Biochemistry: Carbohydrates and Lipids

Question 1

How many covalent bonds can a carbon atom form, and what types of bonds can it create?

Answer 1

A carbon atom can form up to four covalent bonds. It can create single, double, or triple bonds with other atoms, including other carbon atoms.

Question 2

What elements are commonly bonded to carbon in organic molecules?

Answer 2

hydrogen, oxygen, and nitrogen in organic molecules

Question 3

Why is carbon essential in the formation of organic molecules?

Answer 3

Forms four covalent bonds, creates complex and diverse structures like long chains, rings, and branches, which are the backbone of organic molecules.

Question 4

How does a carbon atom complete its valence shell?

Answer 4

A carbon atom completes its valence shell by sharing its four outer electrons with other atoms, forming covalent bonds.

Question 5

What is the ratio of carbon, hydrogen, and oxygen in carbohydrates?

Answer 5

Carbohydrates have a 1:2:1 ratio of carbon, hydrogen, and oxygen (C:H:O)

Question 6

What are the three major groups of carbohydrates, and how are they classified?

Answer 6

The three major groups of carbohydrates are monosaccharides, disaccharides, and polysaccharides. They are classified by size and the number of building blocks they contain.

Question 7

What is the function of glucose in the body, and how is excess glucose stored?

Answer 7

Glucose is the main energy molecule, converted into ATP for energy. Excess glucose is stored as glycogen in the liver and muscles, it may also be stored as fat.

Question 8

What is the difference between dehydration synthesis and hydrolysis in carbohydrate digestion?

Answer 8

Dehydration synthesis joins monosaccharides to form disaccharides or polysaccharides by removing water. Hydrolysis breaks disaccharides and polysaccharides into monosaccharides by adding water.

Question 9

What are some examples of polysaccharides, and what are their roles in organisms?

Answer 9

1. Glycogen (animal glucose storage)
2. starch (plant glucose storage)
3. cellulose (structural component of plant cell walls)

Question 10

What are functional groups, and how do they affect organic molecules like carbohydrates?

Answer 10

• chemical properties, involved in chemical reactions - impact specific properties to organic molecules.

Question 11

What are two distinctive properties of organic molecules dependent on?

Answer 11

The carbon skeleton and functional groups.

Question 12

What is a monosaccharide?

Answer 12

Simplest carbohydrate unit, includes pentose sugars (deoxyribose & ribose), hexose sugars/isomers (fructose, galactose, mannose, glucose), isomers

Question 13

The four functions of Carbohydrates

Answer 13

ATP, component of DNA & RNA, attached to glycoproteins or glycolipids, energy storage (glycogen)

Question 14

Function of glycoproteins and glycolipids.

Answer 14

Membrane structure, connective tissue structure and lubrication fluids, cell-cell recognition

Question 15

Describe the main molecule that supplies energy?

Answer 15

Glucose, converted in ATP, CO2, H2O which aids in cellular respiration.

Question 16

What is a disaccharide?

Answer 16

2 monosaccharides joined together via covalent bond formed by dehydration synthesis.

Question 17

Examples of disaccharides

Answer 17

Lactose, Maltose and Sucrose

Question 18

Why are disaccharides be broken down during digestion, and how is this process carried out?

Answer 18

Disaccharides are too large to be absorbed directly into the body, so they must be broken down into their monosaccharide components. This process is carried out by hydrolysis, which is performed by digestive enzymes

Question 19

What is a polysaccharide?

Answer 19

Many monosaccharides joined together covalently

Question 20

What elements primarily compose lipids, and what is the significance of the low oxygen content in lipids?

Answer 20

Lipids are primarily composed of carbon (C) and hydrogen (H), with very little oxygen (O). The low oxygen content makes lipids more energy-dense compared to carbohydrates, allowing them to store more energy.

Question 21

Why are lipids considered more energy-dense than carbohydrates?

Answer 21

Lipids are more energy-dense because they contain more carbon-hydrogen bonds and less oxygen, which allows them to store more energy than carbohydrates.

Question 22

What does it mean for a molecule to be non-polar, and how does this relate to fatty acids?

Answer 22

A non-polar molecule has equal sharing of electrons in its bonds, and fatty acids are non-polar, meaning they do not mix well with polar substances like water.

Question 23

What is the difference between hydrophilic and hydrophobic molecules?

Answer 23

Hydrophilic molecules can mix with water (water-loving), while hydrophobic molecules cannot mix with water (water-fearing) and tend to push away from it.

Question 24

Why do water and oil (containing non-polar molecules like fatty acids) not mix?

Answer 24

Water and oil do not mix because water is polar, and oil contains non-polar molecules, so they repel each other due to differences in polarity.

Question 25

What are triglycerides made of, and how are they synthesized?

Answer 25

Triglycerides are made of a glycerol molecule and three fatty acid chains. They are synthesized through a dehydration reaction, where water is removed to bond the components.

Question 26

What is the structure of a phospholipid, and what role does it play in the body?

Answer 26

A phospholipid consists of a polar, hydrophilic head, two non-polar, hydrophobic tails, and a phosphate group. Phospholipids are major components of cell membranes, helping with membrane structure and fluidity.

Question 27

How do steroids differ from other lipids, and what are some examples and their functions?

Answer 27

Steroids have four interlocking hydrocarbon rings and various functional groups. Examples include sex hormones (e.g., estrogen, testosterone), cholesterol (for cell membranes and bile production), and bile salts (for fat digestion).

Question 28

What are the functions of fats in the body?

Answer 28

1. Energy storage (triglycerides provide energy when glucose is unavailable). 2. Cell membrane structure (phospholipids and cholesterol). 3. Fat-soluble vitamin absorption (A, D, E, K). 4. Hormone production (e.g., cortisol, testosterone). 5. Insulation and protection of organs.

Question 29

What is the main difference between saturated and unsaturated fats in terms of their chemical structure?

Answer 29

Saturated fats have only single bonds between carbon atoms, with all bonds filled by hydrogen, making them straight and solid at room temperature. Unsaturated fats have one or more double bonds between carbon atoms, causing the chain to bend and making them liquid at room temperature.

Question 30

What are polyunsaturated fats, and why are they considered beneficial?

Answer 30

- two or more double bonds in their fatty acid chains - control blood cholesterol levels

Question 31

Why do unsaturated fats tend to be liquid at room temperature, while saturated fats are solid?

Answer 31

Unsaturated fats have double bonds in their carbon chains, causing the chain to bend and preventing tight packing, making them liquid. Saturated fats have only single bonds and straight chains, allowing them to pack closely and remain solid at room temperature.

Question 32

What is the structure of a phospholipid molecule?

Answer 32

A phospholipid has two fatty acid chains (non-polar tails) and a phosphate group (polar head) attached to a glycerol molecule.

Question 33

How do the polar head and non-polar tail of a phospholipid differ in terms of their interaction with water?

Answer 33

The polar head is hydrophilic (water-loving) and interacts with water, while the non-polar tail is hydrophobic (water-fearing) and avoids contact with water.

Question 34

Why are phospholipids important for cell membranes?

Answer 34

Phospholipids form a bilayer in which the hydrophilic heads face outward toward water and the hydrophobic tails face inward, creating a semi-permeable membrane that controls the passage of substances in and out of the cell.