Presentation on theme: "Genetics of Inheritance"— Presentation transcript:
1 Genetics of Inheritance CST ReviewGenetics of InheritancePart II
2 CHROMOSOMES… -complexes of DNA and protein. -Chromosomes are the package for DNA and genes.-duplicated before the cell divides.-chromosome number is specific for each species. A human cell has 46 [or 23 pairs] while a fruit fly has 8 [or 4 pairs].centromeresister chromatids
3 Cells in the body of sexually producing organisms can be… SOMATIC CELLS-body cellsGAMETES-sex cells-contain the DIPLOID [2n] chromosome number.-produced through MITOSIS.-examples: muscle cell, nerve cell, stomach cell.-contain the HAPLOID [n] chromosome number.-produced through MEIOSIS.-examples: sperm cell and egg cell
4 Fertilization restores the diploid number. Egg is “n” = haploid+Sperm is “n” = haploidZYGOTE is 2n.Repeated mitosis ultimately leads to the development of multi-cellular organism.
5 A picture of all the chromosomes in a somatic cell is a karyotype. A human karyotype reveals 23 pairs of chromosomes. Each pair is called a homologous pair.The 23rd pair is easy to spot [unequal in size]. They are the sex chromosomes, called X and Y.
6 Table of Chromosome Number OrganismChromosome #Human46Corn20Yeast32Onion16Cow60Lily24Dog78Donkey62ChickenEarthworm36ToadPig38
7 CELL CYLEA cell goes through a cell cycle, going through stages of growth and division.
8 Stages of the Cell Cycle Interphase: sometimes called the “resting phase.” This refers to the stage in the life of a cell when it is not dividing.-made up of these sub-stages-a. G1- cells grow in size, cells get ready for DNA synthesis.b. S-phase- DNA replication occurs at this stage.c. G2- cell continues to grow and make proteins.
9 2. Mitosis: cell divides to produce two daughter cells with the same chromosome number as the parent cell. This stage takes only from 1-2 hours.
10 Important points to remember: Chromosomes condense for easy separation [no tangling].Spindle fibers attach to the centromeres, controlling chromosome movement.Sister chromatids separate during anaphase.Cytokinesis [division of cytoplasm and other cell contents] happen during telophase.