3b. Biochemistry - Carbs & Lipids Flashcards
(131 cards)
1
Q
What is biochemistry?
A
Science concerned with the chemical and physiochemical processes and substances that occur within living organisms
2
Q
Which elements are carbohydrates made from?
A
C-H-O
3
Q
How are the carbon atoms usually arranged?
A
In a ring with O2 and H attached
4
Q
Why do carbohydrates have many -OH groups?
A
So they can form hydrogen bonds
5
Q
What is the benefit of carbohydrates having many -OH groups?
A
Smaller carbs such as simple sugars can dissolve easily in water
6
Q
What are the three classes of carbs?
A
Monosaccharides
Disaccharides
Polysaccharides
7
Q
How are monosaccharides constructed?
A
With 3-7 C atoms
8
Q
Examples of monosaccharides
A
Glucose Fructose Galactose Deoxyribose Ribose
9
Q
How are disaccharides constructed?
A
2 monosaccharides joined together by dehydration reaction
10
Q
Examples of disaccharides
A
Sucrose
Lactose
Maltose
11
Q
Which two monosaccharides make up sucrose?
A
Glucose
Fructose
12
Q
Which two monosaccharides make up lactose?
A
Glucose
Galactose
13
Q
Which two monosaccharides make up maltose?
A
Glucose
Glucose
14
Q
How are polysaccharides structured?
A
10s-100s of monosaccharides joined together by dehydration reaction
Long chains of glucose
15
Q
Examples of polysaccharides
A
Glycogen
Starch
Cellulose
16
Q
What characteristic do most monosaccharides have?
A
Sweet taste
17
Q
Which monosaccharide is the sweetest?
A
Fructose
18
Q
How are monosaccharides grouped?
A
Into families named after the number of carbon atoms
19
Q
What are the names of the monosaccharide groups?
A
Triose (3 carbons)
Pentose (5 carbons)
Hexose (6 carbons)
Heptose (7 carbons)
20
Q
What are isomers?
A
They have the same chemical formula but different structures
same number of Lego bricks used to make different structures
21
Q
Examples of isomers
A
Glucose
Galactose
Fructose
22
Q
What is the name of the bond that joins two monosaccharides together to form a disaccharide?
A
Glycosidic bond
23
Q
How is a glycosidic bond created?
A
Through dehydration synthesis
24
Q
How is a disaccharide broken down?
A
Water is put back in during digestion
Known as hydrolysis
25
When is maltose formed?
During the hydrolysis of starch
26
What percentage of cow's milk is lactose?
5%
27
What percentage of human milk is lactose?
7%
28
Why are polysaccharides normally insoluble in water?
They have given up so many -OH groups
29
Do polysaccharides taste sweet?
No
30
Where does the digestion of polysaccharides begin?
In the oral cavity
31
What is the most common type of polysaccharide in the body?
Glycogen
32
What is each glycogen molecule made up of?
Around 60,000 glucose molecules
33
What is the function of glycogen?
Short-term energy
34
Where is most glycogen made?
Liver
35
Where is most glycogen stored?
Liver
| Muscles
36
What can glycogen in the liver be used for?
Maintain blood sugar levels
37
What can glycogen stored in the muscles be used for?
Energy for that particular muscle
38
What is cellulose?
Structural material of plants
| Found in plant cell walls
39
How is cellulose constructed?
Flat, ribbon-like strands
| Joined together with bonds
40
Why can't we digest cellulose?
We don't have the correct enzymes to break down the bonds
41
What is the function of cellulose?
Fibre to assist with the movement of materials through the intestine
42
Which polysaccharide is the main dietary source?
Starch
43
Which foods can starch be found in?
Bread
Rice
Pasta
44
Where does digestion of starch begin?
In the oral cavity
45
What is starch made up of?
20-25% amylose
| 75-80% amylopectin
46
How is amylose constructed?
Single chain of glucose units
47
How does the structure of amylose affect its digestion?
