Things I just can't seem to remember for STEP 1 Flashcards Preview

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1

What structures form the Hesselbach's triangle

- Inferior epigastric artery
- Inguinal ligament
Lateral border of rectus abdomens

* Direct inguinal hernias
Medial inferior gastric artery

2

Amino acids necessary for Purine

"GAG"

Glycine
Aspartate
Glutamine

3

Enzyme that converts ribonucleotides to deoxyribonucleotides

Ribonucleotide reductase

4

What is the rate limiting step of Pyrimidine base produciton

Carbamoyl Phosphate synthetase II
( requires 2ATP molecules)

5

What is the rate limiting enzyme of purine synthesis

Glutamine phosphoribosylpyrophosphate (PRPP) amidotransferase

6

DNA Polymerase in prokaryotes and their function

DNA polymerase III: leading and lagging strand elongation
(5'-->3')
- exonuclease activity proof reads (3'-5')

DNA polymerase I: excises RNA primer and replaces it with DNA
-excises RNA primer in a 5'-3'

7

DNA polymerases in Eukaryotes and their functions

DNA polymerase alpha: puts down RNA primer and makes okazaki fragments on lagging strand

DNA polymerase beta: DNA repair

DNA polymerase delta: leading strand

DNA polymerase gamma: mitochondrial DNA

8

mutation in DNA is transversion vs. transition

Transition -- purine to purine (or pyrimidine to pyrimidine)
Transversion -- purine to pyrimidine (vice versa)

9

Bloom syndrome

mutation of helicase
* blocks DNA replication and repair

clinically:
- hypersensitivity to sunlight
-preceptibility to cancers (leukemias)
-immunosuppression
-facial anomilities

10

What is the start codon and who are the stop codons

Start codon: AUG -- Methionine

Stop codon:
UGA -- U Go Away
UAA-- U Are Away
UAG--- U Are Gone

11

Causes of meningitis in Newborn (6months)

Group B strep
E coli
Listeria monocytogenes

12

Causes of meningitis in Children (6m-6years)

S. pneumoniae
N. meningitidis
H. influenza type B
Enterovirus

13

Causes of meningitis 6-60years old

N. meningitidis ( #1 in teens)
S. pneumoniae
Enteroviruses
HSV

14

Causes of meningitis 60+ years old

S. pneumoniae
Gram negative rods
Listeria

15

What is the enzyme that attaches an amino acid to the tRNA

aminoacyl- tRNA synthetase

_attaches amino acid to 3' CCA sequence
"Can Carry Amino"

If charged an incorrect amino acid, bond is hydrolyzed and aminoacyl- tRNA synthetase will put on the correct one

16

Triad of tuberous sclerosis

seizures, intellectual disability, angiofibromas

17

Enzyme missing in I-cell disease

N-acetylglucosaminyl-1-phosphotransferase --- failure of golgi to phosphorylate mannose 6 phosphate. Proteins are secreted rather than going to lysosomes

- course facial features, clouded corneas, restricted joint movements, and high plasma levels of lysosomal enzymes.

18

Menkes disease

X linked recessive connective tissue disease caused by impaired copper absorption and transport

Defective Menkes protein : ATP7A (recall 7B is Wilson's disease GI chapter)

clinical presentation:
-kinky hair
-Growth retardation
-Hypotonia

19

Biochemical cause of Marfan?

defect in Fibrillin -- a glycoprotein made by fibroblasts that forms a sheath around elastin

20

What bug causes Q fever?

Coxiella burnetii

21

Why can't muscle cells completely break down glycogen? (glycogenolysis)

Muscle cells do not posses Glucose -6-phosphatase. This does not mean that muscle cells cannot undergo gluconeogenesis. They can get up to Glucose-6 phosphate and then use that in glycolysis/ energy but they cannot distribute glucose to other organisms ( like the liver can)

22

What enzyme catalyzes the rate limiting step in carbohydrate digestion?

oligosaccharide hydrolases -- found on intestinal brush border

23

Describe Pyruvate Dehydrogenase Complex

1. mechanism
2. findings
3. treatment if congenital
4. can it be acquired?

X- linked build up of pyruvate that gets shunted to Lactate and Alanine

neurological defects, lactic acidosis, high serum alanine starting in infancy

Increase intake of ketogenic nutrients ( high fats, lysine, leucine)

Yes, arsenic poisoning, thiamine deficiency (alcoholics)

24

What causes Phenylketonuria and what are the physical findings?

Tx?

Loss of phenylalanine hydroxylase or it's co-factor tetrahydrobiopterin (BH4)

Autosomal recessive

Excess phenylalanine-- excess phenylketones in urine
+ neurotoxic effect

Findings: Intellectual disability, growth retardation, seizures, fair skin (melanin is in phenylalanine pathway), eczema, musty body odor

Tx: decrease phenylalanine and increase tyrosine in diet, tetrahjydrobiopterin supplementation

AVOID ARTIFICIAL SWEETENER ASPARTAME

25

What is the name of the disease that is deficient in homogentisate oxidase?

Presentation?

Alkaptonuria (ochronosis)

enzyme is in degenerative pathway of tyrosine to fumarate --> pigment forming homogentisic acid accumulates in tissues.

Autosomal recessive

Findings: dark connective tissue, brown pigment sclerae, urine turns black on prolonged exposure to air. May have debilitating arthralgia (homogentisic acid toxic to cartilage)

26

What is maple syrup urine disease

- mechanism
-who is involved?
- Presentation?
- Tx?

Blocked degradation of branched amino acids due to decrease in alpha-ketoacid dehydrogenase (B1)

" I Love Vermont maple syrup"
Isoleucine
Leucine
Valine

Autosomal recessive
Causes severe CNS defects, intellectual disability, and death

Urine smells like maple syrup

Tx: restriction of isoleucine, leucine, and valine in diet, and thiamine supplementation

27

What is hartnup disease?

- deficient mechanism?
- what do you see clinically?
- treatment?

Autosomal Recessive defect of transporter in intestine and kidneys
-deficiency of neutral amino acids transporters in proximal renal tubular cells and enterocytes

-deficiency of neutral AAs -- tryptophan
- without tryptophan you can't make Niacin
- without Niacin you get Pellagra

- dermatitis, diarrhea, dementia

-tx: high protein diet and nicotic acid

28

What type of infection is a patient with IL-12 receptor deficiency at highest risk for developing?

mycobacterial infections

29

What are the toxins produced by Strep pyrogens?

Streptolysin O:
Hemoysis on blood agar, oxygen labile

Streptolysin S: oxygen stable

Streptococcal pyrogenic exotoxins: A, B, C
-- erythrogenic toxins: red rash of scarlet fever
-- B : necrotising fascitus
-- can work as super antigens TSS

30

Which bacteria secrete enterotoxins?

Vibrio Cholera
ETEC
S. aureus
Shigella
Yersinia
Clostridium spp