T1.3 Membrane Structure

Question 1

Phospholipid

Answer 1

A type of lipid that makes up the cell membrane

Question 2

Phospholipid head

Answer 2

hydrophilic, polar

Question 3

Phospholipid tail

Answer 3

Hydrophobic, nonpolar

Question 4

Amphipathic

Answer 4

Molecule with both polar and nonpolar parts

Question 5

Integral proteins

Answer 5

A protein that’s permanently embedded within the membrane.

Question 6

Transmembrane proteins

Answer 6

A protein that goes totally through the membrane

Question 7

Peripheral proteins

Answer 7

Only temporarily associated with the membrane, can be easily removed from the cell membrane, involved in cell signaling

Question 8

Cholesterol

Answer 8

Interacts with fatty tails of the phospholipids. Moderates the properties of the membrane.:
- Reduces fluidity by immobilizing the outer surface of the membrane
- makes membrane less permeable to small molecules that freely cross
- separates the tails to prevent crystallization
- secures peripheral proteins

Question 9

Glycoprotein

Answer 9

Carbohydrate attached to a protein. Forms distinctive cellular markers that allows cells to recognize each other.

Question 10

Junctions

Answer 10

Membrane proteins connect cells together. Connections between cells that are from multiprotein complexes found in animal cell membranes.

Question 11

Enzymes

Answer 11

Membrane proteins can be enzymes, which speeds up the rate of specific chemical reactions in the cell.

Question 12

Transport

Answer 12

Membrane proteins transport molecules, ions, or substrates across the membrane

Question 13

Cell Recognition

Answer 13

Membrane proteins have glycoproteins that have carbohydrate chains that are unique to the cell, letting other cells recognize each other.

Question 14

Anchorage/Attachment

Answer 14

Membrane proteins attach things to the membrane, such as peripheral proteins, or anchorage the cell onto something

Question 15

Signal Transduction

Answer 15

Membrane proteins take part in transferring molecular signals from the cells exterior to its interior.

Question 16

Davson-Danielli model

Answer 16

The phospholipids are sandwiched between a protein layer.

Question 17

2 Pieces of evidence used to create the Davson-Danielli Model of the membrane

Answer 17

In high magnification, membranes appeared as two dark lines with a lighter colored region in between.
Since proteins are normally dark in EM and phospholipids appear lighter, the membranes had a phospholipid and protein layers

Question 18

What main membrane function did the Davson-Danielli model explain?

Answer 18

The membranes ability to be a barrier despite being thin

Question 19

4 shortcomings of the DD Model

Answer 19

1) Assumed all membranes had identical structures, were of uniform thickness, and a constant lipid:protein ratio, did not explain how membranes could carry out different functions
2) Assumed al membranes would have symmetrical internal and external surfaces
3) Did not account for the permeability of certain substances (pores? nah they totally don’t need that)
4)The temps at which membranes solidified did not correlate with those expected with the proposed model

Question 20

3 pieces of Falsification Evidence for the Davson-Danielli Model

Answer 20

1) Flourescent antibody tagging of membrane proteins: showed they were mobile
2) Freeze fracturing: split open membrane and revealed irregular rough surfaces (bumps were interpreted as transmembrane proteins)
3) Proteins were insoluble in water and varied in size: meant they would not be able to form a uniform layer and not interact with water.

Question 21

Can you draw the fluid mosaic membrane????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

Answer 21

you better

link to video

Question 22

Polarity of channel proteins

Answer 22

Inside is polar and outside is nonpolar

Question 23

What are the six functions of proteins

Answer 23

Enzymes,
Signal Transduction,
Junctions,
Anchorage/Attachment,
Cell Recognition,
Transport