Biological Molecules Practice Flashcards

Comprehensive practice questions covering biology lecture notes on biological molecules, food testing procedures, and DNA structure.

According to the transcript, why are carbohydrates, proteins, and lipids described as organic molecules?

They all contain carbon.

What are the three categories into which most molecules in living organisms fall?

Carbohydrates, proteins and lipids

What is the term for a simple sugar such as glucose?

A monosaccharide

What is formed when two glucose molecules join together?

maltose (a disaccharide)

Which three polysaccharides can form when lots of glucose molecules join together?

starch, glycogen or cellulose

What is the primary monosaccharide used to build glycogen, cellulose, and starch?

glucose

What are most fats (lipids) in the body made up of?

triglycerides

What is the basic unit of a triglyceride?

$1$ glycerol molecule chemically bonded to $3$ fatty acid chains

In terms of state at room temperature, how are lipids divided?

fats (solids at room temperature) and oils (liquids at room temperature)

What are proteins constructed from?

Long chains of amino acids

How many different amino acids are mentioned in the transcript?

About $20$ different amino acids

In the general structure of amino acids, which group is different for each one?

The ‘R’ group

What is the result of even a small difference in the order of amino acids in a chain?

A different protein being formed

Which solution is added to a sample to test for glucose (a reducing sugar)?

Benedict's solution

At what temperature should the water bath be set when testing for glucose?

$$60 - 70\,^\circ\text{c}$$

How long should a test tube be heated in a water bath during a glucose test?

$$5\,\text{minutes}$$

What is the positive color change for a glucose test using Benedict's solution?

from blue to orange or brick red

What substance is used to test for the presence or absence of starch in a food sample?

iodine

What color change indicates a positive test for starch?

from orange-brown to blue-black

Which solution is added to a food sample to test for protein?

Biuret solution

What color change indicates a positive test for protein?

from blue to violet / purple

How much ethanol is mixed with a food sample to test for lipids?

$2\,cm$ of ethanol

After shaking with ethanol, what is added to the mixture in a lipid test?

An equal volume of cold water

What is the positive observation for the lipid test?

A cloudy emulsion forming

Which solution is used to test for Vitamin C?

DCPIP solution

How much DCPIP solution is added to the test tube for the Vitamin C test?

$$1\,cm$$

What observation indicates a positive test for Vitamin C?

The blue colour of the dye disappearing

What does the abbreviation DNA stand for?

deoxyribonucleic acid

What is the structural shape consisting of two strands of DNA wound around each other?

A double helix

What are the individual units of DNA called?

nucleotides

Which two components are the same in all nucleotides?

phosphate and deoxyribose sugar

What are the names of the four different bases found in DNA nucleotides?

Adenine (A), Cytosine (C), Thymine (T) and Guanine (G)

According to the base pairing rules, what does Adenine (A) always pair with?

Thymine (T)

According to the base pairing rules, what does Cytosine (C) always pair with?

Guanine (G)

Which components of the nucleotides form the ‘backbone’ of the DNA strand?

The phosphate and sugar section

In the ladder analogy of DNA, what do the base pairs connect to form?

The rungs of the ladder

What role does DNA play in all organisms?

It contains the instructions for the growth and development of all organisms

What is the side-by-side structure of the DNA 'backbone' compared to in the ladder analogy?

The sides of a ladder

How many fatty acid chains are chemically bonded to glycerol in a triglyceride?

$$3$$

What determines whether a lipid is classified as an oil?

If it is liquid at room temperature