Eukaryotic Cell Structure Chapter 7.3

Cellular boundaries Plasma Membrane/Cell Membrane Fxn-acts as a selectively permeable membrane

The Cell Wall Cell Wall-def-pg.179-a fairly rigid structure located outside the plasma membrane that provides additional support and protection-ONLY IN PLANT CELLS, FUNGI, BACTERIA!!!! Fxn: Cell wall forms an inflexible barrier that protects the cell & gives it support Composed of cellulose, which forms a thick, tough mesh of fibers & is porous to allow molecules to enter the cell

The Nucleus and Cell Control Nucleus Fxns: Nucleus of cell contains the directions to make proteins  the leader of eukaryotic cells Nucleus controls all the activities of the organelles Chromatin-def-pg.180- the master set of directions for making proteins-which are strands of DNA (genetic material) when the cell divides chromatin condenses  forms chromosomes Nucleolus A prominent organelle within the nucleus Fxn: makes ribosomes

The Nucleus and Cell Control Ribosomes Ribosomes-def-pg.181-are the sites where the cell produces proteins according to the directions of DNA Fxn: synthesis of proteins Can be found free floating in cytoplasm & make proteins that perform tasks w/in the cytoplasm Ribosomes have a simple structure, composed of: RNA Protein Not bound by membranes

The Nucleus and Cell Control How ribosomes make proteins? (1) The DNA (the blueprints) within the ribosomes must be translated into RNA then transported to the cytoplasm (2)The RNA and the ribosomes are then transported via the nuclear pores through the nuclear envelope into the cytoplasm Nuclear envelope-def-pg.181- the structure that separates the nucleus from the cytoplasm, made of a double membrane of 2 phospholipid bilayer containing small nuclear pores for substances to pass through Cytoplasm-def-pg181-the clear, gelatinous fluid inside a cell, in which the cell’s organelles are suspended Once the RNA and the ribosomes are in the cytoplasm the proteins can be produced.

Assembly, Transport, and Storage i) Organelles for assembly and transport of proteins Endoplasmic reticulum-def-pg.181- the site of cellular chemical reactions, and it is arranged in a series of highly folded membranes in the cytoplasm Fxn: the site of cellular chemical reactions

Assembly, Transport, and Storage Rough ER-def-pg181- ribosomes in the cytoplasm which are attached to the surface of the endoplasmic reticulum (ER). Fxn: protein synthesis & modifies proteins Each protein made in the rough ER has a particular function Ex/ protein that forms part of the cell membrane a protein released from the cell protein transported to another organelle

Assembly, Transport, and Storage Organelles for assembly and transport of proteins Smooth ER-def-pg182-areas of the ER that are not studded with ribosomes Fxn: Involved in numerous biochemical rxns (i.e. production and storage of lipids) Golgi Apparatus-def-pg.182-a flattened stack of tubular membranes that modifies the proteins. Fxn: sorts proteins into packages and packs them into membrane bound structures call vesicles (like a post office)

Assembly, Transport, and Storage Rough and Smooth Endoplasmic Reticulum

Assembly, Transport, and Storage Golgi Bodies/Apparatus

Vacuoles and storage Vacuoles-def-pg183-membrane bound compartments, which are larger than vesicles used for temporary storage of materials: Sacs used to store: Food Enzymes other materials needed by a cell waste products Animal cells usually don’t contain vacuoles

Vacuoles and storage Plant vacuoles usually contain: Water Sugar Salts Water-soluble pigments Toxic molecules Central Vacuole-def- found only in plant cells, large central vacuoles are filled with sap which gives the cell added support

Lysosomes and recycling Lysosomes-def-pg183-organelles that contain digestive enzymes Fxn: digest excess or worn out organelles, food particles, and engulfed viruses or bacteria Lysosome Membrane fxn: Membrane prevents the digestive enzyme inside the lysosomes from destroying the cell How lysosomes work? Lysosomes fuse with vacuoles & dispense their enzyme into the vacuoles digesting its contents Ex/Amoeba

Energy Transformers Cell organelles require great of energy for: Protein production & modifications, Protein transportation & digestion 2 organelles that provide energy: Chloroplasts (in plants) Mitochondria (in animals)

Chloroplasts and energy Chloroplast-def-pg.184-organelles that capture light energy and convert it to chemical energy Fxn-organelle where photosynthesis is done in a plant cell Chloroplasts have double membranes Thylakoid membranes trap the energy from sunlight & are arranged in stacks of membranous sacs called grana and surrounded by fluid called stroma Plastid-def-pg.184-grp of plant organelles used for storage (i.e. starches/lipids) or may contain pigments Chlorophyll-def-pg.184-traps light energy and gives leaves and stems their green color

Mitochondria and energy Chemical energy generated by chloroplasts is stored in the sugar molecules until it is broken down by the mitochondria Mitochondria-def-pg185- are membrane-bound organelles in plant & animal cells that transform energy for the cell. Fxn of mitochondria-energy that the cell doesn’t use is put into easily accessible bonds so it can be used when energy is needed. Structure of Mitochondria- has an outer membrane & a highly folded inner membrane Inner membrane provides lrg surface area that can fit into a sm space & energy-storing molecules are produced there Mitochondria occur in varying numbers depending on the cell function

Organelles for Support Cytoskeleton-def-pg.185-support structure within the cytoplasm The Cytoskeleton Cytoskeleton can be dismantled & reassembled= cell’s shape changes Composed of a network of: Microtubules-def-pg185- thin, hollow cylinder made of proteins Microfilaments-def-pg185-smaller, solid protein fibers Fxn- Maintain shape of cell Anchor & support many organelles Provide a highway system through which materials move within the cell

Organelles for Cell Division Centrioles Found in animal and protist cells Occur in pairs Made up of microtubules Fxn-play an important role in cell division

Organelles for Locomotion Cilia and flagella Cells can have cilia or flagella which are made up of microtubules that help with locomotion (moving) & feeding Cilia-def-pg.187-short, numerous projections that look like hairs Flagella-def-pg187-longer projections that move with a whiplike motion Cells usually has only 1 or 2 flagella