Week 2

Question 1

2. Identify common sources of saturated fat

Answer 1

mostly from animals (egg, chicken, turkey)

Question 2

2. Identify common unsaturated fats

Answer 2

come from vegetables and oils (avocado, olive oil)

Question 3

2. Where does cholesterol come from?

Answer 3

animals only

Question 4

3. Based on Myplate what are the general characteristic of a healthy diet?

Answer 4

1) 2 cups of fruit 2) 2.5-3 cups of vegetables 3) ~7 ounzes of grains (3.5 oz whole grains) 4), 6 oz protein, 3 cups from the dairy group 5) Fats 5-7 teaspoons

Question 5

4. Describe my plate

Answer 5

MyPlate was developed to prompt consumers to build healthier plates at meal times. The icon for MyPlate emphasizes a serving a fruit, vegetables, protein, grains and dairy. It was developed and is maintained by the USDA Center for Nutrition Policy & Promotion (CNPP). The CNPP focuses on two goals: advance and promote dietary guidance for all Americans and conduct applied research and analyses in nutrition and consumer economics. MyPlate sets daily amounts on the various food groups depending on age and sex, which could be used to create a healthy meal that incorporates all the daily recommended amounts of the various nutrient sources.

Question 6

4. Give functional serving sizes for each food group

Answer 6

The portion sizes are used to limit the amount of calories that enter your diet as well as prevent oversized portions. The portion size for fruits provides consumers with potassium, dietary fiber, vitamin C and folate. For vegetables, the portions provide a source of potassium, dietary fiber, folate and vitamins A and C. and fruits and vegetables should take up half of your plate according to MyPlate. The portion size for protein are important for protein, B vitamins, vitamin E, iron, zinc and magnesium. The portion size for grains are important for dietary fiber, B vitamins, and iron, magnesium and selenium. Lastly, the portion size for dairy provides calcium, potassium, vitamin D and protein.

Question 7

5. What is RDA?

Answer 7

Recommended dietary allowance (RDA): the average daily dietary intake of a nutrient that is sufficient to meet the requirement of nearly all (97-98%) healthy persons

Question 8

5. What is AI?

Answer 8

Adequate intake (AI): Only established when an RDA cannot be determined. Based on observed intakes of the nutrient by a group of healthy persons.

Question 9

5. What is UL?

Answer 9

Tolerable upper intake level (UL): the highest daily intake of a nutrient that is likely to pose no risks of toxicity for almost all individuals. As intake above the UL increases, risk increases

Question 10

5. What is EAR?

Answer 10

Tolerable upper intake level (UL): the highest daily intake of a nutrient that is likely to pose no risks of toxicity for almost all individuals. As intake above the UL increases, risk increases

Question 11

7. List the kcal/g for each of the macronutrients

Answer 11

Carbohydrates: 4 kcal/g, Proteins: 4 kcal/g, Fats: 9 kcal/g, Fiber: 2 kcal/g, Alcohol: 7 kcal/g

Question 12

8. Outline the relationship between food intake and energy output

Answer 12

Individual energy requirements are based on three factors: resting metabolic rate, physical activity levels, and energy used to metabolize food (thermogenesis). The body looks to maintain an adequate energy balance for expenditure. When there is a negative energy balance (intake is less than expenditure), there is weight loss. When there is a positive energy balance (intake is more than expenditure), weight is gained through growth (due to deposition of tissue) or when intake is greater than the body’s needs, the excess is stored as adipose tissue (body fat). ||||||||| Differences in the genetics, body composition, metabolism, and behavior of individuals make it difficult to accurately predict a person’s caloric requirements. However, some simple approximations can provide useful estimates. For example, sedentary adults require about 30 kcal/kg/day to maintain body weight; moderately active adults require 35 kcal/kg/day; and very active adults require 40 kcal/kg/day.

Question 13

9. Distinguish between daily energy expenditure (vs RMR)

Answer 13

daily energy expenditure is the metabolism of macronutrients in three energy-requiring processes: resting metabolic rate, thermic effect of digestion and absorption of food, and physical activity.

Question 14

9. Resting Metabolic Rate (vs daily energy expenditure)

Answer 14

The body’s basal metabolic functions account for the largest proportion (60-75%) of our energy needs, and averages roughly 1,300 to 1,700 Kcal a day for adults. Basal metabolism is devoted to carrying out the body’s involuntary work to maintain life processes. These include respiration, heart rate, circulation, transmission of nerve and hormonal messages, ion transport, and maintenance of body temperature and body tissues/cellular integrity.

