Onramps post lab quiz potato

isotonic plant cell

when a plant cell is immersed in a _______ solution; there is no net movement. The cell becomes flaccid and the plant may wilt.

hypertonic plant cell

plasmolyzed (shriveled)

hypotonic plant cell

when a plant cell is immersed in a __________ solution the cell contents swell due to osmosis until the elastic cell wall exerts turgor pressure on the cell that opposes further water outake.

What does an onion cell look like in 0.15 M NaCl & what type of solution is this

Scaly with ~3 dark spots, hypertonic

What does an onion cell look like in 0.5 M NaCl & what type of solution is this

Scaly with ~5-8 dark spots, isotonic

What does an onion cell look like in Pure Water & what type of solution is this

Scaly with many dark spots, ~15-25 dark spots, hypotonic

Pre-treatment mass, post-treatment mass, change is mass, percent change in mass, of potato in 1.0 M NaCl

5g, 4g, -1g, -20%

Pre-treatment mass, post-treatment mass, change is mass, percent change in mass, of potato in 0.8 M NaCl

4g, 3g, -1g, -25%

Pre-treatment mass, post-treatment mass, change is mass, percent change in mass, of potato in 0.6 M NaCl

6g, 4g, -2g, -33%

Pre-treatment mass, post-treatment mass, change is mass, percent change in mass, of potato in 0.4 M NaCl

4g, 4g, 0g, 0%

Pre-treatment mass, post-treatment mass, change is mass, percent change in mass, of potato in 0.2 M NaCl

4g, 3g, -1g, -25%

Pre-treatment mass, post-treatment mass, change is mass, percent change in mass, of potato in 0.0 M NaCl

3g, 4g, 1g, 33%

A cell's in water, all the solutes r in the cell. What is the state the cell's in

Hypotonic

A cell's in water, solutes r flowing freely in & out the cell. What is the state the cell's in

Isotonic

In passive transport, the concentration gradient across a membrane drives the movement of molecules

Into or out of a cell

Osmosis

Passive transport of water molecules from an area of low solute concentration to an area of high solute concentration Basically, water moves from an area of more water (less dissolved solutes) to where there is less water (more dissolved solutes) through selectively permeable membrane

Tonicity

Compares the solute concentration between two places

Hypertonic solution

solute concentration is higher outside of cell than inside; water moves out of cell

hypotonic solution

A solution in which the concentration of solutes is less than that of the cell that resides in the solution, water moves into the cell

isotonic solution

A solution in which the concentration of solutes is essentially equal to that of the cell which resides in the solution, the cell wont have a net gain of water

Mass=

Post-treatment mass (g) - pre-treatment mass (g)

Percent change in mass

Change in mass/initial mass x 100

Main functions of communication ll membrane

Isolate cytoplasm from external environment & contain cell contents, transport molecules in & out cell, cell recognition & communication

lipid bilayer

double-layered sheet made of oily lipid molecules that forms the core of nearly all cell membranes

Intracellular side

inside the cell, the aqueous cytoplasm

Extracellular side

outside the cell, aqueous extracellular space

Hydrophilic

water loving, phospholipid heads are hydrophilic

What does cholesterol do in the cell membrane?

Adds stiffness and flexibility; maintains fluidity. Can increase viscosity or increase fluidity depending on surrounding molecules

3 types of membrane proteins

Lipid-anchores proteins, integral membrane proteins, & peripheral membrane proteins

Membrane proteins functions

Transporting molecules across membrane, facilitating enzymatic activity, signal transduction between cell's, cell to cell recognition & communication, intercellular joining, serving as an attachment point for the cytoskeleton & extracellular matrix

Some regions of the membrane, called lipid rafts, are denser regions that can support heavier proteins with similar functions. The image below shows a segment of membrane found in a vesicle budding off the golgi apparatus. What structural modifications might be found in a lipid raft? Rafts have a higher concentration of saturated fatty acids and cholesterol molecules, resulting in greater fluidity.

Rafts have a higher concentration of unsaturated fatty acids with short fatty acid tails, resulting in less fluidity and greater stability.

Rafts have a higher concentration of saturated fatty acids and cholesterol molecules, resulting in less fluidity and greater stability.

Rafts have a higher concentration of unsaturated fatty acids with short fatty acid tails, resulting in greater fluidity.

Rafts have a higher concentration of saturated fatty acids and cholesterol molecules, resulting in less fluidity and greater stability.

The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic of all of these extracellular structures? They must permit information transfer between the cell's cytoplasm and the nucleus.

They are constructed of materials that are largely synthesized in the cytoplasm and then transported out of the cell.

They must block water and small molecules in order to regulate the exchange of matter and energy with their environment.

They are composed of a mixture of lipids and carbohydrates.

They are constructed of materials that are largely synthesized in the cytoplasm and then transported out of the cell.

Why does the immune system attack a transplanted organ? Glycoproteins and glycolipids on the surface of the organ are similar to those found on pathogens.

Glycoproteins and glycolipids on the surface of the organ are similar to those found on immune cells.

