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