CLE 3210.1.4 Describe the processes of cell growth and reproduction. Cell Growth & Division In what circumstances do cells grow and develop? Chapter 10 CLE 3210.1.4 Describe the processes of cell growth and reproduction.

Bell Work Recall: What kind of macromolecule is DNA? Nucleic acid DNA is a ______-helix, with specific base pairs _______ & ________; _______ & ________ Double Helix Adenine & Thymine; Guanine & Cytosine What is the monomer for a nucleic acid? 3 parts? & What kind of bond holds the nitrogenous base pairs together?

Cell Growth Which would have larger cells between a baby and an adult? Trick Question: Although an adult is larger than a young child, the cells of both are the same size. Living things grow by producing more cells.

Chapter 10- Section 1: Cell Growth There are two main reasons why cells divide rather than continue to grow indefinitely: The larger the cell becomes, the more demands the cell places on its DNA In addition, the cell has more trouble moving enough nutrients and wastes across the cell membrane

Mitosis and Cytokinesis The process by which a cell divides into two new daughter cells is called cell division. In most prokaryotes, cell division is a simple matter of separating the contents of the cell into two parts. In eukaryotes, cell division is more complex and occurs in two main stages. Mitosis : division of the nucleus Cytokinesis : division of the cytoplasm What is the main difference between a prokaryote and a eukaryote?

Mitosis and Cytokinesis Many organisms, especially unicellular organisms, reproduce by means of mitosis and cytokinesis. What type of reproduction would this be classified as? Its classified as Asexual reproduction since the cells produced are genetically identical to the parent cell. Mitosis is also the source of new cells when a multicellular organism grows and develops.

Chromosomes In eukaryotic cells, the genetic information that is passed from one generation of cells to the next is carried by chromosomes. Chromosomes are made up of DNA, which carries the cell’s coded genetic information- and proteins.

Chromosomes The cells of every organism have a specific number of chromosomes. The cells of fruit flies have 8 chromosomes. Human cells have 46 chromosomes. Carrot cells have 18 chromosomes.

Chromosomes Chromosomes are not visible in most cells except during cell division. (before cell division, chromosomes are referred to as chromatin) This is because the DNA and protein molecules that make up the chromosomes are spread throughout the nucleus. At the beginning of cell division, the chromosomes condense into compact, visible structures that can be seen through a light microscope.

Chromosomes Before cell division, each chromosome is replicated, or copied. Each chromosome consists of two identical “sister” chromatids. Each pair of chromatids is attached at an area called the centromere. When the cell divides, the “sister” chromatids separate from each other.

Identify the Parts of the Chromosome Centromere Two Identical Sister Chromatids

The Cell Cycle The cell cycle is the series of events that cells go through as they grow and divide. During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells, each of which then begins the cell cycle again.

The Cell Cycle What are the four phases of the cell cycle? G1, S, G2, and M Mitosis and Cytokinesis take place during the M phase. Chromosome replication takes place during the S phase. In between the M and S phases, are the G1 phase and G2 phase. The G stands for Gap. Intense growth and activity occur during the G phases.

Interphase Interphase is divided into three phases: G1, S, and G2 The G1 phase: cells do most of their growing. During this phase, cells increase in size & make new proteins and organelles. The S phase: Chromosomes are replicated and DNA molecules are synthesized. The G2 phase: many of the organelles and molecules required for cell division are produced.

Cell Checkpoints - One of the most striking aspects of cell behavior is how carefully cell growth and cell division are controlled. This regulation makes sure that cells don't divide under unfavorable conditions. For instance, when their DNA is damaged, or when there isn't room for more cells in a tissue or organ. If the checkpoint mechanisms detect problems with the DNA, the cell cycle is halted and the cell attempts to repair the damage. If the damage cannot be repaired, cell death or apoptosis, occurs.

Cell Checkpoints Most muscle cells and nerve cells do not divide at all once they have developed. (G0) In contrast, what are some cells that would grow and divide rapidly throughout life? Skin cells Cells of the digestive tract

Mitosis Mitosis is divided into four phases: Prophase, Metaphase, Anaphase, and Telophase (Some say there is a fifth phase – prometaphase)

Mitosis -> Prophase During Prophase The chromosomes become visible. The centrioles separate and take up positions on opposite sides of the nucleus. The centrioles help to organize the spindle. The chromosomes become attached to the spindle fibers. The nucleolus disappears and the nuclear envelope breaks down. Prophase is the longest of the 4 mitosis phases

Prophase What is the function of the spindle? The spindle helps separate the chromosomes.

Mitosis -> Metaphase During metaphase, the chromosomes line up across the center of the cell. Microtubules connect the centromere of each chromosome to the two poles of the spindle.

Mitosis -> Anaphase During Anaphase The centromeres that join the sister chromatids split, allowing the sister chromatids to separate and become individual chromosomes. The chromosomes continue to move until they have separated into two groups near the poles of the spindle.

Anaphase Anaphase ends when the chromosomes stop moving.

Mitosis -> Telophase During Telophase The chromosomes, which were distinct and condensed, begin to disperse into a tangle of dense material. A nuclear envelope re-forms around each cluster of chromosomes. The spindle begins to break apart and a nucleolus becomes visible in each daughter nucleus.

Telophase Telophase is the final phase of Mitosis.

Cytokinesis The process of cell division is not complete with Telophase. As a result of mitosis, two nuclei are formed- each with a duplicate set of chromosomes. Cytokinesis is the division of the cytoplasm surrounding the two nuclei. Cytokinesis can appear to happen at the same time as Telophase.

Cytokinesis In animal cells, the cell membrane is drawn inward until the cytoplasm is pinched into two nearly equal parts. Each part contains its own nucleus and cytoplasmic organelles. In plant cells, a structure known as the cell plate forms midway between the divided nuclei. The cell plate gradually develops into a separating membrane and then the cell wall forms.

Cytokinesis

The goal of Mitosis/ Cytokinesis is to produce 2 identical cells These cells have a full set of chromosomes, therefore they are called diploid.

Cancer Research Paper Due November 17th 1 page; double spaced; 12 point font Include generalized cancer information and cell checkpoint information  Include main differences in benign and malignant tumors  Include key facts about a particular type of cancer; causes, symptoms, & possible treatments  CSE format = include in-text citations (Author, Year) in paper and works-cited page: Author(s). Year. Title. Journal. [date accessed] url

HomeWork Tonight Read Page 253 – Stem Cells What are stem cells? Why are they being studied?

Mitosis Video http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html https://www.youtube.com/watch?v=mXVoTj06zwg