase Once thi...
Meiosis There are two processes by which the nucleus of a eukaryotic cell can divide. These are: Mitosis Meiosis Mitosis gives rise to genetically identical cells and is the type of cell division u...
