Unit 2 Test Flashcards
Which is bigger, a bacterium or a virus?
Bacterium is 100x larger
Which is bigger, an animal cell or bacterium?
An animal cell is 10x larger
How does a transmission electron microscope work?
By sending electrons through a specimen and getting a cross-sectional image of the inside
How does a scanning electron microscope work?
By beaming electrons off of the surface of a specimen to get a 3-D image
How do prokaryotic cells differ from eukaryotic cells
Instead of a nucleus, prokaryotes have a nucleiod, which is an area where the DNA is found. Also, the DNA is round, and prokaryotes have a capsule.
What are the non-membranous organelles?
Cytoskeleton, microvilli, centrioles, cilia, ribosomes, and proteasomes.
What are the membranous organelles?
The nucleus, ER, golgi, lysosomes, peroxisomes, nucleus, and mitochondria.
What are the two types of cilium and what are their purposes?
The primary cilium senses movement, and the motile cilium helps the cell to move.
What are the three proteins found in the cytoskeleton?
Microtubules, intermediate filaments, and microfilaments.
What are proteasomes for?
They contain enzymes called proteases which disassemble and recycle bad proteins.
What is the largest organelle?
The nucleus.
What is chromatin?
Loosely bundled DNA
What is the nucleoplasm?
The inside of the nucleus containing ions, enzymes, nucleotides, and RNA.
What is the ER for?
Protein, carb, and lipid synthesis, storage, transport, and detoxification.
What’s a key difference between the smooth ER and rough ER?
The smooth ER has no ribosomes embedded in it.
What is the Golgi Body for?
The transport of proteins through vesicles.
What are the two “sides” of the Golgi body?
The cis side, which faces the nucleus, and the trans side, which faces away.
What are lysosomes for?
Breaking down substances within a cell?
What are the three “types” of lysosomes and what do they do?
The primary lysosomes are inactive, the secondary lysosomes fuse with different organelles to kill them and are active, and the autolysis lysosomes kill the entire cell.
What are Peroxisomes and what do they do?
They are vesicles containing enzymes which catalyze the production of H2O and O2.
What is epithelial tissue?
Tissue connecting organelles and cells.
What are the three main types of epithelial tissue?
Tight junctions, gap junctions, and demosomes.
What are tight junctions?
A type of epithelial tissue connecting two plasma membranes, preventing the passage of water or other solutes.
What are gap junctions?
A type of epithelial tissue holding two tissues together with channel proteins, allowing rapid communication and ion passage.
What are desmosomes?
A type of epithelial tissue tying two cells together, allowing for twisting and bending (found primarily in epithelial cells).
What are different ways that a cell might move?
With motile cilia, flagellum, phili, or cytoskeletal movement.
How does flagellum differ in bacteria versus eukaryotes?
In bacteria, it works like a rotor and is powered by a proton gradient, whereas in eukaryotes, it works like a whip and is powered by ATP.
What are the two dependent contractions that result in cytoskeletal movement?
Actin and myosin.
What is a microfilament and what is it made of?
A microfilament is two actin filaments wrapped around each other.
What is a microtubule and what is it made of?
One coiled strand of tubulin with a hollow center.
What are some characteristics of a microtubule?
25 nm diameter, maintains shape by resisting compression, moves chromosomes in replication, acts as a “track” for organelle movement.
What are kenesin and dynein?
Two proteins found along the “track” of a microtubule. Kenesin brings organelles to the “+” end, dynein brings organelles to the “-“ end.
Where can microtubules be found?
In the flagellum and cilia.
What does dynamic instability mean?
The constant polymerization and depolymerization of a polymer.
In a microtubule, what is the difference between the “+” and “-“ ends?
The “+” end is where all polymerization and depolymerization takes place, whereas the “-“ end experiences no change.
What are some characteristics of microfilaments?
7-8 nm, resists tension and shearing, helps cells split during mitosis, involved in muscle contraction, conducts cytoplasmic streaming
What are microfilaments made from?
G-actin and F-actin (which is basically just bundled up G-actin)
What is cytoplasmic streaming?
The movement of organelles in a plant cell.
Where are microfilaments found?
Around the perimeter of a cell, and in the microvilli of the small intestine.
What are microvilli?
Tiny projections off of a cell that increase surface area.
What is the difference between the “+” and “-“ ends of a microfilament?
The “+” end faces the cell membrane and polymerizes, while the “-“ side faces away from the membrane and depolymerizes.
How do microfilaments effect cell movement?
When myosin within the microfilaments contracts, it propels the cytoplasm forwards.
What are the characteristics of an intermediate filament?
Made from many proteins, 8-12 nm, permanent structure, keeps organelles in place, bonds cells to each other.
What is pressure potential?
The pressure exerted inside of a cell due to water movement.
When a cell has less water in it than its surroundings, the pressure potential within the cell will be _____.
Low
What is osmotic/solute potential?
The potential of water molecules to move from a high water concentration to a low water concentration.
What is the osmotic/solute potential of water?
0.
If there is a higher concentration of solute within a cell than its surroundings, then the osmotic/solute potential will be _____.
High
Water moves from a ______ concentration of solute to a ______ concentration of solute.
low; high
What is water potential?
The ability of water to move from one concentration to another.
Water moves from a ______ water potential to a ______ water potential.
high; low
What are colligative properties?
Properties of a solution that depend on the solute concentration and nature of a solute, but not on the nature of a solvent.
What’s the difference between permeable, impermeable, and semi-permeable membranes?
Permeable membranes allow substances to pass through, impermeable membranes don’t allow substances to pass through, and semi-permeable membranes allow some substances to pass through.
What does the equation (dQ(s))/(dt)=P*(C(2)-C(1)) represent?
