Review the Cell Theory Take one minute and write down the 3 parts to the Cell Theory 1. 3. 2. All organisms are made up of one or more cells. All cells.

Review the Cell Theory Take one minute and write down the 3 parts to the Cell Theory All organisms are made up of one or more cells. All cells carry on their own life activities New cells can arise only from other living cells by the process of cell division. The larger the cell becomes, the more demands the cell places on its DNA and the more trouble the cell has moving enough nutrients and wastes across the cell membrane. DNA "Overload" In time as the cell grows larger; the DNA can no longer serve its increasing needs Volume increases faster than the surface area of a growing cell Surface Area- to- Volume Ratio The surface area-to-volume will decrease. (causes problems) So, surface area to volume is why the cells of an organism do not grow larger even though the organism grows much larger and why cells stay small. 2 Basic Types of Reproduction To stay small, cells must reproduce. Asexual reproduction one parent; offspring is identical to parent Sexual reproduction two parents; offspring is not identical to parents Overview of Cellular Division- (MITOSIS) Two processes take place Division of the nucleus Division of the cytoplasm Review of the STRUCTURE of the NUCLEUS Nucleus is the control center of the cell Contains DNA (which is the hereditary material needed for the synthesis of all components of each cell ) DNA is found in chromatins - long thin thread like material Humans have 46 (23 pairs) of chromosomes Structure of DNA Each strand is connected by hydrogen bond b/w base pairs Double stranded, twisted molecule Note: Individual chromosomes are not visible when the DNA is present as chromatin Human Karyotype Amt. of time spent by a typical cells in each state: G1 9 hrs. S 10 hrs. G2 2 hrs. Mitosis 1 hr. Life Spans of Various Human Cells Cell TypeLife SpanCell Division Lining of esophagus2-3 daysCan divide Lining of small intestine 1-2 daysCan divide Lining of large intestine6 daysCan divide Red blood cellsLess than 120 daysCannot divide White blood cells10 hrs. to decadesMany do not Smooth muscleLong-livedCan divide Cardiac muscleLong-livedCannot divide Skeletal muscleLong-livedCannot divide NeuronLong-livedMost do not Mitosis Two daughter cells produced from one New cells genetically identical (to each other and also to original cell) Reproduction in many one-celled organisms (ex.: amoeba) For convenience, process is described as occurring in stages or phases. However, it IS a continuous process with no interruptions between one phase and the next. : normal diploid cells always have an even number of chromosomes. : At the beginning of cell division, each chromosome consists of two chromatids. : Each chromatid contains a single DNA molecule. : Daughter cells at the end of mitosis are genetically identical to the original mother cell. : Daughter cells of meiosis are genetically different from the original mother cell, and from each other. 2N diploid cell Two copies of each chromosome. Where do the two copies come from???? Mitosis Summary (IPMAT) 2N 2 identical diploid daughter cells formed Interphase- * Not a part of mitosis; this phase occurs BEFORE mitosis starts nuclear of genetic material (chromatin) are replicated This is CHROMOSOME REPLICATION * cells grow in size * more organelles, nucleic acid, & proteins are produced * centrioles also replicate during this phase RESTING PHASE" Why do you think calling this phase the resting phase is a misnomer? * Chromosomes are NOT visible CELL IN INTERPHASE nucleus chromatin centrioles Animal cell Plant cell Prophase- begins mitosis 1. Chromatin condenses into chromosomes = sister chromatids which now will become visible 2. Centrioles move to opposite sides (poles) of the cell 3. Spindle fibers radiate out from centrioles to form asters 4. Spindles attach to the centromere of chromosome 5. Nuclear membrane & nucleolus disappear The structure and the actual picture of a chromosome. cell in prophase Metaphase- Meta = middle Chromosomes lined up on equatorial plane Draw a cell in metaphase Anaphase - 1. Daughter chromosomes move to opposite poles probably by shortening of spindle fibers 2. Beginning of cytokinesis (cytoplasmic division) cell membrane 'pinches'. 