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Biochemistry Flashcards

1
Q

What is the charge of DNA double helix?

A

Negative

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2
Q

What is the charge of nucleosome?

A

Positive charge

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3
Q

what are histones?

A

Amino acid lysine and arginine (Histones bind to nucleosomes and to linker DNA)

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4
Q

what phase does DNA and histone synthesis occur?

A

During the S phase

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5
Q

what are the characteristics of heterochromatin?

A

Condensed DNA, transcriptional inactive, and sterically inaccessible

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6
Q

What is Euchromatin?

A

Less condesned,lighter on EM, and transcriptionally active

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7
Q

What is DNA methylation?

A

Template strands (Cytosine and adenine) are methylated in DNA replication, so mismatch repair enzymes can distinguish between old and new strands.

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8
Q

what happens in histone methylation?

A

usually suppresses DNA transcription, can can activate it in some cases

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9
Q

what does histone ACETYLATION do?

A

Relaxes DNA coiling and allows for transcription

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10
Q

What are the differences between nucloetides?
Nucloside
Nucleotide?

A

Nucloside: base + deoxyribose (sugar)
Nucleotide: base + deoxyribose +phosphate (linkare 3-5 phosphodiester bond)

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11
Q

What is the difference between a purine and pyrimidine?

A

PURines (A, G) has 2 rings

Pyrimidines (C, U, T) 1 ring

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12
Q

where is Uracil found?

Where is thymine found?

A

Uracil is RNA

Thymine is in DNA

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13
Q

What determines the melting temperature of DNA?

A

Number of C-G bonds (3- H bonds so stronger) then A-T (2 H bonds)

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14
Q

What amino acids are needed for purine synthesis?

A

GAG (gycine, aspartate, glutamine)

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15
Q

What are medications that disrupt pyrimidine synthesis?

A

1) Leflunomide: dihydroorotate dehydroxygenase
2) Methrotrexate, trimethoprim (TMP), pyrimethamine (dihydrofolate reductase)
3) 5-flurocil: forms 5-F-dUMP inhibits thymidylate synthase

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16
Q

What disrupts purine synthesis?

A

6-mercaptopurine and azathioprine: de novo purine synthesis

Mycophenolate and ribavirin: inhibits inosine monophospahte dehydrogenase

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17
Q

What disrupts purine and pyrimidine synthesis?

A

Hydroxyurea: ribonucleotide reductase

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18
Q

what are two medications that act on purine slavage pathways?

Which step do they act on?

A

1) Allopurinol and febuxostat, Probenecid
2) Allopurinol/febuxostat: Act on X0 (which is enzyme) prevents formation of Xanthine to Uric acid)
3) Probenecid: increases the transformation of Uric acid to urine

All these medications are used for gout

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19
Q

what does adenosine deaminase deficiency cause?

A

1) SCID (severe combined immunodeficiency syndrome)

2) Increases dATP, which is toxic to lymphocytes.

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20
Q

What is Lesch-Nyhan Syndrome?

What are the signs?

A

Deficiency in HGPRT enzyme

Symtoms match abbreviation (HyperuricemisGoutPissed off aggresionRetrardation DysTonia

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21
Q

What are features of the genetic code?

A

1) Unambiguous: each codon is 1 amino acid
2) Degenerate/ redundant: most amino acids are coded by mutiple codons (except mehtionin and tryptophan)
3) Comaless/nonoverlapping: read from a fixed point, continuous sequence of bases (except virus)
4) Universal: genetic code is conserved throughout evolution, except in human mitochrondria.

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22
Q

Where does origin of replication of DNA occur?

What is the difference between prokaryotes and eukaryotes promotor?

A

Base pairs, usually promoters (A-T rich segments)

2) Eukaryotes may have more then one promoter

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23
Q

What is the replication fork?

A

Y shaped region where the leading and lagging strands are synthesized

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24
Q

what is the function of helicase?

A

Unwinds the DNA at replication fork

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25
Q

What are the function of single stranded binding proteins?

A

Prevents strands from reannealing

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26
Q

What is function of DNA topoisomerase?

A

Create single or double stranded breaks in the helix to add or remove supercoils

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27
Q

What medications are DNA toposiomerase inhibitors?

A

fluroquinones

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28
Q

What is the function of primase?

A

Makes RNA primer on which DNA polymerase III can initiater replication

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29
Q

What is DNA polymerase III?

A

Prokaryote only, elongates the leading strand by adding deoxynucleotides to the 3’ end.

Synthesis occurs in 5’ to 3’
Proofreads with 3’ to 5’ exonuclease

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30
Q

what does DNA polymerase 1 do?

A

Prokaryote, degrades RNA primer, and replaces with DNA

(has same functions as DNA polymerase III but also excises RNA primer with 5’ to 3’ exonuclase

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31
Q

Is DNA replication semiconservative?

A

Yes

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32
Q

Is DNA replication continuous or discontinuous?

A

It is both. Discontinuous fragments called Okazaki fragments

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33
Q

What is the use of DNA ligase?

A

Catalyzes the formation of phosphdiesterase bond within double stranded DNA

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34
Q

What is function of telomerase?

A

An RNA dependent DNA polymerase that adds DNA to 3’ end of chromosome to prevent lose of genetic material with each replication (eukaryotes only)

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35
Q

Which DNA component is often desregulated within cancer?

A

Telomerase.

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36
Q

What are the severity of DNA damage?

A

silent

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37
Q

What is a transition DNA mutation?

A

Purine to purine (A to G, or C to T)

or pyrimidine to pyrimidine

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38
Q

What is a transversion mutation?

A

Purine to pyfrimidine (A to T) or pyrimidine to purine (C to G)

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39
Q

What is a silent mutation?

A

Nucleotide subsitution, but same amino acid base coded

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40
Q

What is missense mutation?

A

Nucleotide substitution in changed amino acid but with similar chemical structure

(sickle cell)

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41
Q

What is a nonsense mutation?

A

Results in nucelotide with early stop

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42
Q

What is a frameshift?

what are some diseases?

A

Deletion and insertion that causes misreading of all nucloetides downstream
1) Tay sachs, Duchesse muscular dystrophy

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43
Q

What is splice site?

A

Retrained intron in the mRNA (protein is imparied)

Cancer, dementia, epilepsy, B thalasemmia

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44
Q

What is the Lac operon?

