Virginia Tech HNFE 4025 Dr. Anderson Exam 1 Review

metabolism

life sustaining chemical reactions that occur in the cells of our body; takes macronutrients and makes ATP

ATP

what is the life sustaining end product of macronutrient metabolism?

internal

our metabolism adapts in a physiological response to ___________ and external cues, which can be short term or long term

anabolism

___________ metabolism: to build/store

catabolism

___________ metabolism: to breakdown

carbohydrates, lipids, proteins

what are the 3 macronutrients in relation to metabolism?

carbohydrates, lipids

which macronutrient(s) is/are primarily used to produce ATP?

anabolic

glycogen, triglyceride, & protein synthesis are examples of (anabolic/catabolic) metabolism

catabolic

glycogenolysis, lipolysis, & protein degradation are examples of (anabolic/catabolic) metabolism

adenosine (adenine nucleotide + ribose sugar) & 3 phosphate groups (PO4)

what makes up ATP?

metabolic regulation

the response to a stressor that drives metabolism in one way or another

cellular

Metabolic Regulation

- can be short term or long term adaptation

- can be an anabolic or catabolic response

- occurs at a ___________ level

stressor

Metabolic Regulation

(1) ____________: meals, environment, toxins, time of day, exercise, etc.

↓↓↓↓

(2) response: transcription, translation, post-translational modification, signaling, etc.

long term

short term OR long term metabolic regulation?

dealing with DNA or building/destroying enzymes

short term

are post-translational modifications (PTMs) short term or long term metabolic regulation?

allosteric regulation

what type of metabolic regulation involves activating or inhibiting an enzyme via a ligand that binds to a separate site from the substrate binding site on the enzyme?

short term

is allosteric regulation short term or long term metabolic regulation?

competitive inhibition

what type of metabolic regulation involves something else getting in the way of the active site, preventing activation of the enzyme?

short term

is competitive inhibition short term or long term metabolic regulation?

substrates

Importance of Metabolic Regulation

- provision of _____________ (glucose, FAs, amino acids) to meet ATP demand

- ensure ample energy stores

- utilization of the substrate that is most abundant

- ATP production from alternative sources (example: PCr)

short term

Metabolic Regulation

___________________ = immediate adaptability to a stressor; rapid modifications that ensure our cells have adequate energy (ATP) to meet demands of stressors; seconds to minutes

examples:

(1) change from FA metabolism to Glucose metabolism with increases in %VO2max workload (the cross-over effect)

(2) going from fasted state over night to fed state after breakfast

long term

Metabolic Regulation

___________________ = physiological adaptations as a result of stressors applied over time; hours to days; transcription and translation are largely responsible

examples: dietary change, changes in physical activity, exposure to toxins, changes in health status

covalent

Short-Term Metabolic Regulation

Post-translational modifications (PTMs) involve ____________ additions of functional groups proteins during or after protein biosynthesis

transcription

Long-Term Metabolic Regulation

_______________ refers to the translation of genetic information from DNA to mRNA; the reading of DNA by RNA polymerase and the production of mRNA

translation

Long-Term Metabolic Regulation

_____________ refers to the transfer of genetic information from mRNA to make functional proteins via the reading of mRNA by ribosomes

in born

Ramifications of Metabolic Dysregulation

results from inability to adapt short term and/or long term

leads to...

- compromised performance

- compromised health → development of pathology (obesity, diabetes, metabolic syndrome, cancer)

- _____ ________ errors in metabolism (example: PKU)

metabolic regulation

______________ ______________ can occur through transcription of the DNA to mRNA, translation of the mRNA to proteins, or post-translational modifications (PTM) of enzymes; PTMS are transient

transcription factors

protein that binds to a DNA and initiates the transcriptional process; proteins involved in the process of converting, or transcribing, DNA into mRNA; include a wide number of proteins, excluding RNA polymerase

promoter

Transcription Factors

- TFs determine if we are going to get mRNA from each gene

- TFs determine which parts of the DNA get turned into mRNA and which don’t → different functionality of neurons versus muscle cells (for example)

- located in the ____________ region (upstream) of the genes to be transcribed

proteome

PTMs increase the _______________ complexity (after transcription and translation, we end up with lots of different proteins)

phosphorylation

PTMs: which one is described below?

adds a phosphate to serine, threonine, or tyrosine

glycosylation

PTMs: which one is described below?

attaches a sugar, usually to an "N" or "O" in an amino acid side chain

ubiquitination

PTMs: which one is described below?

adds ubiquitin to lysine residue of a target protein for degradation; flags a protein for degradation

SUMOylation

PTMs: which one is described below?

adds a small protein SUMO (small ubiquitin-like modifier) to a target protein

disulfide bond

PTMs: which one is described below?

covalently links the "S" atoms of two different cysteine residues

acetylation

PTMs: which one is described below?

adds an acetyl group to an N-terminus of a protein or at lysine residues

lipidation

PTMs: which one is described below?