The permeability of a membrane.
I don’t think this is super important, but it might be good for you to recognize the equation
What is osmotic pressure?
The force that needs to be applied to a membrane in order to stop osmosis from occurring.
Osmotic pressure is _____ where there is less solute.
lower
Water flows from a _____ osmotic pressure to a _____ osmotic pressure.
low; high
What is osmolarity/osmotic concentration?
The amount of osmoles per liter of solution.
What are osmoles?
The number of moles multiplied by the amount of ionized molecules (NaCl separates into two ions, so you would multiply by two)
What is tonicity/ effective osmosis?
The measure of osmotic pressure when considering the solute that was not able to pass through the membrane.
What is the difference between osmosis and diffusion?
Osmosis is the movement of water across a membrane, while diffusion can be any solute.
What is lyse?
When a cell explodes 💥
Which cell type can’t experience lyse, and why?
Plant cells will not lyse because their cell walls keep them from bursting.
What is the shrinking of a cell called?
In animal cells, it’s called crenation, and in plant cells it’s called plasmolysis.
What is the ideal type of solution for plant cells?
Hypotonic, since water rushing into the cell will not cause it to burst.
What is the ideal type of solution for animal cells?
Isotonic, since too much or too little water going into the cell could cause lyse of crenation.
What does hypertonic mean?
A hypertonic solution is one with a high amount of solute compared to its surroundings.
What does hypotonic mean?
A hypotonic solution is one that has a low amount of solute compared to its surroundings.
What materials make up the cell membrane?
Phospholipids, proteins, cholesterol, carbohydrates, glycolipids (a sugar attached to a lipid), glycoproteins (a sugar attached to a protein), and proteoglycans (a long sugar attached to a protein).
What is the most abundant type of lipid in a cell membrane?
Phospholipids!
Why do we say that a cell membrane is “fluid”?
Because phospholipids and proteins can move laterally across the membrane.
What happens to a cell membrane when the temperature lowers?
The membrane becomes less fluid.
How does the saturation of phospholipids affect fluidity?
If phospholipids are more saturated, the membrane will be less fluid.
Is cholesterol hydrophilic, hydrophobic, or both?
Both! It’s amphiphatic, meaning it has both hydrophilic and hydrophobic ends.
What is cholesterol’s purpose within the membrane?
Connecting phospholipids and regulating the fluidity of the membrane.
How does the length of the tails of a membrane’s phospholipids affect its fluidity?
When the tails are longer, the membrane becomes less fluid.
Why is fluidity important in a membrane?
It allows for the passage of substances through the membrane, lets proteins move from the site of insertion to where they are needed, makes it possible for vesicles to pinch off, and allows for cell division.
Why is it important for a membrane to be a “mosaic”?
It allows for passage of polar, charged, or large substances, cells to signal one another, and for cell-to-cell recognition.
What are the two main carbohydrates found in a membrane?
Glycolysis are attached to lipids, and proteoglycans are longer sugars attached to a protein.
What is the glycocalyx?
The outermost layer of carbohydrates.
What types of substances can pass through a cell membrane?
Small, non polar, non charged solute so, like CO2 and O2.
What types of substances cannot pass through a cell membrane?
Large, charged, or polar molecules, like H2O, macromolecules, ions, and glucose.
Do all molecules immediately diffuse down their concentration gradient?
No, molecular movement is for the most part random.
Do all molecules stop moving once they reach the other side of the membrane?
No, they are constantly moving in dynamic equilibrium.
What is facilitated diffusion?
The process of proteins moving ions, polar molecules, charged molecules, or large substances through the cell membrane.
What are the two main types of proteins used in facilitated diffusion?
Channel proteins and carrier proteins.
Are channel proteins active or passive?
Passive.
Are carrier proteins active or passive?
Active.
What is the difference between active and passive transport?
Active transport requires an energy input, while passive doesn’t.
How do channel proteins “decide” which substances to bring through the membrane?
Based on size and charge.
How do carrier proteins “decide” which substances to bring across the cell membrane?
Based on shape.
What is an electrochemical gradient?
A combination of gradient due to charge and gradient due to chemical concentration.
Are our cells negatively charged or positively charged? Why? How is this important?
Our cells our negative since many of our proteins carry negative charges. This allows us to send electrical signals.
What are the two types of active transport?
Primary and secondary.
How is primary active transport powered?
With the direct use and hydrolysis of ATP.
How is secondary active transport powered?
With the indirect use of ATP and the energy from a different concentration gradient to pump a solute against its own gradient (one substance moves with its gradient, the other moves against)
What are the two types of pumps?
ATP pumps and light pumps, which are found in some bacteria and use light for energy.
What are the two types of secondary active transport?
Uniport, which pumps only one solute, and coupled transport, which pumps two.
What is symport?
A type of coupled transport where one solute moves with its gradient and the other against, but both travel in the same direction.
What is antiport?
A type of coupled transport where one solute moves with its gradient and the other moves against it, but they travel in opposite directions.
What is bulk transport?
The movement of larger substances across the cell membrane in vesicles.
What is exocytosis?
The release of materials from the cell.
What is endocytosis?
When materials are taken into a cell from a vesicle.
What are the two types of endocytosis?
Phagocytosis and pinocytosis.
What is phagocytosis?
“Cellular eating”, where a cell takes in large substances like bacteria.
What is pinocytosis?
“Cellular drinking”, where a cell takes in fluids.
What is receptor mediated endocytosis?
When a cell has receptors for the vesicle it’s taking in (ex: cholesterol in an LDL vesicle)
What are the destinations for a substance that has undergone endocytosis?
A lysosomes, part of the cell membrane, or the Golgi apparatus.
Good luck!!! You’re going to do great!
I know!
