2.3 Carbohydrates and lipids Flashcards
How are monosaccharides linked together?
Via condensation reactions
What is formed as a by product in condensation reactions?
Water
What joins two monosaccharide monomers and to form what?
Glycosidic linkage to form a disaccharide
What joins many monosaccharide monomers to form what?
Glycosidic linkages to form polysaccharides
What are monosaccharides?
One sugar unit that is typically sweet tasting
What is the function of a monosaccharide?
An immediate energy source for cells
What are three examples of monsaccharides?
Glucose
Galactose
Fructose
What is the mnemonic for monosaccharides?
Gives Good Flavour
What is a disaccharide?
Two sugar units
What are disaccharides small enough to be able to do?
To be soluble in water
What is the function of disaccharides?
Transport form
What are three examples of disaccharides?
Lactose
Sucrose
Maltose
What is the mnemonic for disaccharides?
Length supports movement
What are polysaccharides?
Many sugar units
What are the three functions of polysaccharides?
Energy storage
Cell structure
Cell recognition
What are the three examples of polysaccharides?
Cellulose
Glycogen
Starch
What is the mnemonic for polysaccharides?
Can get stored
What is cellulose?
A structural polysaccharide that is found in the cell wall of plants
What is the physical structure of cellulose?
A linear molecule
Composed of B-glucose subunits
Bound in a 1-4 arrangement
Why is cellulose indigestible for most animals?
Because it is composed of B-glucose and most animals lack the enzyme needed to break it down
Why can ruminants digest cellulose?
The presence of helpful bacteria in a specialised stomach
How do caecotrophs digest cellulose?
They will re-ingest specialised faeces that contain digested cellulose
What is starch?
An energy storage polysaccharide found in plants
What is the physical structure of starch?
Composed of a-glucose subunits
Bound in a 1-4 arrangement
What are the two types of starch?
Amylose and amylopectin
What is the difference between amylose and amylopectin?
Amylose is a linear helical molecule
Amylopectin is branched and contains additional 1-6 linkages
What is the preferred storage form in plants and why?
Amylose as it takes up less space
What is the downside to amylose?
It is harder to digest and less soluble
What is glycogen?
An energy storage polysaccharide formed in the liver in animals
What is the physical structure of glycogen?
Composed of a-glucose subunits
Linked by both 1-4 linkages and 1-6 linkages
What is glycogen similar to?
Amylopectin
How may fatty acids differ?
In the length of the hydrocarbon chain and in the number of double bonds
What are saturated fatty acids?
Fatty acids that possess no double bonds
Where do saturated fatty acids originate from?
Animal sources
What is the structure of saturated fatty acids?
Linear
What state are saturated fatty acids at in room temperatures?
Solid
What are unsaturated fatty acids?
Fatty acids with double bonds
What are the types of unsaturated fatty acids?
Monounsaturated and polyunsaturated
What is a monounsaturated fatty acid?
Fatty acid with one double bond
What is a polyunsaturated fatty acid?
Fatty acids with more than one double bond
Where do unsaturated fatty acids originate from?
Plant sources
What is the structure of unsaturated fatty acids?
Bent
What is the state of unsaturated fatty acids at room temperature?
Liquid
What are the two structural configurations of unsaturated fatty acids?
Cis and trans isomers
What is a cis isomer?
The hydrogen atoms attached to the carbon double bond are on the same side
What is a trans isomer?
The hydrogen atoms attached to the carbon double bond are on different sides
What is the way to produce trans fatty acids?
Hydrogenation
What is the structure of trans fatty acids?
Generally linear
What state are trans fatty acids usually in at room temperature?
Solid
What is the largest class of lipids?
Triglycerides
What is the function of triglycerides?
As long term energy storage molecules
How do animals store triglycerides?
As fats
How do plants store triglycerides?
As oils
How are triglycerides formed?
When condensation reactions occur between one glycerol and three fatty acids
What do the hydroxyl groups of glycerol combine with to form an ester linkage?
The carboxyl groups of the fatty acids
What does the condensation reaction with triglycerides produce?