Question 15

10. Moderate vs vigorous activity

Answer 15

1. subjective: percieved exertion 2. objective: heart rate– higher the heart rate, the higher the exercise intensity

Question 16

11. Explain how varying levels of physical activity influence an individual’s nutritional requirements

Answer 16

Sedentary person requires about 30-50% more calories than the RMR, Highly active person may require 100% or more calories above the RMR, Physical activity provides greatest variation in total energy expenditure (TEE= calories expended by thermic effect of food + physical activity + RMR)

Question 17

12. Discuss the oxidation or synthesis of carbohydrates, proteins and fat in the red blood cell, adipose tissue, liver, brain and muscle during the FED STATE

Answer 17

In anabolic (fed) state: Pancreas responds to elevated plasma glucose with increased secretion of insulin and decreased glucagon release, Liver replenishes glycogen stores, Replaces any hepatic proteins, Increases TAG synthesis, Packaged into VLDL which are exported to peripheral tissue, Adipose tissue increases TAG synthesis and storage, Muscle increases protein synthesis to replace degraded protein, Brain uses glucose exclusively as fuel

Question 18

12. Discuss the oxidation or synthesis of carbohydrates, proteins and fat in the red blood cell, adipose tissue, liver, brain and muscle during AND OVERNIGHT FAST

Answer 18

Plasma levels of glucose, AA, and TAG fall > Triggers decline in insulin release and increase in glucagon and epinephrine release, This sets into motion a balancing mechanism between brain, adipose tissue, liver and skeletal muscle guided by, Need to maintain adequate plasma glucose for brain and tissues, Need to mobilize FA from adipose tissue and the synthesis and release of ketone bodies from the liver Liver Degrades glycogen, Initiates gluconeogenesis, Using increased fatty acid oxidation, As a source of energy and reducing equivalents and gluconeogenesis, And for Acetyl CoA production for use in ketogenesis, Adipose tissue, Degrades stored TAG providing free FA’s and glycerol to the liver, Muscle protein is degraded to supply AA for the liver to use in gluconeogenesis, Decreases as ketone bodies increase

Question 19

13. Predict the ratio of glucagon/insulin in the fasting and fed states

Answer 19

Fasting: high ; Feeding: low ||| Glucagon raises concentration of glucose in the bloodstream. Its action is directly opposite of insulin which lowers blood glucose and promotes its storage as adipose tissue.

Question 20

14. Describe the general structure and function of G protein-coupled membrane receptors and identify the general characteristics of second messenger systems associated these receptors

Answer 20

G protein-coupled membrane receptors are receptors that work through extracellular ligand binding to increase the intracellular concentration of second messengers such as cAMP. The hydrophobic polypeptide regions of G protein-coupled receptors spans across the membrane seven times. This region has a pocket in which the agonist ligand can enter and bind. This binding causes a conformational change in the transmembrane region which is transmitted to the cytoplasmic regions of the protein. The changed cytoplasmic regions then activate a G-protein located on the cytoplasmic face of the plasma membrane by replacing a GDP on the inactive G-protein with a GTP. In the active GTP-bound state, the G protein regulates the activity of an effector enzyme or an ion channel. The signal is terminated by hydrolysis of the GTP to GDP where the G-protein is converted to its inactive GDP bound state. The involvement of GTP in the pathway allows for the ligand signal to be transduced because the signal amplification is not dependant on the affinity of the receptor to the ligand but rather the longevity of the GTP binding to the G protein. In addition to activating the G-protein, ligand binding also causes the receptor to bind and activate G-protein-coupled receptor kinases (GRKs) which phosphorylates serine residues in the receptor’s cytoplasmic carboxyl terminal tail. This phosphorylation increases the receptors affinity for a third protein beta-arrestin which, when bound, decreases the receptors affinity for the ligand and allows for removal of the agonist ligand. Beta-arrestin also increases endocytosis of receptors from the membrane for down-regulation.

Question 21

14. cAMP

Answer 21

This pathway involves a GPCR which activates the G protein Gs. Gs then activates catalytic adenylyl cyclase which converts ATP to cAMP. cAMP exerts its effects through the cAMP-dependent protein kinases. These kinases have two regulatory dimers and two catalytic chains. The cAMP binds to the regulatory dimer to release the catalytic chains which diffuse into the cytoplasm and nucleus. cAMP has pathways in many types of cells

Question 22

14. Phosphoinositides and Calcium

Answer 22

Agonist binds to receptor which activates a G protein which activates phosphoinositide-specific phospholipase C (PLC). PLC then splits a component of the phospholipid component of the plasma membrane, phosphatidylinositol-4,5-biphosphate (PIP2) into the two second messengers, diacylglycerol (DAG) and inositol-1,4,5-triphosphate (IP3 or InsP3). DAG stays at the membrane and activates protein kinase C. IP3 diffuses through the cytoplasm to trigger Ca2+ release by binding to ligand gated calcium channels. The elevated cytoplasmic Ca2+ then binds to the protein calmodulin which regulates other enzymes and calcium-dependant protein kinases.

