Ch 6, 3, and 4 - mastering bio homework PDF

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Ch 6, 3 and 4

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Ch 6, 3 and 4 Due: 11:59pm on Sunday, June 9, 2019 You will receive no credit for items you complete after the assignment is due. Grading Policy

Activity: Lipids

Click here to complete this activity. Then answer the questions.

Part A Which of these is NOT a lipid? ANSWER:

cholesterol steroids phospholipid wax RNA

Part B This figure is an example of a(n) _____.

ANSWER:

saturated fat steroid protein nucleic acid unsaturated fat

Ch 6, 3 and 4

Part C Which of these is a phospholipid? ANSWER:

Part D Which of these is rich in unsaturated fats? ANSWER:

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Ch 6, 3 and 4

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lard a fat that is solid at room temperature beef fat butter olive oil

Part E A function of cholesterol that does not harm health is its role _____. ANSWER:

in calcium and phosphate metabolism the most abundant male sex hormone as the primary female sex hormone as a component of animal cell membranes All of cholesterol's effects cause the body harm.

Activity: Selective Permeability of Membranes

Click here to complete this activity. Then answer the questions.

Part A

Ch 6, 3 and 4

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Structure A in the figure is a(n) _____. ANSWER:

receptor molecule enzyme structural protein antibody transport protein

Part B Which of these can RAPIDLY pass directly through the phospholipids of the plasma membrane, without the help of a transport protein?

ANSWER:

A only B only C only D only B, C, and D

Ch 6, 3 and 4

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Activity: Diffusion

Click here to complete this activity. Then answer the questions.

Part A Drag the terms on the left to complete the sentences on the right. ANSWER:

Reset

When molecules move down their concentration gradient, they move from where they are active transport

more concentrated

to where they are less concentrated .

Diffusion across a biological membrane is called passive transport .

Activity: Diffusion and Osmosis

Click here to view this animation. Then answer the questions.

Part A Which of the following factors does not affect membrane permeability?

Help

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Hint 1. What factors allow some molecules to pass through a membrane more readily than others?

ANSWER:

Temperature The saturation of hydrocarbon tails in membrane phospholipids The amount of cholesterol in the membrane The polarity of membrane phospholipids

Part B How can a lipid be distinguished from a sugar?

Hint 1. What is the definition of a lipid?

ANSWER:

A lipid is made up of only hydrocarbons. Lipids are mostly nonpolar. A lipid dissolves in water. Lipids are mostly saturated.

Part C True or false? Osmosis is a type of diffusion.

Hint 1. What process occurs during osmosis?

ANSWER:

True False

Part D What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?

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Hint 1. Think about how oils can be isolated from water.

ANSWER:

Permeability Hydrophobic nature Amphipathic nature Solubility in water

Part E Which of the following particles could diffuse easily through a cell membrane?

Hint 1. Remember that small nonpolar molecules pass most easily through cell membranes.

ANSWER:

Hydrogen ion (H+) Oxygen (O2) Sodium ion (Na+) Glucose

Part F True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.

Hint 1. Think about the orientation of the phospholipids that make up a cell membrane.

ANSWER:

True False

Part G

Ch 6, 3 and 4

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If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?

Hint 1. Consider the movement of water when the solute concentration inside the cell is different from that of the surrounding environment.

ANSWER:

Hypertonic Osmotic Hypotonic Isotonic

Activity: Membrane Structure

Click here to complete this activity. Then answer the questions.

Part A What is the function of Structure E?

ANSWER:

structural support of the cell stabilization of the phospholipids transport across the plasma membrane cell-cell communication detection of environmental change

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Part B Identify Structure D.

ANSWER:

phospholipid bilayer of membrane glycoprotein extracellular matrix cholesterol protein

Part C Identify Structure A.

ANSWER:

extracellular matrix phospholipid glycoprotein cholesterol protein

Ch 6, 3 and 4

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Membrane Transport (1 of 4): Diffusion and Passive Transport (BioFlix tutorial)

Cells require a constant exchange of solutes (ions and small molecules) with the outside of the cell. Many of these solutes undergo passive transport across the membrane. Passive transport occurs without the input of cellular energy. Some solutes are transported into the cell while others are transported out of the cell. Before beginning this tutorial, watch the Membrane Transport animation. Pay particular attention to how passively transported substances diffuse across the plasma membrane down their concentration gradients (without the input of cellular energy). Notice how these passively transported substances either pass directly through the lipid bilayer or move through different types of transport proteins embedded in the plasma membrane.

