Review Flashcards
1
Q
When is a positive nitrogen balance seen?
A
Rapid tissue growth; growing children, pregnancy, illness/trauma recovery
2
Q
When is a negative nitrogen balance seen?
A
Starvation
3
Q
When is kwashiorkor seen?
A
Generally in children under starvation conditions - muscle wasting
4
Q
What is the major nitrogen excretion product in humans?
A
Urea
5
Q
What is the 1st step in nitrogen metabolism? What cofactor is required?
A
Transamination
Vitamin B6
6
Q
What is the 2nd step of nitrogen metabolism?
A
Bimolecular ping pong
7
Q
What is the intermediate of nitrogen metabolism? The final product?
A
alpha-ketoglutarate
Glutamate
8
Q
Where does the 1st portion of the urea cycle occur?
A
In the mitochondrial matrix
9
Q
What is the rate limiting step of the urea cycle?
A
Carbamoyl phosphate synthetase I
10
Q
In what organ does the urea cycle take place?
A
In liver (hepatocyes)
11
Q
Why does an elevated level of ammonia result in decreased ATP production, thus hampering brain function?
A
Excess ammonia is “cleaned up” by the TCA cycle intermediate alpha-ketoglutarate, that depletes NADH production.
12
Q
What amino transmitters does an elevated level of ammonia deplete?
A
Glutamate
GABA
13
Q
How does a build up of ammonia cause the brain to swell?
A
It causes a build up of Glutamine that increases intracellular osmotic balance, causing water to enter astrocytes, causing brain swelling
14
Q
The 5 carbon amino acids are metabolized to glutamate before their final product. What are the 4 amino acids that do so?
A
Glutamine
Proline
Argenine
Histidein
15
Q
To metabolize histidine to glutamate what is required?
A
THF transfer
16
Q
What is required to transaminate glutamate to alpha-ketoglutarate?
A
OAA tranaminase
17
Q
How is glutamine converted into glutamate?
A
By adding NH4
18
Q
What is the metabolism of argenine to alpha-ketoglutarate?
A
Argenine -> Ornithine -> Glutamate -> alpha-ketoglutarate
19
Q
Maple syrup urine disease is associated with what?
A
Branched-chain alpha-keto acid dehydrogenase complex
20
Q
The conversion of propionylCoA to succinylCoA requires what two enzymes?
A
Biotin
Cobalamin
21
Q
What are the two enzymes that are strictly ketogenic?
A
Lysine
Leucine
22
Q
What is lysine converted into?
A
AcetoacetylCoA
23
Q
What is leucine converted into?
A
AcetylCoA
Acetoacetate
24
Q
What amino acids are both ketogenic and glucogenic?
A
The aromatics:
Phe
Tyr
Trp
25
Which enzyme requires tetrahydrobiopterin?
Phenylalanine hydroxylase
26
In which reaction is phenylalanine hydroxylase important?
The conversion of phenylalanine to tyrosine
27
What does tryptophan break down into?
Pyruvate and acetoacetyl CoA
28
How is phenylketonuria passed genetically?
Autosomal recessive
29
Phenylketonuria stems from a deficiency in what?
Phenylalanine hydroxylase
30
What is the result of untreated PKU?
Severe mental retardation
31
A defect in alkaptonuria is called what?
Homogentisate oxidase
32
Maple syrup urine diseases comes from a defect in what?
Branched chain amino acid DH
33
A defect in methymalonylCoA mutase causes what?
Methylmalonic acidemia
34
What causes homocystinuria?
A defect in cystathione synthase
35
Which amino acid is insufficient in infants?
Argenine
36
What are the 10 essential amino acids?
Phe, Trp, Lys, His, Arg, Ile, Leu, Val, Thr, Met
37
Which amino acid can be recycled?
Met
38
What is the transamination precursor to alanine?
Pyruvate
39
What is the transamination precursor to aspartate?
OAA
40
How is asparagine made from aspartate?
By adding NH4
41
Which amino acid is broken down to make tyrosine?
Phenylalanine
42
Alpha-ketoglutarate is a precursor for what three amino acids?
Glutamate
Glutamine
Proline
43
How is glutamine made from glutamate?
By adding NH4
44
Homocistanuria is caused by a lack of what?
