2.3 Carbohydrates Flashcards
What elements are carbohydrates composed of?
C, H, O
What are carbohydrates composed of?
Recurring monomers -> monosacchrides
What are disaccharides?
2 monosacharides join via glycosidic bonds
What are polysaccharides?
Many monosaccharides joined via glycosidic bonds
What are three exmaples of monosaccharides
Glucose, galactose and fructose
What are three examples of disaccharides?
Lactose, maltose and sucrose
What are three examples of polysaccharides?
Cellulose, glycogen and starch
What does the polysaccharide formation depend on ?
The monosaccharide subunits involved andthe bonding arrangement between them
What is cellulose?
A structural polysaccharide foun in the cell wall of plants
What are two structural characteristics of cellulose?
It is a linear moleucles composed of Beta glucose subunits
What is starch?
An energy storage polysaccharide found in plants
What is a structural characteristic of starch?
Composed of alpha glucose subunits
What two forms are carbohydrates found in?
Amylose and amylopectin?
What is the structure of amylose? (3 pieces of info)
It is linear (helical) molecules
Harder to digest and less soluble
Preferred storage for plants
What is the structure of amylopectin?(2 pieces of info)
Branched
Easier to digest and more soluble
what is glycogen?
energy storage polysaccharide formed in liver of animals
what is glycogen composed of?
alpha-glucose subunits linked together by
what are fatty acids?
a long hydrocarbon chain that is found in certain types of lipids
what are fatty acids that possess no double bonds?
saturated fatty acid
what kind of structure do saturated fatty acids have?
- linear in structure
- originate from animal sourses
- typically at room temperature
what are fatty acids with double bonds?
unsaturated fatty acids
what are the two types of unsaturated fatty acids?
monounsaturated
polyunsaturated
what is the structure of unsaturated fatty acids? (3)
- bent
- originate from plant sources
- liquid at room temperature
what 2 distinct fatty acids may unsaturated fatty acids occur in?
cis - hydrogen atoms attached to the carbon double bond are on the same side
trans - hydrogen atoms attached to the carbon double bond are on different sides
what are the characteristics of trans fatty acids?
- don’t occur in nature
- typically produced by an industrial process called hydrogenation
- generally linear in structure
- usually solid at room temp
what are trigylcerides?
the largest class of lipids and function primarily as long-term energy storage molecules
- animals tend to store triglycerides as fats (solid)
- plants ten to store triglycerides as oils (liquid)
how are triglycerides formed? (3)
when condensation reactions occur between one glycerol and three fatty acids
- the hydroxyl groups of glycerol combine w/ the carboxyl groups of the fatty acids to form an ester linkage
- this condensation reaction results in the formation of 3 molecules of water
what can triglycerides be?
either saturated or unsaturated
- dependent on the composition of the fatty acid chains
what types of fats raise or lower blood cholesterol levels?
- saturated and trans fats raise blood cholesterol levels
- (cis) unsaturated fats lower blood cholesterol levels
how are fats and cholesterol packaged?
with protein to from lipoproteins
why are fats and cholesterol used for transport?
because they cannot dissolve in blood
what are the 2 lipoproteins and what do they do?
- low-density lipoproteins (LDL) carry cholesterol from the liver to the rest of the body
- high-density lipoprotein (HDL) scavenges excess cholesterol and carry it back to the liver for disposal
what do LDL and HDLs do to blood cholesterol levels?
- LDLs raise blood cholesterol levels (bad)
- HDLs lower blood cholesterol levels (good)
How do high intakes of certain types of fats differentially affect cholesterol levels in the cloud? (3)
- saturated fats increase LDL levels within the body, raising blood cholesterol levels
- trans fats increase LDL levels and decrease within the body significantly raising blood cholesterol levels
- unsaturated (cis) fats increase HDL levels within the body, lowering blood cholesterol levels
why is high cholesterol in the bloodstream bad?
- lead to the hardening and narrowing of arteries (atherosclerosis)
what happens when there are high levels of LDL in the bloodstream?
- high levels of LDL in the bloodstream, the LDL particles will form deposits in the wall of the arteries
- the accumulation of fat within the arterial walls lead to the development of plaques which restrict blood flow
- the coronary arteries become blocked, coronary heart disease (CHD) will result in heart attacks and strokes
what are 2 main health claims made about lipids in the diet?
- diets rich in saturated fats and trans fats increase the risk of CHD
- diets rich in monounsaturated and polyunsaturated (cis) fats decrease the risk of CHD
what are 3 evidence supporting lipid health claims?
positive correlation has been found between the intake of saturated fats and the incidence of CHD in human populations
- counter- certain populations do not fit this trend (eg. Maasai tribe in Africa has fat-rich diet but low CHD)
in patients who died from CHD, fatty deposits in diseased arteries were found to contain high concentrations of trans fats
- genetic factors may play a role
intervention studies shown that lowering dietary intake of saturated fats reduces factors associated w/ the development of CHD
- counter- validity of intervention studies is dependent on size and composition of cohort, as well as the duration of the study
what is evidence against lipid health claims (2)?
proportion of saturated and trans fats in western diets has decreased over the last 50 yrs but incidence of CHD has risen
- counter - increased carb intake may cause detrimental health effect associated with CHD
- counter - incidence of CHD dependent on a myriad of factors besides dietary intake
what is BMI?
provides a measure of relative mass based on the weight and height of the individual
how can BMI be calculated?
BMI - mass in kg/ (height in m)^2
who should BMI not be a valid indicator?
for pregnant women or professional athletes w/ atypical muscle/fat ratios
what should BMI not be used for?
should not be used as a diagnostic tool and should be used in conjunction with other measurements
what are nomograms?
an alternative way of calculating BMI by using an alignment chart
