Cells Honors Human Anatomy and Physiology Coach Denson

Introduction to Cell Cells are the structural and physiological unit of all living organisms. A cell’s function is determined by its anatomy. Nerve cells are very long Epithelial cells in the mouth are flat like floor tiles. Muscle cells are made of telescoping fibers that can contract. Although cells vary greatly, they have some things in common. All the various parts make a composite cell.

Composite Cell Three main parts in a eukaryotic cell. 1.Cell Membrane Functions: Functions: Boundary of the cell Boundary of the cell Controls entrance and exit to cell Controls entrance and exit to cell Site of many metabolic reactions Site of many metabolic reactions Signal transduction Signal transduction Characteristics Characteristics Extremely thin (only 2 molecules thick) Extremely thin (only 2 molecules thick) Flexible Flexible Somewhat elastic Somewhat elastic Selectively permeable Selectively permeable

Composite Cell Structure Structure Double layer of phospholipids Double layer of phospholipids Water soluble substances can’t pass Water soluble substances can’t pass Lipid soluble substances pass Lipid soluble substances pass Embedded proteins Embedded proteins Receptor proteins extend into and out of the cell Receptor proteins extend into and out of the cell Integral proteins form pores and channels. Integral proteins form pores and channels. Peripheral proteins function as enzymes. Peripheral proteins function as enzymes. Glycoproteins function in recognition and binding. Glycoproteins function in recognition and binding.

Composite Cell Intercellular Junctions Intercellular Junctions Tight junctions fuse adjacent cell membranes. Tight junctions fuse adjacent cell membranes. Desmosomes join cells in “spot welds” Desmosomes join cells in “spot welds” Gap Junctions connect with tiny tubes that allow movement of materials. Gap Junctions connect with tiny tubes that allow movement of materials. 2. Cytoplasm Functions: Functions: Support Organelles Support Organelles Medium for diffusion Medium for diffusion Provide dissolved materials for metabolism. Provide dissolved materials for metabolism. Structure-Cytosol(fluid) and cytoskeleton(protein rod and tubule support) Structure-Cytosol(fluid) and cytoskeleton(protein rod and tubule support) Organelles Organelles

Composite Cell: Organelles: Endoplasmic Reticulum (ER)-Zig-zag appearance in cell Endoplasmic Reticulum (ER)-Zig-zag appearance in cell Rough and Smooth (As as “Flow Control” Rough and Smooth (As as “Flow Control” Structure- Structure- complex membrane tubes, canals, sacs; connect cell membrane and nucleus (Membrane Structure) complex membrane tubes, canals, sacs; connect cell membrane and nucleus (Membrane Structure) Function- Function- Intracellular transport; provide surfaces for protein synthesis and other metabolic reactions. Intracellular transport; provide surfaces for protein synthesis and other metabolic reactions. Ribosomes Ribosomes Structure- Structure- Protein (2) and RNA (2) Protein (2) and RNA (2) Function- Function- Protein synthesis Protein synthesis

Composite Cell: Organelles: Golgi Apparatus Golgi Apparatus Structure- Structure- Stack of flattened membranous sacs (cisternae) Stack of flattened membranous sacs (cisternae) Function- Function- Modify, package, deliver proteins produced by ribosomes on rough ER for cellular export Modify, package, deliver proteins produced by ribosomes on rough ER for cellular export Mitochondria (~1700/Cell) Mitochondria (~1700/Cell) Structure- Structure- Double membrane; inner membrane consists of folds(cristae); non- chromosomal DNA; motile(moves on it’s own) Double membrane; inner membrane consists of folds(cristae); non- chromosomal DNA; motile(moves on it’s own) Function- Function- Assist in releasing energy from glucose in the form of ATP(cellular respiration) Assist in releasing energy from glucose in the form of ATP(cellular respiration)

Composite Cell: Organelles: Lysosomes Lysosomes Structure- Structure- Tiny, membranous sacs containing digestive enzymes; much variety of shape. Tiny, membranous sacs containing digestive enzymes; much variety of shape. Function- Function- Dismantle debris; destroy worn cell parts; break down engulfed material. Dismantle debris; destroy worn cell parts; break down engulfed material. Peroxisomes (special type of lysosomes) Peroxisomes (special type of lysosomes) Structure- Structure- Tiny membranous sacs containing enzymes Tiny membranous sacs containing enzymes (Peroxidase, Catalase) specific to the function. (Peroxidase, Catalase) specific to the function. Can break down hydrogen peroxide Can break down hydrogen peroxide Function- Function- Regulate metabolic reactions that produce dangerous by-products and then break down those by-products Regulate metabolic reactions that produce dangerous by-products and then break down those by-products

