Chapter 8 Cell Reproduction 8 1 Chromosomes 8

Chapter 8: Cell Reproduction

8. 1 Chromosomes

8. 1 Chromosomes

8. 1 Chromosomes u https: //www. youtube. com/watch? v=x. Urlre. Ma. Urs

8. 1 Chromosomes Objectives: I will be able to: u Describe the structure of a chromosome u Identify the differences in structure between prokaryotic chromosomes and eukaryotic chromosomes u Compare u Explain the numbers of chromosomes in different species the differences between sex chromosomes and autosomes u Distinguish between diploid and haploid cells

How Chromosomes are Formed u. DNA – genetic information of the cell u“Double shape” helix

How Chromosomes are Formed u. DNA wrapped around histones u. Histone – protein that supports shape of chromosomes

How Chromosomes are Formed u. DNA wrapped around histones creates chromatin u. Chromatin histones – loosely coiled DNA and

How Chromosomes are Formed u. During cell reproduction, chromatin condenses to form tightly wound chromosomes u. Chromosomes – tightly packed bodies of DNA

How Chromosomes are Formed u. Why must the DNA be so tightly packed?

How Chromosomes are Formed u. DNA → chromatin → chromosome

How Chromosomes are Formed

Chromosome Structure u. Chromosome made of 2 chromatids u. Chromatid – 2 identical halves of a chromosome

Chromosome Structure u. Centromere – where the chromatids are attached

Prokaryote Chromosome u. Review: what are the differences between prokaryotes and eukaryotes?

Prokaryote Chromosome u. Review: what are the differences between prokaryotes and eukaryotes? u. Prokaryotes do NOT have a membrane-bound nucleus nor membrane-bound organelles!!!!!!!!!!

Prokaryote Chromosome uusually has only 1 chromosome u. Chromosome has circular DNA

8. 2 Cell Division

Sunda Colugo

8. 2 Cell Division Learning Targets I will be able to: u Describe the events of cell division in prokaryotes u Summarize the events of interphase u Describe the stages of mitosis u Compare cytokinesis in animal cells with cytokinesis in plant cells

8. 2 Cell Division https: //www. youtube. com/watch? v=Ahg. Rh. Xl 7 w_g

Prokaryote Cell Division u. Binary fission – process of cell division used by prokaryotes u. Review: what shape is prokaryotic DNA?

Prokaryote Cell Division u. Binary fission – process of cell division used by prokaryotes u. Review: what shape is prokaryotic DNA? u. CIRCULAR !!!!!

Prokaryote Cell Division

Eukaryote Cell Division Mitosis – 1 cell divides into 2 cells with same genetic material as parent cell

Cell Cycle

Interphase u 1. Interphase – time when cells are NOT dividing 2. Cell spends most of its time in interphase 3. DNA replicates (doubles) here

4 Stages of Mitosis Prophase 1. DNA turns into chromosomes and become visible 2. Nucleus disappears

4 Stages of Mitosis Metaphase 1. chromosomes move to middle of cell u“metaphase middle” =

4 Stages of Mitosis 1. Anaphase u. Chromatids get pulled apart and start moving to opposite sides of cell

4 Stages of Mitosis Telophase 1. Chromatids arrive on opposite sides of cell 2. Nucleus reforms

Cytokinesis 1. Cytoplasm separates 2. 2 new identical cells are formed

Cytokinesis u. Cleavage – where cell membrane pinches in to separate 2 new cells

Cytokinesis

Prophase Metaphase Anaphase Telophase Cytokinesis Please Make A Terrific Cake

Uncontrolled Mitosis u. Results dividing in cells that do NOT stop u. Eventually ucancer become tumors

Apoptosis u. Apoptosis –cell suicide

8. 3 Meiosis

8. 3 Meiosis (okapi)

8. 3 Meiosis Objectives I will be able to: u Compare the end products of meiosis with the end products of mitosis u Summarize the events of meiosis I u Explain crossing-over and how it contributes to the production of unique individuals u Summarize u Compare u Define the events of meiosis II spermatogenesis and oogenesis sexual reproduction

