3 2 Cell Organelles KEY CONCEPT Eukaryotic cells

3. 2 Cell Organelles KEY CONCEPT Eukaryotic cells share many similarities.

3. 2 Cell Organelles Cells have boundaries The Plasma Membrane • Forms a boundary between a cell and the outside environment • Controls the passage of materials into and out of the cell • Helps to maintain homeostasis

3. 2 Cell Organelles Cells have boundaries • The plasma membrane is selectively permeable - allows some, but not all materials to cross Outside the Cell Oxygen Wastes Invaders CO 2 Water Wastes Inside the Cell Glucose

3. 2 Cell Organelles Cells have boundaries Structure of the Plasma Membrane • Composed of a phospholipid bilayer

3. 2 Cell Organelles Cells have boundaries Other components in the Plasma Membrane Proteins • some span the entire membrane and help materials cross • others are found on the inner and outer surface – anchoring

3. 2 Cell Organelles Cells have boundaries Other components in the Plasma Membrane • Cholesterol – strengthen the membrane • Carbohydrates – cell identification

3. 2 Cell Organelles Cells have boundaries • The Plasma membrane is referred as the fluid mosaic model *Fluid - flexible *Mosaic - pattern

3. 2 Cell Organelles Cells have boundaries The Cell Wall • A rigid structure located just outside of the plasma membrane • Found in plants, fungi, most bacteria, and some protists • Provides protection and support • It is not selectively permeable • In plants, it is composed of cellulose

3. 2 Cell Organelles Cells have an internal structure. The Cytoskeleton - A network of protein fibers that crisscross the entire cell - Three types of fibers a) Microtubules b) Intermediate filaments c) Microfilaments

3. 2 Cell Organelles Cells have an internal structure. • The cytoskeleton has many functions. – supports and shapes cell – helps position and transport organelles – provides strength – assists in cell division – aids in cell movement

3. 2 Cell Organelles Cells have an internal structure. The Cytoplasm -Fills the space between the nucleus and cell membrane -Consists of organelles and cytosol(mostly water)

3. 2 Cell Organelles Several organelles are involved in making and processing proteins. The Nucleus • Storehouse of DNA • Surrounded by a nuclear membrane • Nuclear pores allow large molecules to pass between the nucleus and the cytoplasm • The nucleolus is where ribosomes are produced

3. 2 Cell Organelles Several organelles are involved in making and processing proteins. The Endoplasmic Reticulum • An interconnected network of folded membranes • Important in synthesis and transport of cellular materials • Two types – Rough ER and Smooth ER

3. 2 Cell Organelles Several organelles are involved in making and processing proteins. Rough Endoplasmic Reticulum • Has ribosomes attached • Proteins are made by the ribosomes on the surface, and then move inside the rough ER to be packaged into a vesicle • The vesicle then takes the protein to the Golgi Apparatus

3. 2 Cell Organelles Several organelles are involved in making and processing proteins. Ribosomes • The site of protein synthesis • Can be found attached to Rough ER or free in the cytoplasm

3. 2 Cell Organelles Several organelles are involved in making and processing proteins. Smooth Endoplasmic Reticulum • No ribosomes attached • Produces lipids • Detoxification of drugs and poisons

3. 2 Cell Organelles Several organelles are involved in making and processing proteins. The Golgi Apparatus • Closely layered stacks of membrane – enclosed spaces • Modifies, packages, and transports proteins • The vesicles can then be stored, transported, or secreted

3. 2 Cell Organelles Some organelles transform energy in the cell Mitochondria • Bean shaped organelle with a double membrane • Produces ATP through cellular respiration • The cell uses the ATP for energy • Mitochondria have their own ribosomes and DNA C 6 H 12 O 6 + 6 O 2 = 6 CO 2 + 6 H 2 O + ATP

3. 2 Cell Organelles Some organelles transform energy in the cell The Chloroplast • Organelles that carry out photosynthesis • Found in plant cells • Has two membranes • Contains chlorophyll which absorbs light and gives plants their green color • Also have their own DNA and ribosomes 6 CO 2 + 6 H 2 O + Light = C 6 H 12 O 6 + 6 O 2

3. 2 Cell Organelles Other organelles have various functions. Vacuoles • A membrane bound sac used for storage Ex – water, food molecules, and enzymes • Plant cells have one large vacuole • Animal cells have many small vacuoles

3. 2 Cell Organelles Other organelles have various functions. The Lysosome • Membrane bound organelle that contains digestive enzymes • Digests worn out organelles, food particles, and engulfed viruses or bacteria • Numerous in animal cells • Their presence in plant cells is still questioned by some scientists

3. 2 Cell Organelles Other organelles have various functions. Centrosome and Centrioles • The centrosome is a small region of the cytoplasm that produces microtubules • In animals, it contains a pair of centrioles • Centrioles help DNA divide during cell division

3. 2 Cell Organelles Other organelles have various functions. Cilia Flagella • Short, numerous hair-like • Long projections • Moves in a whip-like motion • Move in a wave-like motion • Used for locomotion • Used for feeding and locomotion