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Transcript
Cell Structures and Their Functions Cell Structure Highly Organized . Specialized structures called organelles in a jelly like substance called cytoplasm Amount and type of organelles is related to function Functions of the Cell Basic Unit of Life -smallest part that still retains characteristics of life Protection And Support – cells secrete substances that provide Movement- occurs because of molecules that are located in specific cells e.g. muscle cells Communication-cells receive information that allow them to communicate with each other eg nerves cell tells muscle cells to contract Cell metabolism and energy release- all the chemical reactions that occur within the cell Inheritance – each cell contains a copy of the genetic information of the individual The Organelles The Nucleus Nucleoli and Ribosomes Rough and Smooth Endoplasmic Reticulum The Golgi Apparatus Secretory Vesicles Lysosomes and Peroxiisomes Mitochondria Cytoskeleton Centrioles Cilia, Flagella and Microvilli The Cell Membrane Cell Membrane Phospholipid Bilayer Protection and Transport Types of Transport Active ( requires ATP) Passive Nucleus Contains the genetic material of cell (DNA) Located near the center of the cell Some cells lose their nucleus as they mature, some have more than one nucleus bone cells Nuclear envelop (outer and inner membranes and nuclear pores) Contains loosely coiled fibers called chromatin consisting of DNA When a cell divides the chromatin becomes more tightly coiled to form the 23 pairs of chromosomes Nucleoli and Ribosomes Nucleoli- are rounded dense well defined nuclear bodies with no surrounding membranes Ribosome's- are the organelles where proteins are produced -may be free -attached to the endoplasmic reticulum -made in the nucleus Smooth and Rough Endoplasmic Reticulum The ER is a series of membranes forming sacs and tubules that extends from the outer nuclear membrane into the cytoplasm Rough ER – has ribosomes attached indicting that it is synthesizing large amounts of protein for export from the cell Protein Synthesis Transcription Translation RNA mRNA t RNA r RNA The Golgi Apparatus Golgi Apparatus- closely packed stacks of curved membrane –bound sacs. Its function is to collect modify , package and distribute proteins and lipids manufactured by the Endoplasmic Reticulum May also chemically modify the proteins by attaching carbohydrates or lipids to them Found in great number in cells tat make a great deal of protein e.g. pancreas Secretory Vesicles a vesicle is a small membrane bound sac that transports or stores materials within cells Secretory vesicles – pinch off from the golgi apparatus and move to the surface of the cell . Their membranes fuse with the cell membrane and release contents to the exterior of the cell Lysosomes and Peroximes Lysosomes are membrane bound vesicles formed from the golgi apparatus . They contain a variety of enzymes that functions as intracellular digestive systems Peroxisomes small membrane bound vesicles containing enzymes that break down fatty acids , amino acids and hydrogen peroxide. Mitochondria Mitochondria- small bean shaped, long threadlike organelles that has inner and outer membranes separated by a space. The outer membranes have a smooth corebut the inner membrane has numerous folds called cristae Site of ATP production within the cells and carry out aerobic respiration muscle cells Cytoskeleton Cytoskeleton- consists of proteins that support the cell , hold organelles in place and enable the cell to change shape. Microtubules, Microfilaments and Intermediate filaments Microtubules Microfilaments Intermediate filaments Centrioles Centosome- a specialized zone of cytoplasm close to the nucleus that is the center of microtubule formation. It contains the centrioles normally oriented perpendicular to each other Shaped like a cylinder and has nine triplets , each consisting of three parallel microtubules joined together. Protein Synthesis DNA in nucleolus is Transcribed to MRNA MRNA is translated at the level of the ribosomal subunits where the codons are read and translated into amino acids The amino acids form peptide bonds to create one larger protein DNA and RNA DNA has 4 nitrogenous bases : adenine, guanine, cytosine and thiamine plus the sugar deoxyribose RNA has 4 nitrogenous bases : adenine, guanine, cytosine and uracil plus the sugar ribose. Remember there are 64 sets of codons (a codon is 3 base pairs) that encode for only 20 amino acids Fate of the Cell Divides ( Mitosis and Meiosis) Differentiates Apoptosis Tumor ( Benign or Malignant) Ages Death * The Cloning of Cells Cell Division Mitosis all cells except sex cell(meiosis) Interphase Prophase Metaphase Anaphase Telophase Cytokinesis Differentiation We learned that through mitosis all cells in an individuals body contain the same amount and type of DNA So, even though the genetic material is the same , why is it that cells do not look and function the same way, example of diverse cells in text The process by which a cell develop special structure and functions is called DIFFERENTIATION. What happens during differentiation? DNA is either active or inactive pending in the cell type via the selective activation of certain portions of the DNA As they mature and differentiate the rate eventually slows and stops Apoptosis Programmed cell death is a normal process by which cell numbers within various tissues are adjusted and controlled . During development any extra tissue s removed, such as the webs between the toes and the fingers. Cellular Aging Cellular Clock after a certain time or number of cell divisions cell death occurs in a given line Death genes turn on causing cells to deteriorate DNA damage over years Free Radicals (unpaired electrons) cause direct damage via mutations Mitochondrial damage causes a loss of energy needed to maintain cell life Cellular Tumor Transformation Tumor- any swelling that occurs within the body malignant- spreads rapidly, can get large benign- can get large Cancer Cancers are malignant spreading tumors Can spread via the lymphatic, hematologic, or local expansion routes Growth becomes out of control and the cancer breaks away from normal control Occur as a result of viruses, toxins Treatment in the form of Chemotherapy Immunotherapy Radiotherapy ‘ Starvation to cancer Cloning A nucleus removed from a differentiated cell can be transferred to an oocyte with the nucleus removed and a complete frog can be formed