1. Features of Life and the Cell

2. Features of Living Things
The word living can be difficult to define
Biologists recognize that ALL living things share certain features
Our textbook describes 8 features of ALL living things

3. Features of ALL Living Things
1. Living things reproduce
This simply means that all living things produce offspring
There are two types of reproduction: sexual and asexual
Sexual reproduction is when two cells combine there DNA to produce a new, unique cell
Asexual reproduction is when one cell simply splits into two new cells

4. Paramecium dividing

5. Cell fertilization

6. Features of ALL Living Things
2. Living things grow
Living things grow by using materials and energy from their environment to increase their size

8. Features of ALL Living Things
3. Living things develop
Development is all the changes that occur in a living thing as it grows

10. Features of ALL Living Things
4. Living things need food
Food, in this context, means an energy source
Organisms are either consumers or producers
Consumers consume, or eat, other living things
Producers (like plants, algae and some bacteria) produce, or make, their own food source

11. Features of ALL Living Things
5. Living things use energy.
Energy can be defined as “the ability to do work”
It is what causes the movement and/or change in matter
All biological functions require energy to carry out their chemical reactions
Consumers eat other organisms to get energy
Producers make their own food during photosynthesis or chemosynthesis

12. Features of ALL Living Things
How do organisms get energy from the food they eat?
This happens by way of a process called cellular respiration
In this process, food molecules (usually a sugar called glucose) are chemically broken down in the cell and new molecules are formed that release energy when the organism needs it

13. Features of ALL Living Things
6. Living things are made of cells
The cell is the basic unit of structure and function in ALL living things
Organisms can be multicellular (made of many cells) or unicellular (made of one cell)

15. Features of ALL Living Things
7. Living things respond to input from their environment
When input is received from the environment, living things react
Sometimes this reaction is a chemical change in the body
Sometimes it is a physical change such as movement
Examples: sweating, plants growing toward light, your dog comes when you call it, flinching when Mrs. Motroni throws something at you

16. Features of ALL Living Things
8. Living things are adapted to their environments
A trait that makes an organism better able to survive in its environment is called an adaptation
Better adapted organisms are able to live longer and reproduce more frequently than less adapted individuals
All of the, roughly, 10 million species on earth are here because they are the best adapted to their respective environments

18. The Chemistry of Life Living things are made of matter What’s matter?
Matter is anything that has mass and takes up space
Matter is made of atoms
Atoms make up the elements
Elements are substances that are made of only one type of atom

20. The Chemistry of Life
Two or more elements that are bonded together form a compound
When chemistry is done and two elements bond together, the properties of the new compound are usually different than the properties of the elements by themselves
Examples: hydrogen and oxygen are elements. They are flammable gases. They are gases at room temperature. When they bond together they make water, which is a liquid at room temperature.
Sodium metal + chlorine gas

21. The Chemistry of Life
Each element has a specific symbol used to represent it.
H for hydrogen, O for oxygen, Na for sodium, W for tungsten
When these combine to make a compound, the symbols are joined to make a molecular formula
Water is H2O, table salt (sodium chloride) is NaCl, sugar is C6H12O6

22. The Chemistry of Life
Most living things are made of the following elements Carbon, oxygen, hydrogen, nitrogen, phosphorus, calcium, and sulfur
These elements combine to make 99% of all the molecules in all living things on Earth

23. Cell Theory
1655, English scientist, Robert Hooke, looks at this slices of cork under a microscope
He observed that the cork was made of many small parts that he called cells
Nineteenth Century, Robert Brown discovers the nucleus, Schleiden and Schwann determine that all plants and animals are made of cells
These experiments lead to the to development of the cell theory

24. Cork cells animal cells
Plant cells

25. Cell Theory The cell theory has three major parts
1. ALL living things are made of one or more cells
2. Cells are the basic unit of structure and function in ALL living things
3. ALL cells come from other, pre-existing cells

26. Watch this

27. Cell Parts and Their Jobs
As you know, cells are the basic unit of structure and function of ALL living things
This means that all living things are made of cells and that the cells carry out all functions necessary for life
There are single-celled organisms and there are multi-celled organisms
Multi-celled organisms, like us, are made of lots of different types of cells. Each type does a specific job in our bodies
Cells, however, contain even smaller things called organelles
Organelles do specific jobs in each cell

