Biochemistry Flashcards
(167 cards)
1
Q
6-mercaptopurine binds to which enzyme to prevent the formation of GMP, IMP, (and indirectly) AMP?
A
HGPRT
2
Q
What does HGPRT do?
A
Hypoxanthine guanine phosphoribosyltransferase takes free hypoxanthine and guanine to make IMP and GMP.
3
Q
Pathophysiology of adenosine deaminase deficiency
A
ADA is used in the breakdown of AMP. If there is a deficiency, there is less DNA precursors
4
Q
There is a compensatory increase in what with Lesch-Nyhan syndrome?
A
A mutation of HGPRT leads to a defective purine salvage pathway, whose goal is to take free bases to make GMP/IMP.
There is a compensatory increase in purine de novo synthesis to make GMP/IMP which leads to excess uric acid production
5
Q
The red/organt sand crystals found in Lesch-Nyhand syndrome are made up of what?
A
sodium urate
6
Q
Symptoms of HGPRT deficiency (Lesch-Nyhan syndrome)?
A
Hyperuricemia
Gout
Pissed off
Red crystals in urine
Tense muscles (dystonia)
7
Q
MOA of allopurinol
A
Blocks xanthine oxidase which converts hypoxanting to xanthing and eventually uric acid
8
Q
What does unambiguous means when it comes to the genetic code
A
Each codon only specifies 1 amino acid
9
Q
Genetic code
Degenerate/redundant meaning
A
1 amino acid can be made by multiple codons.
10
Q
TATA box regions are typically found where?
A
Found in promoters which are upstream of the origins of replication
11
Q
Bloom Syndrome (BLM mutation) results in a defiency of what protein
A
Helicase
12
Q
DNA Polymerase III is found in prokaryotes or eukaryotes?
A
Prokaryotes
It functions to add to the 3’ end of the strand.
It also has proofreading abilities (3-5 exonuclease)
Eukaryotes use alpha.
13
Q
Function of DNA polymerase I in prokaryotes
A
Degrades the RNA primer and replaces it with DNA. Uses 5-3 exonuclease to do this.
14
Q
Ataxia telangiectasia is an autosomal recessive immunodefiency that results in what symptoms
A
Ataxia
Spider angiomas
IgA deficiency
15
Q
Ataxia telangiectasia has a defect in the ATM gene which results in failure to what?
A
Detect DNA damage, leading to an accumulation of mutations. It may have defects in non-homologous end joining.
16
Q
Dysfunction of homologous recombination of DNA is implicated in what gene mutation?
A
BRCA1/2 and fanconi anemia
17
Q
Nucleotide excision repair is defective in what disease?
A
Xeroderma pigmentosum
The body is unable to repair (excise) pyrimidine dimers caused by UV exposure
Note that this is a larger gap of DNA than base excision repair
18
Q
Mismatch repair is defective in what disease?
A
Lynch Syndrome (Hereditary nonpolyposis colorectal cancer)
19
Q
Lynch syndrome (HNPCC) is an autosomal dominant mutation of what genes?
A
MLH1, MSH2. These are mismatch repair genes.
20
Q
Lynch Syndrome is associated with which cancers?
A
Merrill Lynch has CEOS
Colon cancer
Endometrial
Ovarian
Skin
21
Q
Missense mutation
A
Results in a changed amino acid
Example) Sickle cell disease. Glutamic acid –> valine
22
Q
Nonsense mutation
A
Results in a stop codon
23
Q
What are the stop codons?
A
UGA - U Go Away
UAA - U Are Away
UAG - U Are Gone
24
Q
Frameshift mutations are implicated in what diseases?
A
Duchenne muscular dystrophy
Tay-Sachs disease
Cystic fibrosis
25
Do Introns or Exons contain actual genetic information?
Introns are intervening sequences
Exon exit the nucleus and are used for expression
26
What proteins bind to the promoter region of the DNA coding strand?
RNA polymerase II
The point is to start making RNA (transcription) to eventually lead to translation
27
Enhancers and silencers are found where on DNA strands?
They are found upstream to the promotor as well as close to introns in the reading frame
28
Capping of pre-mRNA, addition of poly-A tail, and splicing of introns occurs inside of the nucleus or in the cytoplasm?
Inside of the nucleus
29
Translation of mRNA occurs in the nucleus or in the cytoplasm?
After capping, addition of poly A tail, and splicing of introns, the mRNA is transported to the **cytoplasm** to be translated
30
RNA polymerase II is responsible for making snRNA which combines with other proteins to make snRNPs. snRNPs are used for what?
