carbohydrate and lipids structure function and nutrition Flashcards
what is a carbohydrate
a hydrated carbon
describe a carbohydrate
essential for all living organisms
most abundant class
how are carbohydrates formed primarily
by photosynthesis
what are the basic units of carbohydrates
monosaccharides
what is the general equation of carbohydrates
(CH2O)n
what are carbohydrtes found in
bread beans milk popcorn spaghetti etc
what are the three classifications of carbohydrates
monosaccharides
disaccharides
polysaccharides
what are monosaccharides
simple sugars- monomers
what are disaccharides
two simple sugars linked together by a covalent bind
what are polysaccharides
hundreds or thousands of monosaccharides
give examples of polysaccharides
starch
glycogen
cellulose
where are monosaccharides commonly found
in humans
how are monosaccharides classified in humans
by the number of carbons they contain in their backbone
how many carbons do the major monosaccharides have
four to six carbon atoms
how are carbohydrates formed
by plants in photosynthesis using C02 and water
how else can glucose be generated in animals
glucose is generated by gluconeogenesis
what other molecules can gluconeogenesis occur with
starts with lactate which is produced by anaerobic glycolysis or amino acids or glycerol
what is the pathway of AA producing glucose
AA—> intermediate of the cytric cycle—-> oxaloacetate—> glucose
what is the pathway of lactate into glucose
lactate—> pyruvate—> oxaloacetate —-> glucose
what is the pathway of glycerol into glucose
gluconeogenesis
how is glycerol produced
from the breakdown of lipids
where is triglycerol sotred
in adipose tissue
what is a glucogenic amino acid
an amino acid that can be converted into glucose through gluconeogenesis
what are the glucogenic AA in humans
alanine arginine asparagine aspartic acid cysteine glutaminc acid glutamine glycine
where is fructose found
fruits
veggies
honey
also the digestion of sucrose
where is glucose found
Small amounts are found in some fruits, vegetables and honey
Manufactured foods
Digestion and conversion of other carbohydrates
where is galactose found
digestion of lactose
are disaccharides taken uo by cells
no as some are too large
where does the covalent bond occur in disaccharides
between the anomeric hydroxyl of a cyclic sugar and the hydroxyl second sugar are termed glycosidic bonds
give examples of disaccharides
SUCROSE
LACTOSE
MALTOSE
describe lactose
found in the milk of mammels
consists of galactose and glucose in a B 1,4 glycosidic bond
what bond is found in lactose
b 1-4 glcosidic bond
describe sucrose
derived from sugar cane and sugar beet
what bond is found in sucrose
a 1,2 glycosidic bond
what is lactose made out of
galactose and glucose
what does sucrose made out of
glucose and fructose
what is maltose made out of
glucose and glucose
what bond is found in maltose
a 1,4 glycosidic bond
what are polysaccharides comprised of
multiple monosaccharides joined by glycosidic linkages
what is the predominant monosaccharide found in poly saccharides
D glucose
what is the major form of stored carbohydrate in animals
glycogen
what is glycogen made out of
a homopolymer made from glucose in a a 1,4 glycosidic bond and 1,6 glycosidic bond
when does branch linkages occur in glycogen
every 8-10 residues
describe glycogen
very compact meaning a lot can be stored in a small space
little osmotic effect
what is the major form of stored carbs in plants
starch
when does branching occur in starch
every 20-30 residues
what is unbranched starch called
amylose
what is branched starch called
amylopectin
what enzymes digest starch
amylase in the digestive tract
what is the full name for cellulose
poly(1,4 B D glucopyranoside)
can humans digest cellulose
no as we have no enzyme to digest it
what is roughage
fibrous indigestible material in vegetable foodstuffs which aids the passage of food and waste products through the gut.
