BIOLOGY NOTES GENETICS PART 2 PAGES 166-176

____ Describe the process of meiosis, including independent assortment and crossing over. Explain how reduction division results in the formation of haploid gametes or spores ____ Compare and contrast mitosis and meiosis and relate them to the processes of sexual and asexual reproduction and their consequences for genetic variation Standards 5.4 5.5

Essential Question: What are the advantages of sexual 1. reproduction over asexual reproduction? 1.

Chromosome Number The purpose of the cell ______ with ________ is to make daughter cells that are ________ to the parent cell. This allows the organism to _____, develop and ______ cells Species are ________ for the number of chromosomes they have e.g. cycle mitosis identical grow repair specific fruit fly = 8 chromosomes

the chromosome number has no ______ on the overall ___________ of an organism e.g. In a human ________ cell there are ___ different chromosomes In a human ________ cell, the ___ chromosomes are grouped into __ sets of ___, one chromosome is donated by _____ and the other by _____ effect complexity ferns = 1200 chromosomes / cell somatic 46 somatic 46 2 23 mom dad

Homologous chromosomes = matching pairs of _____________ homologous chromosomes have similar ______ for the body but are not _________ DIAGRAM: chromosomes traits identical

How is it possible for two different parents to form an offspring that has the same amount of chromosomes as they do? A. Sexual reproduction = the process by which chromosomes of __ parents combine to form a new __________ Each parent has to produce _____ that have only ____ the amount of chromosomes as their _______ cells gametes = special, reproductive cells that house only ___ the number of chromosomes as _____ cells e.g. 2 individual cells 1/2 parent 1/2 body egg, sperm

with regard to chromosome number, gametes are described as being ________ while somatic cells are _________ haploid = term used to describe cells with only __ complete set of chromosomes e.g.   diploid = term used to describe cells with ___ complete sets of chromosomes haploid diploid 1 egg, sperm (gametes) 2 body cells (somatic cells)

B. Fertilization = the process of an ____ and _______ combining to produce a new __________ Zygote = the single cell that results from ___________ zygotes are ________ when describing the number of chromosomes within the cell egg sperm individual fertilization diploid

II. The Production of Gametes Since a new cell is being made when an _________ or _______ is formed, the cell ______ is used only instead of ________ there is a process called ________ offspring zygote mitosis cycle meiosis

A. Interphase This include ___, __, and ___ phases which will _____ all the organelles that the new gametes will need as well as copying the ____ B. Meiosis = the process in which _____ are produced that have only ____ the number of chromosomes as _______ cells G2 G1 S copy DNA cells 1/2 parent

Meiosis involves __ divisions after interphase which can cut the chromosome number by ____ for the daughter cells Meiosis division 1 includes: __________, ____________, ___________, and ___________ Meiosis division 2 includes: ___________, ____________, ___________, and ____________ 2 1/2 prophase I metaphase I anaphase I telophase I prophase II metaphase II anaphase II telophase II

C. Cytokinesis divides the resulting __ daughter cells each of which is _______ in chromosome number 4 haploid

III. Gamete Formation Even after the cell cycle with ________, the daughter cells are only ________ NOT fully mature ____ or sperm Gametogenesis = the production of fully mature _________ or sex cells the process to obtain a fully mature _________ will vary by organism in time and according to sex meiosis gametes egg gametes gametes

A. Males- for the __ daughter cells that are produced, __ turn into sperm cells DIAGRAM:   4 4

B. Females - for the __ daughter cells that are produced, only __ becomes an egg due to ________ division of cytoplasm DIAGRAM: 4 1 unequal

IV. Mitosis vs. Meiosis Cycle Mitosis Meiosis diploid haploid somatic Daughter Cells Chromosome Number Product (Type of cell made) Number of Divisions Purpose diploid haploid somatic cells gametes 1 / cycle 2 / cycle to make / replace cells that are identical to make cells with ½ chromosome number