attaches a lipid, such as a fatty acid, to a protein side chain

methylation

PTMs: which one is described below?

adds a methyl group, usually at lysine or arginine residues

hydroxylation

PTMs: which one is described below?

attaches a hydroxyl group (-OH) to a side chain of a protein

methylation

this PTM happens a lot at the promoter region, getting in the way of RNA polymerase binding → transcription inhibition

Allosteric regulation (allosteric control)

PTMs

the regulation of an enzyme by binding an effector molecule at a site other than the enzyme's active site; can be positive or negative

positive effector

Allosteric Regulation

allows the substrate or co-enzyme to more easily bind

negative effector

Allosteric Regulation

makes it harder for the substrate or co-enzyme to bind

products

Allosteric Regulation

usually allosteric effectors are _____________ of the enzymatic reaction that feed back on the enzyme, but can also be upstream substrates or downstream products of the metabolic pathway

allosteric site

PTMs: allosteric regulation

The site to which the effector binds during allosteric regulation is termed the ___________________

acetyl-CoA

PTMs: acetylation

- result from accumulation of ___________________ = product of macronutrient oxidation

- can increase or decrease protein activity, depends on the protein

- can also affect transcription by binding to histones

O-GlcNAcylation

Metabolic Regulation: PTMs

______________________

- the final end product of the hexosamine biosynthetic pathway

- important for proper nutrient sensing and stress regulation by maintaining proper cell signaling and transcription rates

- a result of several components from fatty acid, glucose, and amino acid metabolism

Glutathionylation

Metabolic Regulation: PTMs

______________________

- can increase or decrease activity of a protein, depends on the protein

- cysteine residues are the site of glutathione addition

- glutathione (GSH) is a protein important for preventing oxidative stress

epigenetics

Metabolic Regulation

_______________ refers to modifications to the DNA structure that affects transcription

example: methylation of the DNA (methylating the promoter region changes the ability to transcribe a gene, but doesn’t change the genetic code)

endoplasmic reticulum stress

Metabolic Regulation

_________________________ refers to abnormalities in forming the proper structure or conformation of a protein

transcriptional regulation

controlling the rate of gene transcription by helping or hindering RNA polymerase binding to DNA

upregulation, activation, or promotion

this form of transcriptional regulation increases the rate of gene transcription

downregulation, repression, or suppression

this form of transcriptional regulation decreases the rate of gene transcription

co-activator

Transcriptional Regulation

a protein which works with transcription factors to increase rate of transcription

co-repressor

Transcriptional Regulation

a protein which works with transcription factors to decrease rate of gene transcription

transcriptional-control region

Transcriptional Regulation

TFs regulate by binding to specific DNA sequences termed the __________________________

promoter

Transcriptional Regulation

this transcriptional-control region is usually in an area of a gene called the ____________ region

response elements

Transcriptional Regulation

the specific sequences that the transcription factors bind to are termed ___________ ____________

general, modulatory

Transcriptional Regulation

what are the 2 classes of TFs?

general

Transcriptional Regulation: TFs

______________ TFs are needed for transcription of most protein-coding genes

modulatory

Transcriptional Regulation: TFs

______________ TFs are those that modulate general transcription factors through activation of repression for cell specificity

gene

the individual unit of inheritance; the entire DNA sequence, including introns, exons and non-coding transcription control regions responsible for the production of a polypeptide (mRNA), tRNA or rRNA molecule

☺

understand this image of the layout of a gene

ligand

TF Activation

refers to a substance (substrate, metabolite, protein) that can bind to a transcription factor, which leads to activation

ligands

TF Activation

___________ are important for metabolic control

examples:

- transition from fasted to fed state

- post-absorptive period after a meal

- initiation of exercise

- adaptation to chronic exercise

- over consumption of energy (dependent of macronutrient)

storage

Proteins

- represent about 14-16% of the body weight of healthy adults

- no ____________ form of protein or constituent amino acids

- all proteins have a function: structure (skeleton), movement (contractile proteins), catalysis (enzymes), protection (antibodies), signaling, transport, etc.

- body protein is continually synthesized and degraded (actual amount of each protein reflects its rate of synthesis and breakdown)

more

Enzymes

- type of protein

- catalyze all chemical reactions in cells

- speed up reactions, but are not consumed in the reaction

- most enzymes are highly specific acting on a single substrate molecule or several substrate molecules

- enzymatic reactions can be: equilibrium (rxn goes both ways) or non-equilibrium (rxn goes 1 way; enzymes in these rxns are (more/less) regulated)

hydrolases

Enzyme Types

cleave compounds into two

isomerases

Enzyme Types

transfer atoms within a molecule

ligases/synthases

Enzyme Types

join compounds

oxidoreductases

Enzyme Types

transfer electrons

transferases

Enzyme Types

move functional groups

cofactor

Enzymes

some require a ____________ (eg: zinc, iron, copper) or coenzyme (eg: vitamin B) to carry out a reaction

kinases/phosphorylases

what type of enzymes phosphorylate things?

phosphatases

what type of enzymes take OFF phosphates?

