Unit 2: Biological molecules

Question 1

How is a water molecule structured? Why is water considered polar?

Answer 1

Water is structured with a central oxygen (O) atom and two hydrogen (H) atoms.

Electrons tend to spend more time near the O, giving it a slightly negative charge and the two H a slightly positive charge. Therefore, water is considered a polar molecule.

Question 2

What is hydrogen bonding?

Answer 2

Due to water being a polar molecule, the H of one water molecule is attracted to O of other water molecule.
The bond between H-O is a weak bond called the hydrogen bond.

Question 3

Property of water: liquid at room temp (how & benefit)

Answer 3

Due to hydrogen bonds, water stays in liquid form at room temperature despite being lighter than oxygen gas. (most compounds with low mass is gaseous at room temp)
Benefit: You can drink, cook, and wash with water. Water in our body doesn’t evaporate into gas.

Question 4

Property of water: universal solvent for polar molecules (how & benefit)

Answer 4

Since water is a polar molecule, ions or polar molecules put into water move around and collide, allowing for chemical reactions.
Benefit: Water can facilitate chemical reactions both outside and within human bodies.

Question 5

Property of water: cohesive (clings together) and fills vessels (how & benefit)

Answer 5

Hydrogen bonding makes water molecules cling together, yet water flows freely. This makes water an excellent transport medium, as dissolved or suspended molecules can be distributed evenly in water.
Benefit: Water based solutions such as blood can fill blood vessels and transport nutrients while removing waste.

Question 6

Property of water: temperature rises and falls slowly (how & benefit)

Answer 6

The numerous hydrogen bonds allow water to absorb a lot of heat before boiling. Water can also hold heat, and temperature falls slowly.
Benefit: Protects organisms from rapid temp changes and maintains internal temperature. Allows great bodies of water to maintain a relative constant temp. Water is a good temperature buffer.

Question 7

Property of water: takes a large amount of heat before vaporization (benefit)

Answer 7

Water moderates the Earth’s temperature so life can exist. Sweat is able to be produced and evaporated by body heat to cool down.

Question 8

How does water act as a solvent, temp regulator, and lubricant?

Answer 8

The various properties of water such as its polarity and hydrogen bonding allows it to act as a solvent/temp regulator.
Water’s cohesive property allows it to fill small spaces in the body, reducing friction between moving parts of the body.

Question 9

How does water break up in a solution? (what does it release)

Answer 9

When water dissociates in a solution, it releases an equal number of hydrogen (H+) ions and hydroxide (OH-) ions.

Question 10

Acid (give 2 examples)

Answer 10

Molecules when dissociated in water, releases hydrogen (H+) ions. Adding acid to water will result in an increase of H+.
i.e., hydrochloric acid (HCL), stomach acid

Question 11

Base (give 2 examples)

Answer 11

Molecules when dissociated in water, takes up H+ or releases hydroxide (OH-) ions. Adding base to water will result in an increase of OH-.
i.e., sodium hydroxide (NaOH), oven cleaner

Question 12

Function of buffer

Answer 12

A chemical or a combination of chemicals that keeps pH within normal limits. Buffers resist acidic or basic change as they can take up excess H+ or OH- ions.

Question 13

What are organic molecules?

Answer 13

The molecule of life; always contain carbon (C) and hydrogen (H)

Question 14

What is a monomer? Polymer?

Answer 14

Monomer: Simple organic molecules that exists individually; can link with other monomers to form a polymer
Polymer: Chains of many (3 or more) molecules joined together

Question 15

How are polymers formed? How do they break apart?

Answer 15

Dehydration reaction: an OH (hydroxyl) group of one monomer and an H atom of another monomer are removed to join the two monomers. The removed OH and H forms water.(water is removed)
Hydrolysis reaction: Water is broken down to OH and H. The OH attaches to one monomer and H attaches to the other, breaking the polymer apart. (water is added to the polymer)

Question 16

Carbohydrate

Answer 16

Organic molecule
Quick and short-term energy storage for all organisms. Plays a structural role in woody plants, bacteria, etc. Carbs on cell surfaces play a role in cell to cell recognition.

Question 17

Monosaccharide (general formula)

Answer 17

Name of carbohydrate when the number of carbon atoms are low (from 3-7).
General formula is CnH2nOn, due to the atomic grouping that designates a central Carbon atom with two Hydrogens and oxygen.

Question 18

Glucose (pentose or hexose?)

Answer 18

The most common form of monosaccharide; sugar found in our bloodstream. Monosaccharides with 5 carbon atoms are called a pentose, while 6 carbon is a hexose.
Glucose’s chemical formula is C6H12O6, a hexose.