Composite Cell: Organelles: Centrosomes-made up of 2 centrioles-90 degrees to each other Centrosomes-made up of 2 centrioles-90 degrees to each other Structure- Structure- Nonmembranous; 2 cylinders (centrioles) of a protein microtubules at right angles; near the nucleus Nonmembranous; 2 cylinders (centrioles) of a protein microtubules at right angles; near the nucleus Function- Function- During cell division centrioles migrate to opposite poles, form spindle fibers attached to chromosomes and assist in proper disjunction. During cell division centrioles migrate to opposite poles, form spindle fibers attached to chromosomes and assist in proper disjunction. Cilia and Flagella Cilia and Flagella Structure- Structure- Found on the free surfaces of some cells; distinct cylindrical patter of microtubules, attached to modified centrioles called basal bodies. Found on the free surfaces of some cells; distinct cylindrical patter of microtubules, attached to modified centrioles called basal bodies. Function- Function- Produce undulating motions for moving the cell or moving material past the cell. Produce undulating motions for moving the cell or moving material past the cell.

Composite Cell: Organelles: Vesicles Vesicles Structure- Structure- Membranous sacs that vary in size and contents (i.e. lysosomes, peroxisomes, etc.)……enzymes. Membranous sacs that vary in size and contents (i.e. lysosomes, peroxisomes, etc.)……enzymes. Function- Function- Storage; movement of particles and materials Storage; movement of particles and materials Microfilaments Microfilaments Structure- Structure- Mesh or bundle of actin rods-made up of actin (also in muscles) Mesh or bundle of actin rods-made up of actin (also in muscles) Function- Function- Causes various kinds of internal movement in cells Causes various kinds of internal movement in cells

Composite Cell: Organelles: Microtubules-bigger than microfilaments, made up of tubulin Microtubules-bigger than microfilaments, made up of tubulin Structure- Structure- Long, rigid tubes of tubulin Long, rigid tubes of tubulin Function- Function- Provides cytoskeletal framework Provides cytoskeletal framework Inclusions- not necessary for the cell to stay alive Inclusions- not necessary for the cell to stay alive Structure- Structure- bundle of chemicals that do not directly assist in the function/survival of the cell bundle of chemicals that do not directly assist in the function/survival of the cell Function- Function- Temporary storage of chemicals (melanin, lipids, etc) Temporary storage of chemicals (melanin, lipids, etc)

Composite Cell 3. Nucleus Functions- Functions- Direct the activities of the cell Direct the activities of the cell Safeguard DNA Safeguard DNA Structure Structure Relatively large, spherical Relatively large, spherical Nuclear envelope (phospholipid membrane) Nuclear envelope (phospholipid membrane) Double Bilayer Double Bilayer Nuclear Pores-used for nucleotides to enter the nucleus Nuclear Pores-used for nucleotides to enter the nucleus Nucleoulus Nucleoulus Nonmembranous Nonmembranous Site of ribosome production (RNA part)-where ribosomal RNA is made. Site of ribosome production (RNA part)-where ribosomal RNA is made.

Composite Cell Nucleus continued…. Nucleus continued…. Chromatin Chromatin Loosely coiled DNA Loosely coiled DNA Protein histones act as spools for chromatin Protein histones act as spools for chromatin

Movement into and out of the cell 1.Diffusion 2.Osmosis 3.Filtration 4.Active Transport 5.Endocytosis/Exocytosis

Diffusion Movement from greater concentration to lesser concentration. Movement from greater concentration to lesser concentration. Simple diffusion requires NO ENERGY Simple diffusion requires NO ENERGY Facilitated diffusion uses a carrier molecule to assist materials across the membrane. Facilitated diffusion uses a carrier molecule to assist materials across the membrane.

