Cells and Their Environment Flashcards
movement of substances across the cell membrane either into or out of the cell
Cellular Transport
Components of Cell Membrane
- phospholipid bilayer
- transport protein
allows certain molecules pass through and prevents other molecules from crossing
Semi-permeable membrane
move easily (in & out) the cell membrane
small uncharged molecules
move freely in the interior of the membrane
lipid-soluble substances
do not cross lipid membranes easily unless specific transport mechanisms are present
water-soluble substances
cannot pass through the membrane because of strong electrical charges
ions
cell’s energy chief
Adenosine Triphosphate (ATP)
Processes Involved in Moving Materials Across the Cell Membrane
- Passive Transport
- Active Transport
- Bulk Movement
the movement of a substance across a cell membrane without the input of the cell’s energy
Passive Transport
Types of Passive Transport
- Simple Diffusion
- Facilitated Diffusion
- Osmosis
most common form of passive transport
Simple Diffusion
the random movement of molecules from an area of higher concentration (more molecules) to an area of lower concentration (fewer molecules)
Simple Diffusion
Factors Affecting the Rate of the Diffusion
- temperature
- size of the molecules
the difference between the concentration of a particular molecule in one area and its concentration in an adjacent area
Concentration Gradient
Process of Facilitated Transport
- Protein binds with the molecule (glucose)
- Shape of protein changes based on the size of molecule
- Molecule moves across membrane
help molecules or ions enter or leave the cell and are usually transport proteins
channels
difference between simple diffusion and facilitated diffusion
In simple diffusion, the substance passes between the phospholipids; in facilitated diffusion, there are specialized membrane channels.
the diffusion of water across a semi-permeable membrane
Osmosis
often involves the movement of water
water moves from solutions with higher water (lower solute) concentrations to solutions with lower water (higher solute) concentrations
Osmosis
the concentration of solutes outside is higher than it is inside the cell, the water diffuses out of the cell
Hypertonic Solution
shrinkage of red blood cell
Crenation
shrinkage of bacterial cell
Plasmolysis
the concentration of solute is lower outside the cell than inside, and water moves into the cell
Hypotonic Solution
the concentration of solutes inside is very high than it is outside the cell
Very Hypotonic Solution
bursting of red blood cell
Hemolysis
bursting of bacterial cell
Plamoptysis
the concentration of solutes outside the cell equals the concentration of solutes inside the cell
Isotonic Solution
solution where osmosis do not occur
Isotonic Solution
the movement of a substance across a cell membrane requiring the use of energy; usually occurs against a concentration gradient
Active Transport
Importance of Active Transport
a. Contraction of muscles
b. Transmission of nerve impulses
c. Absorption of nutrients
d. Plants: enables the roots to absorb nutrients from the soil
e. one of the several ways that an organism maintains homeostasis
process used by a cell to transport large molecules, such as polysaccharides or proteins, across its membrane
Bulk Movement
2 Types of Bulk Movement
a. Exocytosis
b. Endocytosis
cell discharges material from inside to outside
Exocytosis
movement of large material from outside to inside
Endocytosis
Process of Endocytosis
- Plasma membrane surrounds material
- Edges of membrane meet
- Membranes fuse to form vesicle
cell engulfs a food particle or other solid substance, rather than a liquid
Phagocytocis
Forms of Endocytosis
a. Phagocytosis (cell eating)
b. Pinocytosis (cell drinking)
organisms that engulf and destroy bacteria
Phagocyte (WBC/leukocyte) & amoebas
the cell membrane encloses a droplet of fluid and its solutes and brings the droplet into the cell
Pinocytosis
the maintenance of a stable set of internal conditions within an organism
Homeostasis
