chap 5 proteins Flashcards
what is the basis structural component of proteins and what does it contain
amino acid -> carbon, hydrogen, oxygen, nitrogen
It is the _ that distinguishes
them from the composition of carbohydrates,
fats, and alcohol
nitrogen
when does a amino acid is essential vs non essential and why is it important
- if nitrogen balance is negative = indispensable
- essential (indispensable) cannot be synthesized by the body and need to be ingested by food
lack of essential AA limits protein synthesis
how many AA are essential vs non essential
9 non, 11 essential
protein quality is determined based on
the amounts and
types of amino acids and the extent to which the amino acids are absorbed
what is the international method for determining protein quality
protein digestibility corrected amino acid score (PDCAAS)
animal protein are termed complete or incomplete protein and why
complete proteins because they contain all the indispensable amino acids in the proper amounts and proportions to each other to prevent amino acid deficiencies and to support growth.
plant protein are considered complete or incomplete protein and why
plant proteins may lack one or more of the
indispensable amino acids or the proper concentrations and are termed incomplete proteins
what is the concept of complementary proteins
pair different plant proteins with each other and bring the total concentration of all the indispensable amino acids to an adequate level.
what determine how a protein functions
primary structure of the polypeptide
what is the primary structure of a protein
sequence of AA forming one or more polypeptide chain
what is the secondary structure of a protein
coiling or folding of its polypeptide chain due to hydrogen bonding within or between AA chain -> give the shape of the protein
what is the tertiary structure of protein
3-D shape of polypeptide caused by weak interaction among side groups and between side group and the fluid environment
what is the quaternary level structure of protein
final 3D structure formed by all polypeptide, composed of 4 polypeptide chain,
what is a conditionally indispensable AA
Under normal conditions, an amino acid that can be manufactured by the body in sufficient amounts, but under physiologically stressful conditions,
an insufficient amount may be produced.
which AA are often limiting
lysine, threonine, cysteine, methionine
what is a complementary protein
incomplete proteins that
when eaten together provide a full complement of all essential amino acids.
what are the protein function in the body
- Enzymes
- Hormones & Cytokines
- Structural proteins
- Transport proteins
- Immune system proteins
- Acid-base regulator
- Fluid regulator
- Energy
where does protein digestion begins
in the stomach when protein is in contact with gastric juice -> denature begin
what is the role of HCI in the gastric juice of stomach
denature protein (change structure) and activate pepsin, enzyme that break polypeptide into smaller unit (10-20% digestion)
where is the majority of digestion of protein occurs
small intestine
where come the digestive enzyme that are activate in small intestine for protein digestion
pancratic juice and cell of the brush border
large polypeptide that entered from the stomach are broken down in what
tripeptide, dipleptide and AA
where protein absorption occurs and which one btw essential or non essential AA are absorbed more rapidly
entire small intestine, non-essential
% of peptides and free AA aborsbed
67% as peptides
33% as free AA
what does exogenous means
originate from outside of the body
what does endogenous mean
originate from inside the body
The amino acid pool contains amino acids recently absorbed
from
food and from the breakdown of skeletal muscle tissue
what is the amino acid pool
free amino acids that are circulating in the blood or in the fluid found within or between cells.
The constant change in the body proteins as
a result of protein synthesis and breakdown is referred to as
protein turn over
what is a major site for amino acid metabolism
the liver
the uses of protein for energy is a catabolic or anabolic process
cata
What is the fate of the amino acids absorbed
from the gastrointestinal tract and transported to
the liver?
20% is used by liver and 50-65% are absorbed by liver
purpose of catabolism
- Degrades damaged proteins
- Provides energy
- Synthesis of other compounds
what is transmination
involves the transfer of an
amino group to another carbon skeleton,
what is deamination
refers to the removal
of the amino group from the amino acid. When the amino group is removed,
the remaining compound is an alpha-keto acid
(a-keto acid), frequently referred to as the carbon
skeleton.
