Ch 7 Membrane, Structure and Function

Question 1

Plasma Membrane

Answer 1

Selectivly permiable
Primarily made of phospholipid bi-layer
Seperates cell from envoriment

Question 2

Fluid mosaic model

Answer 2

Fluid: Phospholipids can easily move around
Mosaic: Various proteins are embeded in it

Question 3

Cholesterol in plasma membrane

Answer 3

In higher tepms it restrains movement

In lower temps it maintains fluidity by preventing tight packing

Question 4

Membrane Proteins

Answer 4

They type of proteins in the mosaic determin the type of functions it can do.

Question 5

Peripheral Proteins

Answer 5

Bound to the surface of the membrane

Question 6

Integral Proteins

Answer 6

Penetrate the hydrophobic core

Question 7

What can cross the membrane

Answer 7

Polar molecules cannot cross because they will not dissolve in the non-polar tails. Non-polar molecules can cross.

Question 8

6 functions of membrane proteins

Answer 8

Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intercellular joining
Attachment to cytoskeleton and ECM

Question 9

Transport proteins

Answer 9

Allow transport of polar molecules across the membrane. Specific for substances that move.

1. Channel: facilitate passage of water
2. Carrier: bind to molecules and can change shape to bring them in.

Question 10

Enzymatic Activity

Answer 10

Have receptor sites inside the cell for a particular molecule that signals it ti=o carry out a specific function

Question 11

Signal transduction

Answer 11

Proteins that have receptor sites outside the cell that my trigger the cell to undergo changes.

Question 12

Inter-cellular Joining

Answer 12

Proteins may hook together to join cells

Question 13

Cell to Cell recognition

Answer 13

Glygoproteins serve as name tags

Helps the body target foreign bodies and protect it’s own cells

Question 14

Attachment to cytoskelleton and extra-cellular matrix

Answer 14

Cytoskeleton may attach to membrane proteins anchoring it in place.

Question 15

Passive transport

Answer 15

Molecules can move across the membrane with no energy being used. They are moving with the concentration gradient to reach equilibrium.

Question 16

Active transport

Answer 16

Requires energy to move molecules across the membrane, being moved against the concentration gradient. Molecules accumulate in higher # on one side of the membrane

Question 17

Tonicity

Answer 17

The ability inside a cell to gain or lose water

Isotonic, Hypotonic or Hypertonic

Question 18

Osmoregulation

Answer 18

The control of water balance of organisms that don’t live in Isotonic enviroments

Question 19

Plant cell tonicity

Answer 19

Turged: Hypotonic enviroment, cell fills with water
Flaccid: Isotonic, may wilt
Plasmolysis: Hypertonic, lose water and cell membrane pulls away from wall.

Question 20

2 types of passive transport

Answer 20

Simple diffusion

Facilitated diffusion

Question 21

Facilitated difusion

Answer 21

How large polar molecules can move across the membrane using channel proteins or carrier proteins.

Question 22

Active transport

Answer 22

Allows cells to have different concentration gradient than the outside environment. ei sodium-potassium pump.

Question 23

Exocytosis

Answer 23

Transport vesicles migrate to the membrane, merge with it and release their contents outside. Exit

Question 24

Endocytosis

Answer 24

Cell takes in macromolecules by forming vesicles in plasma membrane. Enter
Phagocytosis (cell eating)
Pinocytosis (cell drinking)