Splicing of pre-mRNA to make mRNA
31
Does the 5' or 3' end of tRNA carry amino acids (attachment site)?
The 3' end carries amino acids
CCA - Can Carry Amino
32
Eukaryotic ribosomes use what subunits?
Eukaryotes = 40S and 60s --> 80S
Even
33
Prokaryotic ribosomes use what subunits?
Prokaryotic
30S + 50S --> 70S
Prime
34
What are the functions of the 3 sites on tRNA?
A
P
E
A - receives the incoming Aminoacyl-tRNA
P- growing Peptide
E- exit
35
Growth factors (Insulin, PDGF, EPO, EGF) bind to what kind of receptors?
Tyrosine kinase
36
Rb and p53 moderate what checkpoints?
G1 - S phase
Growth to DNA synthesis phase
37
What is the outcome of p53 and Rb activation?
Tumor suppresion = inhibits growth
38
Phosphorylating Rb and p53 results in what outcome?
Phosphorylating Rb causes it to release E2F --> gene transcription and growth
So this essentially deactivates Rb
39
Free ribosomes are responsible for making proteins that are going where?
Staying in the cytoplasm
Going to the mitochondria
Going into peroxisomes
40
Nissl Bodies are found in neurons. What are their function?
Nissl bodies are the RER for neurons. They synthesize peptide neurotransmitters for secretion
41
The rough ER is the site of synthesis for what kind of proteins?
Exported (secreted) proteins as well as proteins that are needed within organelles
Example) mucus-secreting cells of the intestine and antibody-secreting plasma cells have a lot of RER
42
**N-linked** glycosylation occurs where?
The Rough **eN**doplasmic reticulum
43
The smooth ER is the site of synthesis for what?
Steroids
Example) Hepatocytes, adrenal cortex, and gonads are rich in SER
44
Addition of O-oligosaccharides on serine and threonine, adding mannose-6-phosphate to proteins for lysosomal degredation occurs where?
The Golgi apparatus
These are posttranslational events
45
I - cell disease is a lysosomal storage disease that is inherited how?
Autsomal recessive
46
I-cell disease pathophysiology
Defect where the golgi is not able to add mannose-6-phosphate to proteins which leads to the proteins being excreted instead of sent to lysosomes.
47
Outcome of I-cell disease
Lysosomes dont get the digestive enzymes from the golgi apparatus (due to golgi inability to add mannose 6 phosphate). This leads to a buildup of cellular debris int he lysosomes (inclusion bodies)
48
Symptoms of I-cell disease
## Footnote
Lysosomal storage
Coarse facial features
Gingival hyperplasia
Corneal clouding
Restricted joint movement
Claw hand deformities
Increased plasma levels of lysosomal enzymes (since they are being excreted instead of being stored in lysosomes)
49
Peroxisomes are membrane enclosed organelles involved in what?
B-oxidation of VLCFA
a-oxidation of BCFA
Catabolism of amino acids and ethanol
Synthesis of bile acids
50
Adrenoleukodystrophy is a peroxisome disorder that is inherited in what way?
X-linked recessive
51
Adrenoleukodystrophy is a peroxisomal storage disorder due to a mutation in ABCD1 gene which effects what process?
B-oxidation of VLCFA
Without this oxidation, there is a buildup of VLCFA
52
VLCFA buildup due to adrenoleukodystrophy usually deposits where?
Adrenal glands
White Brain matter
Testes
53
Vimentin, desmin, lamins, and neurofilaments are all examples of what size cytoskeletal element?
Intermediate filaments
These are used to maintain cell structure
Used for tumor identification
54
Vimentin is used as an immunohistochemical stain to identify what kind of tumors?
Mesenchymal tumors (sarcoma) as well as endometrial, renal cell, and meningioma
55
Cilia, flagella, mitotic spingle, and axon trafficking are all examples of what size skeletal element?
Microtubules
56
# REaDY?
Dynein is involved retrograde or anterograde movement to microtubule?
Retrograde
57
# AttacK
Kinesin is involved in retrograde or anterograde transport to microtubules?
Anterograde
58
# REaDY
C. tetani toxin, poliovirus, rabies, and HSV use what for **retrograde ** transport to the neuronal cell body?
Dynein arms
59
# AttacK
HSV reactivation use what for anterograde transport down to the axon terminal
Kinesin
60
Primary ciliary dyskinesia is caused from a defect in what structure?
