Cells: Basic Structure and Function PDF

Basic Structure of a Cell 1  Introduction to Cells Cells are the basic units of organisms Cells can only be observed under microscope Basic types of cells: Animal Cell Plant Cell Bacterial Cell 2  N...

Basic Structure of a Cell 1  Introduction to Cells Cells are the basic units of organisms Cells can only be observed under microscope Basic types of cells: Animal Cell Plant Cell Bacterial Cell 2  Number of Cells Organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells that may organize 3  Cells May be Prokaryotic or Eukaryotic  Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles Eukaryotes include most other cells & have a nucleus and membrane- bound organelles (plants, fungi, & animals) 4  Prokaryotes Nucleoid region contains the DNA Cell membrane & cell wall Contain ribosomes (no membrane) to make proteins in their cytoplasm 5  Eukaryotic Cell Contain 3 basic cell structures: Nucleus Cell Membrane Cytoplasm with organelles 6  Two Main Types of Eukaryotic Cells Plant Cell Animal Cell 7  Organelles Very small size Can only be observed under a microscope Have specific functions Found throughout cytoplasm 8  Organelles Found in Cells Examples of Organelles include: Endoplasmic reticulum (rough & smooth) – canals for movement Golgi Bodies – wrap & export proteins Nucleolus – makes ribosomes Lysosomes – digests & gets rid of wastes Ribosomes – makes proteins 9  Golgi Bodies Stacks of flattened sacs Have a shipping side & a receiving side Receive & modify proteins made by ER Transport vesicles with modified proteins pinch off the ends Transport vesicle 10  Lysosome Contain digestive enzymes Break down food and worn out cell parts for cells Programmed for cell death (lyse & release enzymes to break down & recycle cell parts) 11  Nucleolus Cell may have 1 to 3 nucleoli Inside nucleus Disappears when cell divides Makes ribosomes that make proteins 12 Smooth & Rough Endoplasmic Reticulum Smooth ER lacks ribosomes & makes proteins USED In the cell Rough ER has ribosomes on its surface & makes proteins to EXPORT 13  Cell Powerhouse Mitochondrion ( mitochondria ) Rod shape Site of Cellular respiration 14  In Animal Cells: Mitochondria Active cells like muscles have more mitochondria Burn sugars to produce energy ATP 15  Surrounding the Cell Cell membrane Lies immediately against the cell wall in plant cells Made of protein and phospholipids Selectively permeable 16  Cell or Plasma Membrane Cell membrane Living layer Controls the movement of materials into and out of the cell Selectively permeable 17  Cell Wall Cell wall Nonliving layer Gives structure and shape to plant and bacterial cells 18  Cytoplasm of a Cell Cytoplasm Jelly-like substance enclosed by cell membrane Provides a medium for chemical reactions to take place 19  More on Cytoplasm Cytoplasm Contains organelles to carry out specific jobs Examples: chloroplast & mitochondrion 20  Control Organelle Nucleus Controls the normal activities of the cell Contain the DNA Bounded by a nuclear membrane Contains chromosomes 21  More on the Nucleus Nucleus Each cell has fixed number of chromosomes that carry genes Genes control cell characteristics 22  Plant Cell Organelles Chloroplast Contain the green pigment chlorophyll Traps sunlight to make to make sugars (food) Process called photosynthesis 23  Plant Cell Cell wall Dead layer Large empty spaces present between cellulose fibers Freely permeable 24  Plant Cell Cell wall Made of cellulose which forms very thin fibers Strong and rigid Found in plant cells 25  Plant Cell Cell wall Protect and support the enclosed substances (protoplasm) Resist entry of excess water into the cell Give shape to the cell 26  Plant Cell Organelles Vacuole Have a large central vacuole Surrounded by tonoplast Contains cell sap Sugars, proteins, minerals, wastes, & pigments 27 Different kinds of plant cells Onion Epidermal Cells Guard Cells root hair Root Hair Cell 28 vacuole cytoplasm Animal cell No cell wall or chloroplast nucleus Stores glycogen in the mitochondrion cytoplasm for food energy cell glycogen membrane granule 29 Animal Cell Organelles Near the nucleus Paired structures Help cell divide 30 Different kinds of animal cells white blood cell Amoeba red blood cell muscle cell sperm cheek cells nerve cell Paramecium 31 Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm Both have a nucleus Both contain mitochondria 32 Differences between plant cells and animal cells Animal cells Plant cells Relatively Relatively smaller in size larger in size Irregular shape Regular shape No cell wall Cell wall present 33 Differences between Plant Cells and Animal Cells Animal cells Plant cells Vacuole small or Large central absent vacuole Glycogen as food Starch as food storage storage Nucleus at the Nucleus near cell center wall 34  Compound Microscope Instrument for observing small objects Magnify images up to 2000X their size 35 Different parts of a microscope 36 Revolving Eyepiece nosepiece Body tube Objective Coarse adjustment Clip Fine adjustment Condenser Arm Iris diaphragm Stage Condenser Mirror control knob Base 37  The cell is the Basic Unit of Life Cell is the smallest unit of living organisms Unicellular organisms are made of one cell only The cells of multicellular organisms are specialized to perform different functions – e.g. mesophyll cells for photosynthesis and root hair cells for water absorption 38  Levels of organization Cells are grouped together and work as a whole to perform special functions 39  Tissue A group of similar cells to perform a particular function – Animals : epithelial tissue, muscular tissue – Plants : vascular tissue, mesophyll 40  Organ Different tissues group together to carry out specialized functions – Heart : consists of muscles, nervous tissue and blood vessels – Leaf : consists of epidermis, mesophyll and vascular tissue 41 The Structures of a Leaf (Plant Organ) Chloroplast Palisade Mesophyll Cell Spongy Mesophyll Cell Air Space Stoma 42 The Structures of a Heart (Animal Organ) 43  System Several organs and tissues work together to carry out a particular set of functions in a co-ordinated way – Human : digestive, respiratory, excretory, circulatory and reproductive systems – Plant : root and shoot systems copyright cmassengale 44  Levels of Organization CELLS (muscle cells,nerve cells) TISSUES (muscle, epithelium) ORGANS (heart, lungs, stomach) SYSTEMS (circulatory system) ORGANISM (human) copyright cmassengale 45