1.5 Cell Membrane

Question 1

what is the primary function of the cell membrane?

Answer 1

to regulate the transport of materials in and out of the cell

-protects the cell from its surroundings and separates interior from exterior

Question 2

what does it mean for the cell to be selectively permeable?

Answer 2

means its can only allow certain substances to go through

Question 3

what macromolecules make up the majority of the cell membrane structure? what is the primary function of this molecule?

Answer 3

the majority of the cell is composed of lipids which make up phospholipids. its primary function if to form the double membrane which is selectively permeable

Question 4

describe the structure and function of a fibrous protein.

Answer 4

it is tightly coiled and rod-shaped. its function is the support, shape and expands the cell membrane. it also communicates with the external environment using hormones and neurotransmitters

Question 5

describe the structure and function of an integral protein.

Answer 5

It is globular shaped. Its function is to help communicate to the external environment and acts as a transport molecule with a channel

Question 6

describe the structure and function of an peripheral protein.

Answer 6

It is globular shaped. Its function is to help communicate to the external environment and transport molecules including enzymes and glycoproteins which have carbohydrate association

Question 7

what types of molecules can easily cross the membrane?

Answer 7

lipid soluble and very small molecules

Question 8

why must some molecules use a protein transport molecule to pass the cell membrane

Answer 8

large, charged and water-soluble molecules due to the hydrophobic nature of the molecule

Question 9

what are the three basic chemical components of the phospholipid?

Answer 9

the phospholipid consists of a glycerol molecule, two fatty acids, and a phosphate group

Question 10

why is the phospholipid described as being amphipathic?

Answer 10

has both polar and non polar parts

Question 11

explain why the phospholipid orientates the way it does to create the cell membrane.

Answer 11

due to the hydrophobic effect, when the head faces towards the solute because the heads are hydrophilic and the tails face inward because they are hydrophobic

Question 12

what special property of the cell membrane is made possible due to the chemical structure of the phospholipid?

Answer 12

allows the membrane to be fluid and selectively permeable

Question 13

what role does cholesterol play in the cell membrane? describe the chemical structure

Answer 13

cholesterol strengthens the cell and alters its fluidity thickness and compressibility. Cholesterol is a 27-carbon compound with a unique structure, a hydrocarbon tail, a central sterol nucleus made of four hydrocarbon rings, and a hydroxyl group.

Question 14

why do you think the cell membrane model we use is called the fluid mosaic model?

Answer 14

the term mosaic refers to the mixture of phospholipids, cholesterol, proteins, and carbohydrates. the term fluid refers to the fact that the membrane can move

Question 15

what does it mean chemically for a fatty acid to be saturated or unsaturated?

Answer 15

They both have a carboxyl group. Saturated fatty acids have a perfectly straight chain structure and have the maximum number of hydrogens. Unsaturated ones are typically bent and have less than the maximum number of hydrogens possible

Question 16

what is the structure of glycerol?

Answer 16

Glycerol is the three-carbon backbone of triglycerides

Question 17

what goes through the cell membrane easily?

Answer 17

carbon dioxide, oxygen, lipids

Question 18

what doesn’t go through the cell easily?

Answer 18

charges atoms, large molecules, water

Question 19

what percent of the cell membrane consist of protein

Answer 19

50%

Question 20

what does the term transmembrane tell you about the function of a protein

Answer 20

the proteins penetrate all the way through and form chanells for transporting specific proteins

Question 21

how does the spring-like, helical, shape of proteins help move molecules across the membrane?

Answer 21

they use their shape to trap ions that undergo a series of conformational changes to transfer the bound solute across the cell membrane

Question 22

how might a large molecule cross the membrane?

Answer 22

proteins transverse the membrane as beta sheets rolled into basket-like chanells that allow large molecules to pass.

Question 23

what is the structure and function of glycocalyx?

Answer 23

attach to proteins and lipid, states the cell identity

Question 24

how might a larger molecule enter the cell such as a virus?

Answer 24

it enters via membrane invagination where part of the membrane indents and fully engulfs the particles for entry. some viruses have cells that fuse with the cell membrane