Chromosome structure. Chromosomes Example - an organism is 2n = 4. Chromosomes 1 & 2 are homologous chromosomes Chromosomes 3 & 4 are homologous chromosomes.

Slides:



Advertisements
Similar presentations
Meiosis Pgs Modified by Liz LaRosa 2011.
Advertisements

Ch. 8 Cell Reproduction What is cell division? Mitosis
Chromosome Number - Is how many chromosomes a cell has
Ashlee, Lura, Daniel & Eina
Do Now!! o Now What is the purpose of Mitosis?
Meiosis Sex cell (gamete) division= egg and sperm
Meiosis Sex cell (gamete) division= egg and sperm Sex cell (gamete) division= egg and sperm Products= 4 cells all haploid, genetically different Products=
Chapter 8 Cell Reproduction. Chapter overview 3 SECTIONS: SECTION 1CHROMOSOMES SECTION 2CELL DIVISION SECTION 3MEIOSIS.
Meiosis.
Meiosis  Human body cells have 46 chromosomes Meiosis (sexual reproduction) - General Overview Sexual Reproduction and Genetics  Each parent contributes.
WHAT IS MEIOSIS?. I. Organisms can reproduce asexually (DNA from only one parent, identical) or sexually (DNA from two parents) AsexualSexual.
Meiosis Notes.
 Human body cells have 46 chromosomes Meiosis Sexual Reproduction and Genetics  Each parent contributes 23 chromosomes Section 1  Homologous chromosomes—one.
Cell Division Review. What the four major stages of the cell cycle? Which stages make up interphase?
 Human body cells have 46 chromosomes Meiosis Sexual Reproduction and Genetics  Each parent contributes 23 chromosomes Section 1  Homologous chromosomes—one.
Meiosis Chapter 11 Sec. 4. Meiosis Reduces # of chromosomes to half Diploid (2n) to haploid (1n)
Chapter 7 Section 1: Meiosis Grade 10 Biology Fall 2010.
Gamete Production.
 What occurs during the stages of meiosis?  How does the function of mitosis differ from the function of meiosis?  What are three mechanisms of genetic.
MEIOSIS AND SEXUAL REPRODUCTION. Meiosis Process of nuclear division that reduces the number of chromosomes in a cell by half 2 STAGES Meiosis I: Homologous.
3.02: Cell Types and Chromosome Number In an organism, there are somatic cells and there are sex cells. o Somatic cells are all of the body’s cells that.
Meiosis Overview. Sexual Reproduction Defined: Gametes from two separate parents unite Meiosis: Diploid (2n) to haploid (n) cells Mechanism that allows.
Sexual Reproduction and Genetics Chapter : Meiosis MAIN IDEA: Meiosis produces haploid gametes.
Meiosis!! Chapter 10. Meiosis  Purpose: to make sex cells  Gamete: sex cell  Male gamete= sperm  Female gamete= egg (ovum)
Meiosis November Chromosome Number Diploid- 2 sets of chromosomes –In somatic (body) cells; One comes from mother and one from father –Also referred.
Meiosis.
Meiosis Meiosis – process of reduction division
Stages of Meiosis Meiosis is a form of cell division that produces daughter cells with half the number of chromosomes that are in the parent cell. During.
Warm Up #5 Thinking back to MITOSIS:
Stages of Meiosis.
Meiosis Modified by Liz LaRosa 2011.
Cell Division, Mitosis, and Meiosis
Do Now What is the purpose of Mitosis?
Section 2: Meiosis Preview Key Ideas Stages of Meiosis
Before we start…. Mitosis gif.
Meiosis Modified by Liz LaRosa 2011.
Meiosis How Gametes Have Only Half the Number of Chromosomes As Other Cells Modified by Liz LaRosa 2011.
Meiosis Modified by Liz LaRosa 2011.
Chromosomes and Meiosis
MEIOSIS Objective: Students know that meiosis is an early step of sexual reproduction (2a) Students know that gametes are produced during meiosis.
Announcements Take out Meiosis WS to be checked from last class if you did not get it stamped Today: Meiosis Review.
Meiosis Pgs Modified by Liz LaRosa 2011.
Meiosis Sexual Reproduction.
Chromosomes and Chromosome Number
Meiosis Chapter 10.1.
Meiosis Modified by Liz LaRosa 2011.
Meiosis Modified by Liz LaRosa 2011.
Meiosis and Sexual Reproduction
Meiosis I results in 2 haploid daughter cells
Meiosis – a form of cell division that halves the number of chromosomes when forming reproductive cells, such as gametes (egg & sperm cells)
Meiosis Modified by Liz LaRosa 2011.
Stages of Meiosis Meiosis 1 ~
Meiosis.
Ch. 8 Cell Reproduction What is cell division? Mitosis
Meiosis.
Just Meiosis 2018.
Meiosis.
Meiosis.
Meiosis.
Section 11.4 Meiosis.
Do Now What is the purpose of Mitosis?
Lesson: Meiosis Key Questions: How is meiosis different from mitosis?
MITOSIS REVIEW
Meiosis Chapter 10.1.
Meiosis Phases.
Meiosis Modified by Liz LaRosa 2011 *.
Terms Homologous –describes the matching chromosome from each parent (one male / one female) Diploid – term used to describe a cell that contains both.
DO NOW How is meiosis similar to mitosis?.
Meiosis – a form of cell division that halves the number of chromosomes when forming reproductive cells, such as gametes (egg & sperm cells)
Meiosis Making ME!.
Presentation transcript:

