Nutrients Flashcards
What are nutrients and what are the classes?
Nutrients are substances from food that are used by the body for its life functions. They provide energy, building blocks for cellular components, and molecules that aid chemical reactions
Classes:
1. Carbohydrates (first major nutrient)
2. Lipids (second major nutrient)
3. Proteins
4. Vitamins
5. Minerals
6. Water
What elements make up carbohydrates?
Carbon, Hydrogen, Oxygen
What are carbohydrates that are found individually, in pairs, and in long chains called? (based on rings)
Individually: monosaccharides (aka simple sugars)
In pairs: disaccharides
Long chains: polysaccharides
What is the most common carbohydrate?
Glucose (monosaccharide)
How are disaccharides formed?
Two monosaccharides undergoing dehydration synthesis
How are disaccharides broken down into monosaccharides?
A disaccharide undergoes hydrolysis
Dietary sources of carbohydrates?
Plants: starch, sucrose and cellulose
Animals: glycogen and lactose
to be absorbed, carbohydrates must be broken down into monosaccharides
Describe the body’s ability to store carbohydrates
The body has a limited ability to store carbohydrates and they are easily converted to glycogen (stored in liver and muscle) and fat (in adipose tissue) if not used
What are the effects of carbohydrate consumption in excess or reduction?
Excess carbohydrate intake can lead to obesity and elevated blood lipid levels (ex. atherosclerosis)
Reduced carbohydrate intake can lead to increased protein and fat metabolism, loss of muscle mass, and potential acidosis
What are lipids composed of?
Carbon, Hydrogen, Oxygen, Phosphorus (less oxygen than carbohydrates)
What kind of molecules are lipids?
Lipids are non-polar, hydrophobic molecules that are insoluble in water and soluble in other lipids
What are the 4 classes of lipids?
- Triglycerides (triacylglycerols, neutral fats)
- Fatty acids (including eicosanoids)
- Phospholipids
- Steroids (cholesterol, estrogen, testosterone)
What are triglycerides?
A storage lipid, and represent a vast energy reserve in adipocytes, muscle, and liver
They insulate, cushion, and protect vital organs
Excess triglyceride is a cause of obesity
What is the composition of triglycerides?
Triglycerides are made up of 1 glycerol and 3 fatty acid chains
What is glycerol?
Glycerol is a molecule made up of 3 carbon atoms (one per fatty acid)
What are fatty acids?
Fatty acids are long chains of carbon atoms bound with hydrogen atoms (hydrocarbons)
Chain length varies but is typically around 16-20 carbons long
Each fatty acid has a carboxylic acid tail at the end, giving the chain its acidic properties (-COOH)
What determines the solidity of fatty acids at room temperature?
The type of carbon-to-carbon bonds and length
What is the different between saturated and unsaturated fatty acids?
Saturated: if all bonds are single bonds in the chain
Unsaturated: if there is one double bond in the chain
Polyunsaturated: if there are more than one double bond in the chain
What type of fatty acid (saturated/unsaturated) is more stable at room temperature?
Saturated
Where do saturated fatty acids come from?
Primarily from animal sources and are solid at room temperature (called fats)
Where do unsaturated fatty acids come from?
Found in plant sources, and are liquid at room temperature (called oils)
Which type of fatty acid is healthier?
Unsaturated fats / oils
What are hydrogenated oils?
Chemically altered oils in which some double bonds are converted to single bonds by the addition of hydrogen -> more saturated and solid at room temperature (ex. margarine)
What are essential fatty acids?
Linoleic acid or linolenic acids
essential fatty acids are fats that cannot be synthesized by the human body and must be consumed through dietary sources
What reaction does glycerol and 3 fatty acids undergo to become triglyceride?
Dehydration synthesis
What reaction does triglyceride have to undergo to become glycerol and 3 fatty acids?
Hydrolysis
What do hydrogenated oils do to the body’s LDL and HDL
Low density lipoproteins (Bad) are increased in levels in the blood
High density lipoproteins (Good) are decreased in levels in the blood
What are Eicosanoids?
Fatty acid signaling molecules that cannot be synthesized (essential fat) and must be obtained from diet
Derived from a fatty acid called arachidonic acid
types:
-leukotrienes (produced by leukocytes) that are active in the immune system
-prostaglandins: short-chain fatty acids, local hormones (chemical messages)
What are phospholipids composed of?
2 fatty acid chains, glycerol, and a phosphate group
What part of phospholipids are polar and what parts are non-polar?
The phosphate group gives the molecule polarity.
The phosphate head is hydrophilic and the fatty acid tail is hydrophobic
What do phospholipids do?
Phospholipids make up the plasma membrane and are also used in the transport of lipids in blood plasma
What is a micelle?
Micelles are formed by large groups of phospholipids and glycolipids in water, where the hydrophilic heads face the water and the tails are on the inside
How are micelles different from plasma membranes?