Straight chain which limits amount of surface area exposed for digestion
48
What is amylose also known as?
Resistant starch
| as it is digested more slowly
49
What can some resistant starch end up doing in the large intestine?
Feeding the bacteria there
50
How is amylopectin constructed?
Glucose chains but with branches
51
How does the structure of amylopectin affect its digestion?
More surface area available for digestion
| Broken down quickly
52
What affect does the digestion of amylopectin have in the body?
Broken down quickly
= rise in blood sugar levels
= rise in insulin
53
What are the functions of carbs?
Primary fuel for energy production
Also limited amount of energy stored
Fibre
54
What are the therapeutic uses of carbs as fibre?
```
Bowel function
Protect against colorectal cancer
Protect against CVD
Protect against diabetes
Increase satiety
```
55
Which processes are carbs used for?
ATP production
Glycogen synthesis
Triglyceride synthesis
Amino acid synthesis
56
How are carbs digested?
Oral cavity - salivary amylase starts to break down the ends of the long glucose chains
Small intestine - pancreatic amylase (from pancreas) breaks down polysaccharides into disaccharides
Brush border enzymes break them down further - lactase, maltase, sucrase
57
Which elements are lipids made from?
C-H-O
| but in a different ratio to carbs
58
How are lipids different in structure to carbs?
Have fewer -OH groups
59
What does having fewer -OH groups mean for lipids?
They are hydrophobic
60
How do lipids move around the body?
Often bond to a protein to make them more soluble
61
What are lipids bonded to proteins called?
Lipoproteins
62
What is the main form of dietary fat?
Triglycerides
63
How are triglycerides constructed?
A single glycerol molecule
| 3 fatty acid chains
64
How are the fatty acids attached to the glycerol?
By dehydration synthesis and the ester bond
65
How are triglycerides broken down?
By hydrolysis
| like carbs
66
What are the functions of triglycerides?
Protection of body parts/organs
Insulation
Energy
Storing excess calorific intake
67
How are saturated fats constructed?
Single covalent bonds between each of the fatty acid carbon atoms
Each carbon atom is saturated with hydrogen atoms
68
How do saturated fatty acid chains appear?
Very straight
69
What quality does the very straight fatty acid chain give to saturated fats?
More likely to be solid at room temperature
70
Example of a saturated fat
Coconut oil
71
How are monounsaturated fats constructed?
Mainly single covalent bonds between each of the fatty acid carbon atoms but with one double covalent bond between two carbons
72
How do monounsaturated fatty acid chains appear?
```
Slight bent
(due to the double bond)
```
73
What quality does a monounsaturated fat have?
Generally liquid at room temperature because the molecules aren't as packed together
74
Example of a monounsaturated fat
Olive oil
75
How are polyunsaturated fats constructed?
Contain more than one double covalent bond in the carbon chain
76
How do polyunsaturated fatty acid chains appear?
Kinked
77
What quality does a polyunsaturated fat have?
Liquid at room temperature
78
Examples of polyunsaturated fats
Sunflower oil
Rapeseed oil
Vegetable oils
79
How are fatty acids named?
According to the closest double bond to the end of the chain without O2
80
How can you recognise omega 3 from a diagram?
The double bond is 3 carbons up from the end
81
How can you recognise omega 6 from a diagram?
The double bond is 6 carbons up from the end
82
What two configurations are possible within unsaturated fats?
Cis
| Trans
83
What is a cis configuration?
When the H atoms are on the same side of the double bond
84
What is a trans configuration?
When the H atoms are on separate sides of the double bond
85
Which H atom configuration is more prevalent in nature?
Cis
86
How does a cis fatty acid appear?
Bent
87
How does a trans fatty acid appear?
In a line
88
What can fatty acids do to cell membranes?
Cis - makes the membrane more flexible
| Trans - makes the membrane stiffen
89
What, physiologically, can stiff cell membranes lead to?
Oxidative damage
| Leaky cell membranes
90
How can cis fats be turned into trans fats?