Cystathionine B-synthetase
45
Cystathionine B-synthetase is important in the synthesis of ___ from ___.
Cysteine from serine
46
Elevated serum levels of what is a known risk factor of cardiovascular disease?
Homocysteine
47
Elevated serum levels of homocysteine may result from deficiencies in what?
THF
B12
B6
48
What do hydroxylases and oxidases do?
Add OH groups
49
What cofactors can be required for hydroxylases and oxidases?
Tetrahydrobiopterin
| Ascorbate
50
What do decarboxylases do?
Remove COO- groups
51
What cofactor is required in decarboxylase reactions?
Pyridoxine (PLP) (B6)
52
What do methyl transferases do?
Add methyl groups
53
What cofactors can be required in methyl transferase?
Tetrahydrofolate
| SAM
54
What cofactor is needed to methylate epinephrine?
SAM
55
What are the three catecholamine neurotransmitters?
Dopamine
Norepinepherine
Epinephrine
56
Serotonin is synthesized from which amino acid?
Tryptophan
57
In the pineal gland, serotonin can be converted into what?
Melatonin
58
What does prozac do?
Inhibits the re-uptake of serotonine
59
Serotonin is also important in what?
Vasoconstriction
60
Thyroid hormones come from which amino acid?
Tyrosine
61
Thyroid hormones are amine hormones, but act like ___ hormones.
Steroid hormones
62
How does the hypothalamus communicate with the anterior pituitary gland?
Via the portal vein system
63
How does the hypothalamus communicate with the posterior pituitary?
Direct innervation
64
What type of hormones does the anterior pituitary release?
Tropic hormones
65
What are the 6 tropic hormones released by the anterior pituitary?
```
Corticotropin (ACTH)
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
Thyrotropin
Somatotropin
Prolactin
```
66
What are the 4 classifications of ligands?
Peptide
Eicosanoid
Amine
Steroid
67
All signaling molecules use cell membrane associated receptors except for:?
Steroids
| Thyroid hormones
68
Most neurotransmitters are which classification of ligand?
Amines
69
What are the 5 major concepts of cell signals?
```
Signals are:
Specific
Amplified
Desensitized
Integrated
Transient
```
70
How are signals self-limiting?
By breakdown, endocytosis, phosphatases, GTPases and Ca pumps used to limit the signal
71
How does desensitization occur?
Beta arrestin removes some of the beta adrenergic receptors
72
How does the ubiquitin/proteosome pathway work?
Ubiquitin ligases attach ubiquitin to lysine side chains of the proteins;
Ubiquitin acts as a targe for the 26S proteosome
73
What are the 6 major hormone receptor classes?
```
Gated ion channels
Receptor enzymes
Serpentine
Adhesion
Steroid
"Orphan"
```
74
What is an example of an adhesion receptor?
Integrins
75
How does an adhesion receptor function?
Binds molecules in extracellular matrix, changes conformation and alters its interaction with the cytoskeleton
76
How do serpentine receptors work?
External ligand binding to receptor activates an intracellular GTP-binding protein (G) which regulates an enzyme that generates an intracellular second messenger
77
How is inositol released?
Protein Gq stimualtes phospholipase C which releases inositol
78
What are the three major classes of G-proteins?
Gs
Gi
Gq
79
What does Gs stimulate?
Adenylate cyclase
80
What does Gi do?
Inhibits adenylate cyclase
81
How does the cholera toxin interfere with G proteins?
ADP-ribosylates Gs-alpha, making it permanently active
82
If the cholera toxin causes Gs-alpha to be permanently active what is the result?
High cAMP in intestinal epithelium causing secretion of Cl, HCO3 and water into the lumen
83
How does the pertussis toxin interfere with G proteins?
ADP-ribosylates Gi so that adenylate cyclase is not inhibited
84
What does the pertussis toxin cause?
Increased cAMP in the lung epithelium resulting in increased mucous secretion
85
With adenylate cyclase, what is the 2nd messenger, and the kinase that it activates?
cAMP
| Protein Kinase A
86
With guanylate cyclase, what is the 2nd messenger, and the kinase that it activates?
cGMP
| Protein kinase G
87
With phospholipase C, what is the 2nd messenger, and the kinase that it activates?