3. Centromeres divide, forming separate sister chromatids cell in anaphase Telophase- last phase of mitosis 1. Chromosomes reach poles 2. Chromosomes uncoil to form chromatin 3. Spindles & asters disappear 4. Nuclear membrane forms, nucleolus appear 5. Cytokinesis is completed producing two daughter cells 6. Basically the opposite of prophase *cytokinesis cytoplasm division occurs by pinching inward of cleavage furrow final stages of mitosis Telophase and cytokinesis Mitosis (in plants) Plant cell division differs from animal cell division in 2 ways 1. Plants do NOT have centrioles therefore no asters (still have spindles) 2. Rigid cell wall prevents cell membrane from pinching; instead, a cell plate forms which divides the cell in half PLANT CELLSANIMAL CELLS Daughter cells contain the same number of chromosomes as parent cell Daughter cells contain the same number of chromosomes as parent cell. No centrioles present; Spindle forms Centrioles are present; Spindle forms Daughter cells have about half the cytoplasm of parent cell Cytoplasmic division occurs by formation of cell plate Cytoplasmic division occurs by pinching inward of cleavage furrow ASEXUAL REPRODUCTION * Offspring genetically identical to parent & each other *generally rapid * high # of offspring Types of Asexual Reproduction BINARY FISSION - parent divides into 2 equal parts Ex) bacteria, protozoa, some algae BUDDING- Ex) yeast, hydra offspring buds off the parent, identical division of nuclear material but unequal division of cytoplasm Spore Formation- single specialized cells produced by certain organisms that when released, germinate and grow and form new individuals (can be formed sexually or asexually) Ex) bread mold Regeneration- ability of an organism to regrow lost body part a. Relatively simple animals- starfish, hydra, earthworm, planaria b. In humans and other vertebrates, small wounds heal by regeneration of new tissues to replace damaged tissues. Regeneration occurs by mitosis. Vegetative Reproduction- growing new plants from parts of other plants a. bulb- short underground stem surrounded by thick fleshy leaves that contain stored food; tulips, onions, lilies b. corm- resemble bulbs but do not contain fleshy leaves; gladioli, crocuses, water chestnuts e. rhizome- a horizontal stem that grows underground; ferns, irises, water lilies d. runner (stolon)- horizontal stem with buds along the surface of the ground; grasses, strawberry c. tuber- enlarged portion of an underground stem that contains food; white potatoes Artificial Vegetative Reproduction a. cutting- stem, leaves, roots used to produce new individuals b. layering- a stem is bent over & covered with soil and new individuals grow c. grafting- 2 parts of plants are cut & joined together; roses, nectarines Stock- part that contains the roots Scion- added piece on top Advantages *production of new entirely new plants that are genetically identical to the original plant *development takes less time *seedless fruit can be grown *higher yields of fruits or nuts What happens when mitosis (cell division) does not work properly and too many cells are made to quickly? Cancer is a variety of diseases in which cells of the body multiply without control. Cancer can occur in any of the several types of cells that make up the body. Malignancy has been linked with changes in the genetic material of the cells based on three lines of evidence. The daughter cells of a cancerous cell are always malignant, indicating cancer is an inherited property. Chromosome mutations, such as deletions and translocations, are often observed in cancer cells. Oncogenes are genes that cause some kinds of cancer. When oncogenes are turned off they will not cause cancer, but when they are switched on, this leads to uncontrolled growth of cells that we call cancer. Uncontrolled Cell Growth Cancer disorder which some of the bodys own cells lose the ability to control growth. As a result, they form masses of cells called tumors that can damage the surrounding tissues. Causes Radiation exposure Smoking Viral infections Cancer does not respond to the signals that regulate the growth of most cells. 1.High number of cancer cells have a defect in a gene call p53, which normally halts the cell cycle until all chromosomes have been properly duplicated