Micelles are not a double layer like plasma membranes (phospholipid plasma bi-layer)
What does it mean to be amphipathic?
To have both non-polar and polar portions
What are steroids?
Lipids that differ in structure compared to other fats, since they are composed of 4 hydrocarbon rings and a functional group
What is cholesterol?
Cholesterol is produced in the Smooth endoplasmic reticulum of liver cells and is used to synthesize steroid hormones (ex. estrogen, cortisol, testosterone)
It is a vital component in the cell membrane and is used to create bile and vitamin D
It is transported from the liver to the rest of the body through blood. High cholesterol is dangerous as it can lead to atherosclerosis and other health difficulties.
What is cortisol?
Cortisol is a hormone that is important in maintaining normal blood sugar levels and regulating the immune response
What is excess serum cholesterol?
Excess serum cholesterol is associated with risk of heart disease, and high intake of saturated fatty acids may increase the liver’s production of cholesterol
What are dietary sources of cholesterol?
Found in eggs, meat, cheese, and liver
intake should be limited to 200mg per day
What does blood cholesterol travel as?
Lipoproteins
Low-density lipoproteins transport cholesterol from the liver to the rest of the body
High-density lipoproteins pick-up or scavenge excess cholesterol and return it to the liver for disposal in bile salts
(LDL BAD; HDL GOOD)
What is an amino acid composed of?
Amino group
Central carbon
Carboxyl group (carboxylic acid tail)
R group (variable side chain of one or more atoms)
What are proteins made up of?
Amino acids
What kind of bonds hold amino acids together?
Peptide bonds
What is a polypeptide?
A string of over 100 amino acids
What kind of bonding is present between amino acid chains?
Hydrogen bonding along the length of the polypeptide chain creates the secondary structure of the proteins
What are the characteristics of the primary structure of a protein?
The primary structure of a polypeptide is the sequence of amino acids
What are the characteristics of the secondary structure of a protein?
Primarily held together by hydrogen bonds along the length of the polypeptide chain
Bonding creates a spiral or flattened shape (alpha helix and beta sheet)
What are the characteristics of the tertiary structure of a protein?
Coiling and folding of a polypeptide occurs at this stage
Within the cylindrical segments of this globular protein, the polypeptide chain is arranged in an alpha helix
What are the characteristics of the quaternary structure of a protein?
Develops when separate polypeptide units interact to a form a larger molecule
What does boiling to proteins?
Denaturation; by affecting the hydrogen bonds
What are coenzymes and cofactors of proteins?
Coenzymes: vitamins
Cofactors: Ca2+, Mg2+
Enzyme****
What is an endergonic reaction?
Energy is gained through the reaction and small molecules are assembled into larger ones
What is an exergonic reaction?
Energy is lost through the reaction and larger molecules are broken down into smaller ones
What are the subunits of nucleic acids?
Nucleotides?
What is the structure of nucleotides?
Phosphate group, nitrogenous base, and pentose sugar (either deoxyribose or ribose)
How is a sugar phosphate backbone of a nucleic acid created?
Dehydration synthesis
What is the structure of a DNA molecule?
The DNA molecule is a double helix, made up of two complementary strands (nucleotide chains) that are linked by hydrogen bonds between complementary base pairs
What are proteins made up of?
Amino acids
How many amino acids are in the body?
20, each having a different R group
How are amino acids linked together?
Head to tail by a peptide bond to form proteins and polypeptides
What are amino acids made up of?
N-terminal amino group head and carboxylic acid group C-terminal tail
How many proteins can the body synthesize?
Around 10 proteins, the remaining 10 are considered essential amino acids that must be consumed in the diet
What are protein foods that contain all 20 acids? What are protein foods considered if they are deficient in one or more essential amino acids?
Contain all 20 - complete proteins (animal protein)
Not all 20 - incomplete proteins (plant protein)
What element does protein contain that other nutrients do not?
Nitrogen; the only dietary source of this element
some may contain phosphorus and sulfur
How does nitrogen primarily enter and exit the body?
Nitrogen enters through the consumption of amino acids and exits through urea
What is nitrogen balance?
nitrogen input is equal to output
What is negative nitrogen balance?
nitrogen output is greater than input
ex. infection, increased stress, increased cortisol, starvation
What is positive balance?
nitrogen input is greater than output
ex. growth, tissue repair, pregnancy
What is PKU Phenylketonuria?
Rare birth defect resulting from an abnormal gene; defect in phenylalanine hydroxylase which is needed to convert
phe to tyr
requires low phe + high tyr diet
What is Homocystinuria?
Defect in Met metabolism
requires high vitamin b6 and low met diet
What is maple syrup urine disease?
Deficiency in BCKDH
require diet low in leu, ile, val
