Module 3: Cells Flashcards
What is a cell?
The smallest structural unit of all living organisms that is capable of functioning independently.
What are the 3 main parts the cell is divided into?
The plasma membrane, the cytoplasm, and the nucleus
Describe the structure of the plasma membrane?
Surrounds and contains the cytoplasm of a cell. Consists mostly of phospholipids, arranged in a bilayer and proteins most of which are glycoproteins.
Describe the structure of the cytoplasm?
Includes all the cellular contents between the plasma membrane and nucleus. Cytosol and organelles
Describe the structure of the nucleus?
Consists of a double nuclear envelope; nuclear pores, which control the movement of substances between the nucleus and cytoplasm, nucleoli, which produces ribosomes; and genes arranged on chromosomes.
What are the functions of the plasma membrane?
Acts as a barrier separating inside and outside of the cell. Controls the flow of substances into and out of the cell. Helps identify the cell to other cells (immune cells). Participates in intercellular signaling.
Describe simple diffusion: lipid-soluble molecules diffuse through the lipid bilayer.
In simple diffusion there is a net (greater) movement of substances from a region of their high concentration to a region of their lower concentration.
Describe facilitated diffusion
An integral membrane protein assists a specific substance to move across the membrane. The membrane protein can either form channels or function as carriers.
What is osmosis?
Osmosis is the net movement of water molecules through a selectively permeable membrane.
What is an isotonic solution?
One which cells maintain their normal shape and volume.
What happens in a hypotonic solution?
Molecules enter the cells by osmosis faster than they leave which causes the cells to swell and eventually burst which is called hemolysis.
What happens in a hypertonic solution?
Water molecules move out of the cells by osmosis faster than they enter causing the cells to shrink and shrivel up. This is called crenation.
Explain the function of the sodium potassium pump
Na+ ions are expelled from the cell and K+ ions are imported into the cell. The pump does not work unless Na+ and ATP are present in the cytosol and K+ Is present in the extracellular fluid. The sodium potassium pump maintains a low intracellular concentration of Na+
___ is a vital defense mechanism that helps protect the body from disease.
Phagocytosis
Movement of substances down a concentration gradient until equilibrium is reached; do not require cellular energy in the form of ATP is __ __
Passive processes
Movement of a substance by kinetic energy down a concentration gradient until equilibrium is reached is ___
Diffusion
Passive movement of a substance through the lipid bilayer of the plasma membrane is __ __
Simple diffusion
Ex: lipid soluble molecules oxygen, carbon dioxide, nitrogenous gases, fatty acids, steroids, fat-soluble vitamins A D E K, polar molecules like water and urea
Passive movement of a substance down its concentration gradient aided by ion channels and carriers is __ __
Facilitated diffusion
Ex: K+, Cl-, Na+, Ca2+, glucose, fructose, galactose and some vitamins
Movement of water molecules across a selectively permeable membrane from an area of higher concentration to an area of lower water concentration is ___
Osmosis