Chapter 7: Cell Structure and Function Mr. Freidhoff

Random Interesting Cell Fact: The average human being is composed of around 100 Trillion individual cells!!! 100,000,000,000,000,000,000 cells

Robert Hooke 1665 Used simple light microscope. Observed “compartments” in a thin slice of cork. – Called “cells” Many more observations of cells were made after Hooke’s discovery.

The Cell Theory 1.All organisms are made up of cells. 2.Cells are the basic unit of structure and function in living things. 3.All cells come from pre-existing cells. Link

Organelle “Mini Organ” Organelles have specific structure and function within each cell.

Membrane Structure Membranes regulate the transport of substances in and out of the cell. The membrane is made of mostly phospholipids and some proteins.

Phospholipids Draw Hydrophilic Heads Blue Draw Hydrophobic Tails Red Cell Theory Link Hydrophilic Head HYDROPHOBICHYDROPHOBIC TAILTAIL

Phospholipid Bilayer Hydrophobic tails are tucked inside of membrane. Hydrophilic heads are on outside. Membrane is fluid, like a blanket.

Phospholipid Bilayer Cell’s membrane separates its inner aqueous cytoplasm from outer environment surrounding the cell.

Saturated fatty acids make the membrane less fluid than unsaturated fatty acids

Membrane Proteins Many types of proteins are imbedded in the phospholipid bilayer. Proteins transport materials across the membrane and help communicate with other cells. Semi-permeable: Some substances are allowed through, but not all.

Eukaryotic vs. Prokaryotic Eukaryotic More complex cells that contain a nucleus. Large in size. DNA is in long strands. Includes plants and animal cells. Prokaryotic Less complex cells that don’t contain a nucleus. Smaller in size. Circular DNA. Bacteria cells.

Animal Cells vs. Plant Cells Similarities and differences between plant and animal cells. Some organelles found only in plants, not animals and vice versa.

The Nucleus Structure: Circular membrane bound organelle. Function: Houses cell’s genetic information (DNA). – Controls all actions of the cell

Nuclear Membrane Structure: Nuclear Membrane surrounds the nucleus. Function: Protects DNA

Cytoplasm Structure: Aqueous substance within plasma membrane. Function: Holds all of the cell’s other organelles within the plasma membrane.

Mitochondria Function: Generates energy from the breakdown of sugars and fats. Structure: Two membranes, inner membrane folded. Known as the powerhouse of the cell. Found in almost all Eukaryotic cells, not found in prokaryotic cells.

ATP Adenosine Triphosphate ATP transfers energy from the breakdown of food molecules to cell functions. Energy is released when a phosphate group is removed. “Energy Currency” triphosphateadenosine diphosphate tri=3 di=2

Energy Transformation

Chloroplasts Organelle of Photosynthesis. Function: T ransforms solar energy into chemical energy stored as glucose. Also produces some ATP. Structure: Double membrane. Contain pigments. Green in color. Found only in plant cells.

Cell Wall Only found in plant cells. Structure: Rigid, Made of cellulose Function: Gives cell structure and support. Protection for Cell.

Vacuole Structure: Membrane-bound sacs. – Large in plants, smaller in animal Function: Contain nutrients for the cell.

Golgi Body (Apparatus) Function: Organelle that modifies, stores, and routes proteins and other materials around the cell. Structure: Flat, Membrane sacs

Ribosome Function: Creates Proteins Structure: Small, many within a single cell.

Smooth ER Function: Produces lipid molecules Structure: Long network of a folded, tube-like structure.

Rough ER Function: Helps with the production and transport of proteins. Structure: Covered in ribosomes, gives appearance of bumps

Lysosomes Function: Breaks down food vacuoles, damaged organelles, and even dead cells. Structure: Contains digestive enzymes.

Cytoskeleton Structure: Protein filament that stretches around the cell. Function: Provides important structural framework.

Cell Transport

Passive Transport Movement without input of energy. Helps maintain homeostasis. Materials move with the concentration gradient. High concentration  Low concentration 3 Kinds – Diffusion – Osmosis – Facilitated Diffusion Link

Diffusion The movement of molecules. Molecules move from high concentration to low concentration. Molecules tend to “spread out” to reach equilibrium.

Osmosis Diffusion of water across a selectively permeable membrane. Always involves water. Does not require energy from the cell.

Osmosis in Cells Isotonic: Two solutions that have equal concentrations of solutes. Hypotonic: When comparing two solutions, the solution with a lesser concentration (hypo = under). Hypertonic: When comparing two solutions, the solution with a greater concentration (hyper = over).

Facilitated transport Proteins help small molecules move across the plasma membrane. Does not require energy from the cell.

Active Transport Process that moves materials across the plasma membrane. Requires input of energy. Low concentration  High concentration 3 Kinds – Pumps – Endocytosis – Exocytosis

Active Transport Pumps An ATP molecule breaks down into ADP. This releases a phosphate group and a whole lot of energy.

Endocytosis When a cell actively takes large molecules into itself by folding the plasma membrane inward, forming a vesicle

Endocytosis Cells ingest large particles, macromolecules, and fluid. Vesicle: Membrane-bound organelle.

Exocytosis When a cell actively releases large molecules by folding the plasma membrane outward.