Glycoproteins and glycolipids on the surface of the organ are not recognized by the immune system.

Glycoproteins and glycolipids on the surface of the organ are toxic to the body.

Glycoproteins and glycolipids on the surface of the organ are not recognized by the immune system.

Parts of the cell membrane

Carbohydrates, Cholesterol, Phospholipids, Proteins

Cytosol

The soluble portion of the cytoplasm, which includes molecules and small particles, such as ribosomes, but not the organelles covered with membranes.

Types of membrane transport processes

Passive transport & active transport

passive transport

the movement of substances across a cell membrane without the use of energy by the cell

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

types of passive transport

simple diffusion, facilitated diffusion, osmosis

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Concentration gradient

A difference in the concentration of a substance across a distance.

Cellular diffusion

diffusion across the plasma membrane occurs as a solute moves from an area of high concentration to an area of low concentration

When does simple diffusion lccur

With small, non-polar solutes

When does facilitated diffusion occur

When certain large molecules, small charged, or polar molecules can't move through the membrane without the help of channel proteins

types of facilitated diffusion

channel mediated and carrier mediated

Channel-mediated facilitated diffusion

through a channel protein; mostly ions selected on basis of size and charge, moves through water filled channel

Leak channel

An ion channel that is constitutively open, allowing the movement of teh ion across the plasma membrane according to its concentration gradient.

Gated channel

A protein channel in a cell membrane that opens or closes in response to a particular stimulus.

Carrier-mediated facilitated diffusion

a carrier moves a solute down its concentration gradient across the plasma membrane

active proccesses

require energy

types of active processes

active transport and vesicular transport

active transport

Energy-requiring process that moves material across a cell membrane against a concentration gradient

vesicular transport

Transport of large particles and macromolecules across plasma membranes

simple diffusion

Diffusion that doesn't involve a direct input of energy or assistance by carrier proteins.

Channel proteins

A transmembrane protein that forms a pore in a cell membrane, which may open or close in response to a signal. The structure of most channels allows them to admit just one or a few types of ions or molecules.

gated ion channels

A gated channel for a specific ion. The opening or closing of such channels may alter a cell's membrane potential. They allow for flow of ions

Functions of gated ion channels

Helping maintain electrochemical gradient across cell membrane, opening in response to stimulus to allow ion flow, closing to let electrochemical gradient to reform

ligand-gated ion channels

membrane ion channels operated by the binding of specific molecules to channel proteins

voltage-gated ion channels

A specialized ion channel that opens or closes in response to changes in membrane potential

mechanically gated ion channels

found in sensory neurons and open in response to physical forces such as pressure or stretch

light gated ion channels

sensitive to visible wavelengths of light

A simulation is run exploring the random motion of particles and its role in diffusion. At the start of the program, there are 20 blue spheres on one side of the membrane and 10 red spheres on the other side. After a period of time, the distribution of spheres reaches an equal number independent of each other, so that there are 10 blue spheres and 5 red spheres on either side of the membrane. What evidence suggests that diffusion results in a dynamic equilibrium across the membrane? The red and blue spheres move to either side but not at the same time.

The red and blue spheres continue moving to either side, even in equilibrium.

The blue spheres diffuse to one side creating an equilibrium gradient.

The red spheres diffuse to one side creating a concentration gradient.

The red and blue spheres continue moving to either side, even in equilibrium

An experiment was done investigating the rate of glucose transport into a cell based on its external concentration gradient. Glucose requires a membrane carrier protein to move across the membrane and shows low uptake at high concentrations in the absence of the transporter.

Why does the rate of glucose uptake into the cell at high glucose concentrations level out in the graph below? The protein transport sites need ATP to continue.

The pH of the glucose denatures the protein.

The concentration gradient reaches equilibrium.

The protein transport sites are inhibited by glucose.

The protein transport sites are saturated with glucose.

The protein transport sites are saturated with glucose.

What type of molecule might travel into a cell through a channel protein?

oxygen

steroids

carbon dioxide

All of these items would use a channel protein to enter a cell.

water

Water

Protein pump

The term applied to a protein channel/transport protein that is working to move substances against the concentration gradient with the help of cell energy (ATP).

secondary active transport

Form of active transport which does not use ATP as an energy source; rather, transport is coupled to ion diffusion down a concentration gradient established by primary active transport.

Which of the following membrane activities require energy from ATP hydrolysis?

movement of carbon dioxide out of a paramecium

facilitated diffusion of chloride ions across the membrane through a chloride channel

movement of water into a cell

movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell

Na+ ions moving out of a mammalian neuron to reestablish an electrical potential across the membrane

Na+ ions moving out of a mammalian neuron to reestablish an electrical potential across the membrane

Proton pumps actively transport hydrogen ions (H+) across a membrane and generate a pH (or proton) gradient. Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What can be inferred from this observation?

Proton pumps are necessary to all cell membranes.

Cells of each domain evolved proton pumps independently when oceans became more acidic.

Proton pumps must have evolved before any living organisms were present on Earth.

The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism.

Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.

Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.