Week 2 LS7A

Define lysosome.

contains enzymes that break down micromolecules

A bacterial cell, a plant cell, and an animal cell have which component in common?

cytoplasm

The random movement of solute molecules within a solution is referred to as:

diffusion

If the membrane were permeable to salt but not to water, what would occur in this container?

diffusion of salt from B to A, but not of water

The beaker in the illustration contains two solutions of salt with different concentrations (measured by molarity, M). The two solutions are separated by a membrane. If the membrane were permeable to water but not to salt, what would occur in this container?

diffusion of water from A to B but no diffusion of salt

What direction of net movement of molecules occurs during facilitated diffusion?

high concentration to low concentration

What direction of net movement of molecules occurs during simple diffusion?

high concentration to low concentration

The interior region of a phospholipid bilayer is characterized as:

hydrophobic and nonpolar

Assuming that water is moving into the plant cells of the lettuce leaf, what can you deduce about the tonicity of the plant cells compared to the solution it was soaked in?

hypertonic

Fill in the blank. A solution of salt and water is ______ compared to pure water

hypertonic

Fill in the blank. Pure water is ___________ compared to a solution of salt and water.

hypotonic

A protein that is embedded in only one layer of a lipid bilayer is a(n):

integral membrane protein

Define endoplasmic reticulum.

involved in lipid and protein synthesis

Fill in the blank. A 5% solution of glucose (sugar) is _____________ compared to a 5% solution of sodium ions.

isotonic

Define cytosol.

jelly-like internal environment of the cell that surrounds the organelles

What is a "transmembrane" protein?

a protein that spans through the phospholipid membrane

What direction of net movement of molecules occurs during primary active transport?

low concentration to high concentration

What direction of net movement of molecules occurs during secondary active transport?

low concentration to high concentration

What is "mosaic" in reference to the structure of cell membranes?

mixture of different types of molecules, including lipids, proteins, and carbohydrates

Define golgi apparatus.

modifies and sorts proteins and lipids as they move to their final destination

Which molecules can easily diffuse across a plasma membrane?

non-polar gases like O2 and CO2

Define isotonic.

one with a solute concentration equal to that inside the cell

Define hypertonic.

one with a solute concentration higher than that inside the cell

Define hypotonic.

one with a solute concentration lower than that inside the cell

Which cell type do you expect to contain the greatest number of lysosomes?

phagocytes

What type of lipid molecule is the image shown?

phospholipid

The lipid components of cellular membranes often include:

phospholipids and cholesterol

Define mitochondria.

produces ATP which is the energy currency of the cell

What properties of molecules influence how well they are able to cross through the lipid portion of the membrane?

protein transporters can affect ions, water, and nutrients that cannot cross the lipid bilayer on their own

Which cell type do you expect to have the least number of mitochondria?

red blood cells

Why does secondary active transport of molecules across a membrane require an electrochemical gradient?

An input of energy is needed to allow the movement of molecules from an area of low concentration to one of higher concentration.

How do eukaryotic plant and animal cells differ from one another?

Animal cells do not have chloroplasts and cell walls, and plant cells do.

The diagram below shows the changes in potential energythat occur when two different pairs of atoms interact. Curve Xrepresents one pair of atoms and Curve Z represents thesecond pair of atoms. Which pair of atoms forms a bond with lower potential energy?

Atom pair represented by Curve Z

The diagram below shows the changes in potentialenergy that occur when two different pairs of atomsinteract. Curve X represents one pair of atoms and CurveZ represents the second pair of atoms. Which pair of atoms forms a "stronger" bond?

Atom pair represented by Curve Z

During osmosis, there is a net movement of water from a region of _____ to a region of _____.

Both "high solvent concentration; low solvent concentration" AND "low solute concentration; high solute concentration" are correct answers.

Suppose you add many phospholipid molecules to a beaker of oil and stir it vigorously. What will the phospholipids look like in the oil?

D

Compared to when the Na+ channel is closed, how will the transport of Waste molecules change when the Na+ channel is open? The rate of Waste transport out of the cell will:

Decrease

DHA is a component of membranes in algae. In response to increasing sea surface temperatures, what might you expect to happen to DHA levels in algal membranes over time?

Decrease

If membrane fluidity needs to be maintained, which of the following would be most important in a cell as a response to a decrease in temperature?

Introducing more double bonds into the fatty acid chains in the phospholipid bilayer.

Assume you were to drastically increase the concentration of Na+ outside of the cell. What would happen to the movement of waste out the cell immediately after this modification?

It would increase

This phospholipid contains one saturated fatty acid and one unsaturated fatty acid. Which one is which, and how could you tell?

