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Bio 204 > Membranes > Flashcards

Membranes Flashcards

1
Q

Cystic fibrosis

A

Occurs due to improper gene encoding, leads to impaired lung and gastral impairment, no cure lung transplant is often needed

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2
Q

Cystic fibrosis molecular proplems

A

No cl leaves cells, so no sodium enters, so no water enters the cells resulting in dry thick mucus build up

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3
Q

Plasma membrane

A

A semipermeable membrane for the uptake of nutrients and the deposits of waste

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4
Q

Internal membranes

A

Lead to compartmentalization of processes and increased complexity within a cell

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5
Q

Fluid mosaic model

A

Current view of the cell membrane. Proteins float around lipids rather than exist in a ridged form

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6
Q

Lipid molecules in the mosaic model

A

Exist in a bilayer less than 10nm. They vibrate, flex back and forth, spin on their axis, and move sideways to switch places with other lipids

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7
Q

Lipid molecules in the mosaic model don’t

A

Often switch sides between the two sections of the bilayer

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8
Q

Mosaic aspect of the mosaic model

A

Occurs because most membranes have many different proteins.

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9
Q

Proteins role in the mosaic model

A

Transport, attachment, signal, transduction, electron transport and anchor protiens

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10
Q

Anchor proteins

A

Do not more and anchor the cytoskeleton to the membrane

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11
Q

Movement of proteins

A

In slow because they are bigger than the lipids.

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12
Q

Lipids and proteins

A

Are often attached to carbohydrate groups

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13
Q

Mitochondrial membrane

A

Their main job is electron transport so they are high in protein and low in fat

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14
Q

Plasma membrane composition

A

Equal parts lipids and proteins

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15
Q

Myelin sheath

A

Insulates nerve fibers. Is high in fats and low in protein

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16
Q

Protein asymmetry

A

Proteins on one side of the bilayer are different to those on the other because each side has different functions

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17
Q

Example of protein asymetry

A

Glycolipids, carbohydrate groups, hormones and growth factors are on the outside while proteins that bind to the cytoskeleton are on the inside

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18
Q

Proof of fluid mosaic

A

Membranes are fluid and membrane asymmetry

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19
Q

Membranes are fluid experiment

A

1970 Frye and Edidin grew a human and mouse cell while staining their proteins different colors. When the cells were combined they watched the proteins mix

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20
Q

Membrane asymmetry

A

Proved using the freezing fracture technique

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21
Q

Freezing factor technique

A

A block of cells is rapidly frozen in liquid nitrogen and then split open separating the bilayers. With an electron microscope researchers observed different proteins

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22
Q

Lipid fabric of the membrane

A

The foundation of all biological membranes

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23
Q

Lipids include

A

Fats; phospholipids and steroids

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24
Q

Phospholipids

A

Dominant lipid in membranes. They have a head and two long hydrocarbon chains called fatty acids

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25
Q

Membranes can

A

Adjust to a change in lipids as long as the consistency stays the same

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26
Q

Phospholipid head

A

Consists of a glycerol linked to an alcohol or amino acid

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27
Q

Amphipathic

A

All phospholipids are. Contain hydrophobic and hydrophilic parts

28
Q

Fatty acid chains

A

Non polar (hydrophobic)

29
Q

Phosphate containing head

A

Polar (hydrophilic)

30
Q

Fatty acids can be…

A

Saturated and unsaturated

31
Q

Saturated

A

All carbons are bound to the max amount of hydrogens

32
Q

Unsaturated

A

Includes double bonds between carbons, resulting in kinks in the chain

33
Q

In water phospholipids can become

A

Micelle, liposome, of a bilayer. Depends on their concentration and they hydrophobic effect

34
Q

The hydrophobic effect

A

Polar molecules reject hydrophobic molecules. The tails hide from the water and the lowest energy state is reached.

35
Q

Influences of the lipid bilayers fluidity

A

The fatty acid and temperature

36
Q

Fatty acids

A

Saturated are tightly packed and rigid where as unsaturated and loosely packed and have more fluidity

37
Q

Temperature

A

If it is cooled the motion slows and then stops leading to a semi solid gel. The more unsaturated the cooler it can get before it hardens.

38
Q

Too cold problems

A

Decreased permeability, and inhibited function of attached enzymes and receptors

39
Q

Too hot problems

A

The membrane becomes too fluid and Na+, K+, Ca2+ can flow too easily killing the cell

40
Q

Organisms that cannot control body temperature

A

Control the permeability of their membranes by changing the amount of saturated and unsaturated lipids there are

41
Q

Fatty acid biosynthesis

A

The process of forming fatty acids using desaturases

42
Q

desaturases

A

A group of enzymes that take saturated fatty acids and remove a H+ from two carbons and introduce a double bond between them

43
Q

All fatty acids start

A

Saturated

44
Q

desaturase abundance

A

Multiple are needed to make multiple double bonds. Their production is regulated by gene transcription

45
Q

Cyanobacterium

A

A bacteria that shows the relationship between a decrease in temperature and a increase in desaturase transcript, desaturase enzyme and in unsaturated fatty acids

46
Q

Setrols

A

Impact membrane fluidity. Ex cholesterol

47
Q

Cholesterol

A

Found in animals, not plants or prokaryotes. Acts as a buffer to maintain proper fluidity

48
Q

Too hot cholesterol

A

Restrains the movement of lipids

49
Q

Too cold cholesterol

A

Goes between fatty acids and prevents them from associating with each other

50
Q

Membrane protiens

A

Make each membrane unique

51
Q

4 types of membrane proteins

A

Transport, enzymatic, signal, attachment/recognition

52
Q

Transport

A

They can provide hydrophilic channels or shuttle molecules

53
Q

Enzymatic activity

A

Many enzymes are membrane proteins, such as the respiratory and photosynthetic electron transport chain.

54
Q

Signal transduction

A

Carry information from receptor proteins to the inside of the cell

55
Q

Attachment/recognition

A

Exposed to the internal and external membrane, attachment points for the cytoskeleton, and cell to cell recognition

56
Q

Integral membrane proteins

A

Proteins imbedded in phospholipid bilayer

57
Q

Transmembrane proteins

A

IMP that transverse the whole lipid layer, they have domains. Primarily polar amino acids

58
Q

Transmembrane protein domains

A

Regions with very different polarity. Made up of nonpolar amino acids that form an alpha helix

59
Q

Alpha helix

A

A secondary protein structure

60
Q

Amino acid structure

A

A primary structure the allows us the determine the transmembrane protein. Mostly non polar

61
Q

Length of a lipid bilayer

A

17-20 amino acids

62
Q

x-membrane spanning domains

A

The amount of times that a protein spans the membrane

63
Q

Polar amino acids

A

Exposed to an aqueous solution

64
Q

Peripheral membrane proteins

A

Extracellular and are held on by hydrogen and ionic bonding with integral proteins and membrane lipid molecules. A mixture of polar and non polar membranes

65
Q

Peripheral membrane proteins location

A

The cytoplasm side of the membrane and are part of the cytoskeleton.

66
Q

Peripheral membrane proteins purpose

A

Have key enzymes for photosynthesis and cellular respiration

Bio 204 (23 decks)

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