Presentation on theme: "CELLS: THEIR STRUCTURE & FUNCTION. THE CELL THEORY (DEVELOPED AFTER THE DISCOVERY OF THE MICROSCOPE AND THE CELL) HAS THREE PARTS: 1. ALL ORGANISMS ARE."— Presentation transcript:
CELLS: THEIR STRUCTURE & FUNCTION
THE CELL THEORY (DEVELOPED AFTER THE DISCOVERY OF THE MICROSCOPE AND THE CELL) HAS THREE PARTS: 1. ALL ORGANISMS ARE COMPOSED OF CELLS. 2. CELLS ARE THE BASIC UNIT OF LIFE – they are the smallest structures that show all the characteristics of life. 3. CELLS ARISE FROM OTHER PRE-EXISTING CELLS.
1.ALL ORGANISMS ARE COMPOSED OF CELLS. DOES THIS MEAN ALL ORGANISMS – EVEN BACTERIA, VIRUSES, PLANTS & ANIMALS? Most organisms are MULTICELLULAR = composed of many cells. These are the two types --- THE TWO TYPES OF CELLS: PROKARYOTICEUKARYOTIC
1.THEY ARE COMPOSED OF ONLY A PROTEIN COAT AND DNA or RNA. 2.THEY CANNOT LIVE WITHOUT A HOST (ANOTHER PROKARYOTIC OR EUKARYOTIC CELL). 3. THEY CAN PERFORM ONLY SOME OF THE CHARACTERISTICS NECESSARY FOR LIFE. THE VIRUS DEBATE HERE’S THE INFO……………..YOU DECIDE!!!
1. MOVEMENT – Must be able to move food into its body, distribute it to all parts of the body, and eject wastes. 2. METABOLISM AND HOMEOSTASIS – Must be able to make energy from compounds and build tissues. Must know how much is required to keep the body in balance. 3. RESPONSIVENESS – Must be able to respond to the environment – “fight or flight”. 4. GROWTH AND DEVELOPMENT – Grow by taking in raw materials and using them to synthesize new cells. 5. REPRODUCTION – Ability to produce offspring to produce new generations. 6. ADAPTATION – Features that fit them into their environment and help them survive. WHAT ARE THE CHARACTERISTICS OF LIFE? What makes some things living and others nonliving?
ALL CELLS HAVE CERTAIN CHARACTERISTICS: 1.Surrounded by a membrane = PLASMA OR CELL MEMBRANE This membrane separates them from the outside environment. BUT…. It does allow some things in….this makes it SEMI-PERMEABLE. WHAT ARE SOME THINGS IT LETS IN? 2. CELLS ARE THE BASIC UNIT OF LIFE WHAT IS A CELL COMPOSED OF?
THE PLASMA MEMBRANE “ALSO KNOWN AS THE CELL MEMBRANE” STRUCTURE: -Two layers (bilayer) of PHOSPHOLIPIDS AND PROTEINS - Semi- permeable: allows in/out oxygen, carbon dioxide, proteins, glucose, water – some with the use of ENERGY other without FUNCTION: -Separate cell from external environment -Barrier to keep some materials out and allow others in; controls what enters and leaves
2. ALL CELLS INCLUDE – DNA - Since they must reproduce and make proteins for their functioning. The DNA in cells is SEGREGATED into a DNA- containing region.
3. All cells contain – CYTOPLASM Cytoplasm is a “jello” (jelly) like substance It contains: Water, salts and organic compounds It is located inside the CELL MEMBRANE and between the cell membrane and NUCLEAR MEMBRANE. It is in constant motion – bathing and moving the cell structures.
Cell Functions/Jobs A. Digestion B. Secretion – release enzymes and other chemicals C. Metabolism or Respiration D. Excretion E. Absorption F. Reproduction G. Response To Stimulus H. Synthesis – making of proteins and other substances
Cells contain subparticles known as ORGANELLES. WHICH ORGANELLES AND THE NUMBER A CELL CONTAINS DEPENDS UPON THE TYPE OF CELL THAT IT IS. EACH ORGANELLE HAS ITS OWN SPECIFIC STRUCTURE AND FUNCTION.
THE CELL ORGANELLES NUCLEUS STRUCTURE -CONTAINS THE GENES (DNA) ALSO KNOWN AS CHROMATIN (NONDIVIDING CELL) OR CHROMOSOMES (DIVIDING CELL) --SURROUNDED BY A DOUBLE LAYERED MEMBRANE WITH PORES CALLED THE NUCLEAR MEMBRANE -- CONTAINS THE NUCLEOLUS FUNCTION -CONTROLS THE MAKING OF NEW CELLS --CONTROLS THE MAKING OF PROTEINS -- ALSO KNOWN AS THE “BLUEPRINTS”
NUCLEOLUS STRUCTURE - Located within the nucleus, spherical - Contains RNA and proteins FUNCTION - Produces ribosomes (l0,000/min.)
