Lecture 2 - Jan 10 (Part 1 - carbs, lipids, proteins) Flashcards
what are carbohydrates made of
carbon
hydrogen
oxygen
what is the ratio of carbon to water
1:1
Thus, carbohydrates literally means “carbon with water”
what is considered the major source of fuel for the body
carbohydrates
provide examples of carbohydrates
starches
sugars
main source is:
grains
vegetables
legumes
fruits
do dairy and meat products have carbs?
dairy products have some carbs
meats have very little carbs
dietary fibre:
a carbohydrate, but it does not provide energy for cells. because there are no enzymes to actually break fibre down which is why they don’t provide energy for the cells;
there are bacteria that live in our large intestine/colon, and these bacteria live off of fibre so they can grow)
it is actually very important for normal function of the GI tract
Our body converts most of the dietary carbohydrate into what?
glucose which circulates in our blood (final molecule of sugars)
Glucose is taken in by cells and is used for what two purposes?
energy production
stored as glycogen
How do skeletal muscle and liver utilize glucose
Skeletal muscle and liver metabolize glucose to generate energy.
what happens to excess glucose?
Excess glucose not needed by the cell is stored in skeletal muscle and liver
What is the primary energy source for the brain, and how does its supply affect brain function?
The brain primarily relies on glucose for its energy needs and requires a steady supply of glucose to function properly.
what is a lipid
Compounds that are soluble in organic solvents (ex: acetone, ether, and chloroform)
(water is an inorganic solvent which is why they don’t mix)
examples of lipids
Fats, oils, and other fat like substances such as cholesterol and phospholipids that
are found in food
What makes up the largest proportion of lipids
consumed by humans
Triacylglycerols/triglycerides (TG)
(most abundant in the foods that we eat)
Why do lipids undergo specialized processing in the human body?
Because lipids cannot mix with water (non-water miscibility) and the human body is mostly water, they require specialized processing during digestion, absorption, transport, storage, and utilization to be effectively used by the body.
6 Functions of lipids:
energy storage/release (adipose tissue)
insulation and padding of internal organs
cell signalling
cell membrane formation
synthesis of hormones
carriers of fat soluable vitamins (A, D, E, and K; can only mix in an environment that has fat)
what are essential fatty acids
fatty acids we do not make on our bodies don’t produce
what are the two fatty acids Mammals, including humans, cannot produce (essential)
omega-3 fatty acids
* Linolenic acid (18 carbons: 3 double bonds - ω-3)
omega-6 fatty acids
* Linoleic acid (18 carbons: 2 double bonds - ω-6)
Why can’t Mammals, including humans not produce omega-3 and omega-6 fatty acids
because they lack delta-12 and delta-15 desaturases.
another name for omega-3 fatty acids
Linolenic acid (18 carbons: 3 double bonds - ω-3
another name for omega-6 fatty acids
Linoleic acid (18 carbons: 2 double bonds - ω-6)
what are proteins?
Organic compounds made of amino acids (aa)
what elements does protein contain
carbon, oxygen, hydrogen, as well as nitrogen, and sulfur
what can half of the dry weight (once evaporated) of a typical human cell be attributed to
protein
(a lot of protein to make a cell)
*Roles of protein:
➢ Structural components and contractile elements (actin and myosin)
➢ Antibodies
➢ Transporters
➢ Neurotransmitters
➢ hormones
➢ Enzymes
What is the relationship between proteins and enzymes?
Not every protein is an enzyme, but every enzyme is a protein
Approximately how many known AA exist in nature
140AA
Out of the 140 AA known to exist in nature, how many are genetically coded via mRNA and incorporated into various protein
20 AA
what is “post-translation modification”
modifications that take place after the protein is initially synthesized
Human proteins also contain modifications of a few of these aa
Humans are unable to synthesize _____ AA, either at all or in adequate amounts to meet the body’s need for growth and maintenance of tissues and organs; these are essential aa
Humans are unable to synthesize 8-9 AA
Lysine
tryptophan
methionine
valine
phenylalanine
leucine
isoleucine
threonine
histidine (for infants, becomes non-essential in adulthood)
