Structure and Function of Cells
Objective 1 – Specify the characteristics we associate with life and explain why
the cell is considered to be the basic unit of life:
1. Exchange materials with the environment . Some are taken in, some are released. Cells take in
nutrients and nutrient gases, and expel wastes on an ongoing basis. Our cells absorb needed materials
from, and deposit waste materials into, the ECF.
2. Obtains energy from organic materials. Cells take in sugars and metabolize them to obtain energy
which can then be used to perform cellular activities.
3. Can synthesize complex organic molecules . Proteins and fats are only found in living cells or
organisms, or in situations where living cells have depositedthe molecules.
5. Can respond to environmental stimuli . Cells and organisms respond to cold temperatures by moving
somewhere warmer, or by altering their physiology to make more heat.
The cell is the basic unit of live because a cell is the simplest structure that processes all the basic components of
living matter. These processes are assigned to living cells, not the whole organism.
Objective 2 – Describe the chemical, cellular, tissue, and organ system levels of
structural organization in the body.
Cellsare the basic structural/functional units of the body. Composed of chemical substances, organelles,and
membranes that are necessary for life. They do not exist independently of each other.
Chemicals are organic and inorganic molecules.
Tissues are organized groups of cells that carry out specificfunctions. A tissue is a group of similar cells and their
associated intercellular materials, which have similar origins and functions. They also have a similar appearance.
Tissues are then organized intorgans : a structure with a definite form and function composed of 2+ tissue types.
Organs are then arranged intosystems that are consisted of organs that interact to perform a specific function.
These systems then comprise the whole body. Objective 3 – Describe the structure (identify them in a diagram!) and describe
the functions of the followingcytoplasmic components:
Cell (Plasma) Membrane:
Surrounds the cell
Regulates what materials enter and leave the cell
Allows communication with theextracellular environment
Series of interconnected tubes/membranes that extend throughout cytoplasm
o Rough ER –membranes studded with ribosomes; a transport system that processes and sorts
proteins for export to the Golgi complex; produces some distinct groups of proteins
o Smooth ER – a continuation of therough ER without ribosomes; lipid synthesis, metabolism,
transport; sex steroid hormone synthesis in certain cells; drug detoxification
The site where info from DNA is used to make proteins
Two types of ribosomes:
o Free ribosomes – float in the cytoplasm
Produces proteins used immediately in thecytosol (ICF) of the cell
o Attached (“bound” or “fixed”) ribosomes – produces 3 groups of proteins:
Proteins to be exported out of the cell
Cell membrane proteins
Proteins for inside membranous organelles