A

1) Genetic responses to environmental changes
2) Ecoli prefers glucose metabolism, when no glucose, switches to lactose metabolism

High lactose, unbinds the repressor protein from reprressor/operator site and has transcription.

The LAC genes are expressed when there is no glucose and lactose available.

LAC genes are low basal when high glucose, lactose available

LAC genes not expressed if high glucose, and no lactose

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45
Q

what are the types of DNA repair, and when in cell cycle do they occur?

A

1) Nucleotide excision
2) Base Excisions
3) Mismatch repair

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46
Q

What is base excision repair?

When is this type of repair important?

A

Base specific glycosylase removes altered bases
Occurs throughout the cell cycle

Spontaneous or toxic deamination

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47
Q

what is nucleotide excision repair?

What diseases are caused by defective?

A

1) Endonucleases release the oligonucleotides and DNA polymerase ligase and fill, and reseal gap

Occurs in the G1 phase

Xeroderma pigmentosum

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48
Q

What is a mismatch repair?

What diseases?

A

Looks are the strand, and mismatched nucloetides are removed the gap is filled in.

Occurs during the G2 phase

Diseases: HNPCC
(also called Lynch syndrome)

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49
Q

What are mechanism of repairing double stranded DNA?

A

1) Non homologous end joining (2 ends of DNA fragments to repair double stranded breaks) some DNA maybe lost
2) DNA, RNA protein synthesis direction (if have drugs that attack the 3’ end hydroxyl attack

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50
Q

what are the mRNA start codons?

A

AUG or GUG

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51
Q

what is difference between eukaryotes and prokaryotes codons?

A

Eukaroates code for methionine which may be removed before translation is completed

Prokaryotes: n-formylmethionine

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52
Q

What are mRNA stop codons?

A

UGA (u go away)
UAA (u are away)
UAG (u are gone)

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53
Q

What are the regulators of gene transcription?

A

1) Promoter (site were RNA polymerase II and transcription factors bind to DNA upstream from AT CAAT or TATA boxes
2) Enhancer: stretch of DNA factors that alter gene expression by binding to transcription factors
3) Silencer: site where negative regulators bind

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54
Q

What are the different types of RNA polymerase?

A

RNA polymerase 1 (makes mRNA, most rampant)
RNA polymerase 2 (makes mRNA, largest, MASSIVE)
RNA polymerase 3 (makes 5s, rRNA, tRNA): t is the smallest..TINY

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55
Q

what disease associated with RNA polymerase II?

A

alpha-amanitin (death cap mushrooms and causes heptotoxicity)

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56
Q

What medication is associated with inhibition of RNA polymerase?

A

Rifampin

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57
Q

what are the steps of RNA production?

A

1) Transcript is heterogenous (nuclear) becomes hmRNA when modified
2) Capping of 5’ end with 7 methylguanosine cap

3) Polyadenylation of 3’ end (200A)
4) Splicing out introns
CAPPED, SPLICED, and TAILED is MRNA
5) Transported out of nucleus into cytosol
6) P-bodies: exonuclease, and enzymes and stored for future use.

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58
Q

How does splicing of pre-mRNA occur?

A

1) Transcript combines with snRNP and other proteins to form spliceosome
2) Lariat shaped intermediate is formed
3) Lariat removed intron to join the two exons

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59
Q

What are the differences, intron vs exons?

A

Exons contain genetic information for coding of the protein.

Introns are intervening non coding segments of DNA

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60
Q

what are micro RNA?

A

Non coding portions of mRNA that regulate protein expression

(introns can contain the microRNA genes)

They can cause degredation, ot inactivation of target mRNA

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61
Q

what is the shape of tRNA?

A

1) Cloverleaf form
2) Long 3’ end
3) T arm: ribosome binding
4) D arm: tRNA recognition for tRNA synthetase

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62
Q

what is the wobble?

A

Accurate base pairing is usually required in 2 first nucloetide positions of an mRNA, the 3rd wobble may code for the same amino acid (degeneracy of the genetic code).

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63
Q

How does initiation of protein synthesis from mRNA?

A

1) GTP hydrolysis that causes 40S + 60S and 80S to assemble

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64
Q

How does elongation of the protein occur?

A

1) Aminoacryl site: incoming
2) P site: accommodates growing peptide
3) E site holds empty tRNA as it exits.

rRNA catylizes peptide bond
Ribosomes advance nucleotide toward 3’end

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65
Q

How does termination occur?

A

Stop codon is recongized and the polypetide is released

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66
Q

What are some modifications that can occur in post translation of rNA?

A

Removal of N and C terminal peptides

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67
Q

What are some covalent alterations?

A

1) Phosporylation, glycosylation, hydroxylation, methylation, acetylation, ubiqitation

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68
Q

What are chaperone proteines?

A

Intracellular proteins (yeast, HSP 60) that are expressed at high temperatures to prevent denaturing and misfolding

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69
Q

what are parts of M phase?

A

prophase, prometaphase, metaphase, anaphase, telophase

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70
Q

what are the steps of cell cycle?

A 
Synthesis
Mitaosis
G1 (growth)
G2
G0
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71
Q

Where do tumor suppressors act?

A

p53 induces p21 which inhibits cyclin dependent kinases (these are checkpoints) inactivates E2F

Mutations lead to Li-Fraumani syndrome

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72
Q

what cell types (in terms of divison)?

A

1) Permenent (remain in GO and regenerate from stem cells) cardiac, neurons, skeletal, muscles, RBX
2) Stable enter into G1 when stimulated: heptocytes, lymphocytes
3) Labile never have Go, keep dividing (bone marrow, gut epithelium, skin, hair, germ cells)

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73
Q

What is I-cell disease and features?

A

1) Lysosome storage disease.
Golgi apparatus does not phosporylate mannose residue, and proteins are secreted extracellular rather then to lysosomes

Clinical features: 
Coarse facial features
Clouded corneas
Restircted joint movememt
High lysosomal enzymes
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74
Q

What defects in proteosomes have been linked to disease?