IP3, DAG, Ca++
| Protein kinase C
88
What is Cushing's syndrome?
Having excess cortisol causing changes in skin and fat deposit
89
What is cortisol supposed to do?
Mobilize fuel in response to stress
90
What is the pathway to achieve cortisol secretion?
Hypothalamus secretes CRH into portal system
A. pituitary secretes ACTH into circulation
Adrenal cortex secretes cortisol
91
What does ACTH come from?
A large precursor protein that stems from the POMC gene
92
What are the effects of cortisol?
Elevates blood glucose
Mobilizes fat
Increases muscle protein catabolism
Anti-inflammatory
93
How does cortisol act as an anti-inflammatory?
It is a steroid hormone that blocks NFKB signaling by entering the nucleus and changing gene expression
94
What are some symptoms of Cushing's syndrome?
```
Upper body weight gain
Skin darkening, bruising, stretching
Excess hair growth or acne in women
Fatigue & muscle weakness
Mood swings
Menstrual disorder
```
95
Addison's disease results from what?
A cortisol deficiency
96
What are symptoms of Addison's disease?
```
Changes in BP/heart rate
Chronic diarrhea
Patchy darkening of skin
Weakness/fatigue
Loss of appetite
Mouth lesions - buccal mucosa
Salt craving
Slow movement
Weight loss
```
97
What causes the brown patches in Addison's disease?
Excess ACTH - causes melanocyte stimulating hormone
98
What hormones regulate basal metabolic rate?
T3, T4
99
Why is iodine necessary in the body?
To iodinate tyrosine to get thyroid hormones
100
Are thyroid hormones lipophilic or hydrophilic?
Lipophilic (act like steroids)
101
What are symptoms of hypothyroidism?
```
Cold sensitive
Unintentional weight gain
Fatigue
Brittle hair
Constipation
Depression
```
102
What are other names for hypothyroidism?
Myxedema
| Hashimoto's syndrom
103
What are symptoms of hyperthyroidism?
```
Heat sensitive
Weight loss
Exophthalmia
Racing/irregular heart
Insomnia
Diarrhea
Tremor
```
104
What is another name for hyperthyroidism?
Grave's disease
105
What is the role of leptin?
To shut down the hunger response so that there is less adipose - regulates body weight
106
Where does leptin come from?
Adipose
107
As adipose tissues decreases, what happens to adiponectin?
It increases
108
What does adiponectin activate?
AMPK
109
Why is AMPK important, especially in diabetes?
It allows us to bypass the insulin dependence of GLUT4 receptors
110
What does exercise do to AMPK?
Activates it so that it will bring GLUT4 to the membrane
111
What activates Toll receptors?
PAMPs - Pathogen associated molecular patterns
112
What are examples of PAMPs?
Lipopolysaccharide or flagella proteins
113
What do Toll receptors activate?
2 major pro-inflammatory transcription factors:
AP-1
NFkB
114
What is the "master switch" for inflammation?
NFkB
115
How is NFkB activated?
IkB is phosphorylated, ubiquintinated and degraded, allowing NFkB to enter the nucleus
116
What do glucocorticoids do?
Interfere with NFkB
117
How does the thromboxane A2 receptor work?
Hormone binds receptor and activates Gq
Gq activates phospholipase C
Phospholipase C catalyzes the hydrolysis of phosphatidylinositol -4,5-bisphosphate to release diacylglyceral (DAG) and inositol trisphosphate (IP3)
IP3 opens Ca++ channels and DAG activates PKC
118
What activates the two different types of guanylate cyclase?
ANF
| NO
119
What does guanylate cyclase do?
It is a secondary messenger that activates cGMP
120
What are the two types of gyanylate cyclase?
Integral membrane proteins
| Cytosolic protein w/associated heme
121
What activates PKG?
cGMP
122
What does PKG target in the kidneys?
Na+ channels; enhances Na+ excretion (along with water)
123
What does PKG target in the vasculature?
Ca++ channels; lowers cytosolic Ca++, decreases smooth muscle contraction
*Ultimately decreases blood pressure
124
What secretes atrial natriuretic factor? What does it cause to increase?
