Ch 7.2 Cell Structure

How is a cell organized? All Eukaryotic (Animal/Plant) cells have 3 main parts: - Nucleus - Cytoplasm - Cell Membrane

Organelles - Literally means “tiny organs” - Are membrane-bound compartments - Have specialized jobs in a cell - Can be compared to the machines in a factory

Nucleus Is the control center of a cell Contains a cell’s DNA DNA in the form of chromatin DNA bound to proteins Sends coded instructions for making proteins and other molecules

Nuclear Envelope - A two-layer membrane - Covers and protects the contents of the nucleus

Nuclear Pores - Small holes in the nuclear membrane - Allow molecules in and out of the nucleus

Nucleolus - Where ribosomes are assembled

Building Proteins

Ribosomes - Build proteins - Use instructions that come from DNA

Endoplasmic Reticulum (ER) Where lipids and proteins are assembled and transported Rough ER Covered in ribosomes = “rough” Synthesize proteins Smooth ER No ribosomes = “smooth” Synthesize lipids Detoxify drugs

Golgi Apparatus Receives proteins from ER Give proteins an “address tag” Modifies, sorts, and packages proteins and other materials Sends proteins to final destination

Storing and Cleaning Up Vacuoles and Vesicles Vacuoles store water, salts, proteins, and carbs Vesicles store and move materials between organelles Lysosomes Filled with enzymes Breakdown lipids, carbs, and proteins, and other organelles Remove “junk” from cell

Providing Support and Structure Cytoskeleton Maintains cell shape Helps with cell movement Consists of Microfilaments and Microtubules Microtubules help form centrioles, cilia, & flagella

Providing Support and Structure Centrioles Located near the nucleus Help organize cell division Only found in animal cells Cilia and Flagella Extend out from the cell surface Help cells to swim through liquid

How do cells get their energy?

Chloroplasts - Perform photosynthesis Capture energy from sunlight and convert it into food (sugars)

Mitochondria - Perform cellular respiration Convert the chemical energy in food into cellular energy (ATP)

Cell Wall Strong, supportive layer that surrounds plant cells Made of cellulose Also found in prokaryotes, but theirs is not made of cellulose Allow water, oxygen, carbon dioxide, and most nutrients to pass through

Cell Membrane Regulates what enters and leaves the cell Protects and supports the cell Is made of a double layer of lipids called a lipid bilayer

Lipids in the Membrane - Have regions that are hydrophilic “love” water Have regions that are hydrophobic “fear” water Hydrophilic parts face the water and the hydrophobic parts face away from it Make the membrane selectively permeable Some things can cross it, but others can’t

Fluid Mosaic Model Proteins, carbs, and other molecules are embedded in the lipid bilayer This makes the membrane look like a mosaic Since molecules can float and move in the membrane, it acts like a fluid

Differences Between Plant and Animal Cells - Have cell walls - Have chloroplasts No cell walls No chloroplasts

Cell Song-Counting Stars Cell Rap Cell Song-Sails Cell Song-Counting Stars