A

Ubiquitin-proteosome system have been implicated in Parkinsons (do not tag protein properly)

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75
Q 
What diseases do the following stains identify?
Vimentin
DesMin
Cytokeratin
GFAP
Neurofilaments
A

Vimentin: mesnchymal tumors (sarcoma, endometrail carcinoma, renal cell carcinoma)

DesMin (muscle tumor, rhabdomyosarcoma)

Cytokeratin (epithelial tumors squamous cell carcinoma)

GFAP: astrocytoma, glioblastoma

Neurofilatments: neuronal tumors: neuroblastoma

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76
Q

What are drugs that act on microtubules?

A

1) Mebendazole : antihelminthic
2) Griseofulvin: antifungal
3) Cholchicine: antigout
4) Vincristine/ Vinblastine: anticancer
5) Paclitaxel: anticancer

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77
Q

What is the cilia structure?

A

9+2 microtubules doublets

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78
Q

What is Kartagner syndrome?

A

cilia dyskinesia (immotile cilia due to dynein arm defect, results in male and female infertility, increases risk of ectopic pregnancy.

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79
Q

What is the cellular mechanism of Ouabin, and Digoxin?

A

Ouabin (for hypotension and arrythmias) inhibits by binding to the K+ site

Digoxin: Inhibits Na-K ATPase which leads to Na/Ca inhibition

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80
Q

What diseases are associated with the following types of collagen defects?

A

Type 1: Bone (osteogenesis imperfecta type 1)
Type 2: Cartwolage
Type 3: Ehlers Danlos
Type 4: Alport syndrome, Goodpasture

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81
Q

What steps of collagen synthesis are specifically associated with diseases?

A

Collagen hydroxylation deficiency:scruvy
Glycosylation deficiency: osteogenesis imperfecta
Crosslinking: Ehlers Danlos, Menkes Disease

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82
Q

What are features of osteogenesis imperfecta?

A

1) Multiple fractures with little trauma
2) Blue sclera
3) Hearing loss
4) Opalescent teeth that wear easilt.

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83
Q

what are characteristics of Ehlers Danlos syndrome?

A

Inheritance is either dominenet or recessive
Classical (joint/skin) mutation in type 5 collagen
Vascular: Type 3 collagen (vascular and organ rupture)

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84
Q

Characteristics of Menkes disease?

A

1) Kinky hair
2) Growth retardation
3) Hypotonia

Impaired copper absorption (ATP74, Menkes protein is defective)

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85
Q

What disorders are linked to elastin?

A

1) Fibrillin 1( glycoprotein forms sheath around elastin) Marfan
2) Emphysema alpha antitrypsin defeciency (lack of elastase)
3) Wrinkles due to collagen and elastin decrease

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86
Q

How to polymerase cahin reaction work, and what diseases can be tested?

A

1) Amplifies a specific desired fragment of DNA

2) Good for neonatal HIV and herpes encephalitis

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87
Q

What types of blotting techniques are used? What are the diseases which are identified?

A

1) Southern blot DNA
2) Northern blot RNA (gene expression levels)
3) Western blot: protein (HIV)
4) Southwestern blot (DNA binding proteins)

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88
Q

what is flow cytometry used for, and what diseases?

A

1) Assess size, granularity, and protein expression

2) Hemtological abnormalities: paraxymal nocturnal hemoglobinuria, fetal RBC, CD4 count HIV

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89
Q

When are microarrays used?

A

Genetic testing, cancer mutations. DNA probes sent to thousands of nucleic acid sequences to identify specific mutations.

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90
Q

what are enzyme linked immunosrbent assay?

A

detects presence of antigen or antibody in the blood

HBsAg or anti HB

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91
Q

what and when karytype is done?

A

1) Can be done on the sample of blood
2) For trisomies or sex chromosome disorder
3)

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92
Q

when you do flurosecence in situ hybridization, where does flourescence sighting indicate?

A

1) Microdeletion: no fluo at site compared to other chromosome
2) Translocation: fluo outside of the original chromosome
3) duplication: extra fluo on one chromosome relative to homologous

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93
Q

What are steps to cloning?

A

1) Isolate mRNA of interest
2) Expose mRNA to reverse transcriptase cDNA
3) Insert cDNA fragments into bacterial plasmids
4) Transform recombinant plasmids into bactera
5) Surviving bacterial on antibiotics produce cloned DNA

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94
Q

What is codiminece?

A

Both alleles contribute to phenotype (blood type, alpha antitrypsin deficiency)

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95
Q

Variable expressivity?

A

Same gentoype, but the expression of phenotype leads to different seriousness of disease ( neurofibrmatosis type 1)

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96
Q

Incomplete penetrance?

A

Not all the same mutant genotype show the mutant phenotype

BRACA1 does not always results in breast and ovarian cancer

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97
Q

Pleiotrophy?

A

One gene contributes to multiple phenotypes

Phenylketonuria (light skin, intellectual disability and musky body odor)

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98
Q

Anticipation?

A

Increased severity and earlier onset with generations

1) Huntington’s disease

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99
Q

Loss of heteroziosity ?

A

1) Need mutation of the gene, and of the suppressor gene to get disease (2 hit)
2) Retinoblastoma
3) Lynch syndrome HNPCC

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100
Q

What is mosaicism and the disease associated?

A

1) Presence of gentically distinct cell lines within individual

2) Somatic: through multiple cell lines
3) Gonadal: only in egg and sperm cells

McCune-Albright syndrome: mutation of G protein (cafe au lait sports, early puberty, multiple endocrine abnormalities)

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101
Q

Locus heterogeneity?

A

Mutations in different loci, lead to similar disease: Albino

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102
Q

Allelic heterogenity?

A

Different loci mutations lead to the SAME disease

B-thalasssemia

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103
Q

What are assumptions of HArdy-Weinberg genetics?

A

1) No mutation at the locus
2) Natural selection not occuring
3) Random mating
4) No net migration

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104
Q

What is the equation and meaning of HArdy Winberg?

A

PP= homozygous for p allele
qq= homozygous for q allele
2pq: heterozygous

pp+2pq+ qq= 1

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105
Q

What is imprinting?

A

At some loci, only 1 allele is active
If that only allele is inactivated, causes disease

Parder-Willi syndrome
Angelman syndromes (chromosome 15)
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106
Q

Clinical effects of Prader-Willi syndrome?

A

1) Hyperphagia
2) Obesity
3) Intellectual disability
4) Hypogonadism
5) Hypotnia

25% cases due to 2 maternal imprinted genes and no father gene (the maternal is silent)

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107
Q

What is AngelMan syndrome?

