Cell Unit Notes
I. Life Processes - What makes something living?
A. Biotic: Having life’s conditions
Abiotic: Not having life’s conditions
Homeostasis: The condition of maintaining a constant internal environment in living organisms.
B. Characteristics of living Organisms (LIFE)
1. Nutrition - Food for energy and body (cell) repair and development
2. Transport - Move materials were needed in organism
3. Respiration - Able to generate energy for life processes
4. Synthesis - Able to combine matter to make needed products
5. Assimilation - Able to combine products to make body (cell) parts
6. Growth - Changes over time
7. Excretion - Expels waste material
8. Reproduction - Able to produce new living organisms with life
9. Metabolism - Has chemical reactions to maintain homeostasis
II. Development of the Cell Theory
The cell theory took several hundred years to develop. It took new technology and the ability to accept new ideas to accomplish what we have today.
A. Important men to know in Cell Theory Development
1. Robert Hooks: (1665) English - Observed Cork and named small units “cells”
2. Anton von Leeuwenhoek: (1675)Dutch - Made some of first detailed microscopes, observed blood, teeth scrapings, etc.
3. Henry Dutrochet: (1824) France - Proposed that all living things were made of cells
4. Robert Brown: (1831) English - Observed plant and animal cells and named nucleus in both.
5. Matthias Schleiden: (1838) German - Discovered plants composed of cells
6. Theodor Schwann: (1839) German - Discovered animals composed of cells
7. Rudolph Virchow: (1855) German - Determined that cells come from other cells.
B. The cell theory states:
1. All organisms are made of one or more cells.
2. Cells are the basic unit of life. They carry on life activities.
3. Living cells come from other living cells. (Cell division)
III. Cell Diversity
A. Two main types of cells
1. Prokaryote: (prokaryotic) Simple cells that lack a nucleus and many membrane organelles. Example - Bacteria.
2. Eukaryote: (Eukaryotic) Complex cells that have a nucleus and other membrane organelles. Example- plant and animal cells.
B. Cell size
1.Eukaryote cells are much larger than prokaryote cells. Cells range in size from 2 meters(very small just long, giraffe nerve cell in neck) to .2 microns(10-6)
2. Important question: Why are single cells so small?
The surface area to volume ratio increases too much to supply the cell with nutrients and remove waste. The smaller the cell the easier these processes are. Needed materials can't get in and out of the cell fast enough.
C. Cell shape
1. Cells come in most any shape thought of . They are not all round or square. Plant cells hold their shape better because of their cell walls.
IV. Cell Organelles and their functions
A. Organelles are cell structures found inside the cell that perform specific functions for life activities.
1. Nucleus: Controls cells activities. Contains DNA, which makes up chromosomes that carry genetic information
2. Nuclear membrane: Surrounds the nucleus and controls what goes in and out of the nucleus
3. Nucleolus: Found in the nucleus. Helps form RNA and ribosomes.
4. Cell wall: Rigid outside structure found in plant cells and some prokaryote. Composed of cellulose in plants. Gives support, shape and controls what goes in and out of the cell.
5. Cell membrane: (plasma membrane) Thin, flexible envelope that surrounds cell material. Protects and controls what goes in and out of...
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