what are monosaccharides and disaccharides used for
energy store
glycosylation of proteins (proteoglycans, glycoproteins )
structural components (GAGS and glycolipids
carbon skeletons for biosynthesiss of AA
how much glucose entering the body i used for other tissues
70%
what does the energy from glucose come from
the chemical bonds between the carbon atoms
what is produced when pyruvate goes through anaerobic respiration
fermentation either with lactic acid produced in animals and alcohol and C02 in yeast and bacteria
what is the byproduct of fermentation in yeast and bacteria
alcohol and C02
what is the byproduct of fermentation in animals
lactic acid
what is cellular respiration
the process by which energy is captured from glucose
what is the first stage of respiration called
glycolysis
where does the link reaction take place
in the mitochondria
how much glycogen is stored in the muscle
3/4 of the store
how much glycogen is stored in the liver
1/4 of the store
what is glucose converted to
ribose and deoxyribose which are important macromolecules such as and NADPH RNA DNA AND ATP
what is NADPH used for
important for protection against oxidative stress and can be used for other chemicals
what is XS glucose stored as
fat
what material is obtained from glucose
the raw material for amino acids
how do we obtain amino acids
can only synthesis half of the required amino acids (nonessential amino acids)
the remainder is obtained from dietary sources (essential)
What is BMI
body mass index relating to height and weight
What is the equation for BMI
weight in kg divided by height in metres squared
What does SACN stand firm
The scientific advisory committee on nutrition
What did SACN research
High levels of sugar consumption are associated with a greater level of tooth decay
Higher sugar higher risk of the high energy intake
Drinking high sugar beverages results in weight gain and increases BMI
Increasing the risk of developing type 2 diabetes
What is the energy intake
Defined as the total energy content of foods consumed as provided by the major sources of dietary energy
What is energy expenditure
Amount of energy that a person needs to carry out physical functions such as breathing circulating blood digesting food or exercising
What is a positive energy balance
Where energy intake exceeds expenditure causing weight gain
What is negative energy balance
Where energy expenditure exceeds intake resulting in weight loss
What is the recommended total carbohydrate contribute to
50% of daily energy requirement
How much of the 50% should be from free sugars
5% of daily energy requirement
How much of the 50% of sugars should be from natural sugars
45%
What should the daily fibre intake be
Now 30g a day
What is the average fibre intake in the UK
12g per day
What is the definition of a lipid
Biological molecules that are insoluble in aqueous solutions and soluble in organic solvents are classed as lipids
Give examples of lipids
Fats
Oils
Vitamins such as A,E,D and K
Hormones
What are lipids classified into
Fatty acids and it’s derivatives
Cholesterol and it’s derivatives
Lipoproteins
What are fatty acids comprised of
Hydrocarbon chains terminating with carboxylate acids
What does the melting point and fluidity depend on in lipids
The length and degree of saturation of the hydrocarbon
What important roles do fatty acids have
Cellular fuel sources Energy storage within adipose tissue in the form of triacylglycerols Structural functions Composition of hormones Modification of proteins Cell signalling
What groups can fatty acids be divided in
Saturated and unsaturated
Describe saturated fatty acids
Solid at room temperate and usually from animal sources
Give an example of saturated fatty acids
Stearic acid
Describe unsaturated fatty acids
Usually liquid at room temp comes from veggie sources
They are monounsaturated or polysaturated c-c double bonds
What shape can carbon carbon double bonds give
Cis or trans isomers
What type of fatty acid has lower cholesterol
Unsaturated cis fats
How many grams of trans fats should we have a day
5g
Give an example of trans fat
Elaidic acid found in partially hydrogenated vegetable oils
How many grams of saturated fat should men have
30g
How many grams of saturated fat should a women have
20g
What is the basic structure of a triacylglyceride
Glycerol backbone to which three fatty acids are esterified
Describe triglycerides
Fat deposited under skin and throughout body cut heat loss
Protects and cushions organs
Non polar
Long term energy store- high potential energy
More than twice the energy of carbs
What’s are steroids
Steroids are lipids characterised by carbon skeleton consisting of four fused rings
How is cholesterol carried in the blood
As low density lipoprotein and high density lipoprotein
What can too much LDL lead to
Heart disease and stroke
Why is HDL beneficial
Has a positive effect by taking cholesterol from parts of the body where there is too much to the liver where it is disposed
What are hydrogenated fats
Are liquid vegetable oils made creamy when manufactures convert some of the unsaturated fats into saturated ones in a process called hydrogenation
How much fat should we have in the diet
35% of the energy in the diet
How much saturated fats should be provided in the energy intake
11%
How much total fat should women have in their diet
70g of total fat a day
How much total fat do we have for the average male
95g