Dynein arms inside of the cilia
61
Symptoms/Consequences of primary ciliary dyskinesia
Kartagener syndrome
HEaring loss due to eustacian tube cilia
recurrent respiratory infections
Infertility (immotile speramtozoa, increased risk of ectopic pregnancy due to fallopian tube cilia)
62
# 2 strikes? K you're in. 3 strikes? Nah you're not
How many sodium and potassium move via Na/K ATPase
ATP binds
Causing 3 sodium to leave and 2 potassium to come inside
63
Which medication directly blocks Na/K ATPase which indirectly causes an increase in intracellular calcium?
Digoxin. The outcome is increased cardiac contractility
64
Type 1 collagen is found primarly where?
This the most common collagen, found in tendone and bone.
65
Osteogenesis imperfecta has a decreased production of what kind of collagen?
Type I collagen (tendon and bone)
66
Type II collagen is found where?
Cartilage
(Cartwolage)
67
Type III collagen is found where?
Reticular collagen
Skin, blood vessels, early would repair
68
Ehlers Danlos Syndrome is deficient in what type of Collagen?
Type III (found in blood vessels)
(threE D)
69
Type IV collagen is found where?
Basement membrane
(4 under the floor)
70
What type of collagen is defective in Alport Syndrome?
Type IV collagen
71
What type of collagen is defective in Goodpasture syndrome?
Type IV collagen
72
What is the sequence of collagen processing?
Preprocollagen
Procollagen
Tropocollagen
Collagen
73
Hydroxylation of preprocollagen requires which vitamin?
Vitamin C. Deficiency in Vitamin C will lead to scurvy
74
Procollagen is a triple helix formed by hydrogen and disulfide bonds. Issues forming this helix results in what disorder?
Osteogenesis imperfecta
75
Hydroxylation of preprocollagen
and
Glycosylation of procollagen take place where?
In the Rough ER
76
After exiting the cell, procollagen is cleaved at the C and N terminals to form what?
Tropocollagen
77
Osteogenesis imperfecta is inherited in what way?
Autosomal dominant
78
What are the symptoms of osteogenesis imperfecta?
BITE
Bones - fractures
I- eyes - blue sclera
T - teeth imperfections
E - Ear, hearing loss
79
Ehlers-Danlos syndrome - vascular type is due to a defect in what kind of collagen?
Type III collagen
80
Ehlers-Danlos Syndrome classical type (hyperextendible joints and skin) is from a defect in what kind of collagen?
Type V
81
What cofactor is needed for crosslinking of collagen?
Copper
82
Marfan syndrome is a connective tissue disorder due to what genetic defect?
FBN1 gene mutation on chromosome 15.
This results in defective fibrillin-1
83
Where is fibrillin 1 found in the body
it forms a sheath around elastin
84
A Marfan body type looks like what?
Chest wall deformity
Hypermobile joints
Long fingers
Cysteic medial necrosis of aorta
Aortic root aneurysm or rupture or dissection
MVP
Spontaneous pneumothorax
85
What cardiac abnormalities are associated with Marfan syndrome?
Aortic root aneurysm or dissection
MVP
Spontaneous pneumothorax
86
Which syndrome is characterized by a long, slender body type and cardiac abnormalities?
Marfans or Ehlers-Danlos
Marfans Syndrome
87
# BITE
Which connective tissue order presents with blue sclera?
Osteogenesis imperfecta
88
Marfan Syndrome results in what type of lens dislocation?
Upward/temporal
(Fan out)
89
Homocystinuria is commonly due to what enzyme deficiency?
Cystathionine synthase deficiency
90
What is the inheritance of homocystinuria?
Autosomal recessive
91
What is the common vascular complication of homocystinuria?
Thrombosis
92
# SNoW DRoP
What do these blotting procedures detect?
Southern - DNA
Northen - RNA
Western - Proteins
93
Flow cytometry is used to identify what?
Immunophenotype of individual cells
Cells are tagged with antibodies specific to their surface or intracellular proteins
94
Meaning of variable expressivity
2 patients with the disease may have varying severity
Example) NF1
95
Incomplete penetrance meaning
Not everyone with the mutation will have symptoms
Example) BRCA1
96
Pleiotropy meaning
When one gene contributes to multiple phenotypes
Example) PKU has light skin, intellectual disability, musty body odor
97
What is an example of a disease that exhibits anticipitation?
Huntington disease
(Trinucleotide repeat diseases)
98
protooncogenes or tumor suppressors
Which one has a 2 hit hypothesis?
