Transcript Cells: The Basic Units of Life
Cells: The Basic Units of Life
O R G A N I I Z A T O N O F I L F E Tissues Cells Organs Organ Systems Organisms
Cells
•
Every living thing has at least one cell
. – Some have only one and some have trillions.
– Most cells are too tiny to be seen without a microscope.
– A chicken egg is one of the largest cells.
– Not all cells look or act the same.
– You have 200 different kinds of cells: blood cells, bone cells, muscle cells …………
Tissues
• A tissue is a group of cells working together to perform a specific job in the body. The material around and between the cells is also part of the tissue. – Examples of tissue: red blood cells, fat, and muscle
Organs
• When two or more tissues work together to perform a specific job, the group of tissues is called an organ. • – Examples of organs: stomach, heart, intestines, liver, lung, and skin Plants also have different kinds of tissues that work together. A leaf is a plant organ that contains tissue that traps light energy to make food.
Examples of plant organs: stem and roots
The Skin
• The skin is the body’s largest organ. An average-sized person’s skin has a mass of about 4.5 kg (almost 10 pounds!).
Brain Food
• The part of the skin, hair, and nails that we can see is DEAD tissue. Isn’t it strange that we put so much effort into making sure our dead cells look nice?
Organ Systems
• • Organs work together in groups to perform particular jobs. These groups are called organ systems. Each system has a specific job to do in the body.
– Examples: • digestive system breaks down food to use by your body’s cells • nervous system transmits information back in forth between the brain and other parts of the body
There are 11 main organ systems .
• • The organs in the organ system depend on each other. If any part of the system fails, the whole system is affected. And failure of one organ system can affect other organ systems.
Main organ systems : integumentary system, skeletal system, muscular system, nervous system, endocrine system, cardiovascular system, lymphatic system, respiratory system, digestive system, urinary system, reproductive system
Organism : Independent Living
• •
Anything that can live on its own is called an
organism. All organisms are made up of at least one cell.
– organisms made up of one cell –
unicellular
– organisms made up of groups of cells –
multicellular
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The Big Picture
Although unicellular and multicellular organisms can live on their own, they usually do not live alone. Organisms interact with each other on many different ways.
–
Populations
– groups of organisms that are of the same kind and that live in the same area • Example – all the white tail deer in the forest –
Communities
same area • - two or more different populations living in the All the populations combined in the forest (deer, rabbits, snakes, etc..) –
Ecosystems
– all the communities and all the nonliving things that affect it, such as water, soil, rocks, temperature, and light • Ecosystems on land – terrestrial ecosystems • Ecosystems in water – aquatic ecosystems
Discovery of Cells
Seeing the first cells
• 1665 Robert Hooke – British scientist – used cork (soft plant tissue found in the bark of a tree) – He saw tiny boxes and called them cells.
Early discoveries
• 1673 – Anton van Leeuwenhoek – Dutch merchant – used a handmade microscope to look at pond scum – He saw many small creatures. He also looked at blood from animals and teeth scrapings. First to see bacteria and discovered that yeast is a unicellular organism.
The Cell Theory
Matthias Schleiden – 1838 – all plant parts are made of cells Theodore Swann – 1839 - wrote the first part of the cell theory.
o
All organisms are composed of one or more cells.
o The cell is the basic unit of life in all living things.
1858 – Rudolf Virchow – wrote the third part of the cell theory o
All cells come from existing cells
•
All cells have:
– Cell membrane surrounds all cells; acts as a barrier between the inside of the cell and its environment; controls what comes in and what goes out – Hereditary material new cells – cells receive a copy of hereditary material (DNA) It controls all of the activities of the cell and contains the information needed for that cell to make – Organelles – structures within a cell that allow it to live, grow, and reproduce – Cytoplasm cell – fluid that surrounds the organelles within a – Small size – naked eye almost all cells are too small to see with the
• • • •
Amoebas
An amoeba is a single celled (unicellular) organism. It cannot get large enough to be seen. As a cell gets larger, it needs more food and produces more waste. Therefore more material must be able to move in and out through the cell membrane. To keep up with these demands, a growing cell needs a larger surface area through which to exchange materials. As the cell’s volume increases, its outer surface grows too. Go to page 12 to help explain!!! Surface-to-Volume Ratio
Benefits of being Multicellular
• • A single cell as big as you would have an incredibly small surface-to-volume ratio and would not survive because its outer surface would be too small to allow in the materials needed.