By heating them to high temperatures
| Through hydrogenation reactions used to make processed foods and margarine (trans fat)
91
What are essential fatty acids (EFAs)?
Polyunsaturated fatty acids that can't be constructed within the body
Need to be obtained from the diet
92
What are the families of EFAs?
Omega 3
| Omega 6
93
Why is omega 3 important to get from the diet?
The body can't make it from scratch
94
What are the types of omega 3s?
ALA (alpha-linolenic acid)
EPA (eicosapentaenoic acid)
DHA (docosahexaenoic acid)
95
What are the types of omega 6s?
LA (linolenic acid)
GLA (gamma linolenic acid)
AA (arachidonic acid)
96
Sources of omega 3 - ALA
Flaxseeds
Walnuts
Green leafy veg
97
Sources of omega 3 - EPA + DHA
Oily fish
98
Sources of omega 6 - LA
Veg oils
Nuts
Seeds
99
Sources of omega 6 - GLA
Borage oil
| Evening primrose oil
100
Sources of omega 6 - AA
Meat
Dairy
Eggs
101
Should omega 6s be avoided?
No
| For healthy cells and healthy cell to cell communication, a diet would ideally contain a variety of both omega 3 and 6
102
Which EFA is the Western diet rich in?
Omega 6
| particularly AA
103
Why should we consume less omega 6?
It's pro-inflammatory
104
In which order are omega 3s converted?
ALA - EPA - DHA
105
In which order are omega 6s converted?
LA - GLA - AA
106
What is needed to make the conversion of one EFA to another?
Desaturase enzymes to add in double bonds
107
What is the conversion rate for omega 3s and 6s?
10%
| in favour of the EFA in abundance - usually 6
108
Functions of EFAs
```
Fluidity and structure of cell membranes
Synthesis of prostaglandins
Joint lubrication
Transporting cholesterol
Haemoglobin formation
```
109
Why are polyunsaturated fats/EFAs prone to becoming free radicals?
Electrons are lost during heating
| New free radical further reacts with O2 in the air over the cooking pan which makes it even more damaging
110
Where are damaged fats incorporated?
Into cell membranes
111
How is oxidation of fatty acids accelerated?
Heat
Oxygen
Light
112
How are polyunsaturated fats best kept?
In dark glass bottles in fridge
| Never heat up
113
Which fat is best for cooking with at higher temperatures?
Saturated e.g. coconut oil
114
Which is best for cooking with - OO or EVOO?
EVOO
115
What do lipoproteins contain?
Triglycerides
| Cholesterol
116
Where are lipoproteins synthesised?
Liver
117
What are the types of lipoproteins?
VLDL - very low density lipoproteins
LDL - low density lipoproteins
HDL - high density lipoproteins
118
What are VLDL?
Carry newly synthesised triglycerides (those converted from excess carbs) from the liver to adipose tissue
119
What are high VLDL a sign of?
Over-eating
120
What are LDL?
Carry cholesterol from the liver to cells of the body
121
Why do we need LDL?
Repair cells
Support cell membranes
Synthesise sex and adrenal hormones
122
What are HDL?
Collect cholesterol from body cells back to the liver
123
How are phospholipids structured?
Glycerol head
| 2 fatty acid chains
124
What are the qualities of the phosphate head of a phospholipid?
Lots of -OH molecules
Hydrophilic
Polar
Water soluble
125
What are the qualities of the fatty acid tails of a phospholipid?
Hydrophobic
Non-polar
Fat soluble
126
What do the fatty acid tails of the phospholipid contain?
Saturated fat
Unsaturated fat
(to support healthy cell membrane that's not too rigid or fluid)
127
What are steroids?
Lipids formed from cholesterol
128
How do steroids appear?
4 rings of carbon atoms joined together at their base
129
What are sterols?
Steroid bases that contain a -OH group
130
What are steroids used for?
Create hormones
131
What is meant by amphiphatic?
Phospholipids are soluble on one side and insoluble on the other