AMP-activated protein kinase (AMPK)

this enzyme is responsive to AMP to add phosphates to drive ATP synthesis

ATP

AMPK

AMPK can be allosterically regulated

- AMP activates AMPK

- ________ inhibits AMPK

PKA (protein kinase A)

AMPK

AMPK can also be regulated covalently

- AMPK can itself be phosphorylated by what enzyme?

energy balance

State in which energy intake, in the form of food and/or alcohol, matches the energy expended, primarily through basal metabolism and physical activity

90

approx. _____% of the Kcals we ingest are absorbed, with 10% lost in feces, urine, respiration, and non-digestible food

basal metabolic rate (BMR)

Energy Expenditure Breakdown

_________________________ = sleeping metabolic rate + arousal (falling asleep/waking up)

fat free mass (muscle mass)

Energy Expenditure Breakdown

what is the biggest determinant for BMR?

other determinants include age, sex, genetics, hormones/sympathetic NS

65

BMR

- energy expended to maintain base, or resting, functions of the body

- highest proportion (~____%) of total energy budget

- decreases with age (~3-5% per decade after ~30)

height

Factors that INCREASE BMR

- higher lean body mass

- greater ___________ (more SA)

- younger age

- elevated thyroid hormone levels

- stress

- being male

- pregnancy and lactation

- certain drugs (stimulants, caffeine, tobacco)

starvation

Factors that DECREASE BMR

- lower lean body mass

- lower height

- older age

- depressed levels of thyroid hormones

- ____________ or fasting

- being female

thermic effect of food (TEF)

Energy Expenditure Breakdown

energy expended to process food

5-10%

Energy Expenditure Breakdown

Thermic Effect of Food (TEF)

- accounts for ~_______% of total energy budget

- fat requires less energy to digest, transport and absorb

- proteins and carbs require more (transporting glucose and storing glycogen costs ATP)

- proteins require the most (protein synthesis costs ATP)

food

Energy Expenditure Breakdown

Thermic Effect of Food (TEF) determinant is the amount/composition of _______ (hormones/SNS)

spontaneous PA & thermogenesis (NEAT = non-exercise activity thermogenesis)

Energy Expenditure Breakdown

______________________ = fidgeting and shifting in one's seat + facultative thermogenesis

thermogenesis

Energy Expenditure Breakdown

the production of heat, especially in a human or animal body

facultative thermogenesis

Energy Expenditure Breakdown

regulated production of heat in response to environmental changes in temperature and diet

unrestricted activity

Energy Expenditure Breakdown

________________ = physical activity

determinants: intensity, duration, body weight, psychological, environmental, genetics/SNS

20-35

Energy Expenditure Breakdown

Physical Activity (unrestricted)

- average of _________% of total energy budget

- includes everything above basal level (sitting, standing, walking)

- moving large muscles requires more energy

- calculating energy expenditure: energy cost (kcal/kg/min) * Time (min)

food balances

Energy intake can be measured

(1) directly via ______ _____________

- subtract the ending weight from the beginning weight to determine the amount eaten (& any left on the floor of the cage)

- in humans we use food diaries for free living OR participants eat in a food lab

Comprehensive Lab Animal Monitoring System (CLAMS)

Energy Expenditure can be measured….

- using a what? = a closed cage that measures respiration

- in humans we use metabolic chambers or indirect calorimetry with a metabolic hood

ergometers

Energy expenditure during exercise can be measured

- voluntary using a wheel with a counter or assisted using a treadmill with an electric grid that shocks the rodent if they slide off the treadmill- some of these systems can measure gas exchange

- in humans we use treadmills and cycle ______________ mostly using indirect calorimetry with a gas exchange mask

ventilated hood

measures energy expenditure (kcal) and precisely how much fat and CHO is being used to make ATP. Measures are generally less than 1 hour, and extrapolated to 24 h energy expenditure.

Whole room calorimeter

measures energy expenditure (kcal) and precisely how much fat and CHO is being used to make ATP, but for 24 hour periods; using either gas exchange (indirect) or heat produced (direct)

Doubly labeled water

- uses water (2H218O) labeled with stable isotopes; humans consume the water

- isotopes equilibrate with water in the body

- isotopes are recovered in breath (CO2) and urine (water)

- research based tool that is insanely expensive

- very precise tool for measuring energy expenditure

- the rate that the isotopes show up in urine and breath, is proportional to energy expenditure, e.g., higher EE, faster appearance in urine and breath.

facultative thermogenesis

Contributions to Energy Balance

Input

- hunger/satiety mechanisms: central, peripheral

- environmental factors: food consumption, food accessibility, non-hunger related eating

Output

- energy burn: BMR/RMR

- thermic effect of food

- physical activity

- _____________ ____________________