Multicellular organisms grow by producing
MORE cells, not LARGER cells. – An elephant has more cells than you, not larger cells.
Many kinds of cells
• • • •
Having many different cells that are specialized for specific jobs allows multicellular organisms to perform more functions than unicellular organisms.
Different kinds of cells can form tissues and organs with different functions.
Some specialized cells: muscle cells, eye cells, brain cells….
Be glad you are not UNICELLULAR! How boring!
Two types of cells
• • • • •
Prokaryotic Cells
Also called bacteria World’s smallest cells No nucleus Circular DNA (shaped like a rubber band) No membrane-covered organelles • • • • •
Eukaryotic Cells
More complex All other cells Have a nucleus Have membrane-covered organelles Linear DNA stored in the nucleus
Eukaryotic Cells
Animal Cells
1. Nucleus 2. Ribosomes 3. Cell Membrane 4. Endoplasmic Reticulum 5. Lysosomes 6. Mitochondria 7. Golgi Complex
Plant Cells
1. Nucleus 2. Ribosomes 3. Cell Membrane 4. Endoplasmic Reticulum 5. Lysosomes 6. Mitochondria 7. Golgi Complex 8. Cell Wall 9. Large Vacuole 10. Chloroplast
• • •
The Cell's Command Center -- The
Nucleus
Largest and most visible organelle in a eukaryotic cell Surrounded by a nuclear membrane for protection Stores DNA that has information on how to make all the cell’s proteins (almost all chemical reactions important to the cell’s life involve protein) Read more: List of Organelles | eHow.com
http://www.ehow.com/info_8642034_list organelles.html#ixzz23M2NtNGk
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The Energy Plant --
Mitochondria
ATP
(molecule that supplies energy to fuel the cell’s activities) made here from food molecules Bean shaped – surrounded by two membranes Must have oxygen Highly active cells (such as heart and liver) have thousand Powerhouse of the cell
• • • •
Protein Factory --
Ribosomes
Make protein chains out of
amino acids
Smallest but MOST abundant organelle Not covered with a membrane
ALL
cells have ribosomes (prokaryotes included)
The Cell’s Delivery System – Endoplasmic Reticulum
• • • • Membrane-covered compartment that makes lipids and other materials for use inside and outside the cell
Breaks down drugs and other damaging chemicals Internal delivery system
Looks like flattened sacks stacked side by side
Shipping– Golgi Complex Packaging Vesicles
• • • Looks like the ER but is located closer to the cell membrane
Modifies lipids and proteins from the ER and delivers them to other parts of the cell or outside the cell Vesicles
are pieces of the Golgi complex that pinches off and stores the final products
Trash Collector -- Lysosomes
• • • • • Specialized vesicles in animal cells
Contain enzymes Destroy worn-out or damaged organelles Get rid of waste materials and protect the cell from foreign invaders
If the membrane of a lysosome opens, the enzymes will spill out into the cell and kill the cell. (How a tadpole loses its tail)
Plant Cells - Chloroplasts
• • • • • Only found in plants and algae Energy-converter Has two membranes and structures like stacked coins and contains chlorophyll – which makes the chloroplast green
Chlorophyll traps the energy from sunlight and uses it to make sugar in the process
photosynthesis.
Mitochondria then use the sugar to make ATP.
Cell Wall
• • • • Found in plant cells Outside the cell membrane Made of cellulose (sugar)
Provides strength and support to cell membrane
Water cooler Vacuoles
• • • • • Most plant cells have very
large vacuoles
.
Membrane-covered
Stores water and other liquids When full, helps support the cell
When empty, the cell shrivels (causing the plant to wilt)
•
Homeostasis
(1) The tendency of an organism internal conditions or a cell , so as to stabilize to regulate its health and functioning, regardless of the outside changing conditions • (2) The ability of the condition of environment body equilibrium or a cell or stability to seek and maintain a within its internal when dealing with external changes • In humans, homeostasis happens when the body temperature body regulates in an effort to maintain an internal temperature we sweat around 98.6 degrees Fahrenheit. For example, to cool off during the hot summer days, and we shiver to produce heat during the cold winter season .
Connective Tissue
• • Joins, supports, cushions and insulates Examples: blood, bone, cartilage, ligaments, tendons,
Epithelial Tissue
• • Epithelial tissues consist of continuous sheets of cells that provide a protective covering over the whole body They also form the lining membranes of internal organs, cavities, and passageways and cover internal organs
Muscle Tissue
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Contracts or shortens to cause movement
Nerve Tissue
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