Lecture: #11 (Proteins, carbs, and fats: the macromolecules of life)

Question 1

Fuel (energy)

Answer 1

“Fuel” comes from energy stored in chemical bonds
Our fuel comes from food (ie. what we consume).
Breaking bonds and reforming new bonds releases energy that can be harnessed to do “work.”

Question 2

Overview

Macromolecules: Lipids

Answer 2

Major types of Lipids
* Phospholipids
* Steroids
* Fats/Triglycerides → Glycerol and the 3 fatty acids (hydrocarbon tail)

***→Fats/Triglycerides are found in our diets; we get this in a lot of animal fat

***→Saturated and unsaturated fatty acids

Primary function: storing and generating useful energy

• Not water soluble
• Good insulators
• Generate energy
• They are hydrocarbons: composed exclusively of hydrogen and carbon atoms

Question 3

Macromolecules: Lipids

Saturated fatty acids

Answer 3

• Single bonds (Flexible and easily adjustable)
• Straight chains
• Packed together tightly (more dense)
• Solid at room temperature
• ex) Animal fats (bacon, grease, butter)

Less reactive; harder to break down; get built up easier

Question 4

Macromolecules: Lipids

Unsaturated fatty acids

Answer 4

• Double bond between two carbon atoms (doesn’t have as many hydrogens as it could) (locks them in place)
• Kinks or bends where there are double bonds
• Don’t pack together as well (less dense)
• Liquid at room temperature
• ex) Fish and plant fats (corn oil and olive oil)

More reactive; easier for our body’s metabolic machinery to grab onto and extract energy from; easier for the body to digest

Question 5

Macromolecules: Carbohydrates

Answer 5

• Having the oxygen makes it easy to grab onto and rip apart the molecules, forming new ones and obtaining energy.
• Stored in the body as glycogen
• Polymers of monosaccharides (simple sugars)
• Carbohydrates come in two main forms:
  **→Monosaccharides (simple sugars)
  **→Polysaccharides (complex carbohydrates)

Primary function: for fuel

• Carbon, hydrogen, and oxygen (C:H:O —1:2:1) (Cx(H2O)y)
• They have 3-7 carbons

Question 6

Macromolecules: Carbohydrates

Monosaccharides (simple sugars)

Answer 6

Fast energy, readily available, but don’t last long; They are quickly broken down by your body for a rapid energy boost.

ex) In sugary cereals, white rice, and orange juice

Question 7

Macromolecules: Carbohydrates

Polysaccharides (complex carbohydrates)

Answer 7

Release energy slowly over time

ex) in bagels, baked potatoes, pasta… Starch!

These polysaccharides require additional steps to break down into usable glucose, resulting in a slower and more sustained release of energy — You have to cleave the bond between the glucose

Question 8

Macromolecules: Proteins

Answer 8

Built from Amino acids
* The sequence of amino acids in a protein determines its three-dimensional structure
* R chain (there are 20 different amino acids)
* Essential amino acids: The 9 we must obtain from our diet
* complete proteins: Animal-based foods like milk, eggs, and meat contain all nine
* Incomplete proteins: lacking some essential amino acids
* Unlike fats and carbohydrates, proteins contain nitrogen, making them irreplaceable for certain bodily functions. While fats and carbs can convert into each other, protein cannot convert from fats due to the absence of nitrogen.
* Cannot be stored in the body for an extended period

Primary function: constitution of tissue

Question 9

Why do fats taste good?/Why is it that people like fat more?

Answer 9

• When it comes to enhancing taste preferences, adding sugar to food initially increases appeal, but there’s a limit to how much it can positively impact preference. On the contrary, when fats are added to food, the enjoyment and preference tend to continually rise with each addition, creating a more sustained and increasing appeal.
• Ancestors were hunter-gatherers, constantly moving, and couldn’t rely on agriculture for a stable food supply, leading to periods of food scarcity.
• From a survival standpoint, a preference for fats over carbs or proteins was advantageous, as fats store more energy (nine calories per gram compared to four for carbs and proteins).
• This preference for high-energy fats became crucial during famines, as those who consumed fats had a better chance of survival and passing on this trait.
• Evolutionary pressure has influenced modern food preferences, with a genetic predisposition to prefer fatty foods if ancestors lived in unpredictable environments with limited food.
• The preference for high-energy foods, especially fats, is observed not only in humans but also in various animals, highlighting its evolutionary significance.