Test Two Module 4 Flashcards
What is a glycoprotein?
A protein with a carbohydrate (sugar) group covalently attacked to it
What is a glycolipid?
A lipid with a carbohydrate attached covalently
The cells that make up living things are basically?
Organized collections of molecules
Individual molecules are combined to form?
Complexes
Molecular complexes can be combined to form?
Structures
Structures are combined to form?
Intact cells
How do you order cells, molecules, structures, and complexes, into order from INCREASING size?
Molecules, complexes, structures, cells
What are the 5 tenets of cell theory?
- Cells are the smallest units of life that perform all vital physiological functions characteristics of life.
- Cells are the building blocks of all multicellular living things.
- All the cells from the division of preexisting cells.
- All cells are built from the same molecular components and all have essentially the same chemical and molecular composition.
- Each cell maintains homeostasis at the cellular level.
Both the exterior and exterior of cells are ____ ?
Aqueous (watery)
Cells in tissues are surrounded on the exterior by a watery medium known as the ____?
Extracellular fluid or interstitial fluid
What is the interior of cells?
A watery medium known collectively as the cytoplasm
What is the cytoplasm?
Everything inside a cell, except the nucleus.
What is the cytosol?
Everything in cytoplasm except the nucleus and all other organelles (cytosol includes all dissolved smaller molecules.)
What is an organelle?
Large macromolecular structures visible in electron micrographs.
What is the plasma membrane?
The membrane that separates the inside and the outside of the cell. It is the cell membrane on the outside of the cells.
The membrane surrounding the cells is always called the ____, even in plant and fungi and single celled organisms, which don’t have blood or plasma?
plasma membrane
The plasma membrane is made of two main components:
- Membrane lipids
2. proteins
What are membrane lipids?
They group together to form a barrier that separates the inside from the outside of the cell (also known as lipid bilayer, because it is always two lipid thick)
What is a glycoprotein?
A protein with a carbohydrate (sugar) group covalently attached to it
Membrane proteins typically make up __% of the molecules in a membrane?
50%
In the membrane, membrane proteins perform function such as: (3)
- Transporting molecules across the membrane
- Anchoring one cell to another
- Acting as receptors for hormones and other signals
Often in the membrane, the proteins are in the form of?
Glycoproteins
What is the difference between cytoplasm and cytosol?
Cytosol is cytoplasm without orgnaelles.
The overall shape of the cell is maintain by its _______?
Cytoskelton
What is the cytoskeleton?
A network of cytoplasmic protein fibers and tubules that provide support and structure for the cell and transport routes for the cell’s contents.
What are “molecular motors”?
Proteins that move down the tracks while carrying cellular material
Some components of the cytoskeleton act as “tracks” for what?
The movement of large structures around the cell
Some of the cytoskeleton protein fibers provide structure to?
Give the cell its shape
when a cells changes shape, it is because?
The cytoskeleton protein fibers are re-arranged
In addition to creating the shape of the cell, what other function can protein fibers serve?
They can act as tracks for the molecular motors that deliver material around the cell.
Organelles are:
Any large structures that perform a function for that cell
Are all organelle’s bound to their own membrane’s?
many, but not all are bound to their own membranes, which serve to create enclosed chambers to carry out their functions
_____ are the site where protein synthesis takes?
Ribosomes
______ are found floating free in cytoplasm and attached to endoplasmic reticulum?
Ribosomes
_____ are huge complexes of proteins and RNA’s (no membrane)
Ribosomes
Ribosomes are: (3)
- Sites where protein synthesis takes place.
- Are found floating free in cytoplasm and attached to endoplasmic reticulum.
- Are huge complexes of proteins and RNAs (no membrane).
____ are sites where protein degradation/elimination takes place
Proteosomes
____ are huge complexes of proteins (no membrane)
Proteosomes
Proteosomes are: (2)
- Sites where protein degradation/elimination takes place.
- Are huge complexes of proteins (no membrane).
_____ are sites where most of the energy currency molecules used in the cell (ATP) are generated by breaking down food molecules
Mitochondria
_____ consists of two membranes- its outer is smooth and the inner membrane has many folds
Mitochondria
Mitochondria: (2)
- Sites where most of the energy-currency molecules used the cell (ATP) are generated by breaking down food molecules.
- Consist of two membranes – its outer membrane is smooth and its inner membrane has many folds.
_____ consists of a network of folded membranes, creating chambers and channels
Endoplasmic Reticulum (ER)
_____ Subdivided into two types- rough ER and smooth ER
Endoplasmic Reticulum (ER)
Endoplasmi Reticulum: (2)
- Consists of a network of folded membranes, creating chambers and channels.
- Subdivided into two types – rough ER and smooth ER.