Tumor suppressors
Example) Lynch syndrome (MSH1)
Li Fraumenia (p53)
99
B-thalassemia is an example of allelic or locus heterogeneity
Allelic heterogeneity
Different mutations on the same locus results in the same disease
100
Heteroplasmy
Presence of both normal and mutated mtDNA resulting in variable expression
101
Imprinting meaning
When one parent's gene is silenced by methylation.
Disease occurs when the expressed parent's gene is mutated or deleted
102
In Prader-Willi syndrome, is the mother or father's genes silenced?
Mothers genes are silenced
103
What chromosome is effected in Prader-Willi Syndrome
Chromosome 15
104
Symptoms of Prader Willi Syndrome
Hyperphagia (overeating)
Intellectual disability
Hypogonadism
Hypotonia
105
Is the mother or father's genes silenced in Angelman syndrome
The father's gene is silenced
Disease occurs when the maternal allele is damaged or deleted
106
What gene and chromosome is effected on the mothers DNA in Angelman Syndrome
UBE3A on Chromosome 15
107
Symptoms of Angelman Syndrome
Hand flapping
Ataxia
Intellectual disability
Inappropriate laughter
Seizures
108
Is Prader Willi or Angelman syndrome more likely to be due to a uniparental disomy?
Prader Willi
25% of cases is due to maternal uniparental disomy. If the child receives both chromosome 15s from mother and they are silenced via methylation, then the child will have disease
109
Fragile X syndrome and Alport syndrome are examples of what kind of inheritance?
X-linked dominant
110
X-linked recessive disease
Father has disease
Who is at risk
No risk to son (father only passes on y)
Daughters are carriers
111
X-linked recessive
Mother is a carrier
Who is at risk?
Sons have 50% chance of getting disease
112
X-linked dominant disease
Father has disease
Who is at risk
Daughters have 100% risk of being carrier
Sons are not at risk
113
X-linked dominant disease
Mother has disease
Who is at risk
Both daughter and sons have 50% chance of being effected
114
Autosomal recessive
Oh Please! Can Students Who Score High Grades Tell Me Features of the Kidney Disorder ARPKD
Oculocutaneous albinism
Phenylketonuria
Cystic fibrosis
Sickle cell disease
Wilson Disease
Sphingolipidoses
Hemochromatosis
Glycogen storage diseases
Thalassemia
Mucopolysaccharidoses
Friederick ataxia
Kartagener syndrome
115
# Sphingolipidoses
Tay-Sachs disease has what type of inheritance?
Autosomal recessive
116
# Tay Sax
Tay-Sachs Disease has a deficiency in what enzyme
Hexosaminidase A
117
Both Tay-Sachs disease and Neiman Pick have what finding on exam?
Cherry-red spot on macula
118
Which disease has a cherry red spot and hepatosplenomegaly?
Tay-Sachs or Nieman Pick
Nieman Pick
119
What product is accumulated in Tay-Sachs disease?
GM2 ganglioside
120
What enzyme is deficient in Niemann-Pick?
Shingomyelinase
121
What substance is accumulated in Niemann-Pick?
Sphingomyelin
122
# Vice President can't accept money
What are the 5 glycogen storage diseases?
Von Gierke
Pompeii
Cori
Anderson
McArdle
123
What stain is used to see glycogen stored in cells?
Periodic acid-Schiff stain
124
Why do patients have hyperuricemia in Von Gierke disease?
Glucose 6- phosphatase deficiency results in a build up of glucose 6 phosphate which will then shunt to glycolysis for breakdown. This increases pyruvate and lactic acid (lactic acidosis, metabolic acidosis)
The acidic pH decreases uric acid excretion from the kidneys
125
In Von Gierke disease, which processes are not able to be performed?
Glycogenolysis
Glyconeogenesis
Because there is no glucose 6 phosphatase
126
Classic galactosemia usually presents in newborns after receiving breast milk which contains galactose. What are the typical symptoms?
Failure to thrive
Jaundice
Cataracts
Intellectual disability
127
What enzyme is deficient in galactosemia?
Mild - galactokinase
Severe - galactose 1P uridyltransferase (GALT)
128
Newborn starting to have jaundice after breastfeeding? This is indicative of what kind of inborn error of metabolism?
Galactosemia
Severe - GALT deficiency leading to an accumulation of galactose 1 phosphate
129
Glycogen phosphorylase is responsible for releasing glucose 1-phosphate from glycogen. This enzyme is deficient in what disorder?
