NBME#3 block 2 Q1----------------------Q50 - maryam2009

[ArchivalUser]

Please choose and answer the Qs in order.Thank you

[ArchivalUser]

1.A

Adenine or cytosine methylation is part of the restriction modification system of many bacteria, in which specific DNA sequences are methylated periodically throughout the genome.
A methylase is the enzyme that recognizes a specific sequence and methylates one of the bases in or near that sequence. Foreign DNAs (which are not methylated in this manner) that are introduced into the cell are degraded by sequence-specific restriction enzymes and cleaved. Bacterial genomic DNA is not recognized by these restriction enzymes.
The methylation of native DNA acts as a sort of primitive immune system, allowing the bacteria to protect themselves from infection by bacteriophage.

wikipedia

[ArchivalUser]

2.A

Proinsulin is the prohormone precursor to insulin made in the beta cells of the islets of Langerhans, specialized regions of the pancreas

http://www.google.com/imgres?imgurl=http...CCgQ9QEwBA

[ArchivalUser]

3.D

.....Alcohol dehydrogenase....................Acetaldehyde dehydrogenase

Alcohol..........................Acetaldehyde .............................................Acetate
...........NAD.......>NADH.................................NAD.....>NADH............

[ArchivalUser]

4.C pneumonic....HAVE1 M&M
...................................Gq............
H1,alpha1,V1,M1,M3.....................>.Phospholipase C.........>converts lipids into PIP2.....>DAG .......protein C and IP3 ......inc. Ca+

[ArchivalUser]

Q5. C
Dx Psoriasis- plaques and papules with silvery scaling (knees, elbows)
increased stratum spinosum, decreased stratum granulosum
Auspitz sign
Asociated w/ psoriatric arthritis and nail pitting

[ArchivalUser]

6.E

http://www.youtube.com/watch?v=CfZkn7D6dro

[ArchivalUser]

7.C, K-ras involves into spreading the cancer

[ArchivalUser]

7.E
The invasion and metastasis of cancer cells is a complex multistep process involving destruction of basement membranes as an early event in the metastatic cascade.

the invasion of human tumor cells through basement membranes may be the result of net type IV collagenolytic activity that is the result of a balance of activated enzyme species and inhibitors.

[ArchivalUser]

@lovetest ,the Q is about the process of invasion of cancer cells,the other choices are some oncogens C.. and some tumor suppressor genes A,B,D