28. Cytoplasm The cytoplasm is the gel-like fluid inside the cell
All the other cell parts are suspended in the cytoplasm

29. Cell Membrane The cell membrane surrounds the cell
It holds in the cytoplasm
The cell membrane’s two major jobs are to
1. maintain the shape of the cell
2. control what goes into and out of the cell

31. Nucleus The nucleus is a membrane-bound organelle
This membrane is called the nuclear envelope. It has openings in it known as nuclear pores.
It is usually the largest organelle in the cell
The nucleus is considered the “control center” of the cell
This is so because the nucleus contains the DNA
The DNA is the molecule that contains the genetic code and determines what proteins are to be made by the cell and therefore, all the physical traits of an organism
Chromosomes are actually DNA molecules that are all folded up on themselves

33. Nucleolus The nucleolus is found inside the nucleus
Its job is to make very important structures called ribosomes

34. Ribosomes Ribosomes are very small organelles
Their major function is to produce protein molecules
Ribosomes are found floating around in the cytoplasm AND stuck to the side of another organelle called the endoplasmic reticulum

36. Endoplasmic reticulum
This organelle is like a series of highways that connect different parts of the cell together
Its job is to transport materials throughout the cell

38. Golgi Body
The Golgi body is an organelle that looks like a bunch of folded up sacs
Its job is to process protein molecules and get them ready to be used by the cell or by other cells in the body

40. Vacuoles
Vacuoles are liquid filled sacs that are used to store food, water, and minerals
Some vacuoles store waste products until the cell is ready to get rid of them
Most plant cells have a very large vacuole inside of them, this vacuole helps to provide structural support for the cell

42. Centrioles
Centrioles are present in animal cells but NOT in plant cells
They are located near the nucleus and help with cell reproduction

44. Chloroplasts Chloroplasts are found in plant cells NOT in animal cells
They contain the pigment chlorophyll, so they are green
This is why plant leaves are green
Chlorophyll absorbs sunlight and uses it to make sugar molecules during photosynthesis

46. Cell Wall The cell wall is different than the cell membrane
Cell walls are found in plant cells, fungus cells, algae cells, and some bacteria cells but, NOT in animal cells
Their job is to provide protection and support to the cells
Cell walls often remain after the rest of the cell has died
A piece of wood is made of the cell walls of the dead tree cells

48. mitochondria Sometimes called the power house of the cell
This is where sugar molecules are broken down to make useable enrgy for the cell

51. Special Cell Processes: Diffusion and Osmosis
Diffusion is a naturally occurring event where particles move from an area of high concentration (large amount) towards an area of low concentration (small amount)
This happens because ALL particles of matter are in constant motion
Particles bounce of each other and off the inside walls of whatever they are contained in

52. Diffusion Through the Cell Membrane
There are small openings in the cell membrane called pores
These pores allow particles, like oxygen or carbon dioxide, to diffuse into and out of the cell

54. Osmosis
When water diffuses across a cell membrane it is called osmosis
When there is more water molecules inside the cell than out, water will move out of the cell
What happens when there is more water molecules outside the cell than there are inside?

55. Osmosis is Important
Osmosis is important because if too much water leaves the cell it can wilt and die
If too much water enters a cell it can rupture and die
This is why salt is a natural preservative
When food is packed in salt, it dries the food out, this prevents bacteria and fungi from growing on the food
This is also one of the steps in making a mummy

56. Organization Living things are organized in special ways
Single celled organisms perform all life functions in that one cell
Multi-celled organisms have many types of cells, each doing a specific job
Groups of cells that do the same job are called tissues
Bone, muscle, skin, blood, and nerve are examples of different types of tissues

57. organs Tissues can be organized into groups too
Organs are made when groups of similar tissues work together doing a job
What are some organs?

58. Organ system
Organ systems are made when several different organs work together to perform a particular job
Example: the brain, spinal cord, and all the nerves in your body make up the nervous system

59. organism All the organ systems together make the organism
some organisms are only one cell but multi-celled organisms have several organ systems
What are some organ systems?