McArdle Disease
130
Cori disease has a deficiency in what enzyme?
Debranching enzyme involving in breaking down glycogen to glucose.
131
Symptoms of Cori Disease
Hypotonia, mild hypoglycemia (gluconeogenesis is still intact), normal lactic acid
132
Essential fructosemia an autosomal recessive disorder of fructokinase deficiency (1st step). Is this disorder benign or severe?
Benign
133
Excess fructose accumulated because of essential fructosemia results in the fructose being shunted to which process?
Glycolysis - using hexokinase
134
Hereditary fructose intolerance has a deficiency in what enzyme?
Aldolase B which results in an accumulation of fructose 1 phosphate
135
Gi and Gs enzymes signal through which pathway?
Adenylyl cyclase
136
Activation of Gi and Gs enzymes result in the activation of what pathway and increase in what product?
Activates the adenylyl cyclase pathway leading to an increase in cAMP
137
An increase in cAMP after stimulation of Gs enzyme causes PKA to do what?
PKA is a kinase = phosphorylates target enymes
138
RBCs use the HMP shunt to generate what product?
NADPH. This is used to regenerate reduced glutathione which is protective against ROS
139
What is characteristic on blood smear of G6PD deficiency?
Bite cells - after splenic degredation of bulky heinz bodies
140
Where does the HMP shunt occur in the cell?
The cytoplasm
141
Where does the Kreb cycle occur?
The inner matrix of the mitochondria
142
The Kreb cycle typically begins with what substrate?
Pyruvate
143
What are the products of the Kreb cycle
NADH and FADH for the electron transport chain
144
# Can I Keep Selling Sex For Money, Officer
What are the intermediates in the TCA cycle?
Citrate
Isocitrate
a-ketoglutarate
succinyl-Coa
Succinate
fumarate
malate
oxaloacetate
145
Sucrose is broken down into which 2 sugars?
Fructose and glucose
146
In the liver, fructose uses which 2 enzymes to make intermediates for glycolysis?
Fructokinase
Aldolase B
147
In the liver, kidney and brain, galactose is broken down to intermediates for glycolysis using which 2 enzymes?
1. Galaktokinase
2. GALT (galactose-1-phosphate uridyl transferase)
148
GALT deficiency (classic galactosemia) results in increased risk for what infection?
E. coli sepsis
149
Muscles use aerobic or anaerobic glycolysis?
Anaerobic. It produces lactic acid
150
The Cori cycle moves what from muscles to the liver to make glucose?
Lactic acid
151
The urea cycle take place in what location?
Liver cells.
152
The urea cycle results in what products?
Urea and fumarate which then enter the TCA cycle
153
Ornithine transcarbamylase deficiency is implicated in which cycle?
The urea cycle. It results in increased ammonia
154
Urea is measured as what?
BUN
155
High ammonia and low urea is indicative of what defiency?
Ornithine transcarbamylase deficiency
This shows that the liver is unable to turn ammonia into urea
156
Hyperammonemia can cause asterixis which is what
flapping of the hands with wrists extended (hepatic encephalopathy)
157
What is the precursor for Tyrosine
Phenylalanine
158
Tyrosine is a precursor for what products?
catecholamines (dopamine, adrenaline), melanin, and thyroxine
159
Alkaptonuria is due to a deficiency of what enzyme?
homogentisic acid oxidase
160
Alkaptonuria manifests as what symptoms?
Black/blue connective tissue
161
Pathophysiology of albinism
1. Tyrosinase deficiency
2. Tyrosine transporter mutation
162
Homocysteinuria is due to a deficiency in what enzyme?
Cystathionine synthase
or methionine synthase deficiency
163
Symptoms of homocysteinuria
Mental retardation
Osteoporosis
Tall staure
Kyphosis
Lens sublaxation (down and in) -- compare this to Marfan up and out
164
MSUD is due to a deficiency in what enzyme?
a-keto acid dehydrogenase which catalyzes the degredation of branched chain amino acids
165
Thiamine (vitamin B1) is used as a cofactor for which enzymes?
Branched chain ketoacid dehydrogenase
a-ketogluturate
p
transketolase
166
Duchenne muscular dystrophy pathophysiology
Deleted dystrophin gene
Dystrophin helps to anchor muscle fibers to the ECM --> myonecrosis
167
Calf muscles in patients with duchenne muscular dystrophy looks like what
Fibrofatty replacement of muscle
Gower's sign (using hands to help stand)
dilated cardiomyopathy
