Chapter 8: Cell Reproduction

8.1 Chromosomes

8.1 Chromosomes

8.1 Chromosomes https://www.youtube.com/watch?v=xUrlreMaUrs

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

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

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

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

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

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

How Chromosomes are Formed DNA → chromatin → chromosome

How Chromosomes are Formed

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

Chromosome Structure Centromere – where the chromatids are attached

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

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

Prokaryote Chromosome usually has only 1 chromosome Chromosome has circular DNA

8.2 Cell Division

Sunda Colugo

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

8.2 Cell Division https://www.youtube.com/watch?v=AhgRhXl7w_g

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

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

Prokaryote Cell Division

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

Cell Cycle

Interphase 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 “metaphase = middle”

4 Stages of Mitosis 1. Anaphase 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 Cytoplasm separates 2 new identical cells are formed

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

Cytokinesis

Prophase Metaphase Anaphase Telophase Cytokinesis Please Make A Terrific Cake

Uncontrolled Mitosis Results in cells that do NOT stop dividing Eventually become tumors cancer

Apoptosis Apoptosis –cell suicide

8.3 Meiosis

8.3 Meiosis (okapi)

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

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

Meiosis has 2 stages Meiosis I Meiosis II

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

Meiosis I Has 4 phases………guess what they are Prophase I Metaphase I Anaphase I Telophase I and Cytokinesis I

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

Prophase I

Crossing-over occurs here Prophase I Crossing-over occurs here Crossing-over – parts of chromatids break off and attach to neighbor chromatids Allows for the exchange of genetic material between chromosomes from mother and father Genetic recombination – new mixture of genetic material created

Prophase I

Metaphase I Tetrads line up in the middle of the cell

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

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

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

Prophase II Nucleus disappears

Metaphase II Chromosomes are aligned along the middle of the cell

Anaphase II Chromatids separate towards opposite ends of cell

Telophase II Nuclear envelope reforms

Cytokinesis II Cytoplasm splits forming 4 new cells

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

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

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

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

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

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

Bellwork With your tablemate, quietly review prophase, metaphase, anaphase, and telophase (in mitosis, meiosis I, and meiosis II) 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 Different organisms have different numbers of chromosomes

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

Types of Chromosome

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

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

Karyotype What is a karyotype?

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

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

Karyotype (female or male)

Karyotype (what’s wrong with this picture?)

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

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

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

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

Diploid vs. Haploid Cells

3 Stages of Interphase G1 Phase – cells grow S phase – DNA copied G2 Phase – preparation for cell division

Optional 4th Stage of Interphase G0 Phase – cells rest Resting phase