March 22 - Genetics

Question 1

Enhancers

Answer 1

bind activator proteins