A

Paternal imprinting (silent) and maternal one is defective

5% due to paternal uniparental disomy (the gene from mother not received)

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108
Q

What are modes of inhertiance and the disorders associated?

A

1) Autosomal dominant (many generations, male +female)
2) Autosomal recessive (usually only 1 generation)
3) X linked recessive (son of mother have 50% chance)
4)
X linked dominent (50% males and 50% daugthers) : hypophospatemic rickets, fragile X, Alport Syndrome

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109
Q

Mitochondrial inheritance?

A

All female offspring will have

Rare syndromes: MELAS (mitochrondrial encephalopathy), lactic acidosis

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110
Q

Achondroplasia?

A

Autosomal dominenet
FGFR3 mutation
Dwarf, limbs affected more

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111
Q

Autosomal polycystic kidney?

A

Autosomal dominent

PKD1 orPKD2, have large cysts on kidney

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112
Q

Familial adenomatous polyposis?

A

Autosomal dominenent
Colon full of polyps at puberrt
5q mutation

113
Q

Familial hypercholesterol?

A

Autosomal dominent
Elevated LDL
corneal ulcers
Tendon xanthomas

114
Q

Hereditary hemorraghic telangiectasia?

A

Auto.DOm

Blood vessel disorder, branching skin lesions , AVM, GI bleeding

115
Q

Hereditery spheretocytosis?

A 
Auto.Dom
spheroid erythrocytosis (hemolytic anemia, treat by taking out spleen)
116
Q

Huntington?

A 
Auto.Dom
Depression
Choreform movements
Dementia 
Increased dopamine, decreased GABA, decreased Ach
117
Q

Li-Fraumani sydrome?

A

AutoDom.

TP53 mutation, many malignacies at young age (Sarcome, breast, leukemia, adrenal gland)

118
Q

Marfan syndrome?

A

Auto.Dom

FBNI, pectus excavatum, tall, tapering fingers and toes, hypermobile joints

119
Q

Multiple endocrine neoplasia?

A

Auto.Dom
Men 1
Men 2A and 2B with the RET gen

Familial tumors of endocrine glands: pancreas, parathyroid, adrenal medulla,

120
Q

Neurofibroatosis type 1

A

Autosomal Dom.

Cafe au lait spots, optic gliomas, cutaneous neurofibromas

121
Q

Neurofibromatosis type 2?

A 
Autosomal Dom. 
Bilateral acoustic schwannomas
Juvenile cateracs
Meningiomsa
Chromosome 22
122
Q

Tuberous sclerosis?

A

Numerous benign harmartomas

123
Q

Von Hippel-Laudau disease?

A

Autosomal dom.
Numerous tumors both bengin and malignant
Associated with deletion of VHL (tumor suppressor)
3 words for chromosome 3

124
Q

What are some examples of autosomal recessive disease?

A

1) Albino
2) Polykystic disease
3) cystic fibrosis
4) glycogen storage disease
5) mucopolysaccharidose
6) Phenylketonuria
7) Sickle cellanemia
8) Sphingolipidose
9) Thalassemias
10) Wilson disease

125
Q

What are genetics of cystic fibrosis disease?

A

1) Recessive
2) Defect in CFTR gene (chromosome 7)
3) Deletion of Phe 508

most common lethal genetic disease in Caucasian population

126
Q

what is the pathophysicology of cystic fibrosis?

A

1) Misfolded protein (transport protein)
2) Decreases secretion of Cl and increases absorption of NA and increase absortion of the H20
3) Abnormally thick secretion in the GI and the respiratory tract.

127
Q

How is the diagnosis made?

A

1) Cl concentration more then 60 mEq/L

2) Immunoreactive trypsinogen in the newborn

128
Q

what are the complications from cystic fibrosis?

A

1) recurrent pulmonary infections (S. Aureus), P. Aeruginosa
2) Pancreatic insufficiency (malabsorption, steatorrehea)
3) Bilary cirrhsos, and liver disease
4) Infertility in men (no vas deferens, spermatogenesis is affected)
5) Nasal polyps

129
Q

What is the treatment of cystic fibrosis?

A

1) Chest physio
2) Albuterl
3) Aerosolized dornase alfa
4) Azithromyicin (anti-inflammatory for enzyme insufficiency

130
Q

What are some x-linked recessive disorders?

A

1) Ornithine transcarbylase insufficiency
2) Fabry disease
3) Wiscott-Aldrich syndrome
4) G6PD deficiency
5) Hunter syndrome
6) Hemophilia A and B
7) Lesch-Nyhan syndrome
8) Duchenne and Becker dystophy

131
Q

what is cause of duchenne dystrophy (genetic)

A

1) X-linked, frameshift (truncated dystophin protein)

132
Q

what happens in Duchenne dystrophy?

A

1) Inhibited muscle regeneration
2) Starts at the pelvic girdle muscle and progresses superiorly
3) Pseudohypertrophy of the calf muscle due to fibrofatty replacement of the muscle

133
Q

What maneuver defines Duchenne dystrophy?

A

1) Uses the upper extremities to help stand up
2) waddling gait
3) Dilated cardiomyopathy can cause death

134
Q

what protein is not properly coded in Duchenne dystrophy?

A

Dystrophin gene is deleted

135
Q

What is the test for Duchenne dystrophy?

A

1) Western blot

2) Muscle biopsy

136
Q

what is the cause of Becker’s disease?

A

1) Have a non-frameshift mutation
2) also dystropin gene (partially functional)
3) Less severe then Duchenne
4) Onset without adolescent

137
Q

what type of genetic disease is myoclonic type 1?
which gene is affected?
which protein does not work?

A

1) Autosomal dominent
2) DMPK gene
3) myotonin protein

138
Q

What are the symptoms of myotonic type 1?

A

1) Myotonia
2) muscle wasting
3) cataracts
4) testicular atrophy
5) frontal balding
6) arrythmia

139
Q

What gene is responsible for fragile x syndrome?

A

1) FMR1 (methylation and over expression)

140
Q

What are signs of fragile x syndrome?

