Topic 1 Flashcards
1
Q
In which forms can proteins participate in cell to cell signaling
A
in the form of hormones and cytokines.
2
Q
What does proteomics study?
A
it studies the expression,
modification, and regulation of proteins.
3
Q
How do proteins differ from other dietary sources of energy?
A
by inclusion of nitrogen
4
Q
What are the biggest stores of energy in the body?
A
1st biggest- adipose tissue
2nd -protein
5
Q
Amino acids from protein are converted to glucose by the process called ___
A
Amino acids from protein are converted to glucose by the process called gluconeogenesis
6
Q
Name a cyclic AA
A
Proline
7
Q
What is an imino acid?
A
An amino acid with a cyclic nature
8
Q
What are the sulfur containing AA?
A
Methionine and cysteine
9
Q
What is the structure of AA?
A
a molecule with a central carbon to which an amino group, a carboxyl group, and a functional group are attached.
10
Q
What is the least common AA and why?
A
Tryptophan is the least common amino acid in many proteins. Due to its large size.
11
Q
What is collagen made up of?
A
- 1/3 Glycine comprises
- proline and hydroxyproline
12
Q
Are concentrations of AA the same relative to each other?
A
No, amino acid concentrations vary widely among amino acids
13
Q
Where are free AA generally found?
A
inside cells
14
Q
Describe how does the lac operon work
A
Lactose is an inducer
LacI encodes for a repressor and it is made all the time
Lactose can attach to this repressor and block it from attaching to an operator. This switches ON the gene. Enzymes for lactose digestion get produced-> digestion. This will cause the amount of lactose to decrease in the surrounding environment
Lactose no longer binds the repressor-> Gene is OFF-> no transcription
15
Q
On which type of genes due dietary constituents impact upon?
A
Responsive genes
16
Q
Which nutrients can impact a cell via signal transduction pathways?
A
Amino and fatty acids can results in signal transduction pathways
17
Q
Which nutrients can result in DNA methylation?
A
Folic acid
Vitamin B12
Methionine
18
Q
Describe mTORC1
A
mTORC1 is a protein complex that functions as a nutrient/energy/redox sensor and controls protein synthesis. It is essential in controlling cell growth. It regulates protein synthesis and lipid synthesis based on the nutrients available, cellular energy (signal send via AMPK) status and amount of growth factors (via Akt) present
Depending on these factors it can signal to produce more proteins or signal SREBP to produce more lipids which will result in cell growth
19
Q
What influences mTORC1?
A
It is responsive to nutrients, cellular energy status and growth factors
20
Q
How does mTORC1 help cell growth?
A
It activates SREBP to produce more lipids
Also signals to produce more proteins
21
Q
Name abundant elements
A
Carbon, hydrogen, oxygen, nitrogen, phosphorous
22
Q
Name trace elements (13)
A
Calcium, chlorine, Cobalt, Copper, Iodine, Iron, Manganese, Magnesium, Potassium, Sodium, Sulphur, Selenium, Zinc
23
Q
Name detectable elements
A
Boron, Bromine, Chromium, Molybdenum, Silicon, Tin
24
Q
Name raw materials that are required for life
A
Carbon source, nitrogen source, water, oxygen, salts
25
Why is glutamic acid important?
It is a neurotransmitter involved in long term potentiation (learning and memory)
26
What can glutamic acid cause?
Headaches, numbness, tingling sensations, obesity
27
Do we use D or L amino acids?
L-amino acids
28
How to tell which foods contain MSG?
Anything that contains protein hydrolysate, many prepared foods
Fermented foods contain them naturally
29
Difference between RNA and DNA
DNA has two H on 3' end
| RNA has an OH and H. OH makes it unstable
30
What is gout caused by?
It is caused by high uric acid concentration -> uric crystals in joint -> irritation and inflammation
genetically-predisposed disorder characterized by joint inflammation
31
How is gout aggravated?
By animal based diet that contains more purines (nucleic acids) - Adenine and Guanine
32
What is uric acid made of in humans?
Adenine and guanine
33
What is Aspartame made of and what are the potential dangers?
It is a dipeptide made of phenylalanine and aspartic acid
| People with PKU should avoid it
34
Define short, medium, long and very long chain fatty acids
Short 2-6 carbons
Medium 8-10 carbons
Long 12-20
Very long >20 carbons
35
What is the formula for carbohydrates?
Cn(H2O)n
36
What is the molar ratio of carbon to hydrogen to oxygen in carbohydrates?
1:2:1
37
Why are pentoses important?
they are important constituents of nucleic acids
38
What are oligosaccharides?
Carbohydrates made up of 3-10 Carbons
39
Name polysaccharides?
starch, glycogen, pectins, cellulose, and gums
40
Why is chitin special?