Part A - Diffusion All molecules have energy that causes thermal motion. One result of thermal motion is diffusion: the tendency of substances to spread out evenly in the available space. Although the motion of each individual molecule is random, there can be directional motion of an entire population of molecules. Consider a chamber containing two different types of dye molecules, purple and orange. The chamber is divided into two compartments (A and B) by a membrane that is permeable to both types of dye. Initially (left image), the concentration of the orange dye is greater on side A, and the concentration of the purple dye is greater on side B. With time, the dye molecules diffuse to a final, equilibrium state (right image) where they are evenly distributed throughout the chamber.

Drag the labels onto the table to indicate when each statement is true. Labels can be used once, more than once, or not at all.

Hint 1. What is the difference between movement of a single molecule versus movement of a population of identical molecules? When comparing thermal motion and diffusion, it is important to distinguish between the movement of an individual molecule and the movement of a population of identical molecules. Drag the phrases on the left to the appropriate blanks on the right to complete the sentences. Not all phrases will be used. ANSWER:

Ch 6, 3 and 4

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Reset

none of the dye molecules

Help

1. The motion of an individual dye molecule is random whether or not a concentration gradient is present. 2. Diffusion is the net movement of a population of dye molecules

when a concentration gradient

is present.

Hint 2. What molecule movements occur at equilibrium? When the chamber containing the orange and purple dyes is at equilibrium, there are no concentration gradients between sides A and B. Which two of the following statements correctly describe the movement of dye molecules at equilibrium? ANSWER:

For every orange dye molecule that moves from side A to side B, another orange dye molecule moves from side B to side A. There is no movement of orange or purple dye molecules from one side to the other. Each individual dye molecule moves in a random direction. The dye molecules do not move at equilibrium.

Hint 3. Thermal motion and the movements of molecules Molecules are constantly in motion because of their thermal energy. In an aqueous solution containing several different solutes, the thermal motion of any individual molecule (water or solute) appears to be completely random. At one instant, the molecule may be moving in one direction, but in another instant, it may be moving in the opposite direction. When two or more types of molecules are present in a solution, their movement is independent if the motion of one type of molecule is not somehow linked to the motion of another type of molecule. This does not mean that the two types of molecules do not come into contact with each other. Collisions among all molecules in a solution occur randomly and continuously. Independent movement means that when they collide, their motions do not become linked together. Hint 4. Definition of a concentration gradient In cells, it is common for solutes to be maintained at different concentrations on opposite sides of a membrane, including the plasma membrane or an organelle membrane. This difference in solute concentration across a membrane represents a concentration gradient. Substances tend to diffuse down a concentration gradient from regions of higher concentration to regions of lower concentration.

ANSWER:

Ch 6, 3 and 4

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Reset

Help

Part B - Permeability of the lipid bilayer Some solutes are able to pass directly through the lipid bilayer of a plasma membrane, whereas other solutes require a transport protein or other mechanism to cross between the inside and the outside of a cell. The fact that the plasma membrane is permeable to some solutes but not others is what is referred to as selective permeability. Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply.

Hint 1. What are the characteristics of solutes that can pass through a lipid bilayer? Drag the phrases on the left to the appropriate blanks on the right to complete the sentences. ANSWER:

Ch 6, 3 and 4

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Reset

Help

1. Solutes that can rapidly cross a lipid bilayer are typically small and nonpolar .

2. Solutes that are small and polar

can cross a lipid bilayer, but not as quickly.

3. The lipid bilayer is essentially impermeable to solutes that are charged .

Hint 2. Which solutes are nonpolar, polar, or charged? Drag each solute to the appropriate bin. ANSWER:

Reset

Help

Hint 3. Water, an unusual case for transport across the plasma membrane

Water is an unusual molecule because, despite the fact that it is polar, it is small enough to pass directly through the hydrophobic interior of a lipid bilayer, albeit slowly. Rapid movement of water across membranes, however, requires the presence of transport proteins called aquaporins. Watch this clip from the Membrane Transport animation and compare the two methods of water transport across a membrane. Hint 4. Diffusion of lipids across the plasma membrane

Ch 6, 3 and 4

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Lipids are one type of molecule that can cross the plasma membrane directly, without the use of a transport protein. This is because lipids are soluble in the hydrophobic interior of the membrane. Watch this clip from the Membrane Transport animation that shows the diffusion of lipids across the plasma membrane of an epithelial cell lining the intestine.