Chromosome structure

Chromosomes Example - an organism is 2n = 4. Chromosomes 1 & 2 are homologous chromosomes Chromosomes 3 & 4 are homologous chromosomes Chromosomes 1 & 3 came from the mother Chromosomes 2 & 4 came from the father

Life cycle

Cell division - Mitosis The stages of the cell cycle can be broken down into six stages: Interphase, Prophase, Metaphase, Anaphase, Telophase Interphase is the "resting" or non-mitotic portion of the cell cycle. DNA is replicated during the Interphase

Prophase - the first stage of mitosis. The chromosomes condense and become visible The nuclear membrane dissolves

Metaphase The chromosomes line up in the middle of the cell ("the equator")

Anaphase Spindles begin to shorten. This exerts a force on the sister chromatids that pulls them apart. This ensures that each daughter cell gets identical sets of chromosomes

Telophase The chromosomes decondense The nuclear envelope forms Cytokinesis reaches completion, creating two daughter cells

Meiosis Special Type of Cell Division That Occurs in Sexually Reproducing Organisms Meiosis reduces the chromosome number by half, enabling sexual recombination to occur. Meiosis of diploid cells produces haploid daughter cells, which may function as gametes. Gametes undergo fertilization, restoring the diploid number of chromosomes in the zygote

Meiosis Meiosis and fertilization introduce genetic variation in three ways: 1. Crossing over between homologous chromosomes at prophase I. 2. Independent assortment of homologous pairs at metaphase I: Each homologous pair can orient in either of two ways at the plane of cell division. 3. Random chance fertilization between any one female gamete with any other male gamete.

Meiosis The stages of meiosis can be broken down into two main stages, Meiosis I and Meiosis II Meiosis I can be broken down into four substages: Prophase I, Metaphase I, Anaphase I and Telophase I Meiosis II can be broken down into four substages: Prophase II, Metaphase II, Anaphase II and Telophase II

Prophase I The chromosomes condense and become visible The nuclear membrane begins to dissolve The homologs pair up, forming a tetrad Each tetrad is comprised of four chromatids - the two homologs, each with their sister chromatid Homologous chromosomes will swap genetic material in a process known as crossing over

Crossing Over

Metaphase I The tetrads line up along the cell equator

Anaphase I The centromeres break and homologous chromosomes separate (note that the sister chromatids are still attached) Cytokinesis begins

Telophase I The chromosomes may decondense Cytokinesis reaches completion, creating two haploid daughter cells

Prophase II The nuclear membrane dissolves

Metaphase II The sister chromatids line up along the cell equator

Anaphase II The centromere s break and sister chromatids separate Cytokinesis begins

Telophase II Cytokinesis reaches completion, creating four haploid daughter cells