Chitin is a modified polysaccharide containing nitrogen as N-acetylglucosamine that forms the exoskeleton of arthropods such as insects and crustaceans.
41
Describe cellulose
Cellulose consists of glucose units linked by (l–4) bonds to form long, straight chains strengthened by hydrogen bonding
42
How are carbohydrates digested?
breakdown is initiated during mastication and gastric passage by the carbohydrasea-amylase secreted by the salivary glands, continued by pancreatic amylase in the duodenum, and completed by disaccharidases located in the brush-border membrane of the enterocytes in the small intestine
43
What is the predominant dietary polysaccharide?
Starch
44
What is starch made up of?
Glucose only (thus it is a homopolysaccharide) - glucosan or glucan
45
What are the 2 homopolymers that make up starch?
amylose: has linear (1–4) linked a-D-glucose,
amylopectin: a highly branched form containing both (1–4) and (1–6) linkages at the branch points
46
What are the chemical functional groups commonly found in living organisms?
```
Acyl
Amido
Amino
Carbonyl
Carboxyl
Ester
Ether
Hydroxyl
Imino
Phosphoryl
Sulfhydryl
```
47
Name hydroxyl containing AA
Serine and threonine
48
Name AA with an aromatic group
phenylalanine, tyrosine, tryptophan, and histidine
49
Name neutral AA
glycine, alanine, isoleucine, leucine, valine, serine, threonine, phenylalanine and proline
50
Name sulfur containing AA
methionine and cysteine
| homocysteine- not incorporated into protein
51
How's cysteine found in the body?
Cysteine is often found in the body as an amino acid dimer called cystine in which the thiol groups (the two sulfur atoms) are connected to form a disulfide bond.
52
All amino acids exist as __ in solution
| Explain
All amino acids exist as charged particles in solution
in water, the carboxyl group rapidly loses a hydrogen to form a carboxyl anion (negatively charged), whereas the amino group gains a hydrogen to become positively charged.
53
How do basic and amino acids behave in the solution?
The acidic amino acids lose the hydrogen on the second carboxyl group and become negatively charged in solution.
In contrast, the basic group amino acids in part accept a
hydrogen on the second N and form a molecule with a net positive charge
54
Which form of AA does our body recognize- L or D?
L-amino acids
55
Formal definition of carbohydrates
```
The formal definition is a
class of compounds having the formula Cn(H2O)n; that is, the molar ratio of carbon to hydrogen to oxygen is 1:2:1.
```
56
What are oligosaccharides + give examples
carbohydrates with 3 to 10 carbons
| trioses (glycerose C3H6O3), tetroses (erythrose C4HO4) and pentose (ribose)
57
How many carbons are there in polysaccharides?
more than 10
58
Name common polysaccharides
starch, glycogen, pectins, cellulose, and gums
59
What is chitin
modified polysaccharide containing nitrogen as N-acetylglucosamine that forms
the exoskeleton of arthropods such as insects and crustaceans
60
What is a fructosan
a polysaccharide (as inulin) yielding primarily fructose on hydrolysis
61
Why can't we digest cellulose?
Cellulose consists of glucose units linked by beta
(l–4) bonds
we do not produce an intestinal carbohydrase that hydrolyzes
the beta (1–4) linkage
62
Where are raffinose and stachyose found and what are their complications?
Some oligosaccharides, such as raffinose and stachyose, are
found in small amounts in various legumes. They cannot
be digested by pancreatic and intestinal enzymes but they are digested by bacterial enzymes,
especially in the colon.
63
Describe how carbohydrates are metabolized
This breakdown is initiated
during mastication and gastric passage by the carbohydrase a-amylase secreted by the salivary glands, continued by pancreatic amylase in the duodenum, and completed by disaccharidases located in the brush-border membrane of the enterocytes in the small intestine
64
What is the predominant dietary polysaccharide?
Starch
65
Starch consists only of glucose units and is thus a __
Starch consists only of glucose units and is thus a homopolysaccharide
66
What are the homopolymers of starch?
Amylose and amylopectin
67
Amylose vs amylopectin
amylose: has linear (1–4) linked
alpha-D-glucose, and
amylopectin, a highly branched form containing both (1–4) and (1–6) linkages at the branch points
68
Which parts of carbohydrates do salivary and pancreatic amylases act upon?
The salivary and pancreatic amylases act on the interior (1–4) linkages but cannot break the outer glucose-glucose links
69
Does starch hydrolysis occur in the stomach?
