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

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 -Orient themselves so the 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, carbohydrates 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 Plant - Have cell walls - Have chloroplasts Animal -No cell walls -No chloroplasts