Mol Bio

Question 1

TATA box

Answer 1

Promoter region the binds transcription factors and RNA pol II during the initiation of transcription. Located about 25 bases upstream from the beginning of the coding region

Question 2

Homeobox genes

Answer 2

encode DNA-binding transcription factors that play an important role in the segmental organization of the embryo along the cranio-caudal axis

• highly conserved 180 nucleotide sequence
• mutations often result in skeletal malformations and improperly positioned limbs

Question 3

Mitochondrial diseases

Answer 3

• exclusively maternal inheritance
• variable severity of disease is explained the the random distribution of normal and mutated mitochondria btwn daughter cells during mitosis; some cells may be healthy, while other may be affected by genetic mutation (heteroplasmy)

Ex:

• Leber hereditary optic neuropathy- bilateral vision loss
• Myoclonic epilepsy with ragged-red fibers- Myoclonic seizures and myopathy assoc w exercise
• Mitochondiral encephalopathy w lactic acidosis and stroke like episodes (MELAS)

Question 4

DiGeorge Syndrome

Answer 4

Neural crest failed migration of the 3rd(inferior parathyroid and thymus) and 4th (superior parathyroid) pharyngeal/bronchial pouches. Parathyroid and thymus hypoplasia results in T cell def.

• 22q11.2 micro deletion
• PTH def leads to hypocalcemia ->increased neuromuscular excitability, tetany, carpopedal spasms or seizures.
• tapping facial nerve elicits twitching of nose and lips (Chevostek Sign)
• absent thymic shadow
• involvement of the 2nd pouch -> short palpebral fissures, micrognathia, bifid uvula, cleft palate

Question 5

Kinesin

Answer 5

Microtubule assoc, ATP powered motor protein that facilitates the anterograde transport of neurotransmitter-containing secretory vesicles down axons toward synaptic vesicles

Vs
Dyesin: retrograde transport, toward cell body

Question 6

Langerhans cells

Answer 6

Form of dendritic cell most commonly found in the skin and mucous membrane; professional APC cells (interact w T cells)
Most effective form of APC
Derived from myeloid cell line
“Raquet shaped” intracytoplasmic granule -> Birebeck granules

Question 7

Congenital complications of CMV infection

Answer 7

Chorioretinitis ***most common
Sensorineural deafness
Seizures 
Jaundice
Hepatosplenomegaly
Microcephaly

Question 8

Ubiquitin

Answer 8

Protein that undergoes ATP-dependent attachment to other proteins, labeling them for degradation. Enter proteosome and are degraded into small peptides. Impairment can lead to the development of neuro degenerative disorders, including Parkinson’s and Alzheimer’s

Question 9

Primase

Answer 9

DNA dependent RNA polymerase that incorporates short RNA primers into replicating DNA

Question 10

Linkage disequilibrium

Answer 10

2 genetic loci are said to be in linkage disequilibrium when their respective alleles are inherited together in the same gamete more or less often than expected by chance alone. Often the result of physical proximity of genes on the same chromosome

–> genes in close proximity become linked

Question 11

Heteroplasmy

Answer 11

Presence of different Mitochondiral genomes (i.e. Mutated and wild type) within a single cell. Severity of mitochondrial diseases often related to the portion of abnormal mitochondria

Question 12

Pleiotropy

Answer 12

Occurrence f multiple phenotypic manifestations, often in different organ systems, which result from mutation in a single gene