Meiosis – cell division resulting in haploid cells u Produces gametes (sperm and egg cells)

u Meiosis has 2 stages 1. Meiosis I 2. Meiosis II

Meiosis I u Called u Has reduction division 4 stages………guess what they are

Meiosis I u Has 4 phases………guess what they are 1. Prophase I 2. Metaphase I 3. Anaphase I 4. Telophase I and Cytokinesis I

Prophase I u DNA is copied here u DNA coils tightly into chromosome u Nucleus u Tetrad disappears – pair of homologous chromosomes Early Prophase I

Prophase I

Prophase I u. CROSSING-OVER HERE OCCURS u Crossing-over – parts of chromatids break off and attach to neighbor chromatids u Allows for the exchange of genetic material between chromosomes from mother and father u Genetic created recombination – new mixture of genetic material

Prophase I

Metaphase I u Tetrads line up in the middle of the cell

Anaphase I u Each homologous chromosome moves to opposite poles of cell u. Independent assortment – random separation of maternal and paternal chromosomes

Telophase I and Cytokinesis I u 2 new cells produced with half the number of chromosomes (haploid) (n)

Meiosis II u DNA is NOT copied u. Cells undergo division similar to mitosis

Prophase II u Nucleus disappears

Metaphase II u Chromosomes are aligned along the middle of the cell

Anaphase II u Chromatids separate towards opposite ends of cell

Telophase II u Nuclear envelope reforms

Cytokinesis II u Cytoplasm new cells splits forming 4

Development of Gametes u Meiosis results in 4 haploid gametes u Gamete – haploid reproductive cell u Sperm u Egg in human males in human females

Males u 4 spermatids form through meiosis u Spermatids develop into mature sperm cells through spermatogenesis

Females u Oogenesis of ova u Ova u 1 – production – mature egg cells ovum produced during meiosis

Females u Oogenesis of ova u Ova – production – mature egg cells u 1 ovum produced during meiosis u 3 polar bodies also produced u Ovum retains most of the cytoplasm u Why?

Sexual Reproduction u Production of offspring through fusion of sperm and egg u Offspring are genetically different from parents u Allows species to adapt quickly to new conditions

Asexual Reproduction u Offspring come from a single organism u Binary fission and mitosis are examples

Bellwork u With quietly your tablemate, review prophase, metaphase, and telophase (in mitosis, meiosis I, and meiosis II) u Write down a muddiest point (most confusing idea) about mitosis/meiosis, if you have one, to submit. You don’t have to include your name.

Chromosome Numbers u. Different organisms have different numbers of chromosomes

Chromosome Numbers u Different organisms have different numbers of chromosomes Organism Chromosome Number Fruit Fly 8 Pea 14 Human 46 Chimpanzee 48 Goldfish 94 Adder’s Tongue Fern 1, 262

Chromosome Numbers

Types of Chromosome u. Sex chromosomes – determine sex of an organism u. X and Y in humans u. XX = female XY = males u. Humans have 2 u. Autosomes uhumans – all other chromosomes have 44

Types of Chromosome

Autosomes u. Homologous chromosomes - 2 identical copies of each autosomes present in all cells u. One copy from each parent

Autosomes u. Genes – small segment of DNA that code for specific trait (eye color or hair color) u. Many genes located on each chromosome

Karyotype u What is a karyotype?

Karyotype u What is a karyotype? u Photomicrograph u What of chromosomes you made yesterday by cutting and gluing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Karyotype u What is a karyotype? u Photomicrograph of chromosomes u What you made yesterday by cutting and gluing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! u 22 u 2 pairs of homologous chromosomes (44 total) sex chromosomes

Karyotype (female or male)

Karyotype (what’s wrong with this picture? )

Diploid Cells u. Diploid cells – cells with 2 sets of chromosomes uall human cells (except egg and sperm cells) are diploid

Diploid Cell Abbreviation u. Abbreviated u. In as 2 n humans 2 n = 46 chromosomes

Haploid Cell u. Haploid cells – contain only 1 set of chromosomes u. Only sperm and egg cells in humans

Haploid Cell Abbreviation u. Abbreviated u. In as n humans n = 23 chromosomes

Diploid vs. Haploid Cells

3 Stages of Interphase 1. G 1 Phase – cells grow 2. S phase – DNA copied 3. G 2 Phase – preparation for cell division

Optional 4 th Stage of Interphase u. G 0 Phase – cells rest u. Resting phase