Cells and Cell Processes
1. Characteristics of Life
b. Respond to stimuli
c. Exchange energy and materials with the environment
d. Made of cells
f. Grow and develop
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
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
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
i. release energy from the food we eat
ii. break down glucose and other molecules for energy
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
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
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. 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
i. the vacuole is used for storing things inside the cell
ii. plant cells usually have very large vacuoles that