Chapter 2 - Cellular Activity

Question 1

What is the role of the cell membrane?

Answer 1

The role of the cell membrane is to seperate the contents of the cell (the intracellular components) from the outside of the cell (the extracellular environment).

Question 2

What does differentially permeable membrane mean?

Answer 2

It means that the membrane of the cell is able to regulate what goes into and what comes out of, the cell.

Question 3

What makes up the basic structure of the cell membrane?

Answer 3

• Composed of Phospholipid
• Each Phospholipid has a head (hydrophilic) and a tail (hydrophobic)
• These are arranged into two bilayers

Question 4

What other things can be found in the Cell membrane?

Answer 4

• Proteins (carbohydrates can be connected to these proteins)
• Channel proteins
• Cholesterol

Question 5

What are the main functions of the cell membrane?

Answer 5

1. A physical barrier:
2. The regulation of the passage of materials:
3. Sensativity:
4. Support

Question 6

What are the four different membrane proteins?

Answer 6

1. receptor proteins
2. channel proteins
3. carrier proteins
4. cell-identity proteins

Question 7

What is the difference between diffusion and osmosis?

Answer 7

Diffusion is the movement of particles of a liquid or gas, from a high to a low concentration, so that they are evenly distributed over the available space.

Where osmosis is the movement of water molecules through a differentially permeable membrane from an area of hight to low concentration molecules

Question 8

What is a carrier mediated transport?

Answer 8

Carrier mediated transport is the transport of ions or molecules across a cell membrane by special proteins

Question 9

What are two examples of carrier mediated transport and describe them.

Answer 9

Facilitated diffusion: Is the process whereby carrier proteins assist the movement of substances through the cell membrane

Active transport: is the use of energy to move substances (usually ions) across the cell membrane

Question 10

what is vesicular transport?

Answer 10

Vesicular transport is the movement of substances across the cell membrane in membranous bags called vasicles.

Question 11

what are the two different aspects of vesicular transport?

Answer 11

Endocytosis: which is taking liquid or solids into the cell by vesicular transport

Pinocytosis: talking liquids into the cell

Phagocytosis: taking in solid particles

Exocytosis: when the contents of the vesicle inside the cell are passed to the outside

Question 12

What is a passive transport and name three transports which are passive.

Answer 12

a passive transport is when there is no energy used in the movement of the molecule.

1. Diffusion
2. Osmosis
3. Facilitated Diffusion

Question 13

What is an active transport and name three transports which are active.

Answer 13

Is where to make the movement possible the use of energy is required

1. Active transport
2. Endocytosis
3. Exocytosis

Question 14

What are receptor proteins?

Answer 14

Receptor proteins is a protein in the cell membrane sensitive to certain molecules outside the cell that bind with it

Question 15

why are receptor proteins specific?

Answer 15

Receptor proteins are specific because there is always a specific molecule which has to ‘fit’ in the receptor protein, not just any molecule can fit.

Question 16

Why is there variation in the sensativities of cells to hormones and other substances?

Answer 16

This is due to different cells having different types and numbers of receptor proteins

Question 17

What is the lock and key analogy?

Answer 17

The lock and key analogy refers to the receptor protein having a ‘specific’ molecule to bind to it, exactly like how a specific key opens a specific lock.

Question 18

What is DNA?

Answer 18

Deoxyribonucleic Acid contains a code that is the inherited information, or genes, that have been passed on from the parent cell.

Question 19

DNA is made up of…

Answer 19

thousands of nucleotides. Each nucleotide consists of ribose (a 5-carbon sugar), a phosphate group and a nitrogenous base (a base that contains nitrogen atoms).

Question 20

Name the things which make up the composition of a nucleotide.

Answer 20

• phosphate
• sugar
• nitrogenous base: thymine, guanine, cytosine, adenine

Question 21

What are protein molecules made out of?

Answer 21

Protein molecules are made out of long chains of amino acid molecules bonded together.

Question 22

What are ribosomes?

Answer 22

Ribosomes are tiny organelles in the cytoplasm that can read the transcribed code and join the amino acids together in the order specified by the code.

Question 23

What are the fuctions of proteins?

Answer 23

• structure
• transport across membranes
• communication
• cell metabolism
• recognition
• movement

Question 24

What is an enzyme?

Answer 24

• Enzymes are molecules that are needed for chemical reactions to take place in living cells.
• All enzymes are proteins
• Therefore DNA determines not only the cells structure but also the way in which the cell functions.