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Flashcards in Chapter 7 Deck (56):
1

Ampiphatic

A molecule containing both hydrophilic and hydrophobic areas

2

What does the fluid mosaic model state?

That the membrane is a fluid structure with various proteins embedded into it

3

Why can phospholipids move within bilayer?

Hydrophobic interactions are weak

4

What are the two kinds of phospholipid movements?

Lateral (more often) and flip-flop

5

Why do phospholipids in membrane move around?

Create heat to prevent solidification

6

A membrane is fluid in ______ conditions

warmer

7

Cells in colder climates have more ______ to prevent ________

unsaturated hydrocarbon tails
solidificiation

8

How is cholesterol a buffer in both high and low temperatures?

High: cholesterol makes bilayer less fluid by restraining phospholipid movement
Low: cholesterol hinders close packing of proteins, lowering temperature required for solidification

9

What determines the function of the membrane?

Proteins

10

Integral proteins

Proteins that penetrate through whole bilayer

11

Peripheral proteins

Proteins loosely binded to membrane surface

12

Transmembrane proteins

Peripheral proteins that span membrane

13

What does the hydrophobic region of integral proteins consist of?

1 or more stretches of non polar amino acids coiled into alpha helices

14

Major functions of membrane proteins

Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton and extracellular matrix

15

How do cells recognize eachother?

By binding to surface molecules (often carbs) on membrane

16

Membrane carbs may be bonded to ______, creating _______, or more commonly bonded to _______, creating ____________

-bonded to lipids, forming glycolipid
-bonded to proteins, forming glycoprotein

17

Exchange of material with surroundings is controlled by what?

Membrane

18

______ molecules can pass through membrane easily

Hydrophobic

19

List hydrophobic molecules that can pass through membrane

Carbon dioxide, oxygen, hydrocarbons

20

_____ molecules can not cross membrane easily

Polar

21

List some molecules that cannot pass membrane easily

Sugar, water

22

What allows passage of hydrophilic substances

Transport proteins

23

Transport proteins

Allows passage of hydrophilic substances

24

Channel proteins

Transport protein with hydrophilic channel that certain molecules and ions can use as a tunnel

25

Aquaporin

Channel protein that facilitates passage of water

26

Carrier proteins

Transport proteins that bind to molecules and change shape to shuttle across membrane

27

Transport protein is specific to _______

substance that it moves

28

Diffusion

Tendency for molecules to spread out evenly into available space

29

Rule of diffusion

Diffusion of population exhibits net movement in one direction

30

Dynamic equilibrium

where as many molecules cross one way as the other way

31

Concentration gradient

Difference in concentration of substance from one area to another

32

Osmosis

Diffusion of water across selectively permeable membrane

33

Tonicity

Ability of a solution to cause cell to gain/lose water

34

What does tonicity depend on?

The concentration of solutes that cannot cross the membrane

35

Osmoregulation

Control of water balance necessary for adaption to life in hypertonic/hypotonic conditions

36

What's special about the Paramecium?

Pond is hypotonic to cell (water moves into cell), so it has contractile vacuole that acts as a pump

37

Plant cell in hypotonic solution is calledf

Turgid

38

Plant cell in hypertonic solution causes lethal effect called....

Plasmolysis

39

Facilitated diffusion

Passive transport quickened by aid of transport proteins

40

Facilitated diffusion, what do channel proteins do?

-Provide corridors for molecules/ions to move across
-Aquaporins and ion channels

41

Active transport

Movement of substances against concentration gradient, requiring energy

42

Active transport is performed by what?

Carrier proteins

43

What does active transport allow for cell to do?

Maintain concentration gradient different from surroundings

44

What does the sodium-potassium pump do?

Exchanges sodium for potassium across membrane to maintain steep concentration differences

45

How do large molecules cross in bulk?

Packaging into vesicles, requiring energy

46

Exocytosis

Transport vesicles migrate to membrane, fuse, and release contents

47

In which cells is exocytosis useful?

Secretory cells (to export products)

48

Endocytosis

Cells take in macromolecules by forming vesicles from plasma membrane

49

Types of endocytosis

Phagocytosis, pinocytosis, receptor-mediated endocytosis

50

Phagocytosis

Cell engulfs particle in a vacule

51

How is the vacuole created in phagocytosis digested?

When fused with lysosomes

52

Pinocytosis

Cell gulps droplets of extracellular fluid into tiny vesicles

53

Receptor-mediated endocytosis allows...

Allows human cells to take cholesterol in for use in synthesis of membranes/steroids

54

Ligands

Any molecule that binds specifically to receptor site of another molecule

55

Receptor-mediated endocytosis

Binding of ligands to receptor, creating a vesicle

56

Aquaporins speed up....

Rate at which water reaches water potential equilibrium