Problem 16 - Biology Today and Tomorrow with Physiology

Question

Match each molecule with its most suitable description. ________chain of amino acids ________energy carrier in cells ________glycerol, fatty acids, phosphate ________two strands of nucleotides ________one or more sugar monomers ________richest source of energy ________hydrophilic ________number of protons in nucleus a. polar b. phospholipid c. temperature d. DNA e. ATP f. triglycerides \(g\). atomic number h. carbohydrate i. polypeptide molecular jiggling

Step-by-Step Solution

Answer

1. i; 2. e; 3. b; 4. d; 5. h; 6. f; 7. a; 8. g.

Step 1: Analyze the Task

We need to match each description of a molecule or characteristic with the appropriate option provided from a-j. There are 8 descriptions and options to match, meaning we will use 8 of the options provided.

Step 2: Identify Descriptions and Options

Let's label each description with the potential letter it could match to: - Chain of amino acids - Energy carrier in cells - Glycerol, fatty acids, phosphate - Two strands of nucleotides - One or more sugar monomers - Richest source of energy - Hydrophilic - Number of protons in nucleus

Step 3: Match Descriptions to Options

1. **Chain of amino acids**: This must be a protein structure, which is a **polypeptide**. Match this with \(i\): - Answer: i. Polypeptide2. **Energy carrier in cells**: Cells use \( ext{ATP} \) as an energy carrier. - Answer: e. ATP3. **Glycerol, fatty acids, phosphate**: This composition is characteristic of a \( ext{phospholipid} \). - Answer: b. Phospholipid4. **Two strands of nucleotides**: This is the structure of \( ext{DNA} \). - Answer: d. DNA5. **One or more sugar monomers**: Sugar molecules are carbohydrates. - Answer: h. Carbohydrate6. **Richest source of energy**: \( ext{Triglycerides} \) are a primary energy source. - Answer: f. Triglycerides7. **Hydrophilic**: Polar substances are hydrophilic. - Answer: a. Polar8. **Number of protons in nucleus**: This is defined by the \( ext{atomic number} \). - Answer: g. Atomic Number

Key Concepts

Polypeptide

Polypeptides are essential building blocks of proteins. They are long chains formed by linking amino acids together through peptide bonds. Each linkage involves a covalent bond between the carboxyl group of one amino acid and the amino group of another. This creates a backbone from which side chains (R groups) extend, influencing the protein's properties.

• The sequence of amino acids in a polypeptide determines the structure and function of the resulting protein.
• Enzymes, hormones, and structural components of cells are often composed of proteins formed by polypeptides.

Polypeptides can fold into specific three-dimensional structures, crucial for their activity and interaction in biological systems.

ATP

Adenosine triphosphate (ATP) is known as the energy currency of the cell. It stores and supplies energy needed for various cellular processes. ATP consists of an adenosine molecule bonded to three phosphate groups.

• Energy is released when ATP is converted into ADP (adenosine diphosphate) by the removal of the outermost phosphate group.
• This conversion allows ATP to provide the energy required for biological functions like muscle contraction and cellular transport.

Most of the ATP is generated through cellular respiration processes like glycolysis, the citric acid cycle, and oxidative phosphorylation.

Phospholipid

Phospholipids are crucial components of cellular membranes. They are composed of glycerol, two fatty acids, and a phosphate group. This structure allows them to form the phospholipid bilayer, which makes up the cell membrane.

• The phosphate head is hydrophilic, meaning it is attracted to water, while the fatty acid tails are hydrophobic, repelling water.
• This arrangement forms a semi-permeable membrane, regulating the movement of substances into and out of the cell.

The unique properties of phospholipids protect the cell's interior and facilitate communication and transport of molecules.

DNA

Deoxyribonucleic acid (DNA) is the molecule that carries genetic information essential for growth, development, and reproduction in all living organisms. DNA is structured as a double helix with two strands of nucleotides. Each nucleotide contains a sugar, a phosphate group, and one of four nitrogenous bases: adenine, thymine, cytosine, or guanine.

• The two strands are held together by hydrogen bonds between the complementary bases, forming base pairs: adenine pairs with thymine, and cytosine pairs with guanine.
• DNA sequences encode instructions for synthesizing proteins, crucial for cellular functions and heredity.

Genetic information is passed from cell to cell during division and from generation to generation through reproduction.

Carbohydrates

Carbohydrates are organic molecules consisting of one or more sugar monomers. These molecules are vital for providing energy to cells and are commonly known as sugars and starches. Carbohydrates can be classified into three main types: monosaccharides, disaccharides, and polysaccharides.

• Monosaccharides, like glucose and fructose, are simple sugars that serve as building blocks for larger carbohydrates.
• Polysaccharides, like cellulose and glycogen, are complex carbohydrates involved in energy storage and structural support.

Carbohydrates are crucial for energy production, as they are broken down during cellular respiration to produce ATP.

Triglycerides

Triglycerides are a type of lipid known as a fat. They consist of one glycerol molecule connected to three fatty acid chains. As an energy-rich source, triglycerides are stored in adipose tissues and can be broken down to provide energy when needed.

• Triglycerides are the most efficient form of energy storage, providing more than double the energy per gram compared to carbohydrates or proteins.
• They also provide insulation and protection for organs within the body.

Maintaining a balance of triglycerides in the body is crucial for health, as elevated levels can lead to cardiovascular diseases.

Atomic Number

The atomic number of an element is the number of protons in the nucleus of an atom. It defines the element and determines its position in the periodic table. For instance, the atomic number of hydrogen is 1, meaning it has one proton.

• The atomic number is crucial because it uniquely identifies an element.
• It influences the chemical properties and reactions of the element.

In summary, the atomic number is fundamental to understanding an element's identity and characteristics.

Polar Substances

Polar substances have molecules with unequal distribution of charges, leading to partial positive and negative regions. This polarity arises due to differences in electronegativity between atoms within the molecule. Water is a classic example of a polar substance.

• Polar substances tend to be hydrophilic, meaning they can dissolve in water and other polar solvents.
• The ability of the molecules to form hydrogen bonds makes them crucial for biological processes like protein folding and DNA helix formation.

Understanding polar substances is key to studying how molecules interact within living organisms and in various chemical reactions.