Left - unsaturated because it contains double bonds of Carbon (C==C). This gives it its bending shape. Right - saturated because it does not contain any double bonds of carbon.

The diagram below shows a cell with three different membrane transport proteins: The Na+/K+ Pump, the Na+/Waste Co-transporter, and the Na+ Channel. The Na+/K+ Pump is a primary active transporter, and the Na+/Waste Co-transporter is a secondary active transporter; arrows show the direction of net movement of molecules through the Pump and Co-transporter. Lastly, the Na+ Channel can exist in either a closed state (no Na+ can pass through) or an open state (Na+ can pass through); unless otherwise stated, you can assume the Na+ Channel to be in its closed state. The concentration of Waste molecules is ________ inside the cell compared to the outside.

Lower

Does simple diffusion require a protein in the lipid bilayer?

No

Is an input of energy required in facilitated diffusion?

No

Is an input of energy required in simple diffusion?

No

Which of the following molecules (see below) would least likely require a transport protein to cross the plasma membrane of a red blood cell?

O2

Although the phospholipid molecules in the cell membrane can be in constant lateral movement, they very rarely flip from one side of the bilayer to the other. Which of the answer choices could best explain this?

The head groups are repelled by the hydrophobic membrane interior.

Based on your observation, what canyou infer about the movement of water?

There is a net movement of water into the plant cells of the lettuce leaf

A beaker contains two solutions of salt dissolved in water. The two solutions have different concentrations of salt (measured by molarity, M) and are separated by a membrane that is permeable to both salt and water. Which statement is true about the diffusion of these solutions?

There will be a net movement of salt from side B to side A and net movement of water from side A to side B.

What will happen when the Na+ channel is open?

There will be net movement of Na+ into the cell through the channel

Global climate change is causing an increase in sea surfacetemperature. What might you expect to happen to algal membranesover time if they did not change the composition of their membranes?

They would become too fluid

What is a "peripheral" membrane protein?

a protein that does not span to through the phospholipid membrane

What is an "integral" membrane protein?

a protein that spans across the phospholipid membrane

If cells had single-layer membranes like micelles, how would the structures of transmembrane proteins be affected?

Transmembrane proteins would possess a hydrophobic region in the cell interior and a hydrophilic region in the extracellular space.

Does facilitated diffusion require a protein in the lipid bilayer?

Yes

Does primary active transport require a protein in the lipid bilayer?

Yes

Does secondary active transport require a protein in the lipid bilayer?

Yes

Is an input of energy required in primary active transport?

Yes

Is an input of energy required in secondary active transport?

Yes

The plasma membranes of some plant cells use transport proteins to move protons out of the cell against their concentration gradient. This is an example of:

active transport

Define organelle.

any one of several compartments in eukaryotes that divides the cell contents into smaller spaces specialized for different functions

What type of lipid molecule is the image shown?

cholesterol

The plasma membrane is composed of a phospholipid bilayer and associated proteins. What else is commonly found in the plasma membranes of animal cells?

cholesterol

Which eukaryotic organelle is associated with synthesis of proteins?

endoplasmic reticulum

What type of lipid molecule is the image shown?

fatty acid

All cells have:

genetic information

Some plant cells create a high concentration of protons outside the cell to move solutes, such as sucrose, across the plasma membrane into the cell where the sucrose concentration is already relatively high. This type of transport is an example of:

secondary active transport.

Try ranking each of the following molecules from most likelyto cross a pure lipid bilayer to least likely. Which of the following molecules would you expect to be LEAST likely to cross a pure lipid bilayer?

sodium ion

Define nucleus.

storehouse for the cell's genetic information and the site for RNA synthesis

Which eukaryotic cell structure plays a role in protein trafficking and sorting?

the Golgi apparatus

Define tonicity.

the capability of a solution to modify the volume of cells by altering their water content

Define cytoplasm.

the entire contents of the cell enclosed by the cell membrane

What is "fluid" in reference to the structure of cell membranes?

the lipid bilayer is a structure within which molecules move laterally

What does it mean for a membrane to be "selectively permeable"?

the membrane allows some molecules in and out freely, whereas others can only go in and out on the basis of certain conditions, and prevents other molecules from passing through at all

Define osmosis.

the net movement of a solvent, such as water, across a selectively permeable membrane toward the side of higher solute concentration

Define diffusion.

the net movement of molecules form area of higher concentration to lower concentration due to a result of their random thermal motion

What type of lipid molecule is the image shown?

triglyceride

Which of these bonds/interactions has the highest potential energy?

van der Waals' Forces