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Food /exercise diary or essay option-questions? -if consuming the recommended number of servings for each food group for one’s

age and gender one is most likely meeting all of one’s dietary nutrient requirements.

-hence no worries about consuming foods without a food label

No discussion of pathology in the 2104 essay option- any questions on essay or dietary assessmentoption?

94/80AA displacement

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LECTURE 6A PROTEINS

17 Oct. 2017

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a) Proteins defined

contain carbohydrate, hydrogen and oxygen just like lipids and carbohydrates

but proteins also have nitrogen

shape and hence function depends on amino acid side chains

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  Amino acids    Amino definition  Building blocks

Non-essential 

Essential 

Conditionally essential 

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Protein structure

considerable variety of proteins

variety comes from lots of different shapes and hence functions of protein

loss of shape-loss of function heat, acid, beating, chemically (e.g. urea)

get easier digestion and occasionally colour change

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 IDATME of proteins and amino acids

Ingestion - oral, tube (whole protein, or protein hydrosylates or amino acids), IV (amino acids only)

Digestion•Stomach-acid and pepsin•Small intestine lumen-oligopeptides,tri- and

dipeptides, and amino acids formed•Small intestine wall-tri- and dipeptides formed

into single amino acids•Issues of dietary enzymes and pre-digested proteins

 

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IDATME of proteins and amino acids

Digestion

https://www.youtube.com/watch?v=laNhqcMEAHY

 

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IDATME of proteins and amino acids continuedAnimal proteins are generally very digestible and plant proteins are generally less digestible than animal proteins

Proteins vary in their digestibility due to variable dietary protein structures as well as other food ingredients and hence accessibility to protein digestive enzyme active sites

Complete plant proteins -soy - very digestible - close to many animal proteins’

digestibility -quinoa - about 10 % less digestible than soy

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IDATME of proteins and amino acids continued

Digestibility affects availability (WWFQ) of essential and non-essential and conditionally essential amino acids

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IDATME of proteins and amino acids continued

Absorption

-carriers

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Transport  Blood-amino acids alone

or as part of proteins

IDATME of proteins and amino acids continued

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PROTEIN METABOLISM 

DNA to Protein

E:\Media\Animations\chapter6\Protein_Synthesis\0606.html

Fig. 6-7, p. 188

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 PROTEIN METABOLISM

Proteins broken down to amino acids and amino acids then broken down to urea and water

Also have synthesis of non-essential amino acids in the body

Essential and non-essential amino acids and conditionally essential amino acids are made into proteins

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 PROTEIN EXCRETION

Faeces- undigested protein and unabsorbed amino acidsUrine- urea and waterSweat- metabolic water formed by amino acid catabolism

Respiration- CO2 and water from amino acid catabolism

Saliva?-whole proteins

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 STRUCTURE IN THE BODY PrimarySecondaryTertiaryQuaternary Globular Fibrous Undone - heat, chemically, mechanically, pH

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PROTEINS ESSENTIAL OR NOT?

Yes- functions

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PROTEIN FUNCTIONS P. 175-178

CHAPERONES

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PROTEIN FUNCTIONS CONTINUED

ENZYMES

proteasescarbohydraseslipases

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PROTEIN FUNCTIONS CONTINUED

NUTRIENT AND STORAGE PROTEINS

nutrient proteinsovalbumincasein

storage proteinsferritin

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PROTEIN FUNCTIONS CONTINUED

TRANSPORT PROTEINS

lipoproteinshemoglobinglucose transportersamino acid transporters

sodium potassium transporter

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PROTEIN FUNCTIONS CONTINUED

CONTRACTILE OR MOTILE PROTEINS

actinmyosin

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PROTEIN FUNCTIONS CONTINUED

STRUCTURAL PROTEINS

collagenelastinkeratin

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PROTEIN FUNCTIONS CONTINUED

DEFENCE PROTEINS

antibodiesfibrinogenthrombin

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PROTEIN FUNCTIONS CONTINUED

REGULATORY PROTEINS

insulinparathyroid hormone

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PROTEIN FUNCTIONS CONTINUED

RECEPTOR PROTEINS

insulinLDL receptor

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PROTEIN FUNCTIONS CONTINUED

SIGNALLING PROTEINS

insulin sets off signalling cascade forglycogen synthesis

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PROTEIN FUNCTIONS CONTINUED

Energy

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In summary proteins:

•Bind (B)

•Catalyse (C) •Build (B)

PROTEIN FUNCTIONS CONTINUED