RIBOSOMES STRUCTURE - Made of 2 subunits of protein and RNA -- No membrane, spherical -- Located on the Endoplasmic -reticulum and in the cytoplasm FUNCTION - protein synthesis
ENDOPLASMIC RETICULUM STRUCTURE: -Consists of a network of tubes that are continuous with the nuclear membrane TWO TYPES: SMOOTH ER – does NOT contain ribosomes Function = making lipids, breakdown of carbohydrates, muscle contraction, and detoxification of drugs and poisons ROUGH ER – contains ribosomes on its surface (outside) Function = site of PROTEIN production and Transport of proteins
GOLGI BODY OR APPARATUS STRUCTURE -A series of flattened, membranous sacs (looks like pita bread) -- Located near the ER FUNCTION -Packages and stores proteins -- Sends proteins to the cell membrane for EXPORT in small spherical structures called VESICLES.
LYSOSOMES ALSO KNOWN AS “SUICIDE SACS” -STRUCTURE Sphere shaped, membrane bound organelles located in the cytoplasm - Contain DIGESTIVE ENZYMES - More commonly found in animal cells FUNCTION Break down and digest old cell parts, bacteria, food particles - Play a role in early development
MITOCHONDRIA “Powerhouses of a cell” STRUCTURE: -Double membrane structure. The outer membrane is smooth, while the inner membrane is folded, these folds are called CRISTAE. -- The inner most area is called the Mitochondrial matrix. FUNCTION: -Cellular Respiration Glucose is changed to water, carbon dioxide and energy (known as ATP) which the cell can use for its many functions.
PLASTIDS Plastids are PLANT organelles that store chemical energy. They include: AMYLOPLASTS – which store starch LEUCOPLASTS – which store starch, proteins, and lipids CHROMOPLASTS – which contain color pigments CHLOROPLASTS – which contain the green pigment, CHLOROPHYLL
CHLOROPLASTS STRUCTURE: Chloroplasts have a double membrane. The outer membrane is smooth, while the inner membrane forms stacks called THYLAKOIDS. Thylakoids may be joined together to form GRANA. These membranes are bathed in a fluid called STROMA. FUNCTION: PHOTOSYNTHESIS – converting carbon dioxide and water with the help of sunlight into SUGAR and OXYGEN.
VACUOLES STRUCTURE: - Found mainly in plant cells - larger than vesicles - - Single membrane, spherical - -May take up to 90% of a plant cells area FUNCTION: - Store food, excess water, toxins, enzymes, and waste products. - - Digest food and waste - - Pump excess water out of cells
CYTOSKELETON (Cell Framework) STRUCTURE: -Composed of microtubules and microfilaments (protein tubes and threads) FUNCTION: -Microtubules – shape, support and help move organelles around the cell - Microfilaments – muscle contraction, cytoplasmic streaming, and changes in cell shape
CILIA AND FLAGELLA STRUCTURE: -Extensions of cell membranes -Composed of microtubules in a “ 9 + 2” pattern -Driven by ATP -Cilia: numerous and short -Flagella: one or two to a cell and longer FUNCTION: MOVEMENT OF THE CELL Cilia - move back and forth like an oar Flagella – move in a whip-like fashion
CELL WALL Found only in PLANT CELLS STRUCTURE: - composed of CELLULOSE -- Two walls thick -- contains pores FUNCTION: - Protect, strengthen and allow certain materials in and out
PROKARYOTIC CELLS Include bacteria and some algae DO NOT contain all the structures found in eukaryotic cells. Size1-10 microns NucleusNo, circular DNA Ribosomes Yes Cell Wall Yes Other Organelles No Cilia/Flagella Yes
EUKARYOTIC CELLS TWO TYPES: PLANT CELLSANIMAL CELLS
EukaryoticProkaryotic Representative organismPlant and animal cells Bacteria and some algae Size10-50 microns1-10 microns NucleusYesNo RibosomesYes Cell WallPlant onlyYes Other OrganellesYesNo Cilia/FlagellaYes DIFFERENCES BETWEEN EUKARYOTIC AND PROKARYOTIC CELLS
Animal Plant Size10-20 microns30-50 microns ShapeIrregularSquare/Rectang ular Cell WallNoYes LysosomeYesRare ChloroplastNoYes VacuoleSmall or absent Large/90% of cell Cilia/FlagellaBothMostly absent except sperm DIFFERENCES BETWEEN PLANT AND ANIMAL CELLS
3. All cells come from pre-existing cells. SPONTANEOUS GENERATION Living things can arise from nonliving things. EXPERIMENTATION REDI EXPERIMENT – 1600’S BIOGENESIS Life comes from life.
BIOLOGICAL HEIRARCHY ATOMS MOLECULES/COMPOUNDS ORGANELLES – subparticles of cells CELLS TISSUES – group of cells that perform the same function (Example: Four types - Muscle tissue, epithelial tissue, connective tissue, nerve tissue) ORGANS – group of tissues that perform the same function (Example: Stomach – muscle, epithelial, nerve, connective tissue) ORGAN SYSTEMS – group of organs that work together to perform the same function (Example: Digestive System) ORGANISM – group of organ systems that work together to perform a function