proteins and amino acdis

Question 1

functions

Answer 1

digestive enzymes
antibodies
support regulation and expression of dna and rna
support muscle contraction and movement
hormones
move essential molecules around the body
source of energy- 1g protein provides 4kcal

Question 2

structure

Answer 2

proteins are large molecules made up of amino acids
joined by peptide bonds

Question 3

amino acids

Answer 3

consists of a central carbon bound to:
hydrogen
nitrogen containing amino acid group
carboxylic acid group
R group/ side chain which makes it unique

Question 4

types of amino acid

Answer 4

essential- indispensable- cannot be synthesised by the human body, adequate dietary intake needed
non essential- dispensable- can be synthesised by the human body
conditonally indispensable- essential- body cannot produce sufficient amounts of some dispensible amino acids

dietary protein will contain a diverse mix of both essential and non essential

Question 5

digestion and absorption- mouth

Answer 5

mechanical breakdown - takes less than 1 min

Question 6

D&A- stomach

Answer 6

chemical digestion- hydrochloric acid denatures proteins- unfolding 3D structure to reveal polypeptide chain- enzymatic digestion by pepsin forming shorter polypeptides, assisted by chyme

Question 7

D&A- small inestine

Answer 7

protein digestion- digestion by pancreatic enzymes (trypsin, chymotrypsin) and other digesting enzymes proteases lead to the formation of tripeptides, dipeptides and amino acids

Question 8

D&A- intestinal lining

Answer 8

once inside the enterocytes, tri and dipeptides are broken down into single amino acids which are absorbed into the bloodstream + taken up by target tissue

Question 9

dietary protein recommendations

Answer 9

reference nutrient intake for average weight adults is 0.75g/kg BW
=45g/d for average female (60kg)

Question 10

protein needs differ

Answer 10

higher for some populations
-growing children and adolescents
-women who are pregnant/lactating
-athletes
-older adults

Question 11

kwashiokor

Answer 11

protein deficiency
subcutaneous fat is preserved
oedema is present
6months to 3 yo
enlarged fatty liver
muscle wasting mild or absent
will have larger tummy

Question 12

marasmus

Answer 12

protein and energy deficiency
common in infants <1yo
subcutaneous fat not preserved
oedema absent
no fatty liver
severe muscle wasting

Question 13

excessive protein intake

Answer 13

very high protein diets can be harmful
extra protein not used efficiently by body
may impose metabolic burden on bones, kidney and liver
large amounts of protein associated with increased risk of coronary heart disease and cancer

Question 14

protein quality

Answer 14

proteins can be ran by quality- how many AA are present in a biologically available format
dependent on the proportion of protein derived AA from D&A
digestibiloty of indispensable amino acids

Question 15

protein complementation

Answer 15

combining incomplete protein sources to provide all 9 essential amino acids
complementation does not have to be done at the same time to meet protein needs- can be done in 24 hour period

eg beans and vegetables are limited in methionie so can complement with grains, nuts and seeds

Question 16

protein quality scoring

Answer 16

PDCAAS- protein digestibility amino acid score- based on the quality of faecal digestibility (rodent model)
DIAAS- digestible indispendable amino acid score- AA qualoty of food proteins based on ileal digestibility (pig model)- from ileum
WHO recommends DIAAS as is more accurate sample
When looking at protein quality, PDCAAS and DIAAS will result in different digestibility scores- limitation to both methods= only considers raw form of food and only 1g of the food which is different to how much will be consumed

Question 17

protein digestibility

Answer 17

fraction of protein that is available for absorption once it has been ingested

Question 18

skeletal muscle maintenance + growth

Answer 18

body protein is concentrated in skeletal muscle
skeletal muscle accounts for ~50% of total body protein, largest resevoir for amino acids

Question 19

protein and ageing muscle

Answer 19

sarcopenia- biological ageing process is associated with a gradual loss of skeletal mass and function
normally begins age 40-50 and lasts to age 70
associated with reduced mobility, loss of independence and increased mortality
in sarcopenia- muscle has more fatty tissue in it

