Eukaryotic Cell Structure

Transcription

1 Eukaryotic Cell Structure Vocabulary listed for Chapter 7.3: cell wall, chromatin, nucleolus, ribosome, cytoplasm, endoplasmic reticulum, Golgi apparatus, vacuole, lysosome, chloroplast, plastid, chlorophyll, mitochondria, cytoskeleton, microtubule, microfilament, cilia, flagella (Vocabulary words for 7.1, 7.2, and 7.3 are in bold.) Cellular Boundaries 1. Plasma membrane Function Boundary between cell contents and the environment. Allows nutrients to enter cell and waste and other products to exit the cell in a regulated manner (selective permeability) to maintain homeostasis. Structure Phospholipid bilayer (phospholipids composed of phosphate group head, glycerol backbone, two fatty acid tails) with non-polar region on the inside and polar regions on the outside. Also contain transport proteins and other proteins, carbohydrates, cholesterol molecules (which help maintain structure). Fluid mosaic model Location Around all cells; around the nucleus ( nuclear envelope ) 2. Cell wall Function Provide inflexible support and protection Structure Cellulose (a carbohydrate). Very porous; lets molecules through (does not select which ones like plasma membrane does) Location Outside of the cell membrane of cells (plants, fungi, some protists, most bacteria) 3. Nucleus and cell control Nucleus function - Nucleus contains blueprints for proteins; proteins control activities of organelles (membrane-bound structures in cells). Nucleus structure - surrounded by a phospholipid bilayer containing pores; this separates nuclear material from cytoplasm and is called the nuclear envelope. Contains chromatin, nucleolus (which makes ribosomes). Nucleus location in cytoplasm of nearly all eukaryotic cells (not found in prokaryotic cells) Chromatin = strands of genetic material (DNA) found in nucleus of eukaryotic cells (not membrane-bound in prokaryotes) Nucleolus = organelle within nucleus; makes ribosomes

2 Ribosomes Function (like mobile automobile factory) Sites where enzymes and other proteins are built using blueprints (in genetic material, DNA). Structure - Organelles but NOT membrane-bound Location in nucleolus/nucleus; on rough ER; in cytoplasm Ribosomes move out of nucleus (through nuclear pores) and into cytoplasm where they meet up with DNA that was copied in the nucleus and shipped out the nuclear pores into cytoplasm. 4. Cytoplasm Function Supports cell s organelles. Structure - Gelatinous fluid Location - Inside cell membrane but outside the nucleus

3 Assembly, Transport, and Storage 1. Structures for assembly and transport of proteins Endoplasmic reticulum ER function Large workspace. Site of cellular chemical reactions. ER structure - Folded for increased surface area. Rough ER Has ribosomes attached. Ribosomes used to make proteins for a particular purpose become part of cell membrane, shipped out of cell, transported to other organelles. (Ribosomes also floating freely in cytoplasm make proteins to do work in cytoplasm.) Smooth ER no ribosomes. Production and storage of lipids ER location cytoplasm Golgi apparatus Golgi apparatus function Along with vesicles, sort proteins into packages to be sent to various destinations (like post office mail). Golgi apparatus structure - flattened system of tubular membranes that modifies the proteins. Golgi apparatus location - cytoplasm 2. Vacuoles and storage Vacuoles function - temporary storage of materials. Often store food, enzymes, and other materials needed by cell; some store waste products. Vacuoles structure - Membrane-bound sac. In plants often one large vacuole; in animals many smaller vacuoles Vacuoles location - cytoplasm 3. Lysosomes and recycling Lysosome function - Organelles with digestive enzymes. Digest extra or worn out organelles, food particles, engulfed viruses or bacteria. Membrane prevents escape of enzymes. Lysosomes can fuse with vacuoles and dispense their enzymes into the vacuole, digesting its contents like food particles. Cool! Can digest the cells that contain them (ex. Tadpole to frog). Lysosome structure membrane bound; contain digestive enzymes Lysosome location cytoplasm

4 Energy Transformers 1. Chloroplasts and energy Chloroplast function capture light energy from sun to produce food to store for later time Chloroplast structure double membrane (outer membrane; folded inner membrane system, called thylakoid membranes). Thylakoid membranes trap energy from sunlight. Inner membranes arranged in stacks of membranous stacks called grana (look like stacks of coins). Fluid that surrounds the grana membranes is called stroma. Chloroplast location cytoplasm of cells in plants and some protists Plastids group of plant organelles used for storage. Named for their color or pigment contained. Chloroplasts contain chlorophyll (traps light energy and gives leaves and stems green color). 2. Mitochondria and energy Mitochondria function break down and release energy from food (transform energy for the cell). This energy is then stored in other molecules that allow the cell organelles to use the energy easily and quickly when it is needed. Mitochondria structure double membrane (outer membrane and highly-folded inner membrane for large surface area). Energy-storing molecules are produced on the inner folds. Mitochondria location cytoplasm of plant and animal cells. Occur in greater numbers in cells that require more energy.

5 Structures for Support and Locomotion 1. Cellular support the cytoskeleton Function Provides a scaffold for cell shape; assists organelles in moving from place to place within the cell Structure Microtubules (thin, hollow cylinders made of protein) and microfilaments (thin, solid protein fibers) form a constantly-changing framework for the cell. Location cytoskeleton of all cells 2. Cilia and flagella Function Aid locomotion or feeding. For unicellular organisms they are major means of locomotion Structure / characteristics Cilia and flagella composed of pairs of microtubules, with a central pair surrounded by nine additional pairs. All pairs surrounded by the plasma membrane. Outer tubules have protein that allows pair of microtubules to slide along an adjacent pair, causing the cilia or flagellum to bend. Cilia short, numerous, hair-like; move like waves Flagella longer projections that whip around Location Cell surfaces.