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BIO 190: UNIT 1 > Chapter 5: Membranes: The Interface Between Cells and Their Environment > Flashcards

Chapter 5: Membranes: The Interface Between Cells and Their Environment Flashcards

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1
Q

What are the 2 primary components that make up membranes?

A

phospholipids and proteins

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2
Q

What is the key feature of the phospholipid bilayer ?

A

It’s amphipathic; hydrophilic heads face outward and hydrophobic tails face inward

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3
Q

TRUE OR FALSE: Lipids and proteins work against each other

A

FALSE, lipid and proteins work together to carry out various functions in a cell.

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4
Q

What is the main characteristic of a TRANSMEMBRANE PROTEIN?

A

A transmembrane protein spans to both layers (leaflets) of the phospholipid bilayer

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5
Q

Where is a lipid-anchored protein located ?

A

They are located in HYDROPHOBIC areas of the membrane; the amino acid of the protein is covalently attached to a lipid

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6
Q

Where are peripheral membrane proteins located ?

A

They are either non-covalently bonded to parts of other proteins or located in the hydrophilic(polar) regions of the phospholipid bilayer.

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7
Q

What are the two integral proteins ?

A

Transmembrane proteins and lipid-anchored proteins; they are integrated into a hydrophobic region of the phospholipid bilayer.

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8
Q

Is the structure of a membrane fluid?

A

It’s semifluid; lipids and proteins can move in 2 dimensions within the plane of the membrane

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9
Q

How does the length of non polar tails affect the fluidity of a membrane?

A

The shorter the tail, the less likely they are to interact thus creating a more fluid membrane

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10
Q

How does the presence of double bonds effect fluidity ?

A

Double bonds prevent phospholipids from packing tightly, making it more fluid.

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11
Q

Define SELECTIVE PERMEABILITY

A

Membranes allow some molecules and ions to pass but not all; allows cells to maintain a favorable internal environment.

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12
Q

How does simple diffusion move ?

A

down the gradient WITHOUT the use of a transport protein

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13
Q

How does facilitated diffusion move?

A

Down the gradient WITH the use of a transport protein

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14
Q

What makes active transport different from simple and facilitated diffusion ?

A

Substances move AGAINST the gradient, WITH aid of a transport protein AND requires energy

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15
Q

When is a gradient present?

A

When concentration solute is uneven from one side to the other.

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16
Q

Why do cells have gradients ?

A

to maintain internal and external environment

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17
Q

What is a solution called when it has the SAME concentration on both sides of the membrane ?

A

ISOTONIC

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18
Q

What is a solution called when it has HIGHER concentration on the outside than the inside of the membrane ?

A

HYPERTONIC

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19
Q

What kind of solution has LOWER concentration on the outside of the membrane ?

A

HYPOTONIC

20
Q

What is the term for water diffusion across a membrane from high to low?

A

Osmosis

21
Q

What are the two types of passageways for cells to interact ?

A

Channels and Transporters

22
Q

What is the difference between channels and transporters ?

A

Transporters have specific binding sites for ions, and they go through structural changes.

23
Q

What is the difference between PRIMARY active transport and SECONDARY active transport?

A

Primary active transport directly uses ATP while secondary uses stored ATP

24
Q

What is the function of a gap junction? What about plasmodesmata?

A

Gap junctions (in animal cells) provide passageways for intercellular transport; plasmodesmata (in place cells) are channels that connect the cytoplasm of adjacent cells

25
Q

An animal cell is placed in pure water (which contains no solutes). In what direction will water move?

A

Water will move into the cell from the outside because water moves from areas of high free water concentration to areas of lower water concentration.

26
Q

What is this an image of? Label 1-9.

A

This is a close up of a phospholipid bilayer. 1) integral membrane protein, 2) glycoprotein, 3) glycolipid, 4) carbohydrate, 5) phospholipid bilayer, 6) extracellular leaflet, 7) cytosolic leaflet, 8) cholesterol, 9) peripheral membrane proteins

27
Q

T or F: The two leaflets of a lipid bilayer are formed because the non polar phospholipid tails can interact with the polar interior and the exterior of the cell.

A

FALSE; the POLAR head groups of the phospholipids can interact with the polar interior and exterior of the cell

28
Q

What is this an image of? Label 1-4.

A

This is a close up of the phospholipid bilayer. 1) transmembrane protein, 2) lipid, 3) lipid-anchored protein, 4) peripheral membrane protein

29
Q

Cellular membranes play a role in which cell functions?

A

1) cell and nuclear division
2) cell signaling
3) anchoring the cytoskeleton
4) protein sorting

30
Q

What are the three molecular components of cellular membranes?

A

carbohydrates, phospholipids, and proteins

31
Q

The cell membrane is referred to as a mosaic because it is a mixture of what types of molecules?

A

carbohydrates, lipids, and proteins

32
Q

Define exocytosis.

A

The process by which cells move materials from within the cell into the extracellular fluid, via vesicles

33
Q

What are the three biochemical properties of phospholipids that affect fluidity?

A

1) length of non-polar tails
2) presence of double bonds
3) presence of cholesterol (in animal cells)

34
Q

What is one way that solutes that cannot diffused across the membrane can still gain access to the interior of the cell?

A

transport proteins

35
Q

This is a close up of the phospholipid bilayer in the cell membrane. Label 1-5.

A

1) fiber in the ECM, 2) plasma membrane, 3) cytoskeletal filament, 4) linker protein, 5) transmembrane protein

36
Q

This is an image of three different types of diffusion. Label them, left to right.

A

Left: simple diffusion
Middle: facilitated diffusion
Right: active transport

37
Q

The ability of solutes to cross the bilayer by simple diffusion depends on what?

A

size (small diffuse faster than large), polarity (non polar diffuses faster than polar), and charge (non-charged diffuse faster than charged)

38
Q

Passive transport is energetically ______ and tends to _______ the magnitude of a pre-existing gradient.

A

favorable; decrease

39
Q

The primary difference between endocytosis and exocytosis is?

A

the direction of transport

40
Q

Label a-c.

A

a) isotonic
b) hypertonic
c) hypotonic

41
Q

This is an image of different types of transporters. Label a-c.

A

a) uniporter
b) symporter
c) antiporter

42
Q

This is an image of two types of active transport. Label them.

A

a) primary active transport
b) secondary active transport

43
Q

There are four different types of anchoring junctions. This is an image of all four. Label a-d. Label 1-4.

A

a) adherens junctions
b) desmosomes
c) hemidesmosomes
d) focal adhesions
1) cadherins
2) intermediate filaments
3) linker proteins
4) actin filament

44
Q

What is the function of an anchoring junction? What about a tight junction?

A

anchoring junctions link cells to each other and to the ECM; tight junctions form a tight seal between cells and prevent material from leaking between adjacent cells

45
Q

1) Materials inside the cell are packaged into vesicles and excreted to the extracellular environment.

2)The plasma membrane invaginates to form a vesicle that brings substances into the cell.

Name these two processes.

A

1) exocytosis
2) endocytosis

46
Q

During osmosis, what direction does water move across a plasma membrane?

A

Toward the side with a hypertonic concentration of solutes.

47
Q

The sodium-potassium pump functions to pump?

A

sodium ions out of the cell and potassium ions into the cell

BIO 190: UNIT 1 (5 decks)

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