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BIO 241 [Exam #1] > Chapter 6 - Interactions between Cells and The Extracellular Environment > Flashcards

Chapter 6 - Interactions between Cells and The Extracellular Environment Flashcards

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Biology 101 flashcards
1
Q

Materials are transported in and out of a cell through the _____ _______

A

cell membrane

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2
Q

What is vital for all cells to maintain?

A

constant/stable intracellular environment (homeostasis)

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3
Q

The cell membrane is _____ _________.

Explain what this means

A

selectively permeable

only allows substances of certain sizes/charge in/out

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4
Q

Explain why the cell membrane is selectively permeable

A

It is selectively permeable because it brings in molecules it needs and exclude molecules it does not need.

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5
Q

What are the different ways substances can move across the cell membrane?

A
  • passive transport
  • active transport
  • bulk transport
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6
Q

What is another term for passive transport?

A

diffusion

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7
Q

What are two examples of passive transport?

A
  • simple diffusion
  • facilitated diffusion
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8
Q

What are two examples of active transport?

A
  • primary active transport
  • secondary active transport
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9
Q

In passive transport, substances move from a ______ to _________ concentration.

A

higher
lower

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10
Q

In which transport system across the cell membrane do NOT use energy?

A

passive transport

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11
Q

In which transport system across the cell membrane USES energy?

A

active transport

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12
Q

In active transport, substances move from a ______ to _________ concentration.

A

lower
higher

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13
Q

Passive transport is ________ movement of substances from an area of high concentration to low concentration

A

spontaneous (natural)

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14
Q

Define the concentration gradient

A

the concentration difference across a cell membrane

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15
Q

Compare simple diffusion vs facilitated diffusion. Include examples

A

simple diffusion is for movement of small, non-polar and/or uncharges substances and move in/out the cell directly through the cell membrane (ex. o2, co2 (gases), steroids (fats)).

facilitated diffusion is for movement of large, polar, and/or charged substances and are repelled by the phospholipid bilayer (ex. Na+, Cl- (ions), glucose (large)). It requires facilitators to move substanecs in/out of the cell membrane (protein channels+carriers)

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16
Q

Why are steroids allowed to travel straight through the cell membrane but not Na+

A

steroids are uncharged and nonpolar, meaning they use simple diffusion

Na+ is an ion with a positive charge, needing facilitated diffusion.

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17
Q

What is a facilitator? Why are they important?

A

it helps move substances through the cell membrane (protein channels and protein carriers)

it helps move large, polar, and charged particles down the concentration gradient (high -> low)

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18
Q

Compare the different facilitators in facilitated diffusion

A

protein channels

  • embedded in cell membrane
  • closed/open state (gate)
  • move substances high -> low
  • ex: Na+ channel, K+ channel, water channel

protein carriers

  • embedded in cell membrane
  • carrier physically attaches to substance being transported -> changes shape of protein carrier -> opens at opposite end -> releases substance
  • ex: glucose carrier protein
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19
Q

ion channels and protein carriers are mostly ______

A

specific (show specificity)

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20
Q

In facilitated diffusion, which type of facilitator shows specificity?

A

protein carriers are more specific than ion channels because they have to bind to a substance

21
Q

ion channels and protein carriers can show ______ and _________

A

saturation and competition

22
Q

What does it mean when we say channels and carriers can show “competition”

A

some proteins (ion channels and protein carriers) can transport more than one molecule, which causes competition

23
Q

What is saturation and what happens to the rate of particle transport when saturation has been met?

A

when a molecules transport rate reaches its plateau

24
Q

Describe saturation and competition

A

The transport rate increases with increasing molecule concentration until all the carriers are in use -> transportation rates plateau -> saturation has been met

Some proteins are able to transport more than one molecule, which can cause a competition effect

The maximum transport rate is known as the transport maximum (Tm)

25
Q

If saturation is met after reaching a certain molecule concentration, what can you say about the number of channels and/or carriers present in the cell membrane?

A

there is a limited number of channels/carriers

26
Q

T or F: The number of channels and carriers embedded in the cell membrane is constant throughout the life of the cell

A

False, they can be inserted or removed when needed

The amount of carriers are determined by the need of the cell

27
Q

What type of carrier proteins transport glucose?

A

GLUT (1,2,3,4)

28
Q

Active transport requires some form of energy. List the 2 types of energy used in active transport.

A

direct ATP and indirect ATP (another form of E involving ATP; the energy needed to move molecules against their concentration gradient in secondary active transport is acquired by moving Na+ back into the cell)

29
Q

What words indicate a molecule is moving from a high to low concentration?

A
  • moving down the concentration gradient
  • moving with the concentration gradient
  • moving with diffusion
30
Q

What words indicate a molecule is moving from a low to high concentration?

A
  • moving up the concentration gradient
  • moving against the concentration gradient
  • moving against diffusion
31
Q

Compare passive and active transport (which way do substances move)

A

passive transport: high -> low
active transport: low -> high

32
Q

There are 2 types of active transport: _________ active transport and ___________ active transport

A

primary active transport
secondary active transport

33
Q

Primary active transport uses _______ ________ embedded in the cell membrane

A

protein pumps

34
Q

Describe how protein pumps work

A

protein pumps are used in PRIMARY active transport and require direct ATP to change the shape of a pump and open to the other side to release the substance (works kinda like a protein carrier, but needs ATP)

35
Q

What types of pumps are involved in primary active transport? Be specific

A
  • Na+/K+ pump
  • Ca2+ pump
36
Q

The Na+/K+ pump is described as an ________ pump

A

exchange pump

37
Q

Summarize in words what is happening when a Na+/K+ is operating in the cell membrane and draw it out

A

The Na+/K+ pump using ATP to move 3Na+ out the cell and 2K+ into the cell and they both move against the concentration gradient (low -> high). ATP becomes converted into ADP + Pi

38
Q

Where is the Na+/K+ pump found?

A

in all body cells (ex. neurons, cardiac cells)

39
Q

Why is the Na+/K+ pump described as an exchange pump?

A

3Na+ are moving out of the cell in exchange for 2K+ moving in the cell

40
Q

Why does the cell become more negative inside as a result of the Na+/k+ pump operating?

A

There are more Na+ moving out of the cell, than there is K+ moving back in.

41
Q

What can cause the Na+/K+ pump to stop working?

A
  • ATP production is altered
  • Presence of Na+/K+ pump inhibitors
42
Q

Describe secondary active transport

A
  • movement of 2 substances simultaneously across cell membrane; 1 with diffusion (Na+) and 1 against diffusion (a different substance)
  • movement relies on primary active transport (the Na+/K+ pump); indirect use of ATP
43
Q

How does secondary active transport facilitate movement?

A

the energy needed to move molecules against their concentration gradient is acquired by moving Na+ back into the cell (Na+ was originally pumped out of the cell using ATP in primary active transport, the secondary active transport is also considered to be active transport)

44
Q

What are the different types of secondary active transport?

A
  • co-transport/symport
  • counter-transport/antiport
45
Q

Compare co-transport/symport to counter-transport/antiport

A

co-transport/symport: both substances move in the SAME direction (both in or both out)
ex: Na+/Glucose symporter
K+/Cl- symporter

counter-transport/antiport: both substances move simultaneously in the OPPOSITE direction
ex: Na/Ca2+ Exchanger
Na+/H+ Exchanger
Cl-/HCO3- Exchanger

46
Q

How is ATP involved in secondary active transport?

A

1) high [Na+] outside
2) movement of Na+ by diffusion is the driving force for moving the second particle

47
Q

Bulk transport is the movement of relatively _______ macromolecules

A

large

48
Q

What are the different types of bulk transport?
Describe them and give examples

A

endocytosis: movement into the cell; pinching to form a vesicle
ex: protein, hormones, neurotransmitters

exocytosis: movement out of the cell; intracellular vesicle fuses with plasma membrane
ex: cholesterol

BIO 241 [Exam #1] (5 decks)

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