chapter 6: proteins Flashcards
are proteins energy yielding nutrients?
ye bruv
are proteins chemically similar to carbs and fats?
ye bruv
what are carbs mostly composed of?
one, two, or thousands of monosaccharides
–> most of them in the firm of glucose
what are lipids mostly composed of?
fatty acids
building blocks of lipids
fatty acids
building blocks of carbs
monosaccharides
the building blocks of protein
amino acids
the three parts of an amino acid
- amino group (contains crucial nitrogen atom)
- acid group
- the side group (the functional group)
all amino acids contains identical what?
the same amino group, and acid group
the backbone of all amino acids
the amino group, and acid group
the difference between all amino acids?
the side group (the functional group)
how many different amino acids? what makes each different?
20 different amino acids
the side group (the functional group) makes them different
the types of non-polar amino acids
Glycine
Alanine
Valine
Leucine
Isoleucine
Proline
Pherrylalaline
Tryptophan
Cysteine
Methionine
all the negatively charged polar amino acids
acidic amino acids
Aspartic ccid
Glutamic acid
all the positively charged polar amino acids
basic amino acids
Histidine
Lysine
Arginine
all the undercharged polar amino acids
Serine
Threonine
Asparagine
Glutamine
Tyrosine
how many amino acids are essential (must come from diet)
9 of them
where are the non essential amino acids synthesized?
in the liver bruv
amino acid tables sort them based on what?
based on polarity
what molecule do non polar amino acids lack? what bond to they also lack?
oxygen
they also lack hydrogen bonds
what molecule do polar amino acids have that non polar lack? what bond to they have that non polar lack?
they have oxygen
they also have hydrogen bonds
a chain of amino acids linked together
a polypeptide
peptide bonds
covalent bonds that link the amino acids together to form a chain that forms proteins
a completed polypeptide chain
a protein
hemoglobin
a set of 4 polypeptides that come together to form a functional protein that delivers oxygen to cells
what happens to the polypeptide chain when placed in water?
the polar and charged amino acids will be attracted to water molecules thanks to hydrogen bonds
the non polar amino acids will cluster in the middle of the protein shying away from the water molecules
what is the protein shape determined by?
by the sequence of amino acids along the chain
changes to the environment in which the protein is in can cause what?
it can break the hydrogen bonds of its amino acid chain
–> causes the protein to unfold
unfolded protein
denatured
no longer functional
what can cause proteins denature?
a change in temperature or a change of pH
effects of a denatured protein in food
changes the texture and consistency of the food
effects of a denatured protein in the body after ingesting it
the denatured protein is no longer functional
how can we denature proteins in the kitchen?
by changing the pH of our food
ex: putting lime in milk causes its protein to fall apart
–> protein changes shape
by changing the temperature of protein
with whipping on protein
why is denaturing muscle protein from meat an important part of cooking?
collagen (which is protein), denatures
–> this reduces the toughness of the meat
what is muscle tissue made of?
made of protein
what is muscle tissue made of?
made of almost exclusively protein
what is collagen
collagen is protein
appearance of collagen
like a highly woven rope
what does intact collagen do?
it increases the resistance to chewing
which animal has more collagen?
cow moo
especially older animals too
how is collagen denatured?
with slow cooking
protein functions in the body
provide structural support and movement
work as enzymes
work as hormones
maintain fluid balances
regulate pH of fluids
crucial component of cell membranes
source of energy
antibodies are protein
which macro is exclusively used for energy?
carbohydrates
the foundation of bones
collagen fibres
what is keratin?
the outer layer of skin, nails, and hair
it is a hard, and inflexible protein
the most common substance in the body after water
protein
what do enzymes do?
work to digest food in the mouth, stomach, and small intestine
are enzymes protein?
ye bruv
why must enzymes in the digestive cavities be properly folded?
so that the food can easily be digested
–> if not, food won’t get digested
is insulin protein?
ye
why must insulin be injected directly into the blood and not taken orally?
because, once insulin is taken orally, the insulin is denatured
if it is denatured, our body must synthesize insulin by its own
–> of course, this is not possible with type 1 diabetes
so, we must inject directly into the blood
why are plasma proteins necessary?
they maintain the right amount of fluids within our tissues
get fluids back into the capillaries to prevent swelling
what happens to protein in the blood during starvation?
the levels of protein in the blood drop
some escape out of the blood capillaries
why is it bad that protein escape out of the blood capillaries?
- the proteins hydrogen bond with water molecules
- this hydrogen bonded water is not drawn into the capillaries
- this creates an accumulation of fluid and tissue
an accumulation of fluid and tissue because the hydrogen bonded water is not going back into the blood capillaries
basically, it is edema
edema
the cell membrane is made of what?
it is the lipid bilayer
–> this is studded with protein
–> protein are gateways for substances to cross the lipid bilayer
proteins and the immune system
proteins also defend the body against diseases
–> ideal candidates for antibodies
why are proteins ideal candidates for antibodies?
they can shape shift and assume any shift
–> they can bind to pathogens like bacteria or virus infected cells and flag them for destruction
effect of lack of protein on our immune system?
not enough proteins to bind to the pathogens
what does digestion do to protein?
it breaks them down into amino acids
what happens to proteins after they are broken down into amino acids?
they are absorbed and delivered to cells in our body
what contains the information on how the link the amino acids to form function protein?
our DNA
it tells the sequence of amino acids to form a protein
what proportion of our genes code for protein?