Yes, due to residual salivary amylase
70
Describe the digestion by pancreatic a-amylase
Pancreatic a-amylase added to the emptying gastric contents (chyme) in the duodenum cannot hydrolyze the (1–6) branching links and has little specificity for the (1–4) links adjacent to the branching points
71
What is dietary fiber?
all plant polysaccharides and lignins, which are resistant to hydrolysis by the digestive
enzymes of man”
72
What happens in our bodies to soluble and insoluble fiber?
Soluble and insoluble fibers are fermented by the luminal bacteria of the colon
73
What is the standard of sweetness?
Sucrose
74
What is LacI?
gene called LACI that encodes the repressor protein, therefore this gene gets transcribed into mRNA and translated into the repressor protein
o This repressor protein has DNA binding capacity and binds to LAC operator (lacO) in the promoter region of the lac operon genes.
75
What are the possible effects of dietary constituents?
- Can regulate expression of a responsive gene
| - Can modify an enzyme-> production of secondary mediators-> regulation of responsive genes
76
What are the results of responsive genes beign affected?
They are either the only ones affected
| But they can also affect other genes and proteins
77
Where are responsive genes found in eukaryotes?
Nucleus
78
How do nutrients interact with genes via the proteins in the membrane?
amino acids and FA interact with a protein that is embedded on the cell membrane and that protein would initiate a signal transduction pathway for example: phosphorylation.
79
How do nutrients interact with genes via channels?
Some nutrients enter the cell through channels
o Examples: fat soluble vitamins, trace elements, FA, phytochemicals and sterols
o These interact with TF (i.e. nuclear receptors) that will act on the target genes and effect transcription.
80
How do nutrients interact with genes via DNA methylation?
folic acid, B12 and methionine result in DNA methylation -> genes are turned off and not transcribed
81
How do nutrients interact with genes through translation?
iron and others such as cofactors (vitamins) will affect the translation process as necessary to make proteins/machinery active, without cofactors, this machinery does not work even though the mRNA might be there.
82
How's mTORC1, glucose, protein and lipid biosynthesis connected?
There is a regulatory process that involves many enzymes
Protein and lipid synthesis requires a lot of energy which is produced from glucose
• If the amount of glucose entering the cell increases it means that there is the need and possibility to make new lipids and proteins. The information about the increased nutrients, energy and growth factors will be relayed to mTORC1, which will therefore increase protein synthesis and will also relay information to SREBP1 to increase lipid synthesis in order to increase the size of cells.
83
Describe what happens to SREBP and SCAP during low sterol concentration
* In the ER, SREBP is interacting with SCAP which is also interacting with complex called COPII. This whole complex will migrate towards the golgi via ER/golgi transport.
* Once it reaches here, this complex and more specific SREBP protein is processed by proteases that are found in golgi that will undergo proteolytic cleavage and cut off a portion of the SREBP known now just as “SRE”.
* SRE portion migrates to nucleus and binds to sterol response element of SREBP genes and turns on gene transcription so stimulates transcription of the sterol genes in order to increase the concentration of cholesterol in the environment
84
Describe what happens to SREBP and SCAP during saturating sterol concentration
• When there is high amount of sterol in the ER, SREBP remains bound to SCAP -> bound by INSIG instead of COPII, which causes it to be “stuck” in the ER. Therefore, since it is not transported to the golgi, it does not undergo proteolytic cleavage, and does not get transported to the nucleus therefore it does not turn on the sterol genes and the levels of cholesterol decreases.
85
Name amylases found in humans
Salivary
| Pancreatic
86
Describe the mechanism of action of amylases in humans and their final products
o The salivary and pancreatic amylases act on the interior alpha-1,4- linkages but CANNOT break the outer glucose-glucose links. Thus, the final breakdown products formed by the amylases are alpha-1,4-linked disaccharides (maltose) and trisaccharides (maltotriose)
87
Which AA doesn't have optical activity?
Glycine
88
Where are Free amino acids found?
o Free amino acids are generally concentrated inside cells and the concentration of plasma amino acids range dramatically
89
What is hydrolyzed protein?
Hydrolyzed protein is a protein that has been at least partially hydrolyzed or broken down into its component amino acids
A common ingredient in large scale food manufacturing process
90
Sources and Manufacture of Monosodium Glutamate
1. Hydrolysis of proteins (mixture of L-amino acids; produced from a natural product)
2. Chemical synthesis (DL-glutamate; synthetic)
3. Fermentation (L-glutamate; produced naturally)
o L-glutamate made by chemical synthesis is identical to L-glutamate made by fermentation.
o We use almost exclusively the L isomer
91
Do lipids have a common subunit?
No
92
What are the sources of MSG and types of MSG they yield?
- Hydrolysis of proteins (mixture of L-amino acids; produced from a natural product)
- Chemical synthesis (DL-glutamate; synthetic)
- Fermentation (L-glutamate; produced naturally)
