Week 13 Metabolism and Enzymes, Biological Specimens, Accuracy and Precision, and Chromatography

Question 1

What is metabolism?

Answer 1

A sequence of enzyme-catalysed chemical reactions in the cell, involving both anabolic and catabolic reactions

Metabolism is regulated in various ways and occurs as pathways, which are particular sequences of chemical reactions.

Question 2

What are anabolic pathways concerned with?

Answer 2

Processes involved in the assembly of complex organic molecules

Anabolic pathways are characterized by biosynthesis, being reductive, requiring energy, and usually being divergent.

Question 3

What are catabolic pathways related to?

Answer 3

Degradation of complex substances, resulting in the generation of energy

Catabolic pathways are degradative, oxidative, yield energy, and are usually convergent.

Question 4

What role do enzymes play in biochemical reactions?

Answer 4

Enzymes act as catalysts important in regulating the chemistry of cells and organisms

Catalysis is necessary to make essential biochemical reactions proceed at a useful rate under physiological conditions.

Question 5

List four characteristics of enzymes.

Answer 5

• Mostly proteins
• Some RNA molecules act as enzymes
• Reaction specific
• Highly regulated

Question 6

What is the term for the part of an enzyme that binds to the substrate?

Answer 6

Active site

The active site has a 3D arrangement of residues that determines the catalytic rate.

Question 7

What is a substrate in an enzymatic reaction?

Answer 7

The reactant in an enzyme-catalysed reaction, the substance acted upon by the enzyme.

Question 8

What is the significance of the Free Energy of Activation (DG‡)?

Answer 8

It determines the rate (speed) of a chemical reaction

A high activation energy results in a low rate (slower reaction), while a low activation energy results in a high rate (faster reaction).

Question 9

What does a catalyst do?

Answer 9

Increases the rate of a chemical reaction without being consumed in the reaction

A catalyst provides an alternative reaction pathway with a lower activation energy.

Question 10

What is the Michaelis constant (Km)?

Answer 10

Refers to the strength of association between the enzyme and substrate

At Km, the reaction rate is half of the maximum reaction rate (Vmax).

Question 11

Fill in the blank: Enzymes are usually named according to _______.

Answer 11

[function]

Question 12

What are anticoagulants used for?

Answer 12

To allow plasma to be obtained from blood samples

Examples include Heparin, EDTA, Sodium citrate, and Sodium fluoride.

Question 13

What is the difference between serum and plasma?

Answer 13

Serum is the liquid portion of clotted blood, while plasma is the liquid portion of whole blood

Serum is essentially the same as plasma minus clotting proteins.

Question 14

What is chromatography?

Answer 14

An important tool used to analyze and purify proteins, DNA, RNA, and other organic molecules

It separates a mixture into its components or isolates one component from a mixture of others.

Question 15

What are the two phases involved in chromatography?

Answer 15

• Stationary phase
• Mobile phase

Question 16

What is an example of a biological specimen?

Answer 16

• Blood
• Urine
• Faeces
• Solid tissue
• Cerebrospinal fluid

Question 17

True or False: Enzymes can be affected by temperature.

Answer 17

True

Question 18

What happens when blood is taken from the body?

Answer 18

It will clot due to a series of reactions to form fibrin

The remaining liquid component after clotting is serum.

Question 19

What is the optimal temperature for enzyme activity?

Answer 19

Varies, but commonly around 37°C for many enzymes

Enzymes have a limited range of temperatures in which they are active.

Question 20

What is Adsorption in chromatography?

Answer 20

Solid stationary phase and liquid mobile phase

Adsorption is a process where molecules adhere to a solid surface.

Question 21

What is Partition in chromatography?

Answer 21

Liquid stationary phase and liquid or gas mobile phase

Partition chromatography separates compounds based on their solubility in the stationary phase.

Question 22

What is Ion Exchange chromatography?

Answer 22

Solid stationary phase and liquid mobile phase

It involves the exchange of ions between the resin and the sample.

Question 23

What is Size Exclusion chromatography?

Answer 23

Liquid stationary phase and liquid mobile phase

Also known as Gel Permeation or Gel Filtration, it separates molecules based on size.

Question 24

What is Affinity chromatography?

Answer 24

Stationary ligand and liquid mobile phase

It uses specific interactions between a ligand and the target molecule.

Question 25

What does a cation exchanger do?

Answer 25

Exchanges positive ions ## Footnote Cation exchangers can be classified as strong or weak based on their interaction with ions.

Question 26

What does an anion exchanger do?

Answer 26

Exchanges negative ions ## Footnote Like cation exchangers, anion exchangers can also be strong or weak.

Question 27

What does Size Exclusion chromatography resolve?

Answer 27

Molecular components of a mixture and estimates molecular weights ## Footnote It separates based on the size and shape of molecules.

Question 28

What is the role of a polymer-bound ligand in Affinity Chromatography?

Answer 28

Specific for the protein of interest ## Footnote The ligand forms a complex with the analyte while unwanted proteins are washed away.

Question 29

What is Sensitivity in laboratory tests?

Answer 29

Measure of amount of an analyte that can be quantitated ## Footnote A more sensitive test can measure lower amounts of analytes.

Question 30

What is Specificity in laboratory tests?

Answer 30

Represents what is being measured ## Footnote A high specificity test measures only the intended substance.

Question 31

What are the two factors that combine to define test reliability?

Answer 31

* Accuracy * Precision ## Footnote Reliability reflects the quality and consistency of test results.

Question 32

What does Accuracy refer to in laboratory results?

Answer 32

Closeness of measured value to true value ## Footnote Accurate results reflect the actual value of the analyte being measured.

Question 33

What is Precision in laboratory measurements?

Answer 33

How close together a set of measurements are to each other ## Footnote Precision does not indicate how close the measurements are to the true value.

Question 34

What is the relationship between accuracy and precision?

Answer 34

They are independent of one another ## Footnote Accuracy refers to the closeness to the true value, while precision refers to the consistency of results.

Question 35

What is the significance of standard deviation in Precision?

Answer 35

Related to dispersion of data around a point ## Footnote Standard deviation quantifies the variability of a set of measurements.

Question 36

What is the focus of the Laboratory Component of the MEDI1000 End Of Semester Test?

Answer 36

Laboratory sessions from Weeks 7, 10, 11, 12, 13 ## Footnote This part also includes multiple-choice questions.