Flashcards in Chapter 3 - Cellular Level Deck (241)
What is a cell?
Living structural and functional units enclosed by a membrane
What is cell division?
Where one cell divides into two identical cells
What is the name of cell biology?
Cytology - study of cellular structure and function
What are the three main parts of a cell?
1. Plasma membrane
What is the plasma membrane?
The cell's flexible outer surface, separating the cell's internal environment from the external environment
A flexible, sturdy barrier that surrounds and contains the cytoplasm of a cell
What is cytoplasm?
All of the cellular contents between the plasma membrane and the nucleus.
Cytoplasm is divided into what two parts?
1. Cytosol - the fluid portion of cytoplasm
2. Organelles - "little organs", each type has a characteristic shape and specific function
What is the nucleus of a cell?
A large organelle that houses most of the cell's DNA
What is a chromosome?
A single molecule of DNA associated with several proteins
Contains thousands of hereditary units called genes that control most aspects of cellular structure and function
What is a fluid mosaic model?
The molecular arrangement of the plasma membrane resembles a continually moving sea of fluid lipids that contains a mosaic of many different proteins
What is the basic structural framework of the plasma membrane?
What is the lipid bilayer made up of?
Back-to-back layers made up of:
What are phospholipids?
Lipids that contain phosphorus
What is a cholesterol molecule?
Steroid with an attached OH- group
What is a glycolipid?
Lipid with an attached carbohydrate group
What does amphipathic mean?
Both polar and nonpolar parts
What are integral proteins?
Proteins that extend into or through the lipid bilayer among the fatty acid tails and are firmly embedded in it
What are transmembrane proteins?
They span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid
What are peripheral proteins?
Not as firmly embedded in the membrane
Attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane
What are glycoproteins?
Proteins with carbohydrate groups attached to the ends that protrude into the extracellular fluid
What is the glycocalyx?
An extensive sugary coating on the extracellular surface of the plasma membrane. It is composed of the carbohydrate portions of the membrane, glycolipids and glycoproteins
What are the functions of the glycocalyx?
- enables cells to recognize each other
- enables cells to adhere to each other
- protects cells from being digested by enzymes in the extracellular fluid
- it is hydrophilic, attracts a film of fluid to the surface, makes it slippery
What are ion channels?
Pores or holes that specific ions (K+), can flow into and out of the cell
Most are selective, allow only one type of ion through
What is a carrier?
Transports specific substances across membrane by changing shape
Selectively moves a polar substance or ion from one side of the membrane to the other
Also known as transporters
What are receptors?
Recognizes specific ligand and alters cell's function in some way
Serve as cellular recognition sites
Each type of receptor recognizes and binds a specific type of molecule
What is a ligand?
A specific molecule that binds to a receptor
What is an enzyme?
A catalyst to speed up specific chemical reactions inside or outside of the cell
What are linkers?
Anchor filaments inside and outside the plasma membrane
Provides structure, stability and shape
Link two cells together
What do cell-identity markers do?
1. Recognize other cells of the same kind during tissue formation
2. Recognize and respond to potentially dangerous foreign cells