Download CELL NOTES The invention of the microscope made

CELL NOTES
The invention of the microscope made discovery of cells possible. A light microscope
refracts or bends light so that the image is magnified. Robert Hooke looked at cork bark
under the microscope and noticed that there were parts that looked like rooms. He named
those parts cells. Anton van Leeuwenhooke looked at teeth scrapings, rain water, and
blood and noticed that the cells were moving. He discovered that cells were alive.
Mathias Schleiden looked at all types of different plant parts and discovered that all plant
parts contained cells. Theodore Schwann looked at all different animal parts and
discovered that all animal parts contained cells. Rudolph Virchow discovered that you
needed a cell to carry out life functions. The cell theory that was developed by
Schleiden, Schwann, and Virchow says:
1. All living things are made of cells.
2. The cell is the basic unit of structure and function in living things.
3. All living cells come from other living cells.
The tiny parts that make up a cell are called organelles. The cell is like a factory with
each organelle doing a specific job. Some of the main organelles are:
1. The nucleus looks like a ball of string, the strands are DNA. It controls all
activity of the cell.
2. The chromosomes are rod shaped structures that contain genes. They have the
plans for building new cells.
3. The cell membrane is a thin, flexible double lipid layer. It controls what can enter
and leave the cell.
4. The cell wall is the outer boundary of the plant cell, it is filled with a fibrous
material called cellulose. It gives strength and support to the plant cell.
5. The mitochondria is a football shaped organelle that contains membranes where
the process of cellular respiration takes place. It produces energy for the cell by
burning food and oxygen.
6. The chloroplast is an oval organelle that is filled with a green pigment called
chlorophyll. It carries out the process of photosynthesis. It makes sugar for the
plant cell.
7. The ribosome are tiny grain like organelles that are the smallest and most
numerous in the cell. They make protein for the cell.
8. The endoplastic reticulum is a series of tubes that connect the different organelles.
It moves material from one part of the cell to another.
9. The vacuole is an empty sac like organelle. It stores things like water and waste
for the cell.
10. The lysosome is a ball shaped organelle that if filled with digestive enzymes. It
breaks down food and old cell parts for the cell.
There are five cell processes students in this class should be familiar with. They are
photosynthesis, cellular respiration, diffusion, osmosis and cell reproduction.
Photosynthesis takes place in the chloroplasts. It takes water, sunlight, and carbon
dioxide and makes sugar and oxygen. Cellular respiration takes place in the
mitochondria. It takes sugar and oxygen and makes energy, water, and carbon dioxide.
These reactions are exact opposites and allows carbon atoms to be recycled over and over
again.
Diffusion is when material goes from an area of high concentration to an area of lower
concentration. This is how food and water move from the blood into the cell and how
wastes move from the cell to the blood to be removed from the body. Osmosis is a
special type of diffusion where water moves from an area of higher concentration to an
area of lower concentration across a membrane. This allows water to enter or leave the
cell depending on the concentration.
Cell reproduction takes place in the cell cycle. The steps of the cell cycle are:
1. Interphase—during this stage the cell grows, makes a copy of the DNA and
prepares to divide.
2. Prophase—during this stage the chromosomes unravel, shorten and thicked.
3. Metaphase—during this stage the chromosome pairs line up across fromeach
other along the cell equator.
4. Anaphase—during this stage the matching pairs of chromosomes are pulled apart
to opposite ends of the cell.
5. Telophase—during this stage the two groups of chromosomes that were pulled
apart are wrapped in an nuclear membrane and become two nuclei.
6. Cytokinesis—during this stage the cytoplasm pinches in half around each nuclei
and forms two cells.
Cells are organized into levels. The levels are:
1. Cells--the basic unit of life. Examples red blood cells, muscle cells, and nerve
cells.
2. Tissues—a group of similar cells working together to do a job. Example
connective tissue, bone tissue, muscle tissue.
3. Organs—a group of different tissues working together to do a job. Examples—
Hearts, lungs stomach, kidneys, and liver.
4. Organ systems—a group of different organs working together to do a job.
Examples-digestive system, respiratory system, and circulatory system.
5. Organism—a group of different organ systems working together to do a job.
Examples—pine trees, grasshoppers, and humans.