Heart (acting as an endocrine gland)
| By binding to guanylate cyclase receptor, it increases cGMP
125
Why is nitroglycerin used for ischemia near the heart?
It degrades to NO, which binds GC and increases cGMP, that activates PKG which results in relaxation of the heart muscle
126
What are the 3 types of diabetes mellitus?
Type I - Insuline dependent (juvenile)
Type II - Non-insulin dependent (adult-onset)
Gestational
127
What happens in type I diabetes?
Autoimmune destructions of beta cells - lack of insulin production
128
What is the normal value for the fasting plasma glucose test?
Below 100 mg%
129
What is the normal HbA1c level?
6 or lower
130
What is the direct target of insulin?
Muscle
| Adipose
131
What is the direct target of binguanides?
AMPK activator - enhances glucose uptake
132
When is adiponectin activated?
Extended fasting or starvation - reduced triacylglycerols
133
What does AMPK activate?
GLUT4 transporter
134
What is a key substrate in both purine and pyrimidine synthesis?
PRPP
135
What does PRPP do?
Activates C1 on ribose
136
What is the committed step in de novo purine biosynthesis?
Formation of 5-physphoribosyl-1-amine
137
What catalyzes the formation of 5-phosphoribosyl-1-amine?
Glutamine-PRPP amidotransferase
138
Where does the formation of carbamoyl phosphate in de novo pyrimidine biosynthesis take place?
In the cytoplasm
139
What is the committed step in de novo pyrimidine biosynthesis?
Formation of N-Carbamoylaspartate from aspartate
140
What is needed to synthesize deoxyribonucleotides?
Nucleoside diphosphate
| Ribonucleotide reductase
141
What inhibits dihydrofolate reductase?
Methotrexate
Aminopterin
Trimethoprim
142
What energy source is required for the synthesis of dTMP?
NADPH
143
What is the precursor for dTMP synthesis?
dUMP
144
Which base is more often recycled, purines or pyrimidines?
Purines
145
If you don't have any HGPRT, what disease do you get?
Lesch-Nyhan
146
A deficiency in HGPRT causes what?
Gout
147
Guanine and hypoxanthine are formed from what?
Adenine
148
What does ribonucleuotide reductase do?
Converts ribose to deoxyribose - provides deoxyribose for DNA synthesis
149
If you don't have adenosine deaminase, what disease do you have?
SCID (bubble boy)
150
To prevent gout, what would you block?
Xanthine oxidase
151
How is SCID treated?
Gene therapy - no real treatment
152
What enzyme is needed to produce uric acid?
Zanthine oxidase
153
What did Hershey and Chase prove?
Viruses inject DNA
154
What is the DNA "melting" temperature dependent upon?
CG base pairs - more H bonds, so they are a little stronger than AT bonds
155
What components are in mRNA?
Transcriptional start site
Initiation codon
Exons
*No introns!
156
The sense strand and mRNA are both ___ to the template strand.
Complementary
157
What chromosomes make up the nucleolus?
13, 14, 14, 21, 22
158
Ribosome RNA genes are found where?
On the nucleolus
159
What are the levels of DNA compaction from biggest to smallest?
```
Coil
Rosette
Loop
Solenoid
Nucleosome
```
160
What are telomeres?
Buffers at the end of chromosomes
161
What are centromeres?
The part that links the sister chromatids
162
What happens if an alkylating agent donates alkyl groups to bases?
Changes the pairing properties, causing transitions, transversions and/or frameshifts
163
What are the 4 major repair systems?
Mismatch repair
Base-excision repair
Nuclotide-excision repair
Direct repair
164
Which type of mutation repair is for bigger lesions?
Nucleotide excision
165
What is the most specific type of mutation repair?
Direct repair
166
What type of damage does base-excision repair fix?
Abnormal bases
Alkylated bases
Pyrimidine dimers
167
What type of damage does nucleotide-excision repair fix?
DNA lesions that cause large structural changes
168
What type of damage does direct repair fix?
Methylated stuff
169
Xeroderma pegmentosum results from what?
Defect in nucleotide excision repair - specifically the thymine dimer repair system
170
What phenotype is caused by hereditary nonpolyposis?
Colon cancer - due to ineffectivity of mismatch repair