A

1) Intellectual disabity
2) enlarged testes (post-pubertal macroorchidsim)
3) large face
4) long jaw
5) large everted ears
6) autism
7) mitral valve prolapse

141
Q

Menomic to remember the trinucleotide issues with the following diseases:

Huntington disease
Fragile x syndrome
Frederich ataxia
Huntington disease
Myotonic dystrophy
A 
X-Girlfriend First Aid Helped Ace My Test 
Fragile x (X-G) cGg
Frederich ataces (F-A) gAg
Huntington disease (H-A) cAg
Myotonic dystrophy (M-T) cTg
142
Q

What is the genetic cause of Down’s syndrome?

A

1) Meiotic non-disjunction (95%)

2) Unbalanced Robertsonian transolocation (chromosome 14 and 21)

143
Q

What is the incidence of Down’s syndrome?

A

Incidence 1:700

144
Q

What are pre-natal tests for Down’s syndrome? (first trimester) and then second trimester

A

First trimester

1) increased nuchal translucency
2) hypoplastic nasal bone
3) Decreased serum PAPP-A
4) Increased free b-hcg

Second trimester:

1) Decreased alpha fetoprotei
2) Increased B0hcg
3) Decreased estriol
4) Increased inhibin A

145
Q

What is genetic defect for Edwards syndrome?

What is the incidence of Edwards syndrome?

A

Trisomy 18

1:8000

146
Q

What are the features of Edward’s syndrome?

A

1) Intellectual disability
2) Rocker bottom feet
3) Micrognathia (small jaw(
4) Low set ears
5) Clenched hands with overlapping fingers
6) Prominent occiput
7) Congenital heart disease
8) Death within 1 year of birth

147
Q

What are prenatal tests showing for this disease?

A

First semester:

1) PAPP-A decreased
2) Decreased B HCG (Down’s is increased(

Second trimester:

1) Decreased alpha feto protein
2) Decreased b HCG
3) Decresed estriol
4) Decreased or normal inhibin A

148
Q

What is the genetic of Patau syndrome?

A

1) Trisomy 13

149
Q

What is the incidence of Patau syndrome?

A

1:15000

150
Q

What are the clinical features of Patau syndrome?

A

1) Intellectual disaility
2) Rocker bottom feet
3) Mircopthalmia
4) Microcephaly
5) Cleft lip
6) Cleft palate
7) Polyadctyl
8) Congential heart disease
9) Death within 1 year

151
Q

What tests are abnormal in the Patau syndrome?

A

1) B HCG
2) PAPP-A

both are decreased

152
Q

Chromosome abnormality for von Hippel Laudau and renal cell carcinoma ?

A

Chromosome 3

153
Q

Chromosone for PKD2, achondroplasia and Huntington?

A

Chromosome 4

154
Q

Chromosome from Cri-de-chat?

A

Chromsome 5

155
Q

Chromsoms for hemocrhomatosis?

A

Chromosome 6

156
Q

Chromosome for Williams and Cystic fibrosis?

A

Chromosome 7

157
Q

Chromsome for Frederich ataxia

A

Chromosome 9

158
Q

Chromsome for Wilms tumor, B globin gene defects

A

Chromosome 11

159
Q

Chromosome Patau syndroms, Wilson, retinoblastomia ?

A

Chromosome 13

160
Q

Chromosome for Prader-Wilii, Angelman, Marfan?

A

Chromosome 15

161
Q

Chromosome for ADPKD, alpha globin, gene defect, thalassemia?

A

Chromosome 16

162
Q

Chromosome neurofibromatosis, BRCA 1?

A

Chromosome 17

163
Q

Chromosome fro Edwards syndrome?

A

Chromosome 18

164
Q

Chromosome for Down’s Syndrome ?

A

Chromosome 21

165
Q

Chromosome for Neurofibromatosis type 2, Digeorge syndrome? (22q11)

A

Chromosoms 22

166
Q

What does a Robertson translocation look like?

What happens if it is balanced/unbalanced?

A

1) Long arms of the chromosome fuse to the centromere and two short arms are lost
2) Balanced translocation are less bad
3) Unbalanced translocation lead to miscarriage, stillbirth, and chromosomal imbalances

167
Q

What are the deletion for cri-de-chat syndrome?

What are clinical features?

A

1) Microdeletion of short arm for chromosome 5 (46 XX or XY)
2) Clinical features:
a) Severe intellectual disability
b) high pitched mewing and crying
c) epicanthal folds (corner of eyes)
d) Cardiac abnormalities

168
Q

What is Williams syndrome?

What are the clinical features?

A

1) Microdelation of long arm (chromosome 7)
2) Elfin features
3) Intellectual disability
4) Hypercalcemia
5) Well developped verbal skills, very friendly with strangers
6) Cardiovascular problems.

169
Q

What is the 22q11 deletion?

What is the clinical symptoms?

A

Microdeletion of 22q11

2) Cleft palate
3) Thymic Aplasia (T Cell deficiency)
4) Parathyroid aplasia (hypocalcemia)
5) Digeorges syndrome: thymic, parathyroid, and cardiac defects
6) Velocardiofacial syndrome: palate, facial, and cardiac defects

170
Q

What are the fat soluable vitamins?

A

ADEK

171
Q

Why are the fat soluable vitamins more likely to have toxicity?

A

Have tendency to accumulate in fat

172
Q

What type of absorption syndromes will cause fat soluble deficiency?

A

1) Absorption with steatorrhea (cystic fibrosis, sprue, mineral oil intake)

173
Q

which are the water soluable vitamins ?

A 
B1 (thaimine, TPP)
B2 (riboflavin)
B3 (niacin, NAD+) 
B5 (pantothenic acid: CoA)
B6 (pyridoxine PLP)
B7 (biotin)
B9 (folate) 
B12 (cobalamine)
C (ascorbic acid)
174
Q

Water soluable vitamins are washed out easily from the body, which ones are not? for how long?

A

B12 (in liver for 3-4 years)

B9 (liver for 3-4 months)

175
Q

What are symptoms of B 12 complex deficiencies?

A

1) Dermatitis
2) Glossitis
3) Diarrhea

176
Q

Watersoluable vitamins are precursors to what organic cofactors?

A

FAD and NAD+

177
Q

What are the functions of vitamine A (retinol)?

A

1) Antioxidant
2) Retinal pigmanets
3) Differentiation of epithelial cells into specialized tissue (pancreatic cells, mucous-secreting cells)

178
Q

What problems do retinol A treat?

A

1) Acne and wrinkles
2) isoretinoin cystic acne
3) All trans-retinoic acid to treat acute promyelocytic leukemia.

