CELL DIVISION Mitosis and Meiosis ASEXUAL SEXUAL (EUKARYOTES ONLY) I CAN: Compare the advantages of sexual reproduction and asexual reproduction in different situations.

This is a model of the double helix shape of DNA. DNA is the molecule that transfers hereditary information from one cell to the next. This is a model of the double helix shape of DNA. Pg 233

When a cell is dividing, DNA winds up tightly and forms chromosomes in the nucleus of the cell. A Copy of DNA is needed in all cells. A specific portion of the DNA code is called a gene, which has genetic information. Pg 139 The genes are contained within the chromosome.

Humans have 46 (or 23 pairs) of chromosomes A karyotype is a picture showing the arrangement of a full set of human chromosomes. Humans have 46 (or 23 pairs) of chromosomes

HAPLOID vs DIPLOID PRACTICE In animals… Somatic cells (cells of the body) are diploid. This means that each cell has two chromosomes of each type. They are in PAIRS. Biologists use “2N” to symbolize diploid. Gamete cells (egg, sperm) are haploid. This means that each cell has only one of each type of chromosome. Biologists use “N” to symbolize haploid. HAPLOID vs DIPLOID PRACTICE

MITOSIS Mitosis In Action Pg 141 When somatic (body) cells reproduce themselves the process is called MITOSIS. 2N Somatic Cell Daughter Cells Main purposes of mitosis: Growth Repair Asexual reproduction (bacteria) Mitosis leads to the production of two “daughter cells”. Each daughter cell has the same number of chromosomes as the parent cell. Mitosis In Action

Haploid Diploid

The steps of Mitosis: PAGE 141 INTERPHASE - DNA replicates PROPHASE - chromatin condenses into chromosomes/nuclear membrane breaks down METAPHASE - chromosomes are lined up in the middle.. ANAPHASE - Sister chromatids separate and migrate to opposite poles. TELOPHASE - chromosomes decondense CYTOKINESIS. division of cytoplasm

WEEKLY TEST – CELL REPRODUCTION AND ENERGY IT’S TIME TO TAKE YOUR EDUCATION MORE SERIOUSLY… FRESH …MEN AND WOMEN!!!

UNDERSTANDING MEIOSIS STEP 1: GET A LINELESS SHEET OF PAPER ON THE FRONT – GIVE TITLE MY BODY AND HOW IT GROWS AND REPAIRS ITSELF! DRAW AND DESCRIBE THE PHASES OF MITOSIS! (PAGE 175)

UNDERSTANDING MITOSIS VIDEO STEP 2: ON THE BACK!!! NUMBER TO 1- 10 GIVE THE ANSWERS (letter only) to VIDEO QUESTIONS!!!

The steps of Meiosis I and Meiosis II: Pg. 175

MEIOSIS Pg 175 Crossing Over, pg 190 When gamete (sperm or egg) cells reproduce themselves the process is called MEIOSIS. Meiosis reduces chromosome #to half. N 2N Gamete Cell During meiosis, a single diploid cell divides and produces FOUR genetically different haploid cells. In Meiosis there is one chromosome duplication followed by two cellular divisions (into four cells) so Meiosis is broken down into Meiosis I and Meiosis II. 1 N egg 1 N sperm Upon fertilization, a “N” sperm meets a “N” egg and a zygote (2N) is formed. 2N zygote

MEIOSIS IN ACTION

Mitosis Meiosis Compare & Contrast 1 Cell Division Produces Body Cells Produces 2 daughter cells Daughter Cells are Diploid 2N Daughter cells IDENTICAL to parent cells 2 Cell Divisions Produces Sex Cells Produces 4 daughter cells Daughter cells are haploid N Daughter cells are GENETICALLY different from parent cell due to CROSSING OVER of chromosomes Compare & Contrast