Chapter 3

Question 1

What is the plasma membrane?

Answer 1

The plasma membrane is a semi permeable phospholipid bilayer that seperates the intracelullar environment and the extracellular environment. It is embedded with cholesterol to regulate fluidity, carbohydrates for cell signalling, and multi functional proteins

Question 2

What are phospholipids?

Answer 2

The main component of the phospholipid bilayer. They have a phosphate head, which is hydrophillic, and 2 fatty acid tails that are hydrophobic. They arrange in pairs, with the tails pointing inwards and the heads pointing outwards- forming the billayer

Question 3

What is cholesterol?

Answer 3

A lipid steroid embedded in the phospholipid billayer that regulates the fluidity of the membrane. At higher temperatures the cholesterol keeps the phospholipid bound together, whereas in low temperatures the cholesterol keeps the membrane fluid and prevents it from forming a solid boundary

Question 4

What are carbohydrates?

Answer 4

usually in chains outside the cell, rooted in the membrane to lipids ( glycolipids), or proteins ( glycoproteins). They aid with cell to cell communication, signalling, recognition of self/ non self molecules, and adhesion

Question 5

What are integral proteins?

Answer 5

proteins that are a permenant part of the membrane, aids with transport, channels or pumps, that control what enters and exits the cell

Question 6

What is a transmembrane protein?

Answer 6

an integral protein that spans from the inside to the outside of the bilayer

Question 7

What is a peripheral protein?

Answer 7

Temporary proteins that attach to the outside of the membrane

Question 8

What is the cytoskeleton?

Answer 8

the microscopic web of protein filaments in the cytoplasm. It provides structure, support, and transports products around the cell

Question 9

What does the fluid mosaic model mean?

Answer 9

describes the fluid nature of the phospholipid, which is composed of phospholipids, proteins and carbohydrates which looks similar to a mosaic

Question 10

What does polar mean?

Answer 10

polar describes a molecule with both a positive end a negative end. These tend to be hydrophillic

Question 11

What does nonpolar mean?

Answer 11

nonpolar describes a molecule without a clearly positive or negative end. These tend to be hydrophobic

Question 12

What is passive transport?

Answer 12

The movement of molecules across a membrane without the use of energy. Diffusion, facilitated diffusion, and osmosis are three types of passive transport

Question 13

What is diffusion?

Answer 13

The passive movement of molecules from an area of high concentration to an area of low concentration (down the concentration gradient).
Small, nonpolar molecules most commonly use this means of transport

Question 14

What is facilitated diffusion?

Answer 14

The passive movement of molecules down their concentration gradient through a membrane protein. This occurs to large and/ or polar molecules like glucose. The charge, and size of these proteins means they can’t diffuse easily through the plasma membrance, instead they must go through a protein channel or protein carriers.

Question 15

What is a protein channel?

Answer 15

pores or holes in the plasma membrane that let a specific substance through. They open or close depending on whether that cell requires that substance or not

Question 16

What are carrier proteins?

Answer 16

carrier proteins bind to the substance that is being transported and undergo a conformational change to push the substance to the other side of the membrane. They return to their original shape once the molecule has been transported.

Question 17

What is osmosis?

Answer 17

A type of diffusion. It occurs when water moves across a selectively permeable membrane from areas of low solute concentration to areas of high solute concentration. Until it has reached equillibrium

Question 18

What does hypotonic mean?

Answer 18

describes a solution with a lower solute concentration when compared to another

Question 19

What does hypertonic mean?

Answer 19

describes a solution with a higher solute concentration when compared to another

Question 20

What does isotonic mean?

Answer 20

describes a solution with the same solute concentration when compared to another

Question 21

What is active transport?

Answer 21

Active transport uses energy to transport molecules across the plasma membrane, against their concentration gradient. This can be through the means of membrane proteins, or through bulk transport

Question 21

What is active transport?

Answer 21

Active transport uses energy to transport molecules across the plasma membrane, against their concentration gradient. This can be through the means of membrane proteins, or through bulk transport

Question 22

What is ATP?

Answer 22

Adenosine triphosphate, a high energy molecule that when broken down provides energy for cellular processes

Question 23

What is a protein pump ?

Answer 23

A protein pump is a polypeptide that transports molecules across a membrane against its concentration gradient with the aid of ATP

Question 24

What is bulk transport?

Answer 24

Bulk transport is a type of active transport that uses vesicles to move large molecules or groups of molecules into or out of the cell

Question 25

Define exocytosis

Answer 25

The process by which large substances are moved out of the cell. A vesicle inside the cell containing secretory products is transported to the plasma membrane. The membrane of the vesicle and cell fuse, releasing the secretory products

Question 26

Define vesicle

Answer 26

A small, fluid filled organelle enclosed in a phospholipid membrane that transports substances around the cell

Question 27

Define ribosome

Answer 27

an organelle made of rRNA and protein that is the site of protein synthesis. Can be free or attached to the RER

Question 28

What are the steps of protein secretion?

Answer 28

1. Ribosome synthesises the protein 2. The Rough endoplasmic reticulum (RER) folds and transports the proteins 3. Transport vesicle containing the proteins bud off the RER and travel to the golgi body and fuses with the golgi membrane, releasing the protein into the lumen 4. Golgi body modifies and packages the protein 5. Secretory vesicle containing proteins buds off the golgi body, and undergoes exocytosis

Question 29

Define golgi body

Answer 29

An organelle made of flattened sacs of membrane involved in modifying, sorting and packaging proteins

Question 30

Define mitochondria

Answer 30

Mitochondria are membrane-bound cell organelles (mitochondrion, singular) that generate most of the chemical energy needed to power the cell's biochemical reactions. Chemical energy produced by the mitochondria is stored in a small molecule called adenosine triphosphate (ATP).

Question 31

Define endocytosis

Answer 31

A type of bulk transport that moves large substances into the cell. This occurs first with the plasma membrane folding inwards to capture extracellular fluid and the target moleculars. The membrane continues to fold until the two ends fuse, trapping the target molecules in the vessel. The vesicle then buds off the membrane, and then can be transported to the apporpriate cellular location, or fused with a lysosome for digestion

Question 32

Define lysosome

Answer 32

A vesicle containing digestive enzymes

Question 33

Define phagocytosis

Answer 33

endocytosis of solid material or food particles

Question 34

Define pinocytosis

Answer 34

endocytosis of liquid, or dissolved particles