179
Q

What happens if have retinol A deficiency?

A

1) Night blindness
2) Xdry scaly skin (Xerorsis cutis)
3) Corneal degeneration
4) Blind spots on conjunctiva

180
Q

what happens if you have too much retinol A?

A

1) Nausa, vomit
2) Vertigo, blurred vision
3) Alopecia, dry skin
4) Hepatic toxicity
5) teratogenic (cleft palate, cardiac abnromal)

before giving isotertinoin need pregnanct test and two forms of birth control.

181
Q

What is Vitamin B1 (thiamine) a cofactor for?

A

1) Pyruvate dehydrogenase TCA cycle
2) alpha ketoglutarate dehydrogenase (TCA)
3) Transketolase (HMP shunt)
4) Branched-chain ketoacid dehydrogenase

182
Q

What are the diseases caused by B1?

A

1) Wernicke-Korsokoff; confusion, ataxia, confabulation,damage to the mammillary bodies
2) Dry beriberi: polyneuritis, symmetric muscle wasting
3) Wet beriberi: high output cardiac failure

183
Q

What is the physiopathology of vitamin B deficinecy?

A

1) Imparied glucose breakdown (ATP depletion)

2) Seen in malnutrition and ETOH

184
Q

How is diagnosis of vitamin B deficiency diagnosed?

A

1) Increased RBC transketolase activity following B1 adminstration

185
Q

What is the function of Vitamin B2 (riboflavin)?

A

1) Component of FAD and FMN

186
Q

what are the clinical signs of B2 deficiency?

A

1) Cheilosis (inflammation anc scaling of fissures)

2) Corneal vascularisation

187
Q

What is the function of B3 (niacin)?

A

Constuent of NAD+ and NADP+

188
Q

What are the clinical functions of B3?

A

They can be used to lower the levels of VLDL and raise levels of HDL.

189
Q

What are clinical problems associated with B3 deficiency?

A

1) Glossitis
2) Severe can lead to pellgra (scaly red skin that looks like venous insufficiency)
3) Hartnup disease

Symptoms of pellegra include: 
Diarrhea
Dementia
Dermatitis
Hyperpigementation of the limbs

Characteristics of Hartnup disease:

1) Autosomal recessive
2) Deficiency of neutral amino acid

190
Q

What is the treatment for pellegra?

A

1) High protein diet

2) Nicotinic acid

191
Q

What is Hartnup disease?

A

1) Autosomal recessive
2) Deficiency of neutral amino acids (tryptophan), with decrease tryptophan absorption in the gut, which leads to decrease transformation to niacin. This will lead to pellagra

192
Q

What is the function of vitamin B5 (pentothenic acid)?

A

1) essential for coenzyme A

2) For synthesis of fatty acids

193
Q

What is the function of vitamin B6 (pyridoxine)?

A

1) Converted to pyridoxal phosphate which is used for:
a) ALT and AST
b) synthesis of heme
c) Synthesis of neurotransmittors including serotonin, epinephrine, norepinhrine, dopamine, and GABA

194
Q

What happens in deficiency of B6?

A

1) Convulsions
2) Irritability
3) Peripheral neuropathy
4) Sideoblastic anemia

195
Q

what does Vitamin B7 do?

A

Cofactor for carboxylation enzymes (adds a C group)

1) Pyruvate (3C) to oxaloacetate (4C)
2) Acetyl CoA carboxylase (2c) to malonyl CoA (3C)
3) Propionyl-CoA carboxylase (3C) to methylmalonyl CoA

196
Q

How do deficiency of B7 manifest?

A

1) Dermatitis
2) Alopecia
3) Enteritis

Usually due to excessive ingestion of egg whites

197
Q

what is the function of vitamin B9 folate?

A

Converted to tetrahydrogolic acid (THF), important for DNA and RNA

198
Q

Where does B9 (folate come from)?

A

Leafy green vegetables

199
Q

What are diseases assocaited with Vitamin B9 deficiency?

A

1) Macrocytic anemia
2) Megaloblastic anemia
3) Hypersegmented polymorphonuclear cells
4) Glossitis

200
Q

What is seen on vitamin B9 deficiency?

A

1) Increased homocyteine levels

2) Normal methylmalonic acid

201
Q

What are causes of B9 deficiency?

A

1) Phenyltoin
2) sulfonamides
3) Methotrexate

202
Q

What is the function of vitamin B12 (Cobalamin)

A

Cofactor for methoine synthesis

203
Q

What diseases are associated with B12 deficiency?

A

1) Macrocytic anemia
2) Megaloblastic anemia
3) Hypersegmented PMN

204
Q

what are causes of B12 deficiency?

A

1) Malabsorption (sprue, enteritis)
2) Crohn
3) Lack of terminal ileum
4) Pernacious anemia

205
Q

What is function of ascorbic acid?

A

1) Antioxident
2) Facilitates absorption of FE
3) Hydroxylation of prolene and lysine
4) Needed to make dopamine and B-hydroxylase

206
Q

What disease is caused by vitamin C deficiency?

A

Scruvy (swollen gums, bruising, petechiae, perifollicular and subperiosteal hemorrage)

Vitamin C defect, causes Scurvy due to Collagen synthesis deficiency.

207
Q

What are the two types of vitamin D and where do they come from?

A

D2: ergocalciferol (ingested from plants)
D3: Cholecalciferol (consumed in milk, formed in sun-exposed skin)

208
Q

What is the storage form of vitamin D ?

What is the active form?

A

25-OH D3 (storage form)

1,25 (OH)2 D3 (calcitriol) active form

209
Q

How does vitamin D function?

A

1) Increases intestinl absorption of calcium and phosphate
2) Increase bone mineralization at low levels
3) Increased bone absorption at higher levels

210
Q

What happens if there is vitamin D deficiency? (children vs adults)

A

1) Children: rickets (bone pain, deformity)
2) OSteomalacia : bone pain and muscle pain
3) Hypocalcemia: tetany

211
Q

What excabates vitamin D deficiency?

A

1) low sun exposure
2) pigmented skin
3) prematurity

212
Q

What are symptoms of excess vitamin D?

A

1) Hypercalcemia
2) Hypercalcinuria
3) Loss of appetite
4) Stupor

213
Q

What is the function of vitamin E ?

What i effect on warfarin?

