topic 4 Flashcards
what are the 3 macronutrients? what are their calories? how many calories does fiber have?
fats (9cal/g), carbohydrates (4cal/g), and proteins (4cal/g), fiber (2 ca/g)
What elements are the macronutrients made up of?
Fats and carbohydrates: C, H, O
Proteins: C, H, O, N
What are carbohydrates? What is their general formula?
- they are composed of carbon (carbo) and water (hydrate) and thus has a general formula of Cm(H2O)n.
- they give us energy during their consumption (in addition to creating water and CO2)
- carbohydrates + O2 = energy + H2O + CO2
what is glucose oxidation? What happens when the opposite occurs?
glucose oxidation = when carbs are consumed (carbs +o2)
opposite is when glucose produced during consumption is converted back into water and carbon dioxide
Describe sucrose
- disaccharide made up of glucose and fructose
- otherwise known as table sugar
- Broken down by invertase
- Makes up most of brown sugar (sucrose + molasses)
What is the bad news for sucrose?
- It causes glycation: unnatural binding of molecules (Maillard reaction) where there is engagement of protein units that have an NH2 group at one end with carbohydrate units, such that when you heat it, water is quickly given off and leads to browning.
- Advanced Glycation End (AGE) products: 2 protein chains connected to what was a sugar unit, this can cause cataracts (causes clouded lenses and you see blurry, due to protein folding in eye lens which creates clumps) and makes skin not as supple.
Describe glucose
- C6 monosaccharide
- it is sometimes called dextrose
- It makes up cellulose and starch
What characteristic of the carbohydrate structure defines the type of carb that will be built?
Whether the H atoms are up or down is what defines what type of carbohydrate is produced and what kind of features it has
What is the difference between cellulose and starch?
the OH bonds between the glucose molecules, in cellulose the bond is diagonal (OH bond up up) making it indigestible for humans and in starch the OH bond is down and up (digestible)
What makes a food digestible?
whether the enzymes matches up with the reactant (food) molecule in shape. If it is, the enzyme fits in with the reactant food and is able to make products.
Otherwise, there is a mismatch and the food is not digestible
Describe fructose
- monosaccharide,
- usually an individual sweetener because very sweet.
- Honey is very sweet due to its high (39%) fructose content.
Describe maltose
- disaccharide,
- sweetening agent derived from partial hydrolysis of starch,
- maltose = glucose + glucose,
- broken down by maltase which breaks it down into glucose and subsequently converts it into energy through complete oxidation.
Break it down, what is the good news about fructose?
- low glycemic index, so it doesn’t cause blood sugar to rise as much as sucrose, so good substitute.
Break it down, what is the bad news about fructose?
- too much at once isn’t good and modern diet is ~ 10% fructose
- When it enters bloodstream, insulin regulates it but fructose is processed in the liver and if there’s too much it makes fat and too much fat in blood is a risk for heart disease
- Fructose circumvents appetite signaling, so body doesn’t know when it is satiated.
- Some evidence suggests that excess fructose causes insulin resistance which can lead to type II diabetes.
- High fructose drinks have been associated with the risk of gout as excess fructose causes uric acid increase which creates inflamed joints (gout). This does not apply to diet soft drinks. Study says contribution to development of gout is modest.
Describe lactose
- disaccharide,
- lactose = galactose + glucose, has diagonal bond so not digestible (like cellulose), which is why a lot of people are lactose intolerant
- broken down by lactase (aka Lactaid).
- lactose intolerant people tend to have high H concentrations in breath when they consume lactose.
- Northern hemisphere populations tend to have less intolerance frequency.
order these by sweetness: sucrose, honey, glucose, fructose
fructose > honey (39% fructose) > sucrose > glucose
True or false: diet soda is full of fructose
False, diet soda has 0g of fructose.
What is Beano?
enzyme that prevents gas from beans, called alpha-galactosidase which breaks down the sugar from beans that creates gas.
What is amylose and what breaks it down?
a starch which is broken down by amylase, an enzyme produced by the pancreatic and salivary glands, so chewing food helps breaking down carbs. It can also break down amylopectin, a starch like molecule that is easier to digest.
How is High Fructose Corn Syrup (HFCS) made?
- Start off with corn starch: glucose polymer
- This polymer is broken down into single units by 3 enzymes
* alpha-amylase,
* glucoamylase,
* glucose-isomerase - glucose isomerase which converts glucose into high % fructose (up to 90%, super sweet)
- Final result, made into pure glucose aka corn syrup with high fructose content.
True or false: obesity has been linked with HFCS
True, obesity increased with increase of HFCS.
How much of sugar cane is sucrose? Who is the biggest producer?
15%, Brazil
Why is sugar bad for your teeth?
when sugar and S. Mutans, a bacteria in the mouth, come together, they produce lactic acid which eats away teeth and creates cavities. Though gene removal could reduce this effect.
True or false: candy is 50% fructose
False, candy is 98% sucrose