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Chapter 9 Cellular Reproduction Where were we and where are we going next? Chapter 9 Cellular Reproduction 9.1 Cellular Growth • Overview of Cell Division – Mitosis and Meiosis • Asexual and Sexual Reproduction • Diploid vs. Haploid Chapter 9 Cellular Reproduction Mitosis Meiosis • Asexual reproduction • Growth and repair • Somatic chromosomes (body chromosomes) • Diploid (2n) • No Crossing Over • Produces identical daughter cells • Sexual Reproduction • Passing of genetic traits • Sex chromosomes aka gametes (X and Y) • Haploid (n) • Crossing Over • Produces genetically different daughter cells Chapter 9 Cellular Reproduction Asexual Reproduction Sexual Reproduction • No genetic diversity • Can refer to the production of offspring from one parent (binary fission in bacteria) • Produces two identical offspring • Susceptible to diseases and changing environments • Genetic diversity • Production of gametes to fuse with another gamete (XX or XY) • Produces genetically different offspring • Ability to adapt to change in environments Chapter 9 Cellular Reproduction Haploid Diploid • Refers to one set of chromosomes (n) • Humans have ___ chromosomes • Haploid would be ____ • Fruit fly have ___ chromosomes • Haploid would be ____ • Refers to two sets of chromosomes (2n) • Humans have ___ chromsomes • Diploid would be ____ • Fruit fly have ___ chromosomes • Diploid would be ____ Chapter 9 Cellular Reproduction What are chromosomes? • Chromosomes are rod-shaped structures made up of DNA and proteins. • Two chromatids make up a chromosome • Centromeres are attachment points for two chromatids and hold them together • Chromatin are less tightly coiled DNA-protein complex used to form chromosomes Cellular Reproduction Chapter 9 Confused yet? chromatid centromere Condensed, duplicated chromosome Chapter 9 Cellular Reproduction 9.1 Cellular Growth The Cell Cycle The main purpose of cell division – to grow and heal certain injuries. Cells reproduce by a cycle of growing and dividing called the cell cycle. Chapter 9 Cellular Reproduction Cell cycle in three different stages Chapter 9 Cellular Reproduction 9.1 Cellular Growth Interphase is the stage during which the cell grows, carries out cellular functions, and replicates. Mitosis is the stage of the cell cycle during which the cell’s nucleus and nuclear material divide. Cytokinesis is the method by which a cell’s cytoplasm divides, creating a new cell. Chapter 9 Cellular Reproduction 9.1 Cellular Growth The Stages of Interphase The first stage of interphase, Gap1 The cell is growing, carrying out normal cell functions, and preparing to replicate DNA. Chapter 9 Cellular Reproduction 9.1 Cellular Growth The Second Stage of Interphase, S [Synthesis] The cell copies its DNA in preparation for cell division. Chapter 9 Cellular Reproduction 9.1 Cellular Growth The Third Stage of Interphase, Gap2 The cell continues to grow and prepares for the division of its nucleus. Chapter 9 Cellular Reproduction 9.2 Mitosis and Cytokinesis The Stages of Mitosis Prophase The cell’s chromatin tightens. Sister chromatids are attached at the centromere. Two chromatids become one chromosome. Spindle fibers form in the cytoplasm. Chapter 9 Cellular Reproduction 9.2 Mitosis and Cytokinesis The nuclear envelope begins to disappear. Spindle fibers attach to the sister chromatids. Chapter 9 Cellular Reproduction 9.2 Mitosis and Cytokinesis Metaphase Sister chromatids are pulled along the spindle apparatus towards the center. They line up in the middle of the cell. Chapter 9 Cellular Reproduction 9.2 Mitosis and Cytokinesis Anaphase The spindle apparatus begin to shorten. The sister chromatids separate. The chromosomes move toward the poles of the cell. Chapter 9 Cellular Reproduction 9.2 Mitosis and Cytokinesis The sister chromatids now become separate chromosomes. Chapter 9 Cellular Reproduction 9.2 Mitosis and Cytokinesis Telophase Two new nuclear membranes begin to form and the nucleoli reappear. The spindle apparatus disassembles. The pinching between the newly formed cells (called a cleavage furrow) is an indication of telophase. Chapter 9 Cellular Reproduction 9.2 Mitosis and Cytokinesis Chapter 9 Cellular Reproduction 9.2 Mitosis and Cytokinesis Cytokinesis In animal cells, microfilaments constrict, or pinch, the cytoplasm. In plant cells, a new structure, called a cell plate, forms. Chapter 9 Cellular Reproduction 9.2 Mitosis and Cytokinesis Division of two IDENTICAL daughter cells with the same amount of chromosomes (DNA). Chapter 9 Cellular Reproduction 9.3 Cell Cycle Regulation Quality Control Checkpoints The cell cycle has built-in checkpoints that monitor the cycle and can stop it if something goes wrong. Chapter 9 Cellular Reproduction 9.3 Cell Cycle Regulation Abnormal Cell Cycle: Cancer Cancer is the uncontrolled growth and division of cells. Cancer cells can kill an organism by crowding out normal cells, resulting in the loss of tissue function. Chapter 9 Cellular Reproduction 9.3 Cell Cycle Regulation Causes of Cancer Mutations that cause problems in the regulation of cell growth and division Various environmental factors can affect the occurrence of cancer cells.