Question 23

14. cGMP

Answer 23

Ligand binds to GPCR which stimulates membrane bound guanylyl cyclase to produce cGMP which then acts on cGMP-dependent protein kinase. cGMP actions are stopped which the cGMP degrades and by dephosphorylation of the kinase substrates. This pathway is not as diverse as the cAMP pathway.

Question 24

15. Illustrate the general functions of receptor tyrosine kinases and receptor-associated tyrosine kinases

Answer 24

Receptor tyrosine kinases are membrane bound receptors with an extracellular domain for ligand binding. The ligand (some form of trophic hormone such as insulin or epidermal growth factor) binds to the extracellular domain of the monomeric receptor tyrosine kinase. When the ligand binds the receptor converts from its monomeric inactive state to its dimeric (two adjacent receptors join together) active state. The dimerization allows the cytoplasmic residues on the receptors to join together. The tyrosine residues phosphorylate each other and other downstream signaling proteins. Activated receptors catalyze phosphorylation on different target signaling proteins allowing a single receptor to modulate many biochemical processes. These receptors also undergo down-regulation by endocytosis. When the ligand binds to the extracellular domain the receptors are released from the cell surface by endocytosis, reducing the number of receptors available for binding.

Question 25

16. Describe the function, dietary sources, requirement, assessment, deficiency and toxicity for the water soluble vitamin thiamin

Answer 25

Function: coenzyme in the formation or degradation of alpha-ketos by transketolase and in the oxidative decarboxylation of alpha-ketos such as pyruvate and alpha-ketoglutarate. The oxidative decarboxylation of those two acids play a large role in energy metabolism of most cells, most notably in the tissues of the nervous system, water soluble
Dietary sources: yeast, pork, cereal grains
Requirement: RDA 1.4mg
Assessment
Deficiency: Deficiency results in decreased ATP production and impaired cell function. Deficiency can result in Beriberi which can result in tachycardia, vomiting, convulsions, and death if left untreated. Deficiency can also result in Wernicke-Korsakoff syndrome which is often developed by alcoholics where absorption of the vitamin is impaired. Symptoms include apathy, loss of memory, ataxia, and to-and-fro motion of the eyeballs.
Toxicity

Question 26

16. Describe the function, dietary sources, requirement, assessment, deficiency and toxicity for the water soluble vitamin niacin

Answer 26

Function: A biologically active coenzyme and substituded pyridine derivative which forms NAD+ and NADP+ which serve as coenzymes in redox reactions.
Dietary sources: unrefined and enriched grains and cereal, milk, lean meats
Requirement: 14 mg-16 mg/day
Assessment
Deficiency: Deficiency results in pellagra which involves the skin, gastrointestinal tract and CNS. Symptoms pass from dermatitis, to diarrhea, to dementia. Can lead to death if untreated.
Toxicity: Doses 100x the RDA can inhibit lipolysis in adipose tissue which is the primary producer of circulating fatty acids. This can lead to a reduction in plasma triacylglycerol (in VLDL) and cholesterol (in VLDL and LDL). Pharmacologcical doses (1.5-6 mg/day) may lead to dematological conditions

Question 27

16. Describe the function, dietary sources, requirement, assessment, deficiency and toxicity for the water soluble vitamin riboflavin

Answer 27

Function: Riboflavin occurs in two biologically active forms, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). FMN and FAD accept hydrogen to form FMNH2 or FADH2
Dietary sources: wheat bran, eggs, meat, milk, and cheese
Requirement: 1.1-1.3 mg/day
Assessment
Deficiency: Not associated with major human disease but deficiency often accompanies deficiencies of other vitamins. Symptoms of deficiency include dermatitis, cheilosis, and glossitis
Toxicity: non-toxic

Question 28

16. Describe the function, dietary sources, requirement, assessment, deficiency and toxicity for the water soluble vitamin pantothenic acid

Answer 28

Function: Component of coenzyme A (CoA) which functions in the transfer of acyl groups. It is also a component of the acyl carrier protein (ACP) domain of fatty acid synthase.
Dietary sources: eggs, liver and yeast
Requirement no RDA established
Assessment
Deficiency: not associated with a major disease
Toxicity

Question 29

16. Describe the function, dietary sources, requirement, assessment, deficiency and toxicity for the water soluble vitamin biotin

