BSC 219

8/23/12

Intro to Genetics and Cellular Reproduction

 

 

What is Genetics?

            Inheritance and Traits

            Focus on differences but similarities are there

 

Technology has changed way we look at genetics

 

Subdisciplines and approaches

 

Mechanism of Inheritance

            Cell based life           

                        Information passed from cell to cell

 

            Asexual and Sexual reproduction

 

Chromosomes are key unit of inheritance

            Comprise DNA and proteins

            Can exist alone or as homologous pairs (n vs 2n)

            Have alleles that correspond to traits at specific loci

 

Inheritance from one generation of cells to another depends on passing down chromosomes

 

Cell cycle and division:

            Cells have a life cycle

                        Most of life cycle in growth and homeostatic mode called interphase

                        Small part of life cycle in preparing for and undergoing cell division

                                    Progress through cycle is controlled at checkpoints

                                                G1

                                                S

                                                G2

                                                M

 

Mitosis-somatic cell division

            Start with 2n cell and produce two cells with 2n

 

            Important players are centrioles, microtubules, chromosomes, and kinetichores

            Centrioles-control microtubule formation during cell division

            Microtubules-made of protein tubulin and attach to and move chromosomes

            Kinetichore-specific structure on chromosome that attaches to microtubules

 

            Stages:

                        Prophase-

                        Prometaphase-

                        Metaphase-

                        Anaphase-

                        Telophase

 

Sexual reproduction-advantage is in amount of diversity possible among offspring

 

            Each parent provides approximately half of genetic material to offspring

            Requires special cells called gametes that are only n (as opposed to 2n)

            Production of gametes requires process to reduce genetic material

 

Meiosis

            Two stages:

                        Meiosis I-this is where reduction from 2n to n happens

                                    Separation of homologous chromosomes

                        Meiosis II-similar to Mitosis; production of 2 daughter cells

                                    Seperation of sister chromatids

 

            Meiosis I-

                        Prophase I-tetrad formation and crossing over!!

                        Metaphase I-

                        Anaphase I-

                        Telophase I

 

            Meiosis II-very similar to mitosis

                        Prophase II

                        Metaphase II

                        Anaphase II

                        Telophase II

 

Genetic variation from meiosis

 

Mechanisms-

            Chromosome movement

                        Kinetichore and microtubule interactions

 

            Control of what separates when-

                        Cohesin and shugoshin

 

            Meiosis and reproduction

                        Humans-oogenesis and spermatogenesis

                                    Big differences in product yet genetic reduction same