Organisms
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Organism– any living thing
Unicellular organism– single cell or 1 cell (2 kingdoms: protisit & bacteria)
– bacteria, Amoeba, Paramecium, Euglena, Algae
Multi-cellular organism– more than 1 cell or many cells (3 kingdoms: plants, animals& fungi)
– dogs, zebras, sharks…
5 types of organisms (kingdoms)
1) Plants
2) Animals
3) Fungi
4) Protist – (microscopic one celled plants & animals)
5) Bacteria - (one celled organisms)
Six characteristics of all living things
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All living things are made up of cells
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All living things reproduce
asexual or sexual
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All living things perform complex chemical
activities.
ex. eating, digestion, excretion, breathing
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All living things are made up of cells.
Six things living organisms need to survive
All living things grow and develop
All living things respond to stimulus
All living things can move, but only animals
can move from place to place
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water
food
energy
Oxygen/ Carbon Dioxide
living space
maintain a fairly constant body
temperature
*Homeostasis– the ability of an organism to
keep conditions inside the body the same,
even though conditions outside the body
Cell theory
change.
Cells are the basic unit of life
Only living cells can produce new living cells.
Cell structure and function
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Cell wall–The cell wall is the tough, stiff, outer layer of a plant cell. The cell wall protects
and supports the plant so the plant can grow tall.
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Cell membrane– The thin, flexible layer that surrounds all cells and allows materials like food,
water, gases, and waste to pass into and out of the cell.
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Nucleus–The cell structure that controls all activities or actions of the cell. The brain of
the cell.
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Chloroplast–Found only in a plant cell. Produces chlorophyll, which is the green color in
plants. Plants use chlorophyll and sunlight to produce food during photosynthesis.
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Cytoplasm–Liquid like area between the cell membrane and nucleus that holds all cell
structures in place.
Plant Cell
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Cell wall
Cell membrane
Chloroplast
Cytoplasm
Nucleus
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Animal Cell
Cell membrane
Cytoplasm
Nucleus
Cell functions or processes that keep the cell alive:
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Diffusion: The movement of food and gas molecules into the cell and waste products
out of the cell through the cell membrane.
Diffusion helps cells stay alive by moving food, gases, and other materials into the cell so the
cell can change these substances into energy. Diffusion also allows the cell to remove harmful
waste out of the cell that could poison the cell and the entire organism.
2. Osmosis: The movement of water into or out of the cell through the cell membrane.
Osmosis keeps cells alive by moving water into the cell. Without water in the cell the cell would
dry up or dehydrate which would kill the cell and the entire organism.
3. Reproduction or cell division: Cell division or mitosis is the way a cell reproduces. Cells
split or divide to form a new cell that is exactly like its parent cell. Cell reproduction
allows new cells to be formed and allows the organism to grow and develop. One-celled
organisms form a new one celled organism when they go through cell division.
Cell division helps keep the cells alive by reproducing more cells to replace dead or injured cells.
Cell division lets the organism grow and develop as more cells are produced. One-celled
organisms reproduce new one-celled organisms through cell division.
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Respiration: The cell process in which cells break down the gases, water, and food
they take in through the cell membrane and turn the food into energy.
Respiration helps cells stay alive by giving the cells energy to perform a certain job or function.
The cells must have energy to function to keep the cell and organism alive and healthy.