Cellular Boundaries. Cell Organelles. The Nucleus and Cell Control. Cell Membrane. Cell Wall. Nucleus 10/11/2012. Cell Membrane Cell Wall

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1 Cell Organelles Cellular Boundaries Protects cell Support and shape Controls what comes in and out of the cell Selectively permeable the process in which a membrane allows some molecules to pass through while keeping others out. Provides additional support and protection Inflexible barrier Made of cellulose Porous and allows molecules to enter Cannot select what enters into the cell Found ONLY in plant (and fungi) cells The and Cell Control The control center of a cell Contains DNA (directions to make proteins) Every part of the cell depends on proteins. Therefore the nucleus controls the activities of the cell. 1

2 Chromatin Long, tangled strands of DNA found in the nucleus The master set of directions for making proteins When a cell divides, the chromatin condenses to form chromosomes. Nucleolus Found inside the nucleus Makes ribosomes Nucleolus Nuclear Membrane Surrounds the nucleus Controls what enters and leaves the nucleus Ribosomes Site where cell produces proteins according to the directions of DNA. Not bound by a membrane. Simple structures made of RNA and protein. Nuclear Membrane Ribosomes Cont d Can be attached to the ER or free in the cell. Ribosomes attached to the ER have different functions in the cell Make proteins that become part of the cell membrane or are transported to other organelles. Free ribosomes make proteins that are used in they cytoplasm. Assembly, Storage, and Transport 2

3 Endoplasmic Reticulum AKA ER Serves as cell s transport system Two types: Rough: ribosomes are attached Smooth: no ribosomes The smooth ER is used to produce and store lipids. Large surface area due to pleats and folds Golgi Apparatus Sorts proteins and packages them into membranebound structures (vesicles) to be sent to the appropriate destination. Vacuoles Temporary storage of food, enzymes, and materials needed by a cell. Some store waste products. Plant cells have one large vacuole Animal cells have many small ones Lysosomes Contain digestive enzymes that break down excess or worn out organelles, food particles, and engulfed viruses or bacteria. Membrane surrounding lysosome prevents the enzymes from destroying the cell itself. Can fuse with vacuoles, dispense their enzymes, and breakdown the waste stored in the vacuoles. Chloroplast Energy Transformers Site of photosynthesis Transform light energy into usable energy Inner thylakoid membrane traps sunlight Arranged in stacks of membranous sacs called grana Fluid surrounding the stacks is called stroma A type of plastid which are used for storage Some store starches or lipids and some contain pigments. Chloroplasts contain chlorophyll which gives plants their green color Found ONLY in plants (and algae) 3

4 Mitochondria Site of cellular respiration Breaks down sugar to produce energy that the cell can use Occur in varying numbers depending on the function of the cell Powerhouse of the cell Mighty Mitochondria Support and Locomotion Cytoskeleton Maintains cell shape Dismantled and reassembled to change the shape of a cell Contains microtubules and microfilaments Centrioles Act like fishing reels Pull chromosomes apart during cell division Only in animal cells Cilia Short, hair-like projections that move like a wave Used for locomotion Flagella Long, tail-like Moves like whip Used in locomotion 4

5 Cytoplasm Venn Diagram of Eukaryotic Cells Clear fluid that allows all the cell s activities to take place Plant Cell Big Vacuole Chloroplasts Mitochondria Cytoplasm ER with ribosomes Lysosome Golgi Animal Cell Small Vacuole Cilia Flagella Centriole 5