2.1 The Structure & Functions of Eukaryotic Cells

Chloroplasts Derived from photosynthetic bacteria & has DNA A double membrane bound, solar energy capturing organelle Internal thylakoid membrane is stacked (grana) and has pigments for photosynthesis. Liquid medium around thylakoid called stroma.

Chloroplast Micrograph

Photosynthesis It takes place in the thylakoid membranes and stroma Pigments like chlorophyll capture solar energy to make cellular food (ie: glucose) Cyanobacteria closely related to chloroplasts in higher plants.

Mitochondria Have their own DNA A double membrane bound organelle Internal cristae membrane is folded for increased surface area. Aerobic cellular respiration occurs in the cristae and the matrix The liquid medium inside the cristae is called the matrix.

Mitochondria Micrograph

Mitochondria Breaks down high-energy organic molecules (cellular respiration) to store in chemical bonds as chemical potential energy. In addition to glucose, it can also use lipids and proteins The released energy is stored in the form of ATP

Cell Walls It is found in plants, fungi, & many protists Surrounds cell membrane for support and protection (ie: Turgor Pressure in plants) Made of either polysaccharides, glycoproteins or both. It is porous and does little to control access to the cell.

Cytoskeleton It is an internal network of protein fibres It’s made of 3 fibre types Microfilaments Microtubules Intermediate filaments 3 functions: mechanical support anchors organelles help move substances

Microfilament Micrograph

Cell Movement Microtubules & microfilaments - slide against one another for internal cell movement Cilia Short Used to move substances outside human cells Flagella Whip-like extensions Found on sperm cells

Cilia & Flagella Structure Both are extensions from the cell membrane. They’re bundles of microtubules Cilia are short and in large numbers for movement. Flagella are few but longer for locomotion.

Cell (Plasma) Membrane It wraps the cell contents & it’s semi-permeable. It’s a double layer of phospholipids & embedded proteins This “fluid mosaic model” has the hydrophillic heads oriented to the outside and hydrophobic tails to the inside. This controls access in & out of the cell. Includes cholesterol, glycoproteins and glycolipids.

Cell Membrane Micrograph

Phospholipids They are lipid molecules with one glycerol, 2 fatty acids and a phosphate group. The polar head is hydrophyllic head and the non-polar tail is hydrophobic. Most of the fatty acid chains are saturated.

Membrane Proteins 1. Channels or transporters 2. Receptors Move molecules in one direction 2. Receptors Recognize certain chemicals

Membrane Proteins 3. Cytoskeleton 4. Enzymes Microtubules & microfilaments 4. Enzymes Catalyze production of substances

End of Part 3!