L2: THE BUILDING BLOCKS OF LIFE

Question 1

What is an atom?

Answer 1

An atom is the smallest unit of an element that has the chemical characteristics of that element.

Question 2

What are the subatomic particles in an atom?

Answer 2

Protons (positively charged), electrons (negatively charged), and neutrons (neutral).

Question 3

How many natural chemical elements are there?

Answer 3

There are 92 natural chemical elements.

Question 4

Why do elements form bonds?

Answer 4

Elements form bonds to become stable by filling their outer electron shells.

Question 5

How do atoms achieve stability?

Answer 5

Atoms achieve stability by sharing or transferring electrons with other atoms.

Question 6

What is a covalent bond?

Answer 6

A covalent bond is a chemical bond formed when atoms share electrons.

Question 7

How do hydrogen atoms form bonds?

Answer 7

Hydrogen atoms form covalent bonds by sharing electrons to fill their outer shell.

Question 8

What are non-covalent bonds (NCBs)?

Answer 8

NCBs are weaker bonds that form between molecules or within molecules.

Question 9

What type of molecules form hydrogen bonds?

Answer 9

Polar molecules, like water, form hydrogen bonds.

Question 10

Why is water polar?

Answer 10

Water is polar because oxygen has a slight negative charge, and hydrogen has a slight positive charge.

Question 11

How does the ionic bond in salt work?

Answer 11

Sodium (Na+) loses an electron to become positive, and chloride (Cl-) gains an electron to become negative, forming an ionic bond.

Question 12

What happens when salt dissolves in water?

Answer 12

The ionic bond between Na+ and Cl- breaks, and water molecules surround and interact with the ions.

Question 13

What are the four major classes of chemical compounds found in living organisms?

Answer 13

Sugars, nucleotides, amino acids, and fatty acids.

Question 14

What is the predominant element in compounds?

Answer 14

Carbon

Question 15

What is the difference between a monomer and a polymer?

Answer 15

A monomer is a small molecule, while a polymer is a larger molecule made of many monomers joined together.

Question 16

How many atoms do monomers typically have?

Answer 16

Monomers typically have 20 or fewer atoms.

Question 17

What are monosaccharides?

Answer 17

Monosaccharides are simple sugars, such as glucose, composed of carbon, hydrogen, and oxygen

Question 18

What is the ratio of carbon, hydrogen and oxygen?

Answer 18

1:2:1

Question 19

What is a polysaccharide?

Answer 19

A polysaccharide is a long chain of monosaccharides, such as glycogen in mammals.

Question 20

How are disaccharides formed?

Answer 20

Disaccharides are formed when two monosaccharides bond via dehydration (loss of water).

Question 21

What is an example of a disaccharide?

Answer 21

Sucrose is a disaccharide formed from glucose and fructose.

Question 22

What is the role of nucleotides?

Answer 22

Nucleotides make up DNA and RNA, storing genetic information and energy for cells.

Question 23

What are nucleotides?

Answer 23

Nucleotides are organic compounds that consist of a 5-carbon sugar, a base (e.g., A, T, C, G for DNA), and a phosphate group.

Question 24

What are amino acids? What do they consists of ?

Answer 24

Amino acids are the building blocks of proteins, each consisting of an alpha carbon, a carboxyl group (-COOH), an amino group (-NH2), and a side chain (R).

Question 25

How many amino acids are there?

Answer 25

There are 20 different amino acids.

Question 26

How do amino acids form proteins?

Answer 26

Amino acids are linked together by peptide bonds to form proteins (polypeptides).

Question 27

What are fatty acids?

Answer 27

Fatty acids are long carbon chains ending in a carboxyl group (-COOH), and they are components of fats and lipids.

Question 28

What is the difference between saturated and unsaturated fatty acids?

Answer 28

Saturated fatty acids have no double bonds and are solid at room temperature

Unsaturated fatty acids have one or more double bonds and are liquid at room temperature.

Question 29

What are phospholipids?

Answer 29

Phospholipids are molecules made up of a hydrophilic head and two hydrophobic fatty acid tails.

Question 30

How do phospholipids form the cell membrane?

Answer 30

Phospholipids arrange in a bilayer, with hydrophilic heads facing the water and hydrophobic tails facing inward, creating a barrier.

Question 31

What does hydrophilic mean?

Answer 31

Hydrophilic means “water-loving” and describes molecules (like sugars and salts) that interact with water.

Question 32

What does hydrophobic mean?

Answer 32

Hydrophobic means “water-fearing” and describes molecules (like fatty acids) that do not interact with water.