Life at a Cellular Level

Question 1

What is the difference between and endergonic and an exergonic reaction?

Answer 1

An endergonic reaction occurs when the products are of greater free energy than the reactants (non-spontaneous)
An exergonic reaction occurs when the products are of lesser free energy than the reactants (spontaneous)

Question 2

What is the difference between an anabolic and a catabolic reaction?

Answer 2

Anabolic involves the creation of larger molecules from smaller molecules. This requires energy.
Catabolic reactions involve the breakdown of larger molecules into smaller molecules. This releases energy.

Question 3

Describe the structure of the cell membrane.

Answer 3

Phospholipid bilayer containing proteins and carbohydrates.

Forms a selective barrier to entry into the cell.

Question 4

What is an occluding junction?

Answer 4

A tight junction which seals gaps between epithelial cells.

Question 5

What is a desmosome?

Answer 5

A structure linking keratin filaments in two different cells.

Question 6

What is an adheren?

Answer 6

A structure linking actin filaments in different cells.

Question 7

What is a gap junction?

Answer 7

A channel linking the cytoplasm of two cells together, allowing cell to cell communication.

Question 8

What are the three types of filaments involved in the cytoskeleton?

Answer 8

1. Microfilaments
2. Microtubules
3. Intermediate filaments

Question 9

What is the structure and role of microfilaments?

Answer 9

Made of actin

Involved in movement

Question 10

What is the structure and role of microtubules?

Answer 10

Made of tubulin
Involved in holding contents of cell in place
Involved in cell division
Make up cilia and flagella

Question 11

What is the role of intermediate filaments?

Answer 11

Holds contents of cell in place

Question 12

What are the 5 main chemical reactions occurring within living thongs?

Answer 12

1. Hydrolysis/ Condensation
2. Oxidation/ Reduction
3. Internal rearrangements
4. Making/ Breaking carbon bonds
5. Group transfers

Question 13

What are the two laws of thermodynamics?

Answer 13

1. Energy cannot be created or destroyed, it simply transfers from one form to another.
2. All energy transforms ultimately lead to an increase in entropy (disorder)

Question 14

How does the structure of water allow it to be polar?

Answer 14

Electronegative Oxygen attracts electrons of covalent bonds to a greater extent than the Hydrogen.
This gives the Oxygen a slightly negative charge and the hydrogens a slightly positive charge, creating a polar molecule.

Question 15

How is oxygen transported through the blood?

Answer 15

Using haemoglobin

Question 16

How is carbon dioxide transported through the blood?

Answer 16

As a bicarbonate ion

Question 17

What is the hydrophobic effect?

Answer 17

Non- polar molecules arranging themselves in water to minimise disruption of Hydrogen bonding.

Question 18

What is meant by an amphipathic molecule?

Answer 18

A molecule containing both hydrophobic and hydrophilic regions.
E.g. a phospholipid

Question 19

How are hydrophobic lipids transported in the blood?

Answer 19

Within chylomicron

Question 20

What is meant by a conjugate acid/ base pair?

Answer 20

Proton donor and corresponding proton acceptor.

Question 21

What is the difference between a strong and weak acid?

Answer 21

A strong acid fully dissociates.

A weak acid only partially dissociates

Question 22

What is the Henderson-Hasselbach equation?

Answer 22

pH= pKa + log( [A-]/[HA])

Question 23

Describe the phosphate buffer system within the body?

Answer 23

H2PO4 H+ + HPO4-

Question 24

Where does the phosphate buffer system occur within the body?

Answer 24

Inside the cells

Question 25

Describe the bicarbonate buffer system within the body?

Answer 25

H2CO3 H+ + HCO3-

Question 26

Where does the bicarbonate buffer system occur within the body?

Answer 26

Within the plasma