Unit Three Flashcards
Fluid-mosaic model, fluid
Double bonds in the fatty acid tails of phospholipid prevents tight packing
Cholesterol resists changes in membrane fluidity that is caused by temperature changes
Fluid mosaic model, mosaic
Refers to the position and various functions of proteins in the phospholipid bilayer
Phospholipids in the plasma membrane
Polar heads face out and nonpolar tails face in
Properties of the lipid bilayer make it permeable to certain substances
Nonpolar molecules can easily pass through the hydrophobic interior
Amphipathic molecules
Both hydrophilic and hydrophobic regions
Proteins of the plasma membrane
Integrins, receptor proteins, enzymatic proteins, glycoproteins, intercellular junction proteins, transport proteins
Integrins
Structure
Receptor proteins
Receive signals
Enzymatic proteins
Enzymes
Glycoproteins
Cell recognition, allows cell to recognize other cell by a sugar
Intercellular junction proteins
Connects one cell to another
Transport proteins
Transport
How do materials move in and out of the cell
Membranes are selectively permeable
Materials that can move easily between the phospholipids
Nonpolar, hydrophobic molecules
Tails hydrophobic as well, can move through because most of the membrane is hydrophobic
Some materials move through…
Which ones
Transport proteins
Polar molecules and ions
Molecules move across the plasma membrane by
Passive transport and active transport
Passive transport
Energy is not needed to move molecules across the membrane
Three types of passive transport
Diffusion
Facilitated diffusion
Osmosis (diffusion of water)
Diffusion
Molecules can move directly through the phospholipids of the plasma membrane
The net movement of molecules from a high concentration to a low concentration until equally distributed
Gases, water molecules, small, uncharged molecules, lipids (steroid hormones), and lipid soluble molecules (hydrocarbons, alcohols, some vitamins)
Why is diffusion important to cells and humans
Alveoli in the lungs
O2 that we breath in diffuses out of cell membranes of the alveoli, into our blood stream
CO2 waste diffuses through the epithelial cells of the blood vessels, to alveoli
Facilitated diffusion
Large, polar molecules cannot diffuse freely across the cell membrane
They need the help of transport proteins
Facilitated diffusion is the net movement of molecules from a high concentration to a low concentration with the aid of transport proteins
Ions, sugars (glucose), amino acids, water (faster rate) through aquaporins
How do molecules move through the plasma membrane by facilitated diffusion
Channel and carrier proteins are specific
Channel proteins allow ions, small so lutes, and water to pass
Carrier proteins move glucose and amino acids
Facilitated diffusion is rate limited, by the number of proteins channels/carriers present in the membrane
Why is facilitated diffusion important to cells and humans
Cells obtain food for cell respiration (glucose and amino acids)
Neurons communicate
Small intestine cells transport food to bloodstream
Muscle cells contract
Osmosis
Water molecules can move directly through the phospholipids of the plasma membrane
Osmosis is the movement of free water through a semipermeable membrane when solutes can’t move through
Called water potential: tendency of water to move through a membrane
Moves from high to low
Depends on partial pressure of water and solute potential
Movement of water
Water moves from side with greater water potential to lower water potential
Movement stops when partial pressure is equal on both sides
How does osmosis help plants
There is a higher solute concentration inside the plant cell
Water moves into the cell (vacuole)
When the partial pressure of water equals the partial pressure of solutes then it creates TURGOR PRESSURE
Why is osmosis important to cells and humans
The colon absorbs water back into the blood and other stuff that I don’t have in my notes but need to get when she posts the slideshow on classroom
Tonicity
Refers to the total solute concentration of the solution outside the cell
Isotonic, hypotonic, hypertonic
Isotonic
Solutions that have equal solute concentrations as the cells they surround
NEED OTHER PART THAT DONT HAVE IN NOTES YET
No net movement of water, will stay same size
Hypotonic
Solutions that have a lower solute concentration than the cells they surround
What will happen to a cell placed in a hypotonic solution
The cell will gain water and swell
If the cell bursts it’s called lysis
In plant cells with rigid cell walls, this creates turgor pressure
Hypertonic
Solutions that have a higher solute coned train than the cell it surround
What will happen to a cell placed in a hypertonic solution
The cell will lose water and shrink
In plant cells, the central vacuole will shrink and the plasma membrane will pull away from the cell wall
This shrinking is called plasmolysis
Phosphorylate
Introduce a phosphate group into (a molecule or compound)
Cholesterol
Resists changes in membrane fluidity that are caused by temperature changes
Glycolipids
Carbohydrate attached to a phospholipid in the cell membrane
Protozoans
A single-celled microscopic animal of a group of phyla of the kingdom Protista, such as an amoeba, flagella, ciliate, or sporozoan
Contractile vacuole
A membrane-enveloped cellular organelle, found in many microorganism so that periodically expands, filling with water, then contracts, expelling its contents to the cell exterior, thought to be important in maintaining hydrostatic equilibrium
Catalyze
To cause or accelerate a reaction by acting as a catalyst
Active transport
Molecules move from areas of low concentration to areas of high concentration with the aid of ATP energy
Requires transport proteins called Pumps
Against concentration gradient
Active transport
Brings in essential molecules; ions, amino acids, glucose, nucleotides
Maintains internal conditions different from the environment (life)
Vesicle with something attaches to and fuses with cell membrane, releases thing inside out the cell
Sodium potassium pump
Three sodium ions move out of the cell, two potassium ions move into the cell
Used to establish an electrochemical gradient across neuron cell membranes
Exocytosis
Active transport
Movement of large molecules bound in vesicles out of the cell with the aid of ATP energy
Proteins and polysaccharides, whole cells, hormones, mucus, neurotransmitters, waste
Endocytosis
Movement of large molecules into the cell by engulfing them in vesicles, using ATP energy
Phagocytosis, pinocytosis, receptor-mediated endocytosis
Channel proteins
Chanel for lipid insoluble molecules and ions to pass freely through
Ions, small solutes, and water
Carrier proteins
Bind to a substance and carry it across membrane, changing shape in process
Glucose and amino acids
Phagocytosis
Cell eating
Engulfing large molecules, whole cells, bacteria
Macrophages ingesting bacteria or worn out red blood cells
Unicellular organisms engulfing food particles
Pinocytosis
Cell drinking
Engulfing liquids and small molecules dissolved in liquids, unspecific what enters
Intestinal cells, kidney cells, plant root cells
Receptor-mediated endocytosis
NEED
Receptor-mediated endocytosis
Movement of very specific molecules into the cell with the use of vesicles coated with proteins
When specific molecules bind to the receptor proteins, then this stimulates the molecules to be engulfed in a coated vesicle
Ex. Uptake of cholesterol (LDL) by animal cells
