Life at a Cellular Level

Question 1

How do energy transformations in general affect overall entropy?

Answer 1

Energy transformations ultimately lead to increased entropy in the universe

Question 2

How come processes in living organisms that increase order dont actually decrease entropy?

Answer 2

Although the processes create more order, the heat released increases overall entropy

Question 3

Define a dynamic steady state?

Answer 3

A continuous state of materials being supplied & waste removed.
In terms of bio reaction pathways, products from one are used in the next pathway & so never allowed to reach equilibrium.

Question 4

Define Metabolism:

Answer 4

Chemical processes in a living organism that allow food to be used for growth

Question 5

Define Anabolism:

Answer 5

Non-spontaneous reactions, i,e, occur with a +ve delta-G value

Question 6

Define Catabolism?

Answer 6

Spontaenous reactions. I.e. occur with a -ve delta-G value

Question 7

How are catabolic & anabolicreactions related?

Answer 7

Energy produced in catabolic is used in anabolic

Question 8

What is ATP/ADP?

Answer 8

A free energy carrier

Question 9

What does ATP/ADP do?

Answer 9

Couples anabolic & catabolic reactions through the movement of energy by phosphate group transfers

Question 10

NAme the 10 major elements in humans?

Answer 10

Oxygen
Hydrogen
Nitrogen
Carbon
Sodium
Potassium
Sulphur
Phosphorous
Chlorine
Calcium

Question 11

What are functional groups important?

Answer 11

They determine how a molecule acts with others.

E.g. OH lets H bonds & water-solubility. S groups allows di-sulphide bridges

Question 12

Define configuration of a molecule?

Answer 12

Fixed arrangement of atoms in a molecule.

E.g. Cis & trans

Question 13

Define Conformation of a molecule?

Answer 13

Precise not fixed arrangement of atoms in a molecule. (those with free rotation etc)

Question 14

List the 5 types of chemical ractions that occur in living organisms:

Answer 14

• Redox Reactions
• C-C bonds makin/brakin
• Internal rearrangements
• Group transfers
• Condensation/Hydrolysis

Question 15

Example of redox reaction:

Answer 15

Glucose->pyruvate->lactate

Question 16

Example of Internal reaarangement:

Answer 16

Glucose-6-Phosphate -> Fructose-6-Phosphate

part of glycolysis

Question 17

What is cytosol?

Answer 17

The organelles & fluid of the cytoplasm

Question 18

What do nucleoli do?

Answer 18

Site of ribosomal RNA synthesis & ribosomal assembly

Question 19

What does the Smooth ER do?

Answer 19

Synthesises lipids, membranes & repairs them.

Question 20

How many subunits make up a ribosome?

Answer 20

2

Question 21

What does the golgi apparatus synthesise?

Answer 21

Complex polysaccharides

Question 22

What do peroxisomes do?

Answer 22

Contain:=

• Catalases that regulate Hydrogen Peroxide conc.
• Oxidases that do the first part of long chain FA beta-oxidation

Question 23

Whats the function of the cytoskeleton?

Answer 23

Provide strength & support whilst still allowing for cell motility

Question 24

What 2 things make up the cytoskeleton?

Answer 24

Microfilaments

Microtubules

Question 25

What are microfilaments?

Answer 25

Fine actin strands

Components of cytoskeleton

Question 26

What are microtubules?

Answer 26

Components of cytoskeleton

Question 27

What other things do microfilaments/tubules do?

Answer 27

• Microfilaments form microvilli in small intestine

- 9 pairs of Microtubules form cilia

Question 28

Whats the flagellum?

Answer 28

Thin threadlike appendages on cells that allow for movement

Question 29

Define a hydrogen bond?

Answer 29

A special bond between an electronegative atom (usually N or O) and an electropsositve H.
The H must be attached to an electronegative atom already

Question 30

How are H bonds involved in water solubility?

Answer 30

The solute-solute H bond & water-water H bond are replaced by water-solute H bonds

Question 31

Are uncharged molecules water soluble?

Answer 31

No

Question 32

How do uncharged molecules arrange in water?

Answer 32

So as to minimise disruption to water molecules, forming ‘cages’

Question 33

Define Ampithatic?

Answer 33

Contains both hydrophobic & hydrophilic parts.

Question 34

Example of ampithatic molecules?

Answer 34

Phospholipids have hydrophilic phosphate heads & hydrophobic FA tails

Question 35

How do phospholipids arrange in water to minimise disruption?

Answer 35

Into bilayers or round micelles which distance the hydrophobic end from the water molecules.

Question 36

What is pH?

Answer 36

proton conc.

pH = -log[H+]

Question 37

Henderson-Hasselbach equation:

Answer 37

pH = pKa + log [conjugate base]/[acid]

Question 38

What is a buffer?

Answer 38

A weak acid solution which maintains pH despite having acid/alkali added

Question 39

What do NAD, NADH & FAD do?

Answer 39

Act as electron carriers in redox reactions