ANSWER:

oxygen sucrose lipids water carbon dioxide proteins ions

Ch 6, 3 and 4

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Part C - Facilitated diffusion via channels and carrier proteins The majority of solutes that diffuse across the plasma membrane cannot move directly through the lipid bilayer. The passive movement of such solutes (down their concentration gradients without the input of cellular energy) requires the presence of specific transport proteins, either channels or carrier proteins. Diffusion through a transport protein in the plasma membrane is called facilitated diffusion.

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers.

Hint 1. What types of solutes do channels and carrier proteins transport? Channels and carrier proteins are both involved in facilitated diffusion of certain solutes across the plasma membrane. Which of the following statements correctly describes the specificity of these transport proteins for the solutes they transport? ANSWER:

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Channels typically transport small polar molecules such as sugars or amino acids, whereas carrier proteins typically transport water or inorganic ions. Channels typically transport water or inorganic ions, whereas carrier proteins typically transport small polar molecules such as sugars or amino acids. The same types of solutes are transported in both channels and carrier proteins.

Hint 2. How carrier proteins are thought to accomplish transport Unlike channels, which are pores through the membrane, carrier proteins transport solutes across the membrane through a sequence of subtle shape changes. Binding of a solute on one side of the membrane induces a conformational change, which exposes the solute binding site to the opposite side of the membrane. Release of the solute from the binding site induces a conformational change that returns the protein to its initial shape.

Hint 3. How transport proteins provide a hydrophilic path for polar or charged solutes Charged ions and polar molecules such as sugars and amino acids cannot diffuse directly through the lipid bilayer because they are much more stable in the strongly polar environment of water than in the hydrophobic interior of the bilayer. The structure of transport proteins enables them to move charged and polar solutes across the plasma membrane. Transport proteins are integral membrane proteins with both hydrophobic and hydrophilic portions. The amino acids that are in contact with the hydrophobic interior of the lipid bilayer are nonpolar. In contrast, the amino acids composing the pore of a channel protein or the solute binding site of a carrier protein are polar. The polar amino acids provide a hydrophilic path for charged and polar solutes to cross the plasma membrane. The image below shows a potassium channel and its nonpolar and polar components. Note that the interior of the channel (green) is composed of polar amino acids, making a hydrophilic pore through which K+ ions can pass.

Hint 4. Watch the action of carriers and channels during facilitated diffusion

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The passive movement of a solute across a membrane with the help of a transport protein is called facilitated diffusion. Watch this clip from the Membrane Transport animation that shows the two types of transport proteins that participate in facilitated diffusion: a carrier protein involved in fructose transport, and a channel protein (aquaporin) involved in water transport.

ANSWER: Reset

Help

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Making Models: Drawing Membranes Watch this video and complete the practice activity at the end. Then answer these questions.

Part A Your classmate has drawn four membrane models to try to remember how the lipid bilayer is built. Help her to select the best model. ANSWER:

Ch 6, 3 and 4

Part B Interpret the model.

Drag "True" or "False" to the end of each statement. ANSWER:

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Ch 6, 3 and 4

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True

This model shows membrane transport. False

False The many black lines represent amino acid tails. False

The strings of little red dots represent carbohydrates. True The model is called a bilayer because there are two main types of molecules present, lipids and proteins. False

The blue ovals are hydrophobic. False

The blue ovals represent phospholipid heads. True

Part C Which of the following models provides the best representation of facilitated diffusion via a “channel”? ANSWER:

Help

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Part D Four students have done a nice job drawing membrane models. The models are drawn at different scales to serve different purposes.

Order the students’ models from most magnified (enlarged) to least magnified.

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ANSWER:

Rekik, Zubia, Thomas, Elsa Rekik, Thomas, Zubia, Elsa Elsa, Zubia, Thomas, Rekik Elsa, Thomas, Zubia, Rekik

Part E Which student’s model does the best job of showing membrane structure?

ANSWER:

Elsa Zubia Rekik Thomas

Part F Which student’s model does the best job of showing facilitated diffusion of a solute?

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ANSWER:

Zubia Elsa Thomas Rekik

Activity: Condensation and Hydrolysis Reactions

Click here to view this animation. Then answer the questions.

Part A Which polymers are composed of amino acids?

Hint 1. What molecules are formed from joining amino acids together?

ANSWER:

Monomers Carbohydrates Proteins Nucleic acids

Part B

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Which of the following is not attached to the central carbon atom in an amino acid?

Hint 1. What is the basic structure of an amino acid?

ANSWER:

An amino functional group A side chain ("R group") A carboxyl functional group An oxygen

Pa...