Cell Structure and Function By Mrs. Leesa Peery

Outline Cell Theory Cell Size Prokaryotic Cells Eukaryotic Cells Organelles Nucleus Endomembrane System Cytoskeleton Centrioles, Cilia, and Flagella

Cell Theory Cell theory states all organisms are composed of cells and that cells come only from preexisting cells. One of the unifying concepts of biology.

Cell Size Most cells are much smaller than one millimeter. Some are as small as one micrometer.

Small cells are likely to have an adequate surface area for exchanging wastes for nutrients. Cells that specialize in absorption have modifications that greatly increase the surface area per volume of the cell.

Organism Sizes

Prokaryotic Cells Lack a membrane-bound nucleus. Structurally simple. Can be divided into two domains: Bacteria Archaea

Bacteria Three Shapes Bacillus (rod) Coccus (spherical) Spirilla (spiral) Archaea Live in extreme habitats.

Prokaryotic Cells

Prokaryotic Cells Cell Envelopes Include plasma membrane, cell wall, and glycocalyx (layer of polysaccharides outside cell wall). Capsule – Well-organized layer. Form internal pouches (mesosomes).

Prokaryotic Cells Cytoplasm Cytoplasm is a semifluid solution encapsulated by plasma membrane. Inclusion Bodies - Stored granules of various substances.

Prokaryotic Cells Appendages Flagella Fimbriae Sex Pili

Eukaryotic Cells Members of domain Eukarya. Contain membrane-bounded nucleus. Contain specialized organelles. Contain plasma membrane.

Eukaryotic Cell Plasma Membrane

Organelles Organelles of endomembrane system communicate with one another. Basically self-sufficient Compartmentalization allows eukaryotic cells to be larger than prokaryotic cells.

Animal Cell Anatomy

Plant Cell Anatomy

Nucleus Contains chromatin in semifluid nucleoplasm. Condense to form chromosomes. Separated from cytoplasm by double-membrane nuclear envelope. Nuclear pores permit passage in and out of the nucleus.

Anatomy of Nucleus

Ribosomes Composed of large and small subunits that serve in protein synthesis. Subunits made in nucleolus. Occur singly and in groups, and may become attached to endoplasmic reticulum.

Endomembrane System Consists of nuclear envelope, membranes of endoplasmic reticulum, Golgi apparatus, and several types of vesicles. Restrict enzymatic reactions to specific compartments within cell.

Endomembrane System Endoplasmic Reticulum Rough - Studded with ribosomes. Smooth - No ribosomes.

Endoplasmic Reticulum

Endomembrane System Golgi Apparatus Consists of flattened, curved saccules. Modifies proteins and lipids and packages them in vesicles.

Golgi Apparatus

Endomembrane System Lysosomes Membrane-bounded vesicles produced by the Golgi apparatus. Engage in digestion of molecules and apoptosis (programmed cell death).

Peroxisomes Peroxisomes are membrane-bounded vesicles that enclose enzymes. Enzymes are cell-specific

Vacuoles Vacuoles are membranous sacs that are larger than vesicles. Store substances Plants cells typically have a central vacuole that functions in storage of nutrients and waste products.

Energy-Related Organelles Chloroplasts use solar energy to synthesize carbohydrates. Photosynthesis Cellular Respiration Adenosine triphosphate (ATP) is used for all energy-requiring processes in cells.

Energy-Related Organelles Chloroplasts are green due to the green pigment chlorophyll. Stroma Granum

Chloroplast Structure

Energy-Related Organelles Mitochondria are involved in cellular respiration. Produce most of ATP utilized by the cell. Cristae - Inner membrane that encloses matrix. Matrix - Enzymes that break down nutrient molecules.

Mitochondrion Structure

Cytoskeleton Cytoskeleton serves as internal skeleton that maintains cell shape and assists in movement of its parts. Actin Filaments Pseudopods Intermediate Filaments Microtubules

Centrioles, Cilia, and Flagella Centrioles are short cylinders with a 9 + 0 pattern of microtubule triplets that may give rise to basal bodies of cilia and flagella.

Cilia and Flagella Cilia and flagella are hairlike projections with a 9 + 2 pattern of microtubules that aid in cell movement. In eukaryotes, cilia are much shorter than flagella.

Review Cell Theory Cell Size Prokaryotic Cells Eukaryotic Cells Organelles Nucleus Endomembrane System Cytoskeleton Centrioles, Cilia, and Flagella