Osmosis Movement of water from relative greater concentration of water to relative lesser concentration of water. (Selectively Permeable) Movement of water from relative greater concentration of water to relative lesser concentration of water. (Selectively Permeable) Isotonic solution- Isotonic solution- Water concentration is equal on both sides of cell membrane. Net movement=0 Water concentration is equal on both sides of cell membrane. Net movement=0 Hypertonic solution- Hypertonic solution- Water is relatively less concentrated in the solution. Water moves across the membrane out of the cell toward the hypertonic solution. Water is relatively less concentrated in the solution. Water moves across the membrane out of the cell toward the hypertonic solution. Hypotonic solution- Hypotonic solution- Water is relatively more concentrated in the solution. Water is relatively more concentrated in the solution. Water moves across the membrane into the cell away from the hypotonic solution. Water moves across the membrane into the cell away from the hypotonic solution.

Filtration Movement of materials across a membrane due to some force. Movement of materials across a membrane due to some force. Blood pressure-causes blood to be filtered. Blood pressure-causes blood to be filtered. Hydrostatic pressure Hydrostatic pressure

Active Transport Opposite of diffusion Opposite of diffusion Movement of materials from lower concentration to higher concentration Movement of materials from lower concentration to higher concentration Requires Energy (ATP) Requires Energy (ATP) Pump Mechanisms Pump Mechanisms

Endocytosis/Exocytosis Movement of particles across a membrane, but particles are encapsulated within a membrane vesicle. Movement of particles across a membrane, but particles are encapsulated within a membrane vesicle. Pinocytosis- Pinocytosis- Movement of water (“pino”-drink) Movement of water (“pino”-drink) Membrane eventually breaks down inside cell and releases water. Membrane eventually breaks down inside cell and releases water. Phagocytosis Phagocytosis Movement of food particles (“phago”-eat) Movement of food particles (“phago”-eat) Lysosomes attach and break down material Lysosomes attach and break down material Receptor mediated Endocytosis Receptor mediated Endocytosis Protein molecules “receive” specific materials and vesicles are formed around them. Protein molecules “receive” specific materials and vesicles are formed around them.

Cell Cycle Stages that a cell goes through from the time it forms until it divides. Stages that a cell goes through from the time it forms until it divides. Interphase- cell carries out its normal activity; DNA replicates Interphase- cell carries out its normal activity; DNA replicates Mitosis-genetic material divides (Nuclear Division) Mitosis-genetic material divides (Nuclear Division) Cytokinesis- the rest of the cell divides Cytokinesis- the rest of the cell divides Mitosis: Mitosis: Prophase Prophase Metaphase Metaphase Anaphase Anaphase Telophase Telophase

Mitosis Cell division/ Nuclear division Dividing chromosomes

Mitosis: Prophase Chromatin (indistinguishable strands) condenses into chromosomes (visible bodies) Chromatin (indistinguishable strands) condenses into chromosomes (visible bodies) Nuclear membrane disintegrates Nuclear membrane disintegrates Centrioles begin to migrate to opposite poles Centrioles begin to migrate to opposite poles

Mitosis: Metaphase Chromosomes line up on equator between centrioles Chromosomes line up on equator between centrioles Spindle fibers form and attach to chromosome centromeres and centrioles. Spindle fibers form and attach to chromosome centromeres and centrioles.

Mitosis: Anaphase Chromosomes are pulled apart to opposite sides. Chromosomes are pulled apart to opposite sides. Centrioles “reel” in chromosomes to opposite poles. Centrioles “reel” in chromosomes to opposite poles.

Mitosis: Telophase Chromosomes begin to unravel into chromatin Chromosomes begin to unravel into chromatin Spindle fibers detach and disintegrate Spindle fibers detach and disintegrate Nuclear membrane reforms around new nuclei Nuclear membrane reforms around new nuclei

For Mitosis Know… What’s going on in: The nuclear membrane CentriolesChromosomes

Cytoplasmic Division Cytokinesis Cytokinesis Cytoplasm divides Cytoplasm divides Begins during anaphase; ends when two “new” daughter cells are formed. Begins during anaphase; ends when two “new” daughter cells are formed.

Cellular Differentiation Process of cells taking on special anatomy and physiology Process of cells taking on special anatomy and physiology All cells go through this All cells go through this Stem cells have not differentiated yet. Stem cells have not differentiated yet.

Control of Cell Division Loss of telomeres on the ends of chromosomes triggers cell division to stop. Loss of telomeres on the ends of chromosomes triggers cell division to stop. Cell size- Cell size- cells reach a certain size and divides cells reach a certain size and divides Presence of kinases and cyclins Presence of kinases and cyclins Hormones Hormones Local Growth Factor Local Growth Factor Space availability Space availability