An Introduction to Cells Indicator B – 2.1: Recall the three major tenets of cell theory Indicator B – 2.3: Compare the structures and organelles of prokaryotic and eukaryotic cells.
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An Introduction to Cells
Indicator B – 2.1: Recall the three major tenets of cell theory
Indicator B – 2.3:
Compare the structures and organelles of prokaryotic and eukaryotic cells.
Key Concepts
n Cell Theory
n Unicellular vs. Multicellular Organisms n Prokaryotes vs. Eukaryotes
It is essential for you to know:
n All living things are composed of one or more cells.
n Cells are the basic unit of structure of all living things.
n All presently existing cells arose from previously existing cells.
Objectives
n Recall the major tenets of the Cell theory.
n Compare unicellular organisms and multicellular organisms.
n Differentiate between prokaryotic cells and eukaryotic cells.
Vocabulary Words
Please define the following words: 1. cell theory 2. cytoplasm 3. organelle 4. prokaryotic cell 5. eukaryotic cell
The Cell
LIFE IS CELLULAR
Before we begin... ATP (adenosine triphosphate) = ENERGY!
Cells take sugar (glucose) from food and turn it into ATP.
The History of Cell Biology
The History of Cell Biology
A person who studies cells is called a cytologist. They work in the field of cytology.
The History of Cell Biology
Anton van Leeuwenhoek n 1600’s n Became one of the first
people to use a microscope to study nature.
n Was the first person to see tiny living organisms in a drop of water.
The History of Cell Biology Robert Hooke
n 1665 n Saw “cells” in a cork under a light microscope.
The History of Cell Biology Matthias Schleiden
n 1838 n Concluded that all
plants have cells.
The History of Cell Biology Theodor Schwann
n 1839 n Concluded that all
animals have cells.
The History of Cell Biology
Rudolf Virchow n 1855 n Studied cell
reproduction
The Cell Theory
n A cell is the basic unit of life. n All of the scientists’ work contributed to
what is now called the cell theory: 1) All living things are composed of one or more
cells. 2) Cells are the basic units of structure and function
in an organism. 3) Cells come only from the reproduction of existing
cells.
Prokaryotes & Eukaryotes
Biologists divide cells into two main categories:
n Prokaryotes n Eukaryotes
Prokaryotes & Eukaryotes Prokaryotes
n No nuclei n Have cell membrane, cell
wall, plasmid, ribosomes, cytoplasm
n Smaller and simpler n Most bacteria and archae n Divide by binary fission
Prokaryotes & Eukaryotes Eukaryotes
n Have a nucleus n Usually bigger and
more complex n Cell membrane,
cytoplasm, & organelles.
n Plants, animals, fungi, and many microorganisms.
Unicellular Organisms
n Sometimes the cell is the organism. n Do everything that you would expect a
living thing to do. n Include both prokaryotes and eukaryotes.
n Prokaryotes: bacteria and archae n Eukaryotes: some types of algae, protists,
fungi.
Multicellular Organisms
n Made up of more than one cell. n Cells in multicellular organisms are
specialized to perform particular functions within the organism. n This is called cell specialization. n Think:
n blood cells, hair cells, digestive cells, etc.
Levels of Organization
The levels of organization in a multicellular organism are:
n individual cells n tissues n organs n organ systems
Levels of Organization
Cell: nerve cell Tissue: nerve tissue Organ: the brain Organ System: Nervous System
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