Membranes

Question 1

Cystic fibrosis

Answer 1

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

Question 2

Cystic fibrosis molecular proplems

Answer 2

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

Question 3

Plasma membrane

Answer 3

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

Question 4

Internal membranes

Answer 4

Lead to compartmentalization of processes and increased complexity within a cell

Question 5

Fluid mosaic model

Answer 5

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

Question 6

Lipid molecules in the mosaic model

Answer 6

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

Question 7

Lipid molecules in the mosaic model don’t

Answer 7

Often switch sides between the two sections of the bilayer

Question 8

Mosaic aspect of the mosaic model

Answer 8

Occurs because most membranes have many different proteins.

Question 9

Proteins role in the mosaic model

Answer 9

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

Question 10

Anchor proteins

Answer 10

Do not more and anchor the cytoskeleton to the membrane

Question 11

Movement of proteins

Answer 11

In slow because they are bigger than the lipids.

Question 12

Lipids and proteins

Answer 12

Are often attached to carbohydrate groups

Question 13

Mitochondrial membrane

Answer 13

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

Question 14

Plasma membrane composition

Answer 14

Equal parts lipids and proteins

Question 15

Myelin sheath

Answer 15

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

Question 16

Protein asymmetry

Answer 16

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

Question 17

Example of protein asymetry

Answer 17

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

Question 18

Proof of fluid mosaic

Answer 18

Membranes are fluid and membrane asymmetry

Question 19

Membranes are fluid experiment

Answer 19

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

Question 20

Membrane asymmetry

Answer 20

Proved using the freezing fracture technique

Question 21

Freezing factor technique

Answer 21

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

Question 22

Lipid fabric of the membrane

Answer 22

The foundation of all biological membranes

Question 23

Lipids include

Answer 23

Fats; phospholipids and steroids

Question 24

Phospholipids

Answer 24

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

Question 25

Membranes can

Answer 25

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

Question 26

Phospholipid head

Answer 26

Consists of a glycerol linked to an alcohol or amino acid

Question 27

Amphipathic

Answer 27

All phospholipids are. Contain hydrophobic and hydrophilic parts

Question 28

Fatty acid chains

Answer 28

Non polar (hydrophobic)

Question 29

Phosphate containing head

Answer 29

Polar (hydrophilic)

Question 30

Fatty acids can be...

Answer 30

Saturated and unsaturated

Question 31

Saturated

Answer 31

All carbons are bound to the max amount of hydrogens

Question 32

Unsaturated

Answer 32

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

Question 33

In water phospholipids can become

Answer 33

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

Question 34

The hydrophobic effect

Answer 34

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

Question 35

Influences of the lipid bilayers fluidity

Answer 35

The fatty acid and temperature

Question 36

Fatty acids

Answer 36

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

Question 37

Temperature

Answer 37

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.

Question 38

Too cold problems

Answer 38

Decreased permeability, and inhibited function of attached enzymes and receptors

Question 39

Too hot problems

Answer 39

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

Question 40

Organisms that cannot control body temperature

Answer 40

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

Question 41

Fatty acid biosynthesis

Answer 41

The process of forming fatty acids using desaturases

Question 42

desaturases

Answer 42

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

Question 43

All fatty acids start

Answer 43

Saturated

Question 44

desaturase abundance

Answer 44

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

Question 45

Cyanobacterium

Answer 45

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

Question 46

Setrols

Answer 46

Impact membrane fluidity. Ex cholesterol

Question 47

Cholesterol

Answer 47

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

Question 48

Too hot cholesterol

Answer 48

Restrains the movement of lipids

Question 49

Too cold cholesterol

Answer 49

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

Question 50

Membrane protiens

Answer 50

Make each membrane unique

Question 51

4 types of membrane proteins

Answer 51

Transport, enzymatic, signal, attachment/recognition

Question 52

Transport

Answer 52

They can provide hydrophilic channels or shuttle molecules

Question 53

Enzymatic activity

Answer 53

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

Question 54

Signal transduction

Answer 54

Carry information from receptor proteins to the inside of the cell

Question 55

Attachment/recognition

Answer 55

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

Question 56

Integral membrane proteins

Answer 56

Proteins imbedded in phospholipid bilayer

Question 57

Transmembrane proteins

Answer 57

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

Question 58

Transmembrane protein domains

Answer 58

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

Question 59

Alpha helix

Answer 59

A secondary protein structure

Question 60

Amino acid structure

Answer 60

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

Question 61

Length of a lipid bilayer

Answer 61

17-20 amino acids

Question 62

x-membrane spanning domains

Answer 62

The amount of times that a protein spans the membrane

Question 63

Polar amino acids

Answer 63

Exposed to an aqueous solution

Question 64

Peripheral membrane proteins

Answer 64

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

Question 65

Peripheral membrane proteins location

Answer 65

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

Question 66

Peripheral membrane proteins purpose

Answer 66

Have key enzymes for photosynthesis and cellular respiration