Chapter 3 Flashcards
Parts of a cell?
- Plasma membrane
- Cytoplasm
- Nucleus
Plasma membrane
Separates internal environment from external environment
Cytoplasm components
- Cytosal
- Organelles
What is in the nucleus?
chromosome which contains thousands of genes
What’s the lipid bilayer made of?
(75%) Phospholipids, (20%)cholesterol, (5%)glycolipids
What are amphipathic molecules?
They have both polar and non polar parts. Hydrophilic head is polar. Hydrophobic tail is non polar.
Integral proteins
Firmly embedded in lipid bilayer, and transmembrane protein (spans entire lipid bilayer)
Peripheral proteins
Attached to polar heads or integral proteins. Many are glycoproteins they have carbohydrate groups attached to the ends that protrude into the extracellular fluid.
Glycocalyx
The portion of carbohydrate glycolipifs and glycoproteins that form an extensive sugary coat
Membranes function?
- Ion channels
- Carriers
- Receptors
- Enzymes
- Linkers
- Cell-identity markers
The lipid bilayer is highly permeable to what molecules?
Oxygen, carbon dioxide, and steroids
The lipid bilayer is moderately permeable to what?
Small, uncharged polar molecules like water and urea
What is the lipid bilayer impermeable too?
Ions and large molecules such as glucose
What do transmembrane proteins do?
Act as channels and carriers increasing the plasma membranes permeability to a variety of ions and uncharged polar molecules
What part of the plasma membrane is more positively charged and what’s negatively charged?
Inner surface is more negatively charged where as outer surface is more positively charged
Electrochemical gradient
Combined influence of the concentration gradient and the electrical gradient on movement of a particular ion
What are the two types of transport
Passive and active
Diffusion
Passive transport
Both the solutes, and solvent undergo diffusion
Factors that influence the diffusion rate?
- Steepness in concentration gradient
- Temperature - higher temp equals faster diffusion
- Mass of the diffusing substance- larger mass = slower diffusion rate
- Surface area- more surface = faster diffusion
- Diffusion distance- more distance something needs to diffuse over the longer it takes
Simple diffusion
Passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport proteins
Important in the movement of oxygen and carbon dioxide between blood and body cells, and between blood and air within the lungs during breathing
Different types of facilitated diffusion?
Channel-mediated facilitated diffusion
Carrier-mediated facilitated diffusion
Channel-mediated facilitated diffusion
A solute moves down its concentration gradient across the lipid bilayer through a membrane channel usually ion. Ions can only diffuse at particular sites. Most channels are for potassium ions and chloride ions few being for sodium ions and calcium ions
When is a channel said to be gated?
Part of the channel protein acts as a “plug” or “gate”, changing shape in one way to open the pore and in another way to close it
Carrier-mediated facilitated diffusion
A carrier moves a solute down its concentration gradient across the plasma membrane
There is a transport maximum on how much can be moved at once
Used by glucose the body’s preferred energy source
What effect does insulin have on facilitated diffusion?
Increases the transport maximum
Osmosis
Water moves through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration
What are the two ways water molecules move through plasma membrane via osmosis?
- Simple diffusion
- Aquaporins
What are aquaporins?
(AQPs) integral membrane proteins that function as water channels. They play a critical role in controlling the water content of cells
Responsible for the production of cerebrospinal fluid, aqueous humor, tears, sweat, saliva, and the concentration of urine.
Osmotic pressure
The higher the solute concentration the higher the solutions osmotic pressure
Hemolysis
Rupture of red blood cells from hypotonic solution
Crenation
Shrinkage of cells do yo hypertonic solution
What are the two sources of cellular energy that drive active transport?
- Energy obtained from hydrolysis of adenosine triphosphate (ATP)
- Energy stored in an ionic concentration gradient is the source in secondary active transport
Primary active transport
Often called pumps
Most prevalent one being the sodium potassium pump
Secondary-active transport
A carrier protein simultaneously binds to Na+ and another substance and then changes it’s shape so that both substances cross the membrane at the same time
Symporters in secondary active transport
When the transporters move two substances in the same direction
Antiporters in secondary active transport
When two substances move in opposite directions across the membrane
Endocytosis and exocytosis have what in common?
Transport vesicles
What are the three types of endocytosis?
Receptor-mediated endocytosis, phagocytosis, bulk-phase endocytosis
What are the steps in receptor-mediated endocytosis?
- Binding
2.vesicle formation - Un coating
- Fusion with endosome
- Recycling of receptors to plasma membrane
- Degradation in lysosomes
Phagocytosis
“Cell eating” Faygo sites carry out phagocytosis two main types of Faygo sites are macrophages located in many body tissues and neutrophils a type of white blood cell
Bulk-phase endocytosis
“ cell drinking” Carried out by most body cells during bulk phase endocytosis the plasma membrane folds in word and forms of vesicle containing a droplet of extracellular fluid the vesicle pinches off from the plasma membrane and enters the cytosol
What types of cells is exocytosis especially important in?
- Secretory cells that liberate digestive enzymes hormones mucus or other secretions
- nerve cells that release substances called Nero transmitters