Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Step 1 > Test 15 BC > Flashcards

Test 15 BC Flashcards

1
Q

What contributes to the compact nature of heterochromatin and its transcriptionally INACTIVE state?

A

HEAVILY methylated DNA

Tight association with NON-acetylated histones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

A 17 y/o F is being evaluated for short stature and primary amenorrhea.

A

Turner Syndrome= only 1 X chromosome (45, XO)

Chromosomes in her epithelial cells likely have heavily methylated DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens to one X chromosome in normal females?

A

Normal 46, XX females, one X is deactivated by lyonization to form condensed heterochromatin. This is called a Barr body and is found at hte periphery of hte nucleus.

Methylation Makes DNA MUTE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is mosaicism of the X chromosome accomplished in females?

A

DNA methylation–cystine residues are converted to methylcystine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What causes hypoxia induced lactic acidosis?

A

Low activity of pyruvate dehydrogeanse (oxidative phosphorylation pathway) and a high activity of lactate dehydrogeanse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What converts PEP to pyruvate?

A

Pyruvate Kinase (last step in glycolysis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What bidirectional enzyme interconverts pyruvate and lactate?

A

Lactate Dehydrogenase

*Pyruvate to lactate in anaerobic conditions (skeletal muscle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What role does lactate DH play in the liver?

A

Lactate generated from working skeletal muscle is taken up from the blood and converted to pyruvate for gluconeogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What enzyme converts pyruvae to oxaloacetate?

A

Pyruvate carboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What converts 2 phosphoglycerate to PEP?

A

enolase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the primary method of metabolizing dietary fructose in patients w/ essential fructosuria that is not present in normal individuals?

A

Fructose is metabolized to fructose -6- P

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are substrates for aldolase B?

A

F1P (fruct metabolism)

F1,6BP (glycolysis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What enzyme converts glucose to sorbitol?

A

Aldose reductase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What causes sxs in pyruvate DH def?

A

PDH def PREVENTS the conversion of pyruvate to acetyl CoA so it is instead shunted to lactic acid and alanine> lactic acidosis and increased serum alaninein these patients.

Can range from neonatal death to mild episodic sxs in adults.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do you tx pts with PDH def?

A

Lysine and Leucine are the onLy pureLy ketogenic AA

Increase intake of ketogenic nutrients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

All steroid producing cells (adrenals, gonad, liver) must have a well developed…

A

SMOOTH ER

Contains enzymes for steroid and phospholipid biosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the site of synthesis of secretory proteins and N-linked oligosaccharide addition to many proteins?

A

RER

Mucous secreting goblet cells

Ab secreting Plasma cells

Both RICH in RER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why is ornithine transport into the mitochondria essential for urea formation?

A

Ornithine is needed to combine with carbamoyl phosphate in the mitochondria to form citruline in the urea cycle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens if there is a defect in the urea cycle?

A

Defects in the urea cycle lead to the accumulation of ammonia> neurological damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How do you treat urea cycle defects?

A

protein restriction> less AA catabolism > less ammonia production

21
Q

Mneumonic for remembering urea cycle?

A 
Ordinarily (ornithine)
Careless (carbamoyl  phosphate)
Campers (Citruline)
Are (Aspartate)
Also (Argininosuccinate)
Frivolous (Fumurate) 
About (Argnine)
Urination (Urea)
22
Q

An infant presents w/ loss of motor skills, hepatosplenomegaly and a cherry rod spot on the macula.

A

Niemann Pick Disease

Death before age 3

23
Q

Sphingomyelinase enzyme def> accumulation of sphingomyelin in phagocytes

…foamy histocytes in liver, spleen, skin (SOAP)

A

Niemann Pick disease

Gradual deposition of sphingomyelin in CNS also causes neuo degeneration> loss of previous acquired motor abilities

24
Q

Def in Hexosaminidase A> G2 ganglioside accumulation

A

Tay Sachs

25
Q

Deficiency in alpha-L-iduronidase>

heparan sulfate and dermatan sulfate accumulation

A

Hurler Syndrome

GARGOYLISM, corneal clouding

26
Q

Def of glucocerebrosidase>

glucocerebroside accumulation

A

Gaucher

27
Q

Def of alpha galactosidase> ceramide trihexoside accumulation

A

Fabry

28
Q

Peripheral neuropathy, angiokeratomas, cardio/renal disease

A

Fabru

29
Q

Def of HGPRT

A

Lesch-Nyhan syndrome (uric acid metabolism)

30
Q

What can niacin be synthesized from?

A

tryptophan (synth requires B6 and B2)

31
Q

What vit def leads to dermatitis, diarrhea, dementia?

A

Niacin = Pellagra

32
Q

What is a precursor/constitutent of NAD+/NADP+?

A

Niacin

33
Q

What vitamin is used to treat dyslipidemia?

A

B3= Niacin

Lowers VLDL
Increases HDL

34
Q

What does a P50 shift from 26 to 20 mm Hg indicate?

A

The affinity of Hb for O2 is increased (LEFT shift, LUNGS)

35
Q

How would a high-oxygen-affinity Hbs affect delivery of O2 to peripheral tissues?

A

Reduced ability to release O2 in peripheral tissues> renal hypoxia, increased EPO synthesis, compensatory erythrocytosis (increased RBC)> helps maintain normal O2 delivery> pts are asymptomatic

36
Q

What causes hypoxia induced hemolysis?

A

Sickle cell disease

Deoxygenated HbS>
polymerizes>
excessive RBC sickling>
irreversible cell membrane damage

(shifts O2 curve RIGHT)

37
Q

Hemolysis after taking antimalarials, sulfonamides, or ingestion of fava beans.

A

G6PD def

38
Q

What is the regulatory substance that stimulates KATP channel closure in insulin producing beta cells?

A

ATP

39
Q

What is the MC cause of AR xeroderma pigmentosum?

A

UV specific endonuclease def

40
Q

A 6 y/o caucasian male presents w/ recurrent skin lesions on his face and upper extremties that rapidly progress to cancer.

A

Xeroderma pigmentosum

41
Q

What enzymes are non-functional in xeroderma pigmentosum?

A

UV-specific endonucleases that prevent repair of pyrimidine dimers after UV light exposure

42
Q

Specific endonucleases release oligonucleotides containing damaged bases> DNA Pol and ligase fill land reseal the gap in G1.

A

Nucleotide Excision repair

43
Q

What happens in the skin after UV damage?

A

Pyrimidine dimers are formed in cell DNA>
recognized by specific endonuclease>
initiates repair by nicking strand at thymine dimer>
signals removal and replacement of damaged DNA.

44
Q

Mutation three bases upstream from the AUG start codon is associated with what disease?

A

thalassemia intermedia

45
Q

What is the Kozak sequence?

A

Initiates translation (mRNA binding to ribosomes);. Consists of a sequence defined by RccQUG (R is adenine or guanine)

46
Q

What is thalessemia intermedia?

A

A form of beta thalassemia that is less clinically severe.

Hypochromic, microcytic thalessemia

47
Q

What plays an important role in mRNA quality control in the cytoplasm?

A

P bodies

contain exonucleases, decapping enzymes and micro RNAs and play an important role in mRNA translation regulation and mRNA degradation

**RNA storage

48
Q

Capping 5’ end, polyadenylation of 3’ end and splicing out of introns all occurs where…

A

Nucleus following trxn

Step 1 (69 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions