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BIO108: General Physiology > Lecture 2a: Cell Membrane Structure > Flashcards

Lecture 2a: Cell Membrane Structure Flashcards

1
Q

The cell membrane is ____ and allows a ____ to move

A

> flexible
unicellular organism

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2
Q

Functions of the Cell Membrane

A
  • Acts as a boundary
    Gateway to the Cell
  • Controls what enters and leaves cell
  • Regulates chemical composition
  • Maintains homeostasis
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3
Q

2 layers of globular proteins with phospholipid inside to make a layer and then join 2 layers together to make a channel for molecules to pass

A

Sandwich Model

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4
Q

Proposed the Sandwich Model

A

Danielli & Davson

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5
Q

Proposed the Unit Membrane Model

A

Robertson

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6
Q

States that the cell membrane is composed of an outer layer of protein with phospholipid bilayer inside; believed all cells same composition,

A

Unit Membrane Model

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7
Q

Proposed the Fluid Mosaic Model

A

Singer & Nicholson

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8
Q

States that the cell membrane is composed of a phospholipid bilayer with proteins partially or fully imbedded

A

Fluid-Mosaic Model

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9
Q

What makes the cell membrane “Fluid”?

A

It has the consistency of olive oil at body temp which allows it and proteins to move freely within the layer like its liquid.

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10
Q

What makes the cell membrane a “Mosaic”?

A

Due to the proteins that forms a collage that differs on either side of membrane and from cell to cell

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11
Q

A harsh ionic detergent

A

Sodium Dodecyl Sulfate (SDS)

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12
Q

A gentler, non-ionic detergent

A

Triton X-100

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13
Q

Formation of sphere is ______ .

A

Energetically favorable

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14
Q

What happens to the cell membrane at low temperatures?

A

Hydrocarbons are tightly packed, cell membrane is in a gel phase.

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15
Q

What happens to the cell membrane at higher temperatures?

A

The bilayer “melts” which allows movement in the cell membrane

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16
Q

How does the phospholipids move in the cell membrane?

A

Lipids can move laterally and rotate 360 degrees

17
Q

How does proteins move in the cell membrane?

A

Proteins move laterally

18
Q

How does cholesterol affect the cell membrane at body temperature?

A

It lessens fluidity by restraining the movement of phospholipids.

19
Q

How does cholesterol affect the cell membrane at colder temperatures?

A

It maintains fluidity by not allowing phospholipids to pack close together.

20
Q

The Planar Rings of Cholesterol Make the Membrane ______ , ______ , and ______ .

A

(1) More Rigid
(2) Less Permeable
(3) Resistant to Low Temperature Crystalization

21
Q

Performs the same function as cholesterol but in plant cell membrane

A

Sterols

22
Q

Classifications of Membrane Proteins

A

(1) Peripheral Membrane Proteins
(2) Integral Membrane Proteins
(3) Transmembrane Proteins

23
Q

Are proteins that dissociate from the membrane following treatments with polar reagents that do not disrupt the phospholipid bilayer.

A

Peripheral Membrane Proteins

24
Q

Can be released only by treatments that disrupt the phospholipid bilayer.

A

Integral Membrane Proteins

25
Q

Span the lipid bilayer with portions exposed on both sides of the membrane.

A

Transmembrane Protein

26
Q

Types of Membrane Proteins

A

(1) Channel Protein
(2) Carrier Protein
(3) Cell Recognition Protein
(4) Receptor Protein
(5) Enzymatic Protein
(6) Attachment Protein
(7) Intercellular Junction Protein

27
Q

A channel for lipid insoluble molecules and ions to pass freely through.

A

Channel Proteins

28
Q

Binds to a substance and carries it across
the membrane; changes
shape in the process

A

Carrier Protein

29
Q

Binds to chemical messengers (Ex. hormones) which sends a message into the cell causing cellular reaction

A

Receptor Proteins

30
Q

Carry out enzymatic reactions right at the membrane when a substrate binds to the active site

A

Enzymatic Proteins

31
Q

Attach to cytoskeleton (to maintain cell shape and stabilize proteins) and/or the extracellular matrix (integrins connect to both)

A

Attachment Proteins

32
Q

Binds cells together

A

Intercellular Protein

33
Q

Transmembrane Proteins of opposite cells attach in a tight zipper-like fashion

A

Tight Junctions

34
Q

Channel proteins of opposite cells join together providing channels for ions, sugars, amino acids, and other small molecules to pass.

A

Gap Junctions

35
Q

Cytoplasmic plaques of two cells bind with the aid of intermediate filaments of keratin

A

Desmosomes

36
Q

What provided the first evidence that the cell membrane consists of lipid bilayers?

A

Studies of the red blood cell plasma membrane

BIO108: General Physiology (7 decks)

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