Answer 29

Function: coenzyme in carboxylation reactions where it serves as a carrier of activated CO2. It is also covalently bound to the e-amino groups of lysine residues in biotin-dependant enzymes.
Dietary sources
Requirement
Assessment
Deficiency: deficiency doesn’t occur naturally because biotin is widely distributed in food and because a large amount of the requirement is provided by bacteria in the intestine…deficiency symptoms (dermatitis, glossitis, nausea) have been found if you eat raw eggs (20 raw eggs/day) because raw eggs contain a protein, avidin, which tightly binds biotin, disallowing absorption into the intestine.
Toxicity

Question 30

17.Identify the factors that should be considered when determining a person’s caloric needs

Answer 30

1. genetics, 2. body composition, 3. metabolism, and 4. behavior of individuals, and 5. activity level have to be considered.

Question 31

18. Calculate BMI and use it to evaluate the body weight status of adults

Answer 31

BMI equation: (weight in kg)/(height in meters)2
BMI Values: 18.5-24.9 = Healthy
25-29.9 = Overweight
≥30 = Obese
>40 = Extremely Obese
Anyone more than 100 pounds overweight is considered severely obese.

Question 32

19. Describe the major factors that contribute to the epidemic of overweight and obesity

Answer 32

Introduction of televisions, automobiles, computers, and energy-sparing devices in the workplace and at home all have lead to a decrease in physical activity and a sedentary lifestyle for many. These sedentary lifestyles coupled with palatable, energy-dense foods, that are cheap and easily accessible have lead to a sharp increase in obesity rates around the world. Eating behaviors, such as snacking, portion size, variety of foods consumed, an individual’s unique food preferences, and the number of people with whom one eats also influence food consumption. Susceptibility to obesity appears to be a combination of one’s genetic makeup and his environment. Environmental factors such as maternal over or under nutrition may ‘set’ the body regulatory systems to try and maintain a higher or lower level of body fat.

Question 33

20. Define microbiome or normal flora

Answer 33

The total community of microbes (commensal, mutualistic, and pathogenic) found within a specified environment.

Question 34

21. Identify a potential role of the human microbiome in maintaining human wellness

Answer 34

Microbes such as Bacteroides thetaiotaomicron, heavily populate the small intestine and break down many of the complex carbohydrates people ingest into products that can be absorbed by the body. Humans absorb 15%-20% of their daily caloric intake this way. E. coli also provides humans with vitamin B12 . The human microbiome also helps prevent infection by competing with and preventing the growth of pathogenic species. For example, the acidic fermentation products produced by lactobacilli in the female genitourinary tract help maintain a low pH. The low pH dissuades colonization by various pathogenic microbes. Another example, a polysaccharide produced by B. fragilis stimulates production of an anti-inflammatory cytokine that will prevent gastrointestinal colitis caused by Helicobacter hepaticus.

Question 35

22. Explain the term “generation time” and the various factors that can affect it.

Answer 35

Generation time is the species-specific time period for doubling of a population (e.g., by bacterial cell division) in a given environment, assuming no depletion of resources. This length of time it takes for a population to divide is affected by bacterial species, type of medium, temperature, and pH. For cells in culture, generation time is also known as doubling time. Generation time is important information because it gives us an idea how rapidly a pathogen will cause disease symptoms. A pathogen with a very short generation time will present disease symptoms quicker than one with a long generation time.

Question 36

23. Describe the concept of quorum sensing and its importance.

Answer 36

Quorum sensing is the ability of bacteria to sense the presence of other bacteria via secreted chemical signals called autoinducers. For some bacteria, quorum sensing is related to gene regulation. The bacteria will secrete small molecule, autoinducers, into the extracellular environment. When the bacterial population has grown large enough, the concentration of extracellular autoinducers passes the critical threshold and the autoinducer will reenter the bacterial cells and bind to a regulatory molecule. This regulatory molecule then becomes activated and can act as a transcription factor to turn on or off transcription of target genes. LUXR is a common regulatory molecule involved in quorum sensing.
Quorum sensing plays an important role in pathogenesis. Pseudomonas aeruginosa (a pathogen that commonly infects those with cystic fibrosis) uses quorum sensing to ensure that the bacterial population grows large enough before the cells start releasing virulence factors (proteases and other enzymes that destroy lung tissue). By waiting to release these virulence factors, which alert the immune system, the bacteria grows large enough to have a chance to overwhelm the host. This induction mechanism uses two interconnected quorum sensing system called Las and Rhl.
Quorum sensing is also used for different bacterial species to communicate with one another. Quorum sensing also allows for communication between prokaryotic and eukaryotic cells. The seaweed Enteromorpha release motile zoospores that seek out and attach to Vibrio anguillarum bacterial cells because the zoospores sense the autoinducer, AHL, release by the bacteria.