90% of our protein
18,000 of our genes
what gives cells their characteristic shape and functions?
proteins
where is our DNA?
our DNA is in each nucleus of each of our cells
–> each nucleus contains the same exact copy of our DNA, but not all the genes are turned on
steps to protein synthesis
not a crucial flashcard, don’t waste your time
- the segment of our DNA, the gene, gets copied into an mRNA
- the mRNA exits the nucleus and binds to to a ribosome
- the ribosome builds the protein
- as the mRNA molecule is read, different amino acids are fished out from inside the cell and brought one by one to the growing polypeptide chain
- the amino acids are fished out by the tRNA and led by the polypeptide for it to grow
- once the polypeptide is complete, it is released, and forms into three dimensional proteins
the machine that will build the protein
the ribosome
effects of bad diet on our amino acids?
our body cells will lack many of the important amino acids
what happens if our diet is missing essential amino acids?
the protein synthesis cannot proceed
any partially made polypeptides are dismantled , and its amino acids are returned to the pool
our cells lack the proteins necessary to carry out their work
do we need all 2o amino acids?
ye bruv
role of the stomach in protein digestion
the HCL (hydrochloric acid) in it denatures the food protein
the HCL (hydrochloric acid) also activates pepsin
pepsin
a stomach enzyme that will cut the denatured protein into smaller polypeptides
role of the small intestine in protein digestion
it is connected to the pancreas, which secretes more protein splitting enzymes into the small intestine
these enzymes break down the already small polypeptides into even smaller polypeptides and amino acids
the end products of protein digestion
amino acids
after being absorbed, where do amino acids go? (role of intestinal cells in protein digestion)
they go to the hepatic portal vein to then go to the liver, and the rest of the body
how efficient is protein digestion and absorption?
it is very efficient
very little dietary protein escapes digestion and is eliminated in feces
role of the liver in the absorption of protein?
keeps some of the amino acids for its needs and releases the rest into the general circulation
protein turnover
the recycling of protein
–> proteins are broken down into amino acids
–> these amino acids are used to build new homes
what would happen without protein recycling?
we would need enormous amounts of protein from food everyday
we would need enormous amounts of food simply to get the nitrogen we need
hemoglobin
protein inside RBCs (red blood cells)
carries oxygen to the cells of the body
how many hemoglobin molecules in one RBC (red blood cell)
important
280,000,000 hemoglobin molecules in one RBC
–> RBCs have almost nothing else
why do RBCs have short lifespan
they have almost only hemoglobins
what happens to hemoglobins when RBCs die
they are turned into amino acids and repurposed elsewhere
what % of protein is nitrogen
16%
Nitrogen equilibrium formula
Intake + Retention = Losses
Intake: from food (dietary protein)
Retention: Protein turnover (recycling amino acids)
Losses: Nitrogen losses in urine
Nitrogen balance meaning
the amount of nitrogen (N in) compared to the amount of nitrogen excreted (N out) in a given period of time
Positive nitrogen balance
when protein turnover and nitrogen intake are more than nitrogen losses
Intake + Retention > Losses
when are we in positive nitrogen balance?
pregnancy
lactation
resistance exercise
recovery from illness
growing children
Negative nitrogen balance
when protein turnover and nitrogen intake are less than nitrogen losses
Intake + Retention < Losses
when are we in negative nitrogen balance?
starvation
emotional and other types of trauma
astronauts because muscles are not being used
what happens if our body lacks carbs or lipids?
the body will sacrifice body protein for energy through deamination
deamination
the removal of the amino group
–> we are left with a carbon skeleton (the energy stored in the protein)
—-> can use it to make glucose or lipids
what happens if we eat too much protein?
our liver will deaminate it
it will be stored as fat and not muscle (unless engaged in resistance exercise)
can proteins have negative effects on health?
yeee bruuuv
two ways proteins can negatively affect health
food allergies
celiac disease
what is allergy?
hypersensitivity caused by the immune system to certain substances
the most common allergies
pollen allergies
food allergies
similarity between pollen allergies and food allergies
they come from specific proteins found in certain plant families
what causes food allergies?
when our body mistakenly reacts to certain proteins in food as though it weree a harmful invader
–> our immune system launches an attack against foreign proteins
life threatening food allergies are caused by what?
peanuts
tree nuts
milk
eggs
soy
wheat
fish
a food allergy that is severe as fuuuu
anaphylaxis
food allergies are on the rise or nah?
why or why not?
yeee
genetics and food preparation seem to play a major role
do children usually outgrow their food allergies?
yeee
which food allergies are usually not outgrown?
nut allergies
seafood allergies
wheat allergies
celiac disease
and autoimmune disorder that affects the small intestine
the immune system responds to the presence of gluten in the lumen of the small intestine
–> it damages in the Villi
what happens when villi get damaged?
malnutrition because nutrients can no longer be absorbed
proportion of Canadians with celiac disease
1/133
treatment of celiac disease
getting rid of gluten in diet
non celiac gluten sensitivity (NCGS)
symptoms when we consume gluten but not the disease itself
–> can present with intestinal and extra-intestinal symptoms
we would be better without gluten
why has gluten increased in there last 10,000 years?
through selective breeding of agricultural crops
downside of a gluten free diet
complicated and expensive
how much protein do we actually need?
EAR: 0.66g / kg
RDA: 0.8g / kg
when does protein intake increase?
pregnancy
breast feeding
infancy and childhood
recovery from serious illness
blood losses
burns
what are the DRIs and RDAs of the 9 essential amino acids based on?
Adults: maintaining nitrogen balance
Children (ages 10-12): maintaining positive nitrogen balance
what influences protein quality?
the amino acid composition
protein digestibility
what composes a high quality protein?
contains all essential amino acids in adequate amounts
a well absorbed
what composes a low quality (incomplete) protein?
lacks 1 or more essential amino acid
poorly absorbed
what proteins are considered high quality proteins
animal protein (especially eggs)
plant proteins (especially legumes)
–> still lack at least two essential amino acids
protein complementation
the process of mixing incomplete plan-based proteins sources to provide all essential amino acids without adding animal proteins
