Biochemistry Ch 8. Biological Membranes

Question 1

Fluid mosaic model

Answer 1

Accounts for the presence of lipids, proteins, and carbohydrates in a dynamic, semisolid plasma membrane that surrounds cells

Question 2

Phospholipid bilayer components

Answer 2

Lipids primary component both by mass and mole fraction, has proteins embedded in it, carbohydrates and extracellular ligands also present

Question 3

Biological membranes movement

Answer 3

Not static, lipids move freely in the plane of the membrane and can assemble into lipid rafts, proteins and carbohydrates may also move within the membrane but are slowed by their relatively large size, flippases also cause movement

Question 4

Lipid rafts

Answer 4

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Question 5

Flippases

Answer 5

Specific membrane proteins that maintain the bidirectional transport of lipids between the layers of of the phospholipid bilayer in cells

Question 6

Triacylglycerols membrane

Answer 6

Acts as a phospholipid precursors, along with free fatty acids, and are found in low levels in the membrane

Question 7

Free fatty acids membrane

Answer 7

Acts as a phospholipid precursors, along with triacylglycerols, and are found in low levels in the membrane

Question 8

Glycerophospholipids membrane

Answer 8

Replace one fatty acid with a phosphate group, which is often linked to other hydrophilic groups

Question 9

Cholesterol membrane

Answer 9

Present in large amounts and contributes to membrane fluidity and stability

Question 10

Waxes membrane

Answer 10

Present in very small amounts, if at all, they are most prevalent in plants and function in waterproofing and defense

Question 11

Proteins membrane

Answer 11

Located within the cell membrane and can act as transporters, cell adhesion molecules, and enzymes

Question 12

Transmembrane proteins

Answer 12

Can have one or more hydrophobic domains and are most likely to function as receptors or channels

Question 13

Embedded proteins

Answer 13

Most likely part of a catalytic complex or involved in cellular communication

Question 14

Membrane associated proteins

Answer 14

May act as recognition molecules or enzymes

Question 15

Carbohydrates membrane

Answer 15

Can form a protective glycoprotein coat and also function in cell recognition

Question 16

Glycoprotein coat

Answer 16

Created by carbohydrates in biological membranes

Question 17

Extracellular ligands membrane

Answer 17

Can bind to membrane receptors, which function as channels or enzymes in second messenger pathways

Question 18

Cell cell junctions

Answer 18

Regulate transport intracellularly and intercellularly

Question 19

Gap junctions

Answer 19

Allow for the rapid exchange of ions and other small molecules between adjacent cells

Question 20

Tight junction

Answer 20

Precent paracellular transport, but do not provide intercellular transport

Question 21

Paracellular transport

Answer 21

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Question 22

Desmosomes

Answer 22

Anchor layers of epithelial tissue together

Question 23

Hemidesmosomes

Answer 23

Anchor layers of epithelial tissue together

Question 24

Concentration gradients

Answer 24

Help to determine appropriate membrane transport mechanisms in cells

Question 25

Osmotic pressure

Answer 25

A colligative property, the pressure applied to a pure solvent to prevent osmosis and is used to express the concentrations of the solution, conceptualized as a “sucking” pressure in which a solution in drawing water in, proportional to its concentration

Question 26

Colligative property

Answer 26

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Question 27

Passive transport

Answer 27

Does not require energy because the molecules is moving down its concentration gradient or from an area with higher concentration to an area with lower concentration

Question 28

Simple diffusion

Answer 28

Does not require a transporter, small, nonpolar molecules passively move from an area of high concentration to an area of low concentration until equilibrium is achieved

Question 29

Osmosis

Answer 29

Describes the diffusion of water across a selectively permeable membrane

Question 30

Facilitated diffusion

Answer 30

Uses transport proteins to move impermeable solutes across the cell membrane

Question 31

Active transport

Answer 31

Requires energy in the form of ATP or an existing favorable ion gradient, may be primary or secondary depending on the energy source

Question 32

Secondary active transport

Answer 32

Classified as either symport or antiport

Question 33

Endocytosis

Answer 33

Method of engulfing material into cells

Question 34

Exocytosis

Answer 34

Method of releasing material to the exterior or cells

Question 35

Pinocytosis

Answer 35

Ingestion of liquid into the cell in vesicles form from the cell memebrane

Question 36

Phagocytosis

Answer 36

Ingestion of larger, solid molecules

Question 37

Membrane potential

Answer 37

Maintain by the sodium-potassium pump and leak channels

Question 38

Nernst equation

Answer 38

Calculates the electrical potential created by one ion

Question 39

Goldman-Hodgkin-Katz voltage equation

Answer 39

Calculates the resting potential of a membrane at physiological temperature, is derived from the Nernst equation

Question 40

Outer mitochondrial membrane

Answer 40

Different from the cell membrane, highly permeable to metabolic molecules and small proteins

Question 41

Inner mitochondrial membrane

Answer 41

Different from the cell membrane, surrounds the mitochondrial matrix where the citric acid cycle produces electrons used in the electron transport chain and where many other enzymes important in cellular respiration are location, does not contain cholesterol