A

1) Antioxident (protects RBC and membranes)

2) Enhances effect of warfarin

214
Q

How is vitamin E deficiency manifest itself?

A

1) Hemolytic anemia
2) Acanthycytosis
3) Muscle weakness
4) Spinocerebeller tract demeylination

215
Q

How to differentiate between vitamin E and vitamin B12 deficiency?

A

Have neurological presentation (but vitamin E does not have megaloblastic anemia or hypersegmented PMN, or increased methylmalonic acid.

216
Q

What are function of vitamin K?

A

Cofactor for glutamic acid, synthesizes the proteins required for blood clotting

217
Q

What factors of blood clotting are affected by vitamin K?

A

II, 9, 7, 2, 10
Protein C
Protein S

218
Q

Why are newborns given vitamin K injection at birth?

A

1) To prevent hemorrhagic disease
2) Have elevated Pt and aPTT (normal bleeding times)
3) Have sterile intestines, and can’t synthesize vitamin K

219
Q

What is the function of zinc?

A

1) essential for activity of 100 enzymes

220
Q

what are consequences of zinc deficeincy?

A

1) Delayed wound healing
2) Decreased adult hair (axillary, facial)
3) Acrodermatitis enteropathica

221
Q

What are two conditions that result from malnutrition?

A

1) Kwashiokor

2) Marasmus

222
Q

What are the clinical symptoms of Kwashiokor?

A

1) Malnutrition
2) Edema
3) Anemia
4) Fatty liver

(theink of child with swollen abdomen)

223
Q

What are cause of marasmus and the clinical symptoms?

A

1) Insuffiient calories (loss of tissue, and muscle wasting)

224
Q

What chemical causes ETOH hangover?

A

Accumulation of acetaldehyde

225
Q

How does ethanol affect the NADh/NAD +ratio in the liver?

A

1) Increases the ratio of NADH/NAD+
2) Causes: a) lactic acidosis
b) fastin hypoglycemia
c) heptosteatosis

226
Q

How many ATP does aerobic metabolism produce?

A

1) 32 ATP through malate/aspertate shuttle (heart+ liver)

2) 30 ATP through glycerol 3-phosphate (muscle)

227
Q

How many ATP for anaerobic metobolism?

A

1) 2 net ATP

228
Q

What is cause of fructosuria?

A

1) Autosomal recessive(defect in fructokinase)

2) Fructose appears in the blood and urine

229
Q

What is fructose intolerance?
What are symptoms?
What is treatment ?

A

1) Deficiency in aldolase B (autosomal recessive)
2) Leads to accumulation of fructose-1-phosphate which inhibits glycogeneolysis and glucogenesis
3) Hypoglycemia, jaundice, cirrhosis, vomiting
4) Treatment is to decrease fructose and sucrose intake.

230
Q

What is galactokinase deficiency?

A

Deficiency of galactokinase, causes accumulation of galactitol (autosomal recessive)

231
Q

what are symptoms of galactokinase deficiency?

A

1) Galacititol accumulates in the body
2) Usually mild condition, autosomal recessive
3) Galactose appears in the blood, and in the urine
4) Infantile cataracts, intellectual disability

232
Q

what is treatment for galactokinase deficiency?

A

1) Relatively mild (autosomal recessive)

233
Q

what is classic galactosemia?

A

1) Absence of galactose-1-phosphate uridyltransferase.

234
Q

What are the symptoms of classic galactosemia?

A

1) Failure to thrive
2) Jaundice
3) Hepatomegaly
4) Infantile cateracts
5) Intellectual disabillty
6) Can cause e coli sepsis

235
Q

What is the pertinence of sorbital in diabetes?

A

1) glucose vs (aldose reductase) is converted to sorbitol.
2) If the tissue doesn’t have enough enzymes for this transformation, can have accumulation with osmotic damage (cataracts, retinopathy, periphereal neuropathy)

236
Q

Where does lactase act?

A

1) on the brush border to digest lactose

237
Q

In what type of people is it common?

A

2) Asian
3) African
4) Native American

238
Q

What are the types of lactase deficiency?

A

1) Insufficient lactase enzyme
2) Primary: age dependent decline after childhood
3) Secondary: loss of brush border due to gastroenteririts
4) Congenital

239
Q

What do patients with lactase deficiency show?

A

1) Stool with low PH
2) Breath with high hydrogen content
3) If patient has herreditary lactose intolerance, the biospy will be normal.

240
Q

What are the symptoms and treatment for lactose deficiency?

A

1) Bloating
2) Cramps
3) Flatulence
4) Osmotic diarrhea

Treatment:

1) Avoid dairy product
2) Lactose pills
3) Lactose free milk.

241
Q

what are the different amino acids?

A

1) essential
2) Acidic
3) Basic

Essential:

Glucogenic:

1) Methionine
2) Valine
3) Histidine

Glucogenic/ketogenic:

1) Isoleucine (Ile)
2) Phenylalanine (Phe)
3) Threonine (Thr)
4) Tryptophan (Trp)
5) Ketogenic : Leucine, lysine

Acidic:

1) Aspartic
2) Glutamic (Glu)

Basic:

1) Arginine
2) Lysince
3) Histadine

242
Q

What are enzymes of urea cycle?

A

1) Ordinar Careless Crapper are Also Frivolous About Urination

Ornithine
Citrulline
Aspartate
Arginosuccinate
Fumarate
Urea
243
Q

How is ammonia processed in the body?

A

1) Occurs in the muscle first and then the liver
2) The cahill cycle and the cori cycle link the muscles to the liver.
3) Starts with ammonia, and after processed by muscle and the liver, results in urea.

244
Q

What are signs of hyperammonia?

A

1) Tremor (asterix)
2) Slurring speech
3) Somnolence
4) Cerebral edema
5) Blurring of vision

245
Q

What happens (cellular level) when the ammonia accumulates?

A

1) Depletes alpha ketoglutate, leading to inhibition of TCA cycle

246
Q

What are possible treatments for high levels of ammonia?

A

1) Lactulose to acidfy the GI tract and trap NH3 for excretion
2) Rifaximin to decrease colonic ammoniagenic bacteria
3) Benxoate, phenylacetate, or phenylbutyrate to bind the ammonia.

247
Q

What is N-acetylglutamate synthase deficiency?

A

Causes hyperammonia

248
Q

What is orinthine transcarbylase deficiency?

