Cell Transport
What type of molecules is the membrane impermeableto?
Large, charged, or polar molecules have to fit through a channel protein or be endocytosed/exocytosed (ex: proteins, amino acids, glucose)
What does hypotonicmean?
Low solute concentration
Describe the hydrophilic and hydrophobic parts of the cell membrane
The heads of both layers point outward to be near the water (they're hydrophilic) outside of the cell and inside of the cell. The tails of both layers are tucked inside the two layers of heads because they're hydrophobic
What is facilitated diffusion?
The movement of large or polar or charged molecules from an area of high concentration to low concentration (i.e. down the concentration gradient) through a protein channel without the use of energy to reach a state of equilibrium
What's active transport?
The movement of molecules from an area of low concentration to high concentration (i.e. against the concentration gradient) that requires an input of energy
How does a cell membrane pump work?
Actively transports molecules against their concentration gradient using a channel protein
What is a concentration gradient?
A difference in concentration on either side of a membrane
What molecule do cells use as cellular energy?
ATP
What types of organisms are made up of prokaryotic cells?
Bacteria
How are endocytosis and exocytosis similar?
Both: require ATP, require vesicles, are moving molecules across the cell membrane
What are the similaritiesbetween phagocytosis and pinocytosis?
Both: types of endocytosis, move molecules across a membrane by engulfing them into a vesicle, require the use of ATP
What are the three types of active transport?
Cell membrane pumps, endocytosis, exocytosis
What are the four things found in all cells?
Cell membrane, cytoplasm, ribosomes, DNA
What's the function of the mitochondria?
Cell respiration converts glucose into energy in the form
What three organelles do plant cells have that animal cells don'thave?
Cell wall, chloroplasts, large central vacuole
What's the one organelle that animal cells have but plant cells don'thave?
Centrioles
What's the name of the liquidthat includes all the organelles and the cytosol?
Cytoplasm (all organelles + cytosol EXCEPT nucleus)
How are endocytosis and exocytosis different?
Endocytosis molecules are entering the cell Exocytosis molecules are leaving the cell
What does isotonic mean?
Equal solute concentrations
List at least three differencesbetween prokaryotic and eukaryotic cells.
Eukaryotic cells larger; DNA stored in nucleus; contain more organelles Prokaryotic cells smaller; DNA is freefloating in cytoplasm; contain very few organelles
How is facilitated diffusion differentfrom simple diffusion?
Facilitated diffusion requires the use of a protein channel (which is an integral protein) while simple diffusion can take place directly between the phospholipids of the bilayer
Why is the membrane considered a fluidmosaic model?
Fluid the parts are moving around (i.e. not stuck in one place) Mosaic the cell membrane is made of many parts (phospholipids, cholesterol, carbohydrates, and proteins)
What does hypertonic mean?
High solute concentration
A single celled paramecium (animal) is moved from its normal freshwater habitat to salt water.
If the single celled paramecium normally lives in freshwater, it must be isotonic to the freshwater. Moving it to the salt water would cause it to now be in a hypertonic environment, causing water to leave the cell and enter the solution until the concentration of solute is equal on both sides. The paramecium will shrivel.
What are the two types of membrane proteins called? Explain each.
Integral proteins go all the way through the membrane (ex: channel proteins) Peripheral sit on one side of the membrane or the other (ex: receptors)
What type of a solution surrounds animal cells? Why?
Isotonic solution to prevent water from entering the cell (if the solution was hypotonic) or leaving the cell (if the solution was hypertonic)
Why is the cell membrane considered selectively permeable?
It lets some molecules pass through but prevents others from passing through
What's homeostasis?
Maintaining a stable internal body condition (ex: stable temperature, blood glucose level, etc) despite changes
What's the function of the ribosomes?
Make proteins
What does it mean when something has reached a state of equilibrium?
Molecules are moving back and forth across a membrane, but there is no net movement (i.e. the concentration of molecules remains the same on both sides of the membrane)
What is endocytosis?
Molecules enter into the cell by being engulfed by the cell membrane and put into a vesicle
What is the cell membrane made out of?
Mostly phospholipids with proteins, carbohydrates, and cholesterol embedded within the phospholipid bilayer
What is osmosis?
Movement of water from an area of high water to low water (aka The movement of water from an area of high solute to low solute) without the use of energy
What unicellular organismundergoes phagocytosis? Why does this occur?
Paramecium used to engulf its food
What are the two types of endocytosis?
Phagocytosis and pinocytosis
What is the differencebetween phagocytosis and pinocytosis?
Phagocytosis engulfing of large food molecules or whole cells Pinocytosis engulfing of solute dissolved in liquid
What's the function of the chloroplast?
