1F03 - UNIT 3

Amino Acids

* building block of protein
* contain C, H, O, N
* joined by peptide bonds
* 9 essential and 11 non-essential

Protein Structures

**primary:** amino acid sequence

**secondary:** interactions between amino backbones

**tertiary:** R group interaction

**quarternary:** 2+ polypeptide interactions

Denaturation

* loss of stability, shape, function
* by heat + acid

Protein Absorption

* in small intestine

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1. amino acid → enterocyte (intestinal cells)
2. used for energy and protein synthesis
3. unused → liver

Protein Synthesis

**transcription:** mRNA uses DNA template to copy info

**translation:** tRNA attaches amino acids (based on mRNA) in ribosome

Roles of Proteins

* building materials
* hormones
* enzymes
* transporters

Deamination

* removes amino acids containing N


* forms ammonia and keto acid

Ammonia → Urea

* NH3 + CO2 → urea

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* direct relationship to dietary protein intake (requires H2O)
* in the liver
* urea into blood through kidney

Protein Turnover

making and breaking proteins (1-2% a day)

Amino Acid Pool

* no storage
* constant
* used to make other proteins
* for energy

Nitrogen Balance

* difference between nitrogen intake
* change in total body protein
* positive, equilibrium, negative

Protein During Endurance Exercise

* amino acid oxidation → < 5% of energy production in athletes
* acute exercise causes a small increase in leucine oxidation
* may result in small increase in requirement
* protein consumption during exercise is not improved performance

Protein Intake vs Strength Gains (Meta-Analysis)

* improvement of 1 rep max with protein during resistance training
* overall: improvement / more in trained athletes

Factors Determining Protein Quality

1. digestibility
2. amino acid composition

Digestibility

**animal:** 90 - 99 %

**soy+legume:** > 90 %

**plant:** 70 - 90 %

Protein Digestibility Corrected Amino Acid Score (PDCAAS)

* scale of protein quality / 0 to 100

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dairy/eggwhite/beef/chicken = 100

soybean = 94

legumes = 50s and 60s

gluten = 25

Complete Protein Sources

* contain all essential amino acids
* chicken, salmon, soy, beef, whey, quinoa

Complementary Proteins

* combining plant proteins to create full amino acid complement


* pea flour (67) + whole wheat flour (40) = combined flour (82)

Plant-Based Protein

* decreased greenhouse gas emission
* can make up for low quality
* decreased diseased risk

Protein Energy Undernutrition (PEU)

* insufficient intake of protein, energy, both
* most prevalent form of malnutrition
* infections from degradation of antibodies
* reversible
* marasmus and kwashiorkor

Transfer of Energy (ATP)

* energy is captured in ATP
* negative charges of phosphate are vulnerable to hydrolysis
* cleaving P groups releases energy

Enzymes

* proteins
* facilitate reactions
* remain unchanged

Coenzymes

* complex and organic
* required for enzyme function
* derivatives of vitamines

Fates

**acetyl CoA:** makes fat and energy

**glycerol → pyruvate:** makes glucose or acetyl CoA

**fatty-acids → acetyl CoA:** oxidation (2C at a time)

**aa → energy**

* glucogenic (converted to pyruvate or enter TCA)
* ketogenic (converted to acetyl CoA)

Glycolysis: Glucose to Pyruvate

* 6C to 2(3C)
* in cytoplasm
* hydrogens attach to coenzyme
* produce ATP and NADH

Anaerobic Energy Production

* when lacking oxygen/mitochondria
* fast ATP but not sustainable

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1. converted to lactate/lactic acid
2. lactate to liver
3. converted back to glucose
4. glucose back to muscles (cori cycle)

Pyruvate Oxidation: Pyruvate to Acetyl CoA

* pyruvate enters mitochondria
* carbon removed from pyruvate
* produces CO2 and NADH
* decarboxylation, redox, synthesis

Tricarboxylic Acid (TCA) Cycle

* releases H+ and electrons

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1. acetyl CoA + oxaloacetate = citrate
2. 2 carbons stripped/released as CO2
3. 8 H+ (and electrons) released to ETC
4. oxaloacetate regenerated and cycle continues

Electron Transport Chain (ETC)

* uses H+ atoms to create ATP

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1. coenzymes deliver H+ and electrons to inner mitochondrial membrane
2. simultaneously:


1. electrons pass through carriers → form water
2. H+ pumped into outer compartment
3. H+ flow through pump to create ATP
4. ATP to cytosol for cell use

Energy Balance

* energy in = energy out
* a shift in balance causes weight changes
* changes can be rapid or gradual
* excess energy is stored as fat

Energy In: Food Intake Factors

* appetite
* hunger
* satiation
* satiety

Energy Expenditure Components

* basal metabolism (BMR and RMR)
* physical activity
* food consumption (thermic affect of food)
* adaptation responses

Estimating Energy Requirements (EER) Influencers

* sex
* growth
* age
* physical activity
* body composition and size

Body Mass Index (BMI)

* standards for body weight → relative weight for height
* related to disease risk, based on population average, increased accuracy with waist circumference

BMI Classification

**< 18.5** : underweight

**18.5 to 24.9 :** healthy weight

**25 to 29.9 :** overweight

**> 30 :** obese

Body Fat Assessment Methods

* waist circumference
* skinfolds
* bioelectrical impedance
* DEXA

Fat Distribution

* visceral fat (central obesity)
* subcutaneous fat

Waist Circumference

* indicator of visceral fat

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women: > 35 inches

men: > 40 inches

Female Athlete Triad

* relationship between disordered eating, amenorrhea, osteoporosis
* leads to increase chance of stress fractures

Relative Energy Deficiency in Sport (REDs)

* includes men
* psychological. arrow goes both ways
* many physiological systems affected by low energy availability

Consequences of REDs

* ostopenia/osteoporosis
* decreased training adaptation
* decreased metabolism control
* decreased fertility
* thyroid dysfunctions

REDs Impacting Factors

* body image
* drive for thinness
* EDs
* making weight
* unintentional LEA
* lack of understanding of maturation

REDs Healing Guidelines

* fuel
* no diets + fasting
* carbs!
* daily energy balance
* decrease fibre intake
* strength training

Energy Availability

EA = EI - EEE

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* relative to FFM
* healthy: 40-45 kcal/kg FFM/day

Energy Distribution Across Day

* athletes with menstrual disorder had more time spent in energy deficit
* decreased RMR / decreased estradiol / increased cortisol / decreased T3
* athletes with low RMR had 2x more time in energy deficit
* increased cortisol / decreased testosterone