What are findings?

A

1) X linked recessive
2) Interferes with body’s ability to eliminate ammonia

Findings:

1) Increase orotic acid in blood and urine
2) Decrease BUN

249
Q

what are the derivatives of the following amino acids?

1) Phenylalanine
2) Tryptophan
3) Histidine
4) Glycine
5) Glutamate
6) Arginine

A

Phenyalanine- NE and epi
Tryptophan NAD, NADP+, Serotonin, Melatonin
Histidine: Histamine
Glycine: Heme
Glutamate: GABA and glutatione
Arginine: Creatinine, Urea, Nitric oxide.

250
Q

What is phenyketonuria?

A

1) Decreased phenylalanine hydorxylase—-> phenylalanine—> excess phenylketones in urine

251
Q

What are symtoms of phenylketonuria?

A

1) Intellectual disability
2) Growth retardation
3) Seizures
4) Fair skin
5) Eczema
6) Musty body odor

252
Q

If there is maternal PKU (not properly treated)?

A

1) Microcephaly
2) Intellectual disability
3) Growth retardation
4) congential heat defect

253
Q

What are the genetics of PKU?

A

1) Avoid aspartame

254
Q

When and why should newborns be screened for PKU?

A

2-3 days after birth (before that the maternal enzyme is being used)

255
Q

What is a distinguishing characteristic of PKU?

A

1) Has a musty body odor.

256
Q

What is the basis of Maple Syrup urine disease?

A

1) Blocked degradation of branched amino acids (isoleucine, leucine, valine)
2) Increase ketoacids in the blood

257
Q

What are the symptoms of maple syrup disease?

A

1) CNS defects
2) intellectual disability
3) Death

258
Q

How to treat maple syrup urine disease?

A

1) Restrict isoleucine
Leucine
Valine
Thiamine

259
Q

What is alkaptonuria?

A

1) Congential deficinecy of homogentisate oxidase
2) Recessive
3) Usually benign

260
Q

What are the symptoms of alkaptonuria?

A

1) Blue-black connective tissue and sclera
2) Urine turns black when exposed to air
3) Painful arthalgias

261
Q

What is homocytinuria types?

A

1) Cystathionine synthase deficiency
Treatement:decrease methionine, increase cysteine, incease B12

2) Methionine synthase deficiency (Increase mehtionin in the diet)

262
Q

what are symptoms of homocystinuria disease?

A

1) Increased homocysteine in the urine
2) intellectual disability
3) Osteoporosis
4) Kyphosis
5) Thrombosis
6) Mi

263
Q

What is the cause of cystinuria?

A

1) Hereditary defect of renal PCT and intestinal amino acid transporter that prevents resorption of cysteine, ornthine, lysine, arginine
2) Autosomal recessive (common 1:7000)

264
Q

How to test for cystinuria?

A

Urinary cyanide-nitroprusside test

265
Q

What is the treatment of Cystinuria?

A

1) Urine Alkanization (K, citrate, acetazolamide)

2) Chelating agents: penicillmine

266
Q

What are the signs of cystinuria?

A

1) Reccurrent precipitation of hexagonal cysteine stones.

267
Q

How is glycogen regulated by epinephrine?

A

Epinephrine activates the glucagon receptor, which will transform glycogen to glucose (this occurs within the muscle or the liver)

268
Q

There are 12 tyoes of glycogen storage disease, what type of stain is used to identfy them?

A

Periodic acid (Schiff stain)

269
Q

What are the types of liver storage diease ?

A

1) Von Gierke’s disease
(fasting hypoglycemia, increased glycogen in the liver. )
Increase uric acid, heptomegaliy

: Glucose-6-phosphate

Treatement: oral glucose, and cornstarch
Has imparied glucogenesis

2) Pompe disease (deficient lysosomal 1,4 glucosidase)

Hypertrophic cardiomegaly
Exercise intolerance

Pomp trashed the pump (heart, liver, and muslce)

3) Cori disease (deficiency 1,6 glucosidase) mild accumulation of dextrin, and glucogenesis is intact

4) McArdle disease: (myophophorylase deficient)
Increased glycogen in the muscle, leading to painful muscle cramp and myoglobinuria i the urine

270
Q

Name the lysosomal storage diseases?

A

1) Fabry disease ( alpha galactosidase)

2) Gaucher disease (Glucocerebrosidase)
3) Niemann-pick disease: sphingomyelinase
4) Tay-Sachs: Hexosaminidase
5) Krabbe disease : galacroberbroidase
6) Metachromatic leukodystrophy: arylsulfase

271
Q

What type of metabolism occurs after being fed?

Which hormone is acting?

A

1) Glycolysis
2) Aerobic respiration

Insulin stiumulates storage of lipids, proteins, and glycogen

272
Q

What is the type of metabolism fasting (between meals)?

Which hormone is acting?

A

1) Hepatic glycoenesis (major)
2) Hepatic glucognesis

Homrone: glucagon, and epinephrine which use fuel reserves

273
Q

What type of metabolism after 1-3 days of starvation?

A

1) Hepatic glycogenolysis
2) Adipose release of FFA
3) Muscle and liver
4) Hepatic glucogenesis from peripheral lactate and alanine

274
Q

What is the metabolism after day 3 of starvation?

A

Adipose stores (ketone bodies) are the main source of energy

amount of stores determines survival time

275
Q

What is the use of cholesterol?

A

1) Production of bile, steroids, and vitamin D

276
Q

Which enzyme is responsible for cholesterol synthesis?

A

1) HMG-CoA

statins reversibly inhibit this enzyme

277
Q

what are the two types of lipoproteins? What are they responsible for?

A

LDL: cholesterol from the liver to tissues
HDL: cholesterol from the tissues to the livr

(H D L is healthy)

278
Q

What are the familial types of dyslipidemia?

A

1) Hyperchylomicronemia
2) Familial hypercholesterolemia
3) Hypertriglyceridemia

279
Q

What is the clinical picture of each kind of familial dyslipidemia?

A

1) Hyperchylomicronemia: Pancreatitis, hepatosplenomegaly, eruptive xanthomas
2) Familial hypercholestolemia (LDL, cholesterol) : MI before 20, tendon xanthomas, corneal arcus
3) Hypertriglyceridemia (VLDL, TG) acute pancreatitis.

US (17 decks)

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