2.2 Lipids Flashcards
What are organic solvents?
Solvents containing carbon, such as ethanol
What atoms are lipids made of ?
Carbon, hydrogen and oxygen. Like carbohydrates, but they have a higher proportion of hydrogen and lower proportion of oxygen.
What are lipids? Are they soluble or insoluble?
A diverse group of compounds that are insoluble in water but soluble in organic solvents
Why are lipids a good energy sources?
They contain twice the amount of energy as carbohydrates
Where are lipids stored?
Adipose tissue (fat)
What is adipose tissue used for?
Layers of fat around organs provide protection, such as around your kidneys. Fat can also provide warmth by reducing heat loss under skin.
When are fatty acids produced?
When fats in our food/diet are broken down
What are fatty acids used for?
They are essential for many things, for instance they are used in plasma membranes
If a fatty acid is monounsaturated what does it have?
It contains one double bond
If a fatty acid is polyunsaturated what does it have?
It contains many double bonds
What does it mean if a fatty acid is saturated?
It means it contains no double bonds
What molecules do fatty acids contain?
Carbon and hydrogen molecules
What type of chains do saturated fatty acids form and what does this mean about their attractions?
They form straight chains, consequently molecules can line up closely forming strong attractions between all molecules
Due to strong attractions what do saturated fatty acids have, and why?
They have high melting points as a lot of energy is needed to overcome the attractions
What state are saturated fatty acids at, at room temperature?
They tend to be solid at room temperature
What are triglycerides and what are they used for?
The are a type of lipid used for energy storage, insulation and protection.
Where are triglycerides found?
In fatty tissues under skin and layers of fat surrounding organs to provide protection
What does a triglyceride consist of?
A glycerol backbone and 3 fatty acids
Are triglycerides soluble or insoluble in water?
They are insoluble
What reaction occurs to form a triglyceride and what bond is formed?
- a condensation reaction (water is lost)
* an ester bond is formed
What is another name for this process?
Esterification
What does the structure of a phospholipid consist of?
A phosphate group, a glycerol head and two fatty acid tails
Is a phospholipid hydrophilic or hydrophobic?
It is amphipathic, both hydrophilic and hydrophobic
What part of a phospholipid is hydrophilic?
The phosphate group
What does hydrophilic mean?
It loves water
What part of a phospholipid is hydrophobic?
The fatty acids
What does hydrophobic mean?
It doesn’t like water
What does the phospholipid do in water and why?
It forms a double bilayer spontaneously in water otherwise the fatty acids would have to be in contact with water
What do phospholipids play a key role in?
Forming cell membranes as they are able to separate the aqueous environment
What are sterols?
Lipids that are neither fats nor oils
What are sterols otherwise known as?
Steroid alcohols
Give an example of a sterol:
Cholesterol
What happens when sterols react with water?
They are amphipathic; the hydroxyl group in sterols are polar as it is attracted to water
Where is cholesterol made and what role does it play?
It is made in the liver and intestines, it plays an important role in the formation of the cell membrane, it becomes positioned between the phospholipids adding stability to the cell
What does cholesterol do?
It regulates cell membrane fluidity:
• it keeps them fluid at low temperatures (stops them freezing)
• it stops them becoming too fluid at high temperatures
What are made using cholesterol?
Vitamin D, steroid hormones and bile
What are the roles of lipids?
- membrane formation
- hormone production
- electrical insulation (fatty sheath)
- waterproofing (birds feathers)
- energy storage
- thermal insulation
