Exercise 4 The Cell—Anatomy & Division

What is a cell? Structural & functional unit of ALLLLLL living things Structural & functional unit of ALLLLLL living things Different sizes & shapes Different sizes & shapes Different functions Different functions Components may vary but have many common features Components may vary but have many common features

Cell Compartments Plasma membrane (plasmalemma) Plasma membrane (plasmalemma) Separates cell’s contents from outside environment Separates cell’s contents from outside environment Controls what goes in and out of the cell Controls what goes in and out of the cell Nucleus Nucleus “control center” of cell “control center” of cell DNA DNA Cytoplasm Cytoplasm Fluid AND other contents outside the nucleus Fluid AND other contents outside the nucleus

PLASMA MEMBRANE NUCLEUS CYTOPLASM Lab Fig. 4-3

Cytoplasmic Organelles Chromatin (in nucleus) Chromatin (in nucleus) DNA + proteins—when not replicating, DNA is in this threadlike form all over the nucleus DNA + proteins—when not replicating, DNA is in this threadlike form all over the nucleus Chromosome (in nucleus) Chromosome (in nucleus) When DNA replicates, chromatin becomes tightly coiled, short, rod-shaped When DNA replicates, chromatin becomes tightly coiled, short, rod-shaped Nucleolus Nucleolus Dense protein & RNA mass in nucleus Dense protein & RNA mass in nucleus Forms ribosomes which are then transported to cytoplasm Forms ribosomes which are then transported to cytoplasm

CHROMATIN NUCLEOLUS Lab Fig. 4-3

Lecture Fig. 3-14

Cytoplasmic Organelles Ribosome Ribosome RNA RNA Where proteins are made Where proteins are made Cytoskeleton (“support beams”) Cytoskeleton (“support beams”) Protein fibers Protein fibers Centrioles: paired cylinders at right angles (important in cell division, makes microtubules) Centrioles: paired cylinders at right angles (important in cell division, makes microtubules) Microtubules: thin hollow tubes (transport things in the cell, rigidity) Microtubules: thin hollow tubes (transport things in the cell, rigidity) Mitotic spindle of microtubules forms between centrioles during cell division Mitotic spindle of microtubules forms between centrioles during cell division

RIBOSOMES MICROTUBULES CENTRIOLES Lab Fig. 4-3

Cytoplasmic Organelles Cytoskeleton (“support beams”) Cytoskeleton (“support beams”) Microfilaments: proteins, important in muscle cells; cell-shape Microfilaments: proteins, important in muscle cells; cell-shape Intermediate filaments: proteins, cell- stabilizers—resist pulling forces Intermediate filaments: proteins, cell- stabilizers—resist pulling forces

INTERMEDIATE FILAMENTS MICROFILAMENTS Lab Fig. 4-3

Cytoplasmic Organelles with Membranes Nuclear membrane (envelope) Nuclear membrane (envelope) 2-layered 2-layered Porous: materials moving to/from nucleus & cytoplasm Porous: materials moving to/from nucleus & cytoplasm Mitochondria Mitochondria 2-layered membrane with inner folds 2-layered membrane with inner folds Powerhouse of cell Powerhouse of cell Transforms energy from food into a form usable by the cell…aerobic respiration  ATP Transforms energy from food into a form usable by the cell…aerobic respiration  ATP

MITOCHONDRIA NUCLEAR MEMBRANE Lab Fig. 4-3

Cytoplasmic Organelles with Membranes ER: Canal network continuous with nuclear membrane Smooth endoplasmic reticulum (ER) Smooth endoplasmic reticulum (ER) Synthesizes lipids Synthesizes lipids Rough endoplasmic reticulum (ER) Rough endoplasmic reticulum (ER) Ribosomes attached to surface Ribosomes attached to surface Protein synthesis and transport Protein synthesis and transport Lab Fig. 4-3 SMOOTH ER ROUGH ER

Cytoplasmic Organelles with Membranes Golgi apparatus Golgi apparatus Cluster of flattened sacs near rough ER Cluster of flattened sacs near rough ER Proteins made in ER come here to get packaged and shipped out of the cell or to the cell’s cytoplasm Proteins made in ER come here to get packaged and shipped out of the cell or to the cell’s cytoplasm Secretory vesicles: pinch off the golgi, to plasma membrane, release contents from the cell Secretory vesicles: pinch off the golgi, to plasma membrane, release contents from the cell Lysosome: sack with digestive enzymes (digest foreign material, old cell parts) Lysosome: sack with digestive enzymes (digest foreign material, old cell parts) Peroxisome: sack with oxidase enzymes (use oxygen to detoxify—free radicals, kidney, liver) Peroxisome: sack with oxidase enzymes (use oxygen to detoxify—free radicals, kidney, liver)

SECRETORY VESICLES GOLGI APPARATUS Lab Fig. 4-3

Cell Membrane Phospholipid bilayer Phospholipid bilayer Phospholipids Phospholipids Hydrophobic tails Hydrophobic tails Hydrophilic heads Hydrophilic heads Cholesterol Cholesterol Lipid, helps stabilize cell membrane Lipid, helps stabilize cell membrane Proteins Proteins Move around, aid in transport Move around, aid in transport “fluid mosaic model” “fluid mosaic model”

FLUID-MOSAIC MODEL PHOSPHOLIPID BILAYER PROTEINS CHOLESTEROL HYDROPHOBIC TAILS HYDROPHILIC HEADS

Cell Division: MITOSIS Interphase Interphase Prophase Prophase Metaphase Metaphase Anaphase Anaphase Telophase Telophase Cytokinesis Cytokinesis

Cell Division: MITOSIS Interphase Interphase Normal cell activities PRIOR to division Normal cell activities PRIOR to division Lab Fig. 4-4

Cell Division: MITOSIS Prophase Prophase Chromosomes form as sister chromatids Chromosomes form as sister chromatids Centrioles separate, mitotic spindle forms Centrioles separate, mitotic spindle forms Nuclear membrane & nucleolus break down Nuclear membrane & nucleolus break down Lab Fig. 4-4

Cell Division: MITOSIS Metaphase Metaphase Chromatids migrate along spindle to the middle---- metaphase plate Chromatids migrate along spindle to the middle---- metaphase plate Lab Fig. 4-4

Cell Division: MITOSIS Anaphase Anaphase Centromeres split & chromosomes split into 2 chromosomes which migrate to opposite ends of the cell Centromeres split & chromosomes split into 2 chromosomes which migrate to opposite ends of the cell Lab Fig. 4-4

Cell Division: MITOSIS Telophase Telophase Reverse of prophase Reverse of prophase Chromosomes uncoil into chromatin Chromosomes uncoil into chromatin Spindle breaks down Spindle breaks down Nuclear membranes each end Nuclear membranes each end Nucleoli appear in each nucleus Nucleoli appear in each nucleus Lab Fig. 4-4

Cell Division: MITOSIS Cytokinesis Cytokinesis Division of cytoplasm Division of cytoplasm Starts at end of telophase Starts at end of telophase 2 new cells are formed, each genetically IDENTICAL to the “mother” cell 2 new cells are formed, each genetically IDENTICAL to the “mother” cell