Question 19

Structure and function of starch

Answer 19

Storage form of glucose molecules found in plants.

Structure is a fairly straight chain, few branching off.

Question 20

Structure and function of glycogen

Answer 20

Storage form of glucose molecules found in animals.

Structure has a lot of side branches that stem off from the main chain.

Question 21

Structure and function of cellulose

Answer 21

Chain of glucose molecules found in plant cells, contributing to its strong nature.
Structure is an alternating position of the glucose molecules, with no branching off.

Question 22

Fats/Lipids (function and structure)

Answer 22

Organic molecule
Long-term energy storage, insulates against heat loss, forms a protective cushion around major organs.
Structure: One glycerol molecule with 3 fatty acid molecules. Sometimes called a triglyceride due to its 3-part structure.

Question 23

Why are fat/oil unable to mix with water? What are emulsifiers? (examples)

Answer 23

Fat/oil lack polar groups, so there is no electrical attraction with water.
Emulsifiers allow fat/oil to mix with water. They have a polar end and a non polar end. The nonpolar end project inwards of a fat/oil molecule while the polar end projects outwards to the water. i.e., soaps, detergent, bile

Question 24

Saturated vs Unsaturated fatty acids

Answer 24

Saturated: No double covalent bonds between carbon atoms, as it is “saturated” with all the hydrogen it can hold. Solid at room temperature such as lard or butter.
Unsaturated: Has a double covalent bond between carbon atoms whenever there is less than 2 hydrogen per carbon atom. Liquid at room temperature such as vegetable oil.

Question 25

Phospholipids (function and structure)

Answer 25

Organic molecule, primary component of cell membranes
Constructed similar to fats, but instead of the third fatty acid, a phosphate group made of phosphate and nitrogen exists.
The glycerol and the phosphate group make up the head, which is polar and hydrophilic. The two fatty acid molecules form the tail, which is non-polar and thus hydrophobic.

Question 26

Steroids (function and structure)

Answer 26

Organic molecule; important component of animal cell’s membrane, as well as giving rise to other steroids like sex hormones.
All steroids have a fused backbone of four carbon rings. The function of different steroids is differed by the arrangement of the rings and the groups attached.

Question 27

Functions of protein (8)

Answer 27

Organic molecule

• Make up the body,
• influence cellular metabolism,
• aid in movement of cells and contraction of muscles,
• transport molecules in the bloodstream,
• fuse with foreign substances and reduce harm to the body
• regulate substances entering/exiting the cell
• carry molecules within the cell
• speed up chemical reactions

Question 28

Amino acids structure and function

Answer 28

Proteins are polymers.
Amino acid is the monomer that join together to form protein.
Made up of a central carbon and hydrogen atom, and 3 groups. 1. Amino group (H2N) 2. Acid (carboxyl) group (COOH) 3. Remainder group. It is the ‘R’ group that differs one amino acid to another.

Question 29

Peptide bond formation (polypeptide)

Answer 29

The bond that joins two amino acids. Consists of an O, C, Nitrogen (N), and H atom.
The dehydration synthesis removes a H atom from one amino acid and a OH group from another. The amino acid without a H is left with a N-H group and the amino acid without an OH is left with a C=O group. The polarity of H and O atom forms a hydrogen bond between the N-H and C=O group.

Question 30

4 levels of protein organization

Answer 30

Primary: The linear sequence of amino acids held by peptide bonds
Secondary: The polypeptide takes on an orientation. Colliding of the amino acid chain results in an alpha helix (spiral) or folding of the chain results in a pleated sheet. The hydrogen bond between peptide bonds holds this shape in place
Tertiary: The final 3-D shape. Hydrophobic portions are packed inside the shape, while hydrophilic portions are on the outside to make contact with water. All of covalent, ionic, and hydrogen bonding occur between the R groups to hold the shape in place.
Quaternary: Some proteins with more than one polypeptide such as hemoglobin or enzymes have a quaternary structure. The primary, secondary, and tertiary structure of each polypeptide is arranged to create the fourth structure

Question 31

Denaturation of protein

Answer 31

Protein exposed to extremes in heat and pH undergo irreversible changes in their shape called denaturation. This is when the normal bonding between the R groups have been disturbed; the protein can no longer perform its usual function

Question 32

Adenosine Triphosphate (function and structure)

Answer 32

Organic molecule; The energy currency used for all cellular processes. Used instead of glucose since glucose has TOO much energy for cells.
Structured with a adenosine base (adenine + ribose) and three phosphate groups. The last two phosphate groups’ bond is unstable. It is the breakdown of this bond, creating ADP + P, that releases the energy used by cells.