2.2 Lipids Flashcards Preview

A Level Biology > 2.2 Lipids > Flashcards

Flashcards in 2.2 Lipids Deck (37):
1

What are organic solvents?

Solvents containing carbon, such as ethanol

2

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.

3

What are lipids? Are they soluble or insoluble?

A diverse group of compounds that are insoluble in water but soluble in organic solvents

4

Why are lipids a good energy sources?

They contain twice the amount of energy as carbohydrates

5

Where are lipids stored?

Adipose tissue (fat)

6

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.

7

When are fatty acids produced?

When fats in our food/diet are broken down

8

What are fatty acids used for?

They are essential for many things, for instance they are used in plasma membranes

9

If a fatty acid is monounsaturated what does it have?

It contains one double bond

10

If a fatty acid is polyunsaturated what does it have?

It contains many double bonds

11

What does it mean if a fatty acid is saturated?

It means it contains no double bonds

12

What molecules do fatty acids contain?

Carbon and hydrogen molecules

13

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

14

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

15

What state are saturated fatty acids at, at room temperature?

They tend to be solid at room temperature

16

What are triglycerides and what are they used for?

The are a type of lipid used for energy storage, insulation and protection.

17

Where are triglycerides found?

In fatty tissues under skin and layers of fat surrounding organs to provide protection

18

What does a triglyceride consist of?

A glycerol backbone and 3 fatty acids

19

Are triglycerides soluble or insoluble in water?

They are insoluble

20

What reaction occurs to form a triglyceride and what bond is formed?

• a condensation reaction (water is lost)
• an ester bond is formed

21

What is another name for this process?

Esterification

22

What does the structure of a phospholipid consist of?

A phosphate group, a glycerol head and two fatty acid tails

23

Is a phospholipid hydrophilic or hydrophobic?

It is amphipathic, both hydrophilic and hydrophobic

24

What part of a phospholipid is hydrophilic?

The phosphate group

25

What does hydrophilic mean?

It loves water

26

What part of a phospholipid is hydrophobic?

The fatty acids

27

What does hydrophobic mean?

It doesn't like water

28

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

29

What do phospholipids play a key role in?

Forming cell membranes as they are able to separate the aqueous environment

30

What are sterols?

Lipids that are neither fats nor oils

31

What are sterols otherwise known as?

Steroid alcohols

32

Give an example of a sterol:

Cholesterol

33

What happens when sterols react with water?

They are amphipathic; the hydroxyl group in sterols are polar as it is attracted to water

34

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

35

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

36

What are made using cholesterol?

Vitamin D, steroid hormones and bile

37

What are the roles of lipids?

• membrane formation
• hormone production
• electrical insulation (fatty sheath)
• waterproofing (birds feathers)
• energy storage
• thermal insulation

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