Three molecules of water
What are the two types of triglycerides and what does it depend on?
Saturated or unsaturated depending on the composition of the fatty acid chains
What type of fats raise blood cholesterol levels?
Saturated fats and trans fats
What type of fats lower blood cholesterol levels?
Cis unsaturated fats
As fats and cholesterol cannot dissolve in blood what happens?
Fats and cholesterol are packaged with proteins to form lipoproteins for transport
What do low density lipoproteins do?
Carry cholesterol from the liver to the rest of the body
What do high density lipoproteins do?
Scavenge excess cholesterol and carry it back to the liver for disposal
What do LDLs affect blood cholesterol levels?
They raise them
What do HDLs affect blood cholesterol levels?
Lower them
What does the relationship between saturated fats and LDL levels do?
Saturated fats increase LDL levels which raise blood cholesterol levels
What do trans fats do to LDL and HDL levels and what does that do?
Trans fats cause increase in LDL levels and decrease in HDL levels
What do unsaturated cis fats do to HDL levels and what does that do?
Increase HDL levels which lowers blood cholesterol levels
What does high cholesterol levels result in?
The hardening and narrowing of arteries
What do LDL particles do when there are high levels of LDL in the bloodstream?
Form deposits in the walls of the arteries
What does the accumulation of fat within the arterial walls lead to?
The development of plaques which restricts blood flow
What causes coronary heart disease?
When coronary arteries become blocked
What are the two health claims main about lipids in the diet?
Diets rich in saturated fats and trans fats increase the risk of CHD
Diets rich in unsaturated cis fats decrease the risk of CHD
What are the three ways evidence has been collected about lipid health claims?
Epidemiological studies comparing different population groups
Intervention studies that monitor cohorts following diet adjustments
Experimental designs utilising animal models or data from autopsies
What is the counter argument to the positive correlation between intake of saturated fats and CHD in populations?
Certain populations do not fir the trend like the maasai tribe
When talking about lipid health claims what have intervention studies show?
That lowering intake of saturated fats reduces the risk of CHD
What is a counter point to intervention studies on lipid health claims?
That the validity of intervention studies is dependent on the size, composition of participants and duration of study
What is the argument to support lipid health claims about patients who died from CHD?
fatty deposits in diseased arteries were found to have high concentrations of trans fats
What is a counter to the argument about patients who died from CHD?
Genetic factors may play a role
What is an argument against lipid health claims in their entirety?
Saturated and trans fats have decreased but CHD has risen
What counters the argument that lipid health claims don’t exist?
Increased carbohydrates may cause health effects associated with CHD
Incidence of CHD is dependent on other factors not just diets
What are the five key ways that lipids and sugars differ?
(sodas)
Storage
Osmolarity
Digestion
ATP yield
Solubility
Tell me about storage for carbohydrates?
Short term energy storage
Tell me about storage for lipids?
Long term energy storage
Tell me about Osmolarity for carbohydrates?
More effect on osmotic pressure
Tell me about Osmolarity for lipids?
Less effect on osmotic pressure
Tell me about digestion for carbohydrates?
More easily digested
Used for aerobic or anaerobic respiration
Tell me about digestion for lipids?
Less easily digested
Can only be used for aerobic respiration
Tell me about ATP yield for carbohydrates?
Stores half as much ATP per gram
Tell me about ATP yield for lipids?
Stores twice as much ATP per gram
Tell me about solubility for carbohydrates?
Water soluble as monomers
Easier to transport
Tell me about solubility for lipids?
Not water solubility
More difficult to transport
What does the body mass index do?
Provides a measure of relative mass based on the weight and height of the individual
Why is the body mass index used?
To identify potential weight problems in sedentary adults
What is the formula to calculate body mass index?
mass in kg/ (height in m)2
For which groups of people are BMI values not a valid indicator for and why?
Athletes and pregnant women with atypical muscle/fat ratio
What is an alternative way of calculating body mass?
Nomograms
What do nomograms do?
Nomograms display height and weight on perpendicular axes and then assign BMI values to colour coded regions