_____ is where proteins to be sent outside of cell are synthesised
Rough ER
_____ is where new membrane lipids are synthesized and Ca2+ ions are stored
Smooth ER
What are the dots on the rough ER that make it appear “rough”?
The ribosomes doing the synthesis
Why is the smooth ER considered smooth?
The lack of ribosomes
What happens in the smooth endoplasmic reticulum?
New lipids are synthesized and calcium ions are stored.
_____ consists of a stack of flattened, folded membranes, which create various unconnected chambers?
Golgi apparatus or Golgi body
_____ is where non-cytosolic proteins are packaged for delivery to their destination (to organelles, or for insertion into the plasma membrane, or for export out of the cell, etc.)
Golgi apparatus or Golgi body
Golgi body/Golgi Apparatus:
- Consists of a stack of flattened, folded membranes, which create various unconnected chambers
- Where non-cytosolic proteins are packaged for delivery to their destination (to organelles, or for insertion into the plasma membrane, or for export out of the cell, etc.)
_____ are membrane bound sacs containing degradative enzymes?
Lysosomes
_____ is where materials are sent for dismantling and degradation when they unwanted molecules, damaged organelles, or invading pathogens
Lysosomes
Lysosomes: (2)
- Are membrane-bound sacs containing degradative enzymes.
- Where materials are sent for dismantling & degradation when they unwanted molecules, damaged organelles, or invading pathogens.
_____ consists of two membranes (called the nuclear envelope) with large protein complexes that serve as nuclear pores to allow material in and out
Nucleus
_____ is where DNA, the genetic material is stored and maintained?
Nucleus
Nucleus: (2)
- Consists of two membranes (called the nuclear envelope) with large protein complexes that serve as nuclear pores to allow material in and out.
- Where DNA, the genetic material, is stored and maintained.
_____ are membrane bound extensions of the cells exterior plasma membrane?
Cilia
____ contain protein fibers that move, thus moving each cilium with them?
Cilia
_____ on a single cell move materials along the cell’s surface?
Cilia
Cilia: (3)
- Are membrane-bound extensions of the cell’s exterior plasma membrane.
- They contain protein fibers that move, thus moving each cilium with them.
- Cilia on a single cell move in unison and can move materials along the cell’s surface.
_____ are short membrane bound extensions of the cells exterior plasma membrane?
Microvilli
_____ contain immobile protein filaments that maintain their structure?
Microvilli
_____ serve to increase surface area on cells so more materials can be absorbed at the same time?
Microvilli
Microvilli: (3)
- Are short membrane-bound extensions of the cell’s exterior plasma membrane.
- They contain immobile protein filaments that maintain their structure.
- They serve to increase surface area on cells so more materials can be absorbed at the same time.
What is diffusion?
The spontaneous spread of a substance from areas of high concentration to areas of low concentration
When molecules are left on their own they do what?
they move randomly
In areas of high concentration, where there are a lot of molecules, what do the molecules do?
The molecules bump into each other more frequently, bumping them into less crowded areas. Which causes the substance to spread out until all the molecules have evenly spread out over the space available
What are the molecules always doing?
Moving
Diffusion is said to cause molecules to spontaneously do what?
Move down their concentration gradient
The direction of spontaneous movement is always?
down the concentration gradient
Diffusion continues until?
A substance is evenly spread out
During diffusion, once there is no more concentration gradient there is no more?
net movement. Individual molecules continue to move randomly, but random movements of some molecule in one direction are balanced by random movements of another molecule in the opposite direction – and the whole stays evenly spread out.
Diffusion down the concentration gradient is always _____ ; but various factors can effect how rapidly it occurs
Spontaneous
Higher temperature can cause diffusion to?
Diffuse faster
Larger surface can cause diffusion to?
Diffuse faster
Higher gradient can cause diffusion to?
Diffuse faster
Smaller particles can cause diffusion to?
Diffuse faster
A solid will diffuse the?
slowest
A liquid will diffuse?
faster
A gas will diffuse the?
fastest
osmosis is simply the?
diffusion of water
Diffusion of water (osmosis) is only notable when there is?
a barrier or membrane between two volumes of water.
All cells membranes (plasma membrane, mitochondrial membrane, nuclear envelope, etc) are _____?
selectively permeable
What is a selectively permeable membrane?
A membrane across which some molecules can across, but others cannot.
_____ is one of the molecules that can always freely cross all cell membranes, of every cell type and every organelles type, so osmosis is always a consideration with cells
Water
Osmosis/diffusion of water occurs _____ down the concentration gradient of water.
Spontaneously
In which direction does osmosis ALWAYS occur?
Down the water concentration gradient.
______ will have the highest concentration of water – the water molecules will fill all the available space
Pure water
If there are any _____ in the water, they will take up space, so fewer water molecules will be present, and the water concentration will be lower than pure water
dissolved substances
Any time you have different concentrations of a dissolved material across a cell membrane: (2)
- The side with the higher concentration of dissolved material will have the dissolved material diffuse out of that side if it can.