Photosynthesis converts sunlight energy into glucose
What are the three types of passive transport?
Simple diffusion, osmosis, facilitated diffusion
What types of organisms are made up of eukaryotic cells?
Plants, animals, fungi, protists
What is exocytosis?
Process of putting something that needs to be exported into a vesicle and letting it fuse with the inner part of the cell membrane causes the contents of the vesicle to be dumped outside the cell; could be proteins or waste that's being exocytosed
What's the function of the cell wall?
Protects the cell, provides structure and rigidity
What's the job of the sodium potassium pump?
Pumps sodium and potassium across the cell membrane against each of their concentration gradients using a channel protein
What type of molecules is the membrane permeableto?
Small, noncharged, nonpolar molecules can fit directly between phospholipids (ex: CO2 and O2
What is one example of a cell membrane pump?
Sodium potassium pump
What's the function of the nucleus?
Store and protect the DNA; tells the cell what to do (i.e. acts as the command center)
Listand explainthe five factors that affect the rate of diffusion.
Temperature - increasing temperature causes diffusion to occur more quickly because as the temperature increases, molecules move around more quickly, causing diffusion to occur more quickly Concentration gradient - the steeper the concentration gradient (i.e. the bigger the difference between the concentration on either side of the membrane), the more quickly diffusion will take place Size - small molecules can diffuse directly through the phospholipids (assuming they're also noncharged and nonpolar), so diffusion occurs more quickly than when large molecules have to wait to go through a channel protein Charge - noncharged molecules can diffuse directly through the phospholipids (assuming they're also small and nonpolar), so diffusion occurs more quickly than when large molecules have to wait to go through a channel protein Surface area of cell - increasing the surface area (without increasing the volume) increases the rate of diffusion because there are more locations along the membrane where diffusion can take place
What are the three parts to the cell theory?
The cell is the basic unit of structure and function; all cells come from preexisting cells; all living things are made out of cells
What's passive transport? Does it require energy?
The net movement of molecules from an area of high concentration to low concentration (i.e. down their concentration gradient) to reach a state of equilibrium without the use of energy (NOTE: molecules always are moving in both directions across a cell membrane; during passive transport, there is a net (i.e. overall) movement of molecules in one direction; once equilibrium has been met, molecules still move across the membrane but equally in both directions)
What is diffusion?
The net movement of molecules from an area of high concentration to low concentration directly across the phospholipid bilayer (NOTE: molecules always are moving in both directions across a cell membrane; during passive transport, there is a net (i.e. overall) movement of molecules in one direction; once equilibrium has been met, molecules still move across the membrane but equally in both directions)
A plant cell, containing an 8% solute concentration, is placed in a solution containing 2% solute.
The plant cell is hypertonic to the solution so water will enter the cell until the concentration of solute is equal on both sides. Turgor pressure will increase inside the plant cell, but the cell will not burst because of the strong cell wall.
An animal cell, containing a 5% solute concentration, is placed in a solution containing 10% solute.
The solution is hypertonic to the cell so water will leave the cell and enter the solution until the concentration of solute is equal on both sides. The animal cell will shrivel.
At equilibrium, is there a net movementof molecules? Are molecules still moving? Explain.
There is no net movement, but molecules are still moving they move back and forth in equal amounts
How is facilitated diffusion similarto simple diffusion?
They are both types of passive transport moving molecules from an area of high concentration to low concentration (i.e. down the concentration gradient) without the use of energy to reach a state of equilibrium
What is plasmolysisand when does it take place? What types of cells (plant, animal, or both) undergo plasmolysis?
When a plant cell is placed in a hypertonic solution, water will leave the cell. The decrease in water within the cell causes the cell membrane to pull away from the cell wall and the pressure against the inside of the cell wall to decrease. This is called plasmolysis.
What is turgor pressureand when does it take place? What types of cells (plant, animal, or both) undergo turgor pressure?
When a plant cell is placed in a hypotonic solution, water will enter the cell. The increased pressure pushing out on the inside of the cell wall is called turgor pressure.
What happens when an animal cell loses water?
When an animal cell is placed in a hypertonic solution, water will leave the cell, causing the cell to shrivel
What is cytolysisand when does it take place? What types of cells (plant, animal, or both) undergo cytolysis?
When an animal cell is placed in a hypotonic solution, water will enter the cell, which could cause the cell to burst (which is called cytolysis)
What types of cells in our bodiesundergo phagocytosis? What are they engulfing?
White blood cells phagocytose bacteria cells and other foreign invaders
Does active transport require energy?
Yes