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Cells
Discovery of the Cell:
 Robert Hooke (1665)-observed a thin slice of cork under a compound microscope and saw thousands of tiny,
empty chambers he called “cells.”
 Anton van Leeuwenhoek-observed pond water with a single lens microscope and found thousands of tiny
organisms floating around.
Cell Theory:
 All living things are composed of cells.
 Cells are the basic units of structure and function in living things.
 New cells are produced from existing cells.
Prokaryotic Cells - cells that do not contain nuclei.
 Generally smaller and simpler.
 Genetic material is not contained in the nucleus.
 Example: bacteria
Eukaryotic Cells – cells that contain nuclei.
 Generally larger and more complex.
 Contain dozens of structures and internal membranes and are highly specialized.
 Genetic material contained in nucleus.
Inside the Cell “Factory”
Organelles – structures found in eukaryotic cells that act as specialized “organs” for the cell.
The cell is divided into two major parts: the nucleus and the cytoplasm.
Cytoplasm - the portion of the cell outside the nucleus. Fluid-like substance.
Nucleus – the control center of the cell. “main office of factory” or brain.
 Contains nearly all the cells’ DNA and with it the coded instructions for making proteins and other important
molecules.
 Surrounded by a nuclear envelope.
o Two membranes
o Contains nuclear pores that allow material to move in and out of the nucleus.
 Contains chromatin
o DNA bound to protein that is spread throughout the cell.
o Condenses to chromosomes during cell division that contain genetic information passed from one
generation of cells to the next.
 Contains a nucleolus
o Small, dense region in the center of the nucleus
o Where ribosomes are assembled.
Ribosomes – site of protein assembly.
 Small particles of RNA and protein found throughout the cytoplasm.
Endoplasmic Reticulum – two types: Rough & Smooth.
 Site where lipid components of the cell membrane are assembled, along with proteins and other materials that
are exported from the cell.
 Rough ER – lined with ribosomes.
 Involved in protein synthesis.
 Smooth ER – no ribosomes present.
 Contain enzymes that perform specialized tasks such as synthesis of membrane lipids and
detoxification of drugs.
Golgi Apparatus – the “packaging” area of the cell.
 Modifies, sorts and packages proteins and other materials from the endoplasmic reticulum for storage in the
cell or secretion outside the cell.
Lysosomes – the “clean-up crew” of the cell.
 Small organelles filled with enzymes
 Function in the digestion or breakdown of lipids, carbohydrates and proteins in the cell so they can be used.
 Also breakdown organelles that are too old to function correctly.
Vacuoles – “storage room” of the cell.
 Found primarily in plant cells and small single-celled organisms.
 Function to store materials such as water, salts, proteins and carbohydrates.
Mitochondria – “power plant” of the cell.
 Convert chemical energy stored in food into compounds that are more convenient for the cell to use.
 Have 2 membranes – outer and the inner is folded up inside the organelle.
 Contains it’s own DNA
Chloroplasts – solar energy supply
 Found only in plants
 Capture the energy from sunlight and convert it into chemical energy in the process called photosynthesis.
 Have 2 membranes and inside have large sacs of membranes that contain chlorophyll.
 Contains it’s own DNA.
Cytoskeleton – support structure and transportation system of the cell.
 Network of protein filaments that help the cell to maintain its shape and are also involved in movement.
 Contains 2 primary protein filaments – microfilaments and microtubules.
Cell Membrane – the entry gate of the cell.
 Regulates what enters and leave the cell and also provides protection and support.
 Consists of a lipid bilayer with proteins embedded within.
Cell Wall – found mainly in plants.
 Provides support and protection for the cell.
 Lies outside the cell membrane.