- The side with the higher concentration of dissolved material will have water diffuse into that side if it can
Cell membranes are selectively permeable, so there will be situations where there is a solute at different concentrations across a membrane that is?
- not allowed across the membrane – only water will be able to diffuse across.
- This can cause the side with the higher solute concentration/lower water concentration to increase in volume! (And the other side to decrease.)
- The movement of water that changes the volumes of both sides of the membrane can be prevented if a force is applied to the growing side.
- This will force the water molecules back through the membrane, against their concentration gradient.
- Note, forcing water back through the membrane is not spontaneous. It required a force.
What is osmotic pressure/osmotic potential?
The force of a concentration gradient of water that equals the force (hydrostatic pressure) needed to block osmosis across a selectively permeable membrane.
What is the concept of using pressure to force water to move against its concentration gradient, enough to undo whatever diffusion of water would otherwise have happened spontaneously?
Osmotic pressure or osmotic potential
The _____ the osmotic pressure/potential of a solution, the more likely water will diffuse into that solution
Greater
Another term for osmotic pressure/osmotic potential?
Tonicity
The greater the osmotic pressure the _____ the tonicity?
higher
We just use ____ as a comparison for comparing a solution on one side of a membrane to the solution on the other side of the membrane.
Tonicity
Usually, we use tonicity to compare?
compare the solution outside of a cell to the cytoplasm inside a cell.
What is the relationship between osmotic pressure and tonicity?
The higher the osmotic pressure, the higher the tonicity
What is a isotonic solution?
A solution that does not cause osmotic flow of water across the membrane. (same)
When the solution outside the cell is isotonic: (3)
- Solutes in the solution outside the cell are at equal concentration as solutes in cytoplasm inside cell (so there are equal water concentrations both inside and outside cell).
- The solution around the cell causes water to neither enter nor leave the cell.
- As a result, the cell neither shrinks nor expands in an isotonic solution.
What is a hypotonic solution?
A solution outside of a cell or container that causes osmotic flow of water across a membrane out of the hypotonic solution (into the cell/container).
When the solution outside the cell is hypotonic: (3)
- The solution outside the cell has less solutes (more water) than the cytoplasm inside cell.
- The solution outside the cell causes water to enter the cell.
- As a result, the cell expands in a hypotonic solution.
What is a hypertonic solution?
A solution outside of a cell or container that causes osmotic flow of water across a membrane into the hypertonic solution (out of the cell/container).
When the solution outside the cell is hypertonic:
- The solution outside the cell has more solutes (less water) than cytoplasm inside cell.
- Solution outside the cell causes water to leave the cell.
- As a result, the cell contracts in a hypertonic solution.
To maintain homeostasis, a cell needs to: (2)
- Allow certain compounds in and other compounds out.
- And the cell needs to regulate when these molecular movements in and out occur.
Membrane lipids act as _____ to most molecules, but not all.
barriers
Non-hydrophobic molecules cannot cross the barrier made by _____?
Membrane lipids
Channels: (2)
- Membrane proteins that provide little more than a tunnel through which molecules can diffuse.
- Transport is always passive, which means the molecules always travel down the molecule’s concentration gradient.
What happens in passive transport?
Molecules always move down the concentration gradient
Gated Channels: (4)
- Membrane proteins that provide little more than a tunnel through which molecules can diffuse, but the tunnel has a barrier or gate that can be opened or closed.
- The cell can regulate when the barrier or gate is open or shut .
- When barrier/gate is open, transport is always passive, down the molecule’s concentration gradient.
- When barrier/gate is closed, nothing is transported through it.
Pumps: (2)
- Membrane proteins that use up energy in the form of ATP (the energy currency of the cell) to move a molecule in the direction it would not diffuse spontaneously
- Transport by pumps is always active, up the molecule’s concentration gradient
What happens in active transport?
Any movement of molecules across a cell membrane that is only ever against (up) a concentration gradient
carrier proteins: (3)
- Membrane proteins that bind a specific molecule on one side of a membrane and release it on the other side
- Transport by carriers can be passive, and only move molecules down their concentration gradients; it depends on the specific carrier
- Transport by carriers can also be active, and always move molecules against their concentration gradient; it depends on the specific carrier
Membrane transporter proteins that are always passive transport?
Channels (even gated channels)
Membrane transporter proteins that are always active transport?
Pumps
Membrane transporter proteins that can be active transport or passive transport?
Carrier proteins
A cell membrane is _____ because its membrane proteins select which molecules can cross the membrane under what circumstances.
selectively permeable
A _____ usually allows only one molecule in its tunnel like center.
specific transporter protein
The _____ channel only lets water across, no other molecules.
aquaporin
