THE CELL. Definition of Cell A cell is the smallest unit that is capable of performing life...
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Transcript of THE CELL. Definition of Cell A cell is the smallest unit that is capable of performing life...
THE CELL
Definition of Cell
A cell is the smallest unit that is capable of performing life functions.
Cell Theory
1. All organisms are composed of cells
2. Cells are the basic units of structure and function in organisms
3. All cells come from preexisting cells
Two types of cells Prokaryotic
Pro / karyote
Before / nucleus (Greek)
Prokaryotes: more primitive cells that lack a true nucleus. Eukaryotic
Eu / karyote
True / nucleus
Eukaryotes: cells that have a true membrane bound nucleus that contains the DNA
Prokaryotic cells
Two domains in living world: Archaea and Bacteria
These are prokaryote E. coli bacteria on the head of a steel pin.
Bacteria
For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria.
Richard Dawkins
Archaea
•Not discovered until late 1970s
•Once thought to inhabit only extreme environments: hot springs, deep sea trenches, under the earth, salt flats (extremophiles) but now known to live everywhere
•Leading scientists to rethink how life arose in early days of Earth
Prokaryotic Cell•Cell wall – protects cell and gives it shape
•Plasma membrane – regulates movement of materials in and out of cell
•Cytoplasm – gel-like liquid that contains parts that do work of the cell
•Ribosomes – build proteins
•DNA – hereditary material sits loose in the cell, is not in nucleus
Very small: .1-10 microns
Prokaryotes play a huge role in our lives Yes, harmful diseases
TB
Rod shaped cells (bacilli)
Strep throat
Circular shaped cells (cocci)
Lyme disease
Spiral shaped cells (spirochete)
But life wouldn’t exist as we know it without them Cyanobacteria: their ability to
photosynthesize created the oxygen-rich atmosphere that exists today
•Digestion – E coli in our intestines helps us break down food to get the nutrients we need
• Decomposers: recycle nutrients
Example: nitrogen-fixing bacteria: help plants that we eat obtain enough nitrogen to grow
Biotechnology: solutions for major problems Example: environmental clean-up
Example: Faster growing, disease resistant, more nutritious food
Example: Cure diseases
Eukaryotes
Includes 4 kingdoms:
Protists Fungi
PlantsAnimals
(including us)
Eukaryotes vs. ProkaryotesBig differences: Have a membrane-bound nucleus that
encloses the DNA* DNA is organized as chromosomes Have other membrane-bound organelles to
carry out cell life processes Much larger (10-100 microns) Specialize to form multicellular organisms
Advantages of each kind of cell architecture
Prokaryotes Eukaryotes
simple and easy to grow
can specialize
fast reproduction multicellularity
can live in many different environments
can build large bodies
Vocabulary Be able to define/explain theseCell Theory
Prokaryote
Eukaryote
Bacteria
Archaea
Unicellular
Multicellular
Nucleus
Cytoplasm
Ribosomes
Membrane