B1.1

Question 1

Lipids

What is Adipose Tissue?

Answer 1

• Composed of specialized cells (adipocytes) that store triglycerides as stored energy.
• They make up body fat.
• How much of this tissue depends on caloric/ energy intake.
• When excess energy is taken in, the body will store that extra energy as triglycerides inside adipose tissue
• This tissue is a long term storage that can be broken down if food intake is insufficient.

Question 1

Lipids

What are phospholipids?

Answer 1

• A modified triglyceride–>(a typical lipid that contains a glycerol backbone and three fatty acids), that contains a glycerol, two fatty acids and a phosphate group.
• Formed by condensation reactions –> three waters produced for one phosphlipid.
• They make up the phospholipid bilayer –> makes up cell membranes.

Question 2

Lipids

What does Amphipathic mean?

Answer 2

• Molescules that have both hydrophilllic (polar) regions and hydrophobic (non-polar) regions.
• Phospholipids are amphipathic becuase the head that contains the phosphate and glycerol is polar while the fatty acid tails are non polar.
• This property impacts how the bilayer forms of cell membranes.

Question 3

Lipids

What are Endotherms

Answer 3

• They maintain a steady internal temperature regardless of changes in the external temperature. (birds and mammals are exotherms.)
• Blubber aids in trapping metabolic heat –> to maintain a warm body temperatures in colder environments. As it is made of adipose tissue –> an important application fo lipids.

Question 4

Lipids

Non-polar Covalent bonds and Lipids

Answer 4

• Lipids are defined by long fatty acid chains that are primarily made of bonds between carbon and hdyrogen.
• The bonds between hydrogen and carbon is a non-polar covalent bond that generates no weak bonds. –> meaning that lipids do not dissolve in water.

Question 5

Lipids

Saturated, Monounsaturated and Polyunsaturated fatty acids.

Answer 5

Fatty acids vary depedning on the presence/ no presence of double bonds between the carbons in the chain.
- Saturated fatty acids: have only single bonds.
- Monounsaturated fatty acids: they have one double bond between carbons causing them to have a ‘bent’ shape and lower melting points resulting in them being liquid at room temperature.
- Polyunsaturated fatty acids: have more than one dhouble bond.

Question 6

Lipids

Triglycerides as long term storage:

Answer 6

Characteristics of triglcerides that makes them ideal for long term storage include:
- Chemically stable so no energy lost over time.
- They release more than twice as much energy per gram.
- Do not dissolve in water so form droplets in the cytoplasm and do not pull water by osmosis.
- Poor conductors of hear so conserve body heat.
- Can be liquid at room temp and absorb shock.

Question 7

Lipids

The structure of steroid hormones.

Answer 7

• They are groups of hormones (chemical messengers) that are made up on lipids (most hormones are protein based.)

They have a common structure: which includes 4 fused carbon rings.
- 3 of the carbon rings are ‘cyclohexane rings’ –> 6 carbons.
- The other 1 carbon ring is a ‘cyclopentange’ rings –> 5 carbons.

EG: sex hormones - estrogen and testosterone.