Cells and Cell Processes

1.         Characteristics of Life

            a.         Order

            b.         Respond to stimuli

            c.         Exchange energy and materials with the environment

            d.         Made of cells

            e.         Homeostasis

            f.         Grow and develop

            g.         Reproduce

            h.         Evolve

2.         Cell Theory says three main things about cells:

            a.         All living things are made up of one or more cells.

            b.         Cells are the basic unit of life.

            c.         All cells come from other cells.

3.         All cells are organized into levels of structure

            a.         Organisms - the entire living thing

            b.         Organs and organ systems - a collection of tissues working together

            c.         Tissues - a collection of similar cells all working together to do a job

            d.         Cells - the smallest living unit of a living thing

            e.         Organelles - small parts of cells which each have a special job

            f.         Molecules - tiny pieces which make up all the parts of the cell

4.         The cell membrane is the outer boundary of all cells.

            a.         It contains special molecules called phospholipids which keep water from passing through. These molecules are made mostly of fat.

            b.         It controls what comes into and goes out of the cell.

            c.         It also has proteins stuck in it

            d.         It is very important for homeostasis.

5.         Cells are made of various parts (organelles) which each have a specific function.

            a.         Cell wall

                        i.         Found in plants, bacteria, and fungi

                        ii.        Not living like the cell membrane

                        iii.       because it is not living it requires pores for things to get in and out.

                        iv.       made of cellulose. Cellulose is what we call fiber and is an important part of our diet

                        v.         protects the plant cell and gives it strength and structure

                        vi.       because it is so strong the plant does not need a skeleton

            b.         Cytosol

                        i.         all the liquid which fills the cell

                        ii.        cytosol is mostly water

                        iii.       it is important because all of the chemical reactions in the cell take place in water.

            c.         Nucleus

                        i.         controls the activities of the cell

                        ii.        contains the DNA (genetic information)

                        iii.       DNA is in the form of chromosomes

                        iv.       surrounded by the nuclear membrane which is similar to the cell membrane

                        v.         the nuclear membrane controls what goes in and out of the nucleus

            d.         Mitochondria

                        i.         release energy from the food we eat

                        ii.        break down glucose and other molecules for energy

            e.         Ribosome

                        i.         make protein for the cell

                        ii.        most cells have 1000s of ribosomes

                        iii.       some proteins stay inside the cell, some proteins leave the cell

            f.         ER

                        i.         ER is used to move substances from one place in the cell to another

                        ii.        it is like a complex system of tunnels or passageways

                        iii.       some ER has ribosomes attached and some does not

            g.         Lysosome

                        i.         lysosome break apart worn out cell parts

                        ii.        like a little recycling center

                        iii.       the parts are then reused to make new cell parts

            h.         Cilia and flagella

                        i.         some cells have cilia (like tiny hairs) that are use for movement

                        ii.        some cells have a flagellum (like a tail) used for movement

            i.         Chloroplast

                        i.         contain a green pigment called chlorophyll

                        ii.        this pigment absorbs light from the sun

                        iii.       the chloroplasts make glucose (the main food) for the plant

                        iv.       this process is called photosynthesis

            j.         Vacuole

                        i.         the vacuole is used for storing things inside the cell

                        ii.        plant cells usually have very large vacuoles that they use to store water

                        iii.       the vacuoles of animal cells are not as large but they have many more

            k.         Cell membrane

                        i.         the cell membrane only allows certain things to enter and leave the cell

6.         Cell have to take in nutrients and get rid of wastes.

            a.         Diffusion

                        i.         diffusion - the movement of molecules from where there are more to where there are fewer

                        ii.        molecules move on their own. It's like they "want" to spread out.

                        iii.       most things move into and out of the cell by diffusion

                        iv.       the cell does not have to spend any energy doing this

                        v.         if there is lots of something outside the cell, it will try to move inside.

            b.         Osmosis

                        i.         osmosis is the diffusion of water through a membrane

                        ii.        you could say it is when water moves from where there is more water to where there is less water

                        iii.       lots of things dissolved in water (like salt) means there is less water

                        iv.       not much dissolved in water (like salt) means there is more water

                        v.         it happens without the use of cell energy

                        vi.       in certain conditions it can be a problem for cells

                        vii.      imagine a cell is in pure water. There is more water outside the cell than inside so water will move inside and the cell will swell. It could even burst.

                        viii.     imagine a cell is in very salty water. There is more water inside the cell than outside so water will move out of the cell and the cell will shrivel.

                        ix.       this is why organisms like things to stay the same (homeostasis)

7.         All cells come from other cells through the process of cell division

            a.         remember that the cell theory says that all cells come from other cells

            b.         new cells are made when a cell divides

            c.         two new cell results each time a cell divides

            d.         Cell division is divided into several stages

                        i.         Interphase

                                    (1)       the time when a cell is not dividing

                                    (2)       the cell uses this time to get ready to divide and to do it's normal functions

                                    (3)       the most important job is to copy all of the DNA (or genetic material) in the cell

                                    (4)       this is important so that each new cell has all the same DNA as the original cell

                        ii.        Prophase

                                    (1)       the nuclear membrane is gone

                                    (2)       the DNA has doubled. Notice that each chromosome is now doubled and the copies stay attached

                        iii.       Metaphase

                                    (1)       the pairs of attached chromosomes line up at the middle of the cell

                        iv.       Anaphase

                                    (1)       the pairs of chromosomes start to move apart from each other

                        v.         Telophase

                                    (1)       the cell starts to lengthen

                                    (2)       the chromosome pairs have moved to opposite ends of the cell

            e.         The result is that two new, identical cell are made

8.         Most cells get energy through the process of cellular respiration

            a.         all living need energy to do the things they need to do

            b.         organisms obtain energy from food

            c.         energy is released when food is broken down by chemical reactions

            d.         the main source of energy is glucose (a sugar)

            e.         glucose + oxygen ➝ carbon dioxide + water + energy

9.         Plant cells make food (glucose) using photosynthesis.

            a.         plants use the green pigment chlorophyll to absorb light from the sun

            b.         chlorophyll is found in the chloroplasts

            c.         this energy is used to make food (glucose)

            d.         what do you notice about the process of photosynthesis?

            e.         carbon dioxide + water + energy ➝ glucose + oxygen