Test 3, Lecture 1

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Which statement does not describe the three main components of a phospholipid?

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1

Which statement does not describe the three main components of a phospholipid?

  • phosphate group

  • glycerol or 3-carbon alcohol

  • 2 fatty acid chains

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2

According to the video Inside the Cell Membrane, what does it mean that a cell is semi-permeable?

“It lets some material through, but not others”

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3

According to the video Inside the Cell Membrane, the fluid mosaic model is a way to describe a cell membrane. The word “fluid” implies movement, and this is true for the cell membrane. How?

“the components are floating around, they’re not static” proteins move around the cell membrane, so nothing is moving them in place

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4

According to the video Inside the Cell Membrane, a phospholipid is amphiphilic. What does this mean?

  • amphiphilic means that two different parts of a phospholipid are hydrophobic and hydrophilic

  • head of a phospholipid is polar (hydrophilic)

  • tail of the phospholipid is nonpolar (hydrophobic)

  • phospholipids arra/nge themselves into a phospholipid bilayer where nonpolar areas are away from water & separated from the outside and inside of a cell

  • water can be found on both outside and inside areas of a cell

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5

According to the video Inside the Cell Membrane, why is cholesterol in your cell membrane critical?

“If temperatures drop, cholesterol can actually function like spacers between the phospholipids—keeping them from becoming too packed.”

OR (both are correct)

“cholesterol can actually function to connect phospholipids to keep them from becoming too fluid in warm temperatures”

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6

According to the video Inside the Cell Membrane, proteins can also be found within a cell membrane. What are the names of the two types they mention in the video?

Peripheral Proteins

  • tend to be on the peripheral area of a membrane

Integral Proteins

  • go through the membrane

  • peripheral proteins can sit on them

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7

According to the video Inside the Cell Membrane, what are integral proteins used within the cell membrane?

“With their potential to go through the membrane, are frequently involved in transporting methods for different types of materials”

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8

According to the video Inside the Cell Membrane, what are peripheral protein used for regarding the cell membrane?

  • they are more loosely attached since they’re generally not stuck in the membrane

  • acting as enzymes to speed up reactions

  • attaching cytoskeleton structures to help with cell shape

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9

According to the video Inside the Cell Membrane, what are the components of a glycoprotein and glycolipid?

glycoprotein: have carbohydrates bound to them

glycolipid: carbohydrate attached to a phospholipid

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10

According to the video Inside the Cell Membrane, what can glycoproteins and glycolipids be used within (or on the outside) or a cell membrane?

  • both can identify the cell as belonging to the organism — self/nonself

  • involved in cell signaling (help fight viral and bacterial diseases)

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11

Which statement does not describe a reason why the lipid bilayer of your membrane can be called “fluid?”

  • Proteins can move since they can transport because they are not static.

  • They are in there loosely. They can easily move through the bilayer

  • bilayer is fluid because of hydrogen bonding and van der Waals forces

  • no cytoskeleton to prevent movement

  • cholesterol in the membrane, so fluid-based temperature

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12

The fluid mosaic model was created by Singer and Nicolson in 1972. That stated that the cell membrane is composed of a _____________ which provides a flexible matrix and imposes a barrier to permeability.

phospholipid bilayer

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13

The fluid mosaic model was created by Singer and Nicolson in 1972. That stated that the cell membrane contains ______________ which can float or are embedded in the membrane and provide transport of substances and information to cross the membrane.

transmembrane proteins

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14

The fluid mosaic model was created by Singer and Nicolson in 1972. That stated that the cell membrane contains a(an) _______________ which is structurally supported by intracellular proteins that reinforce the membrane’s shape (spectrin is an example).

inferior protein network

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15

Recent findings have discovered the plasma membrane is not homogeneous and contains microdomains with distinct lipid and protein compositions. These portions of the cell membrane are called _______________ and are heavily enriched in cholesterol and saturated fatty acids which makes it “thicker” than other areas of the plasma membrane.

lipid rafts

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16

Which statement describes a possible function of a lipid raft

  • cell signal reception: receiving tons amount of signals here because there are tons of glycolipids which mark things

  • cell movement

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17

Proteins within the plasma membrane can be multifunctional. Which statement does not accurately describe the function of different transmembrane proteins?

  • goes through the entire structure

  • embedded in the actual membrane

  • transfers different substances and chemicals in and out

  • they need to go through the proteins themselves otherwise, they will bounce off of the plasma membrane

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18

According to the video Diffusion, what is the definition of diffusion?

Diffusion is when the net movement of a substance travels down its concentration gradient.

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19

According to the video Diffusion, diffusion is the movement of ions from an area of___ concentration to an area of ____________ concentration until equilibrium is reached.

high, low

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20

According to the video Diffusion, a concentration gradient is itself a form of _______________ energy.

potential

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21

According to the video Diffusion, what does it mean that diffusion is a passive transport?

“an input of energy is not needed; we say that passive transport does not require added energy”

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22

According to the video Diffusion, how to active transport different from passive transport? (know the one simple difference)

active needs energy, passive does not

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23

According to the video Diffusion, _______________ is when molecules still have a net movement of high concentration to low concentration, but they may be too large or have other characteristics that prevent them from directly traveling across the selective cell membrane (they need to use a carrier or channel).

facilitated diffusion

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24

According to the video Diffusion, how can distance affect the rate of diffusion?

The greater the distance that needs to be traveled, the slower the diffusion rate.

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25

According to the video Diffusion, how can temperature affect the rate of diffusion?

A higher temperature generally would mean there is more movement of the molecules so the diffusion rate is increased-

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26

According to the video Diffusion, how can the characteristics of the solvent affect the rate of diffusion?

solvent very dense means slow the molecules down and decrease the diffusion rate.

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27

According to the video Diffusion, how can characteristics of the substance traveling affect the rate of diffusion?

a substance with a greater mass will have a lower diffusion rate when compared

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28

According to the video Diffusion, how can characteristics pf the barrier affect the rate of diffusion?

if diffusion is a cell, and the barrier is a cell membrane. Small non-polar substances pass through a cell membrane easier than something large or polar.

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29

Which type of molecules can easily go and pass through the phospholipids bilayer of your cell membrane during simple diffusion (i.e. which type do not need a carrier or channel)?

gases, uncharged polar molecules, tiny molecules

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30

In order to diffuse many different ions and larger molecules across the plasma membrane, your cell must use protein channels and carriers. Why is this the case (the definition of an ion channel we discussed in class is the hint)?

transmembrane proteins can transfer different substances in and out, they need to go through the proteins themselves or they will bounce off of the plasma membrane which is semi-permeable. The plasma membrane is nonpolar because of the tails of the fatty acids

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31

How is the direction of the net movement of molecules determined when simple diffusion is occurring? (hint…there are two answers we discussed in class)

  1. Substances in high concentration of water will move to places of low

concentration of water

  1. Even when equilibrium is reached, the substances and water still moves around

    1. Very small non-polar molecules have no problem passing through the phospholipid bilayer

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