Chapter 3 The Cell Flashcards
Basic Process of Cells
- Cell metabolism
- Transport of substances
- Communication
- Cell reproduction
Cell Metabolism
sum of all chemical reactions that cell caries out to maintain life:
1. Anabolic reactions (build up)
2. Catabolic reactions (break down)
3. Oxidation-reduction (conversion)
Anabolic reactions
building reactions, small molecules bonded together to form macromolecules
Catabolic reactions
break down macromolecules into smaller molecules
Oxidation-reduction
reactions convert energy into ATP for cells to fuel its process
Transport
Substances the cell has produced or ingested and transports to a variety of destinations
Communication
Communicates between itself, its surrounding environment, and other cells (chemical and electrical signals)
Cell reproduction
By cell division, process necessary for growth and development and replacement of old, damaged cells
Animal cell components
-Plasma membrane
-Cytoplasm : cytosol, organelles, cytoskeleton
-Nucleus
Plasma membrane
phospholipid bilayer that surrounds each cell, isolating internal structures and process from external environment. (creates barrier)
Functions:
-provides structural support, means of communication with its surrounding and other cells, and cell identification.
-Defines intracellular space (contains intracellular fluid, ICF or cytosol), separates it from extracellular space.
Cytoplasm consist of
- Cytosol
- Organelles
- Cytoskeleton
Cytosol
intracellular fluid; mostly water dissolved solutes, inclusions, and proteins (site of many important chemical reactions)
Organelles
cellular machines with very specific functions, suspended in cytosol. Separate potentially damaging chemical reactions from surrounding cell structures
Cytoskeleton
network of protein filaments, creates and maintains shape, hold organelles in place, provides transportation for substances within cell
Nucleus
-Most cells contain a nucleus
-Single roughly spherical organelle
-Enclosed in phospholipid bilayer
-Contains most of cells DNA, primary location for making most RNA
- DNA and RNA control organelle function by coding for and synthesizing proteins
Cell size and diversity
-Enable performance of specialized functions
ex: Structure Function core principle
Structure of Plasma Membrane
Phospholipid
(Within the plasma membrane) Allows plasma membrane to form effective barrier between ECF and cytosol
-Interact with water in both fluid compartments without falling apart.
-Repel water, keeping ECF and cytosol separated.
Polar (head)
Head of phospholipid (hydrophilic)
Non polar (2 tails)
2 tails of phospholipid (hydrophobic)
Amphiphilic
Phospholipids are amphiphilic:
-Phosphate group (hydrophilic polar head) on the outside
-Two fatty acids (hydrophobic tails) in the middle
Membrane proteins
Main component of plasma membranes: 2 types
1. intergal proteins
2. peripheral proteins
Integral proteins
Span entire membrane, ‘transmembrane’ proteins
Peripheral protiens
found only on one side of membrane or other
Functions of Membrane proteins
- Channels
2.Carrier proteins
3.Receptors
4.Enzymes - Structural support
6.Link
Channels
Transmembrane proteins allow certain substances to cross membrane and pass into or out of cell
Carrier proteins
integral proteins bind, change shape, and directly transport substances into and out of cell
Receptors
Bind to chemical messengers (ligands), trigger sequence of events within cell.
ex: cell to cell communication
Enzymes
Speed up chemical reactions, vital to maintaining homeostasis
Structural Support
When bound to cytoskeleton:
-Give cells shape
-Help maintain structural integrity
Link
link adjacent cells to one another (zipper):
-Anchor cells within tissue
-Allow cell-to-cell communication
Cholesterol
Lipid; stabilizes plasma membranes fluid structure during temp changes
Glycolipids and Glycoproteins
Carbohydrate bond to either lipid or protein; identify cell as part of the body (cell recognition)
Agonists
Mimic ligands’s actions; stimulate receptor.
ex: narcotic pain killers such as morphine mimic actions of endorphins
Antagonists
Inhibit ligands actions by blocking receptor.
ex: antihistamines block receptors for histamine.
Selective Permeability
Allows certain molecules to cross , prohibits passage of other molecules. Critical to survival of cell.
Passive Transport
Substance crosses plasma membrane by not requiring energy.
- Diffusion
-Simple and Facilitated - Osmosis
Active Transport
Substance crosses plasma membrane by requiring energy
Variable determining how substance is able to move across plasma membrane
- Type of substance
- Plasma membrane permeability to substance
- Concentration of substances in cytosol and ECF
Concentration Gradient
Force that drives many types of passive transport
-High concentration; means more molecules
-Low concentration; means less molecules
Diffusion
Movement of solute molecules from high concentration to low concentration, until equilibrium (no net movement) is reached.
Simple Diffusion
Mostly non-polar solutes (oxygen, carbon dioxide, lipids and hydocarbons) pass through phospholipid bilayer without membrane protein.
Facilitated Diffusion
Charged or polar solutes (ions and glucose) cross phospholipid bilayer with help of membrane protein (carrier or channel).
Osmosis
Passive process, where solvent (usually water) moves across membrane.
-Water moves from area with lower concentration of solute (more water molecules) across membrane to area with higher concentration of solute (less water molecules)
Water movement across plasma membrane
- Through channel proteins- aquaporins (primary route for osmosis of water)
- Through phospholipid bilayer directly
Osmosis Pressure
Driving force exerted by solute molecules
-Causes water molecules to move until equilibrium reached.
-Pressure applied to solution to prevent water from moving into it by osmosis
Hydrostatic Pressure
Force water exerts on walls of its container
Osmosis V Diffusion
*Diffusion – movement of solute across plasma membrane from higher solute concentration to lower solute concentration (with concentration gradient)
*Osmosis – movement of solvent across plasma membrane from area of lower solute concentration to area of higher solute concentration
Tonicity
Way to compare osmotic pressure gradients between two solutions: cytosol and ECF
Isotonic Solution
Both fluids have approximately the same concentration of solute, no net movement of water across plasma membrane, no volume changes in either fluid compartment .
-Normally ECF is isotonic to cytosol
Hypertonic ECF Solution
Solute concentration of ECF if higher than inside cell, more water molecules inside cell than outside, osmotic pressure gradient pulls water out of cell, cell shrink (crenates), loses water by osmosis.
- Greater ability to cause osmosis than cytosol
Hypotonic ECF Solution
Solute concentration of ECF if lower than inside cell, more water molecules in ECF than inside cell, osmotic pressure gradient pulls water into cell, cell swells and possible ruptures, will gain water.
-Less ability to cause osmosis than cytosol
Active Transport
Require energy (ATP) to proceed as solutes move against concentration gradients (low to high concentration)
-Primary active transport
-Secondary active transport
3 Types of Pumps in plasma membrane
- Uniport
- Symport
- Antiport
Uniport
Transport single substance through membrane in one direction (into or out of cell)
Symport
Transport two or more substances through membrane in same direction (into or out of cell)
Antiport
Transport two or more substances in opposite directions through membrane
Primary Active Transport
*Sodium-potassium pump (Na+ / K+) pump or(Na+ / K+) ATPase) – most vital for maintenance of Na+and K+concentration gradient homeostasis
*Na+concentration is ten times greater in ECF than cytosol; K+ concentration is ten times greater in cytosol than ECF
*Pump maintains steep concentration gradients by transporting 3Na+out and 2K+ into cell(against concentration gradients) for every ATP molecule hydrolyzed