Question 20

optimal protein intake (older adults)

Answer 20

for healthy older adults- 1-1.2g/kg bw per day
for older adults with acute/chronic illness- 1.2-1.5g/kg bw
daily physical activity is recommended for all older adults as well as resistance training
nutrition in combination with exercise is considered optimal for maintaining muscle function

Question 21

higher protein needs

Answer 21

older adults have higher protein needs
skeletal muscle is comprised of muscle proteins that are continuously being remodelled
a key metabolic process of muslce remodelling is muslce protein synthesis (MPS) where AA are incorporated inot new functional muscle proteins
older adults have resistance to the positive effects of dietary protein on the synthesis of protein- anabolic resistance

Question 22

anabolic resistance

Answer 22

MPS- muscle protein synthesis- increases in net gain in muscle protein
MPB- muscle protein breakdown
response to anabolic stimulus (MPS and MPB) is greater in young compared to elderly which can explain muscle loss- in older adults there is less MPS in response to stimulus

Question 23

animal protein pros

Answer 23

source of high quality dietary protein for a large proportion of the global population, contain ideal combination of indespensable AA + unlikely to elicit any specific AA deficiences, highly digestible, contributes to micronutrient intake (eg vit b12)

Question 24

animal protein cons

Answer 24

red and processed meat can increase risk of colorectal cancer, animal production is associated with greenhouse production and nitorgen pollution, unsustainable burden on global resources inclduing land and fresh water

Question 25

greenhouse gases of protein

Answer 25

beef and lamb highest
cheese, pork and poultry lower
tofu beans and nuts lowest

Question 26

reduce impact on environment

Answer 26

reduce excessive consumptions of animal derived protein
replace animal derived protein with alternative sources
feed livestock more sustainable protein sources eg insects + larvae meal

Question 27

alternative protein sources

Answer 27

have potential to offer more sustainable protein sources for human consumption + animal feed
needs to be safe, affordable and acceptable to the consumer
meat and dairy replacements with plant proteins, cultured/ cultivated meat, fermentation derived protein eg mycoprotein

Question 28

fungal derived dietary protein sources

Answer 28

mycoprotein- whole food produced by the continuous cultivation of the filamentous fungus Fusarium venenatum
complete protein source
biomass fermentation used the rapid growth of some protein rich microorganisms to make large amounts of protein

Question 29

advantages of plant based proteins

Answer 29

lower GHG emissions
lower T2D risk
increased dietary fiber
less saturated fatty acids
lower CVD risk
phytochemicals and antioxidants

Question 29

animal protein vs plant based- muscle

Answer 29

effects on muscle mass outcomes
plant based alternatives can be used the same as animal proteins
can increase fat free mass

Question 29

plant protein + lipids

Answer 29

plant protein can have cholesteral lowering effects
replacing meat with plant proteins can have positive impact on cardiovascular health
mycoprotein can also have positive impact on cholesteral levels (decreased)

Question 30

limitations of plant based diet

Answer 30

lower protein content
lower digestibility
lower essential amino acid content

Question 31

plant protein- solutions

Answer 31

protein content- increase portion size, combine food group, protein isolate
lower digestibility- soaking, cooking, use of probiotics and digestive enzymes
lower EAA- foritfication of protein supplements with specific amino acids + complementation

Question 32

blended protein approaches

Answer 32

can be used by consumers of animal based proteins who want to consume a more sustainable diet

Question 33

essential amino acids

Answer 33

isoleucine
tryptophan
leucine
histadine
methionine
lysine
valine
threonine
phenylalanine

PLLITTHMV

Question 34

complementation examples

Answer 34

beans- limited in methionine so complement with grains, nuts and seeds
grains- limited in lysine and threonine so complement with legumes
nuts/seeds- limited in lysine, complement with legumes
veg- limited in methionine so complement with grains, nuts and seeds
corn- limited in tryptophan and lysine so complement with legumes

legumes- high in lysine, threonine, tryptophan
garins, nuts, seeds- high in methionine