transamination in the liver allows what
liver to manufacture dispensable AA from indispensable AA
creatine synthesis begin where and end where
begin in kidney and completed in liver
what happen with ammonia
- in muscle: form glutamine from glutamate
- in liver: converted to urea
- can also be excreted in sweat
AA that undergo significant oxidation in muscle
Asparagine
¡ Aspartate
¡ Glutamate
¡ Isoleucine
¡ Leucine
¡ Valine
the source of approximately half of the ATP used by the liver
comes from
aa
% of the total energy that come from AA is
3 to 5% but during higher prolonged intense exercise AA is an important source of energy
why AA can be a major source of energy during endurance exercise
due to depletion of glycogen -> result in increased oxydation of leucine
which AA are the only one that cannot make glucose
leucine and lysine
AA will be converted in what to produce glucose
pyruvate
what is nitrogen balance
the difference between total nitrogen (protein) intake and total nitrogen loss (via the urine and feces), usually determined over several weeks.
net protein balance involve what
muscle protein synthesis (MPS) = muscle protein breakdown (MPB)
.
Positive net protein balance occurs when
MPS > MPB
Adults who want to be in a muscle growth state must achieve
positive nitrogen balance and positive net
protein balance.
when does a person is in a positive nitrogen balance
When intake is greater than loss
protein intake > _ is not recommended
2.5
high quality protein allow what
++ protein synthesis
does protein intake before exercise has an effet
no
does protein intake during exercise has an effet
unclear but may maximize anabolic responses
how munch protein intake is recommended throughout the day
25-35g
what is the anabolic window
first hour or two after exercise -> intake of protein after exercise = increase AA in blood = increase MPS
whey protein is high in which AA
leucine
effect of protein intake after exercise
support muscle growth, increase strength and power and body composition
strategies to maximise protein intake after resistance exercise
- Immediately after exercise, when possible, but no later than 2 hours after exercise
- High-quality protein containing a large amount of indispensable amino acids (such as egg white, whey, casein, and soy)
- ~15 to 25 g of protein (0.25 to 0.3 g/kg) as a food, beverage, or protein supplement
- For maximum protein synthesis, high quality protein source containing ~1.7 to 2.4 g of leucine
which protein is considered high quality
milk, dairy, egg, whey protein isolate
for athlete that don’t consume animal product which source of protein is important
soy
how munch protein intake prior to sleep
> 40g
The amount of protein associated with maximum protein synthesis after resistance exercise is
25g or > 2g/kg/d
Protein intake in athletes with disordered eating or eating disorders
0,7-1.2 g/kg
what happen under starvation (protein)
hormonal balance change -> decrease insulin production, muscle and fat cell become resistant to insulin -> decrease MPS because insulin promote uptake of AA by muscle celll -> increase MPB
daily energy deficit should an athlete dieting have + daily protein intake
500 kcal, 1.8 g/kg and as high as 2.7
is protein supplement better than food source
no better or worse
protein supplement usually contain what
whey, casein, egg, soy proteins
carnosine is in greater concentration in type 1 or 2 fiber
type 2
which AA is the rate limiting factor of carnosine manufacture
beta-alanine
role of carnosine in the muscle
buffer acid and maintain muscle pH within normal range -> important to enhance buffering during high-intensity
Glutamine supplementation does/does not
appear to be effective as a way to
enhance the functioning of the immune
system
does not
Glucosamine/chondroitin sulfate is
generally effective/ not effective for reducing
joint pain
not effective
The chemical composition of proteins
differs from carbohydrate or fat because of the presence of
nitrogen
the primary structure of the protein determines its
function
The amino acids that are most rapidly
absorbed from the intestine are:
indispensable
which athlete would use protein as an energy source to the greatest extent
ultra endurance athletes
amount of protein recommended daily for athletes in training on a kg of body weight basis is:
1.0 to 1.8g
Which of the following is (are) recommended for post exercise intake:
a. low-fat chocolate milk
b. fruit-in-the-bottom yogurt
c. turkey sandwich
d. all of the above
d
why do athlete who restrict their energy intake need more protein
more protein will be burned for energy
which of the following systems is highly dependent on protein because of rapid cell turnover:
a. renal c. neurologic
b. immune d. cardiovascular
b
how do whey and Casein differ
each is compromised of different amino acids
which of the following is not an example of complementary protein or mutual supplementation:
a. red beans and rice
b. pinto beans and corn tortillas
c. tofu and rice
d. scrambled eggs with nonfat milk
d. scrambled eggs with nonfat milk
what is the AA considered conditionally indispensable in long distance runner
glutamine
what is the mechanism for beta-alanine supplementation
prevention of the breakdown of cartilage