Question 37

24. Describe the morphology and arrangement of bacterial cells using acceptable scientific terms (cocci, bacilli, etc).

Answer 37

Bacteria are usual between 0.4 and 10 µm and generally fall into one of three categories. Cocci - spherical in shape, bacilli - rod shaped, and neither rod or spherical. While cocci and bacilli can be found in many different taxon’s of bacteria, those in the other category are usually unique to the taxon and some examples include; spirochetes which are tightly wound spirals such as those causing Lyme disease. Spirochetes should not be confused with spirillum, which are bacilli that are twisted into a looser spiral.
Bacteria have an inner and an outer membrane with a cell wall separating the two. The cell wall is comprised of a single molecule, peptidoglycan (syn. With murein) that is comprised of some relatively unique components such as d-alanine that forms cross bridges with m-diaminopimetic acid. Many antibiotics target this murein as it is unique to bacteria. Vancomycin works by prevent cross bridge formation from d-alanine to m-diam. And therefore the cell wall of the bacteria cannot form.

Question 38

25. List some important gram-positive bacteria and their morphology and arrangement.

Answer 38

Gram positive
No outer membrane
Thick cell walls, 3-20 layers
Teichoic acid (see next question)
Possible s-layer and capsule
Ex. Streptococcus pyogenes, strep throat

Question 39

25. List some important gram-negative bacteria and their morphology and arrangement.

Answer 39

Gram negative
Inner and outer membrane
Thin cell walls, 1 layer
Possible s-layer and capsule
Ex. E. coli

Question 40

25. List some important acid fast bacteria and their morphology and arrangement.

Answer 40

Often stain as Gram pos. even if actually G547ram neg.
Named due to ability to hold pigments in the presence of acids
They hold the pigment due to high mycolic acid content
The Ziehl–Neelsen stain, also known as the acid fast stain, will color these bacteria red on a blue background.
Ex. All Mycobacterium, including those responsible for tuberculosis and leprosy.

Question 41

26. Describe where teichoic acids are found and their importance.

Answer 41

They are found threaded throughout the peptidoglycan. They have a negative charge and help to retain the Gram stain. Essential these are what we are actually visualizing in a Gram stain.

Question 42

27. Describe the components and functions of the outer membrane of Gram-negative bacteria.

Answer 42

The outer membrane’s inward facing side has murein lipoprotein that connects the membrane with the cell well. The main outward facing protein is lipopolysaccharide (LPS). LPS is known as an endotoxin. Endotoxins are harmless in an intact and functioning cell, however should the cell become lysed they are toxic and therefore using antibiotics to kill bacteria containing LPS can lead to patient death. Another common structure are porins. Porins are proteins that are effectively acting as holes in the cell membrane allowing the passage of non lipid soluble molecules. These are used for the acceptance of nutrients, however they can also be used to deliver molecules that are toxic to the bacteria, such as antibiotics. The number of large and small sized porins can be up and down regulated with environment. Usually in nutrient rich environments the large ones are down regulated to reduce risk of taking in toxins.

Question 43

28. Describe and give examples of live vaccines

Answer 43

Use living microbes
Relatively easy to create
Made from weakened “attenuated” microbes
Usually have to be refrigerated creating logistics issues
Contraindicated for people with compromised immune systems
ex. Measles, mumps, and Rubella (MMR-II)

Question 44

28. Describe and give examples of inactivated vaccines,

Answer 44

Use microbes killed in lab (chemicals, heat, or radiation)
Weaker immune response, therefore often require multiple doses over time (boosters)
Usually no need to refrigerate, and can even be freeze dried
ex. Polio vaccine and typhoid

Question 45

28. Describe and give examples of toxoid vaccines

Answer 45

Used in cases of treating diseases from bacteria toxin
Toxins converted to toxoid with formalin (aqueous formaldehyde)
Body recognizes toxoid and produces a natural immune response to associated toxin.
ex. Tetanus and diphtheria

Question 46

28. Describe and give examples of subunit vaccines.

Answer 46

Laboratory created using only a portion of original microbe
Manufactured in one of two ways: either the entier bacteria are gown then chemical seperated into the subunits that are gathered and used for the vaccine creation or the specific antigen molecules are created using recombinant DNA, this results in a “recombinant subunit vaccine.”
Very low chance of adverse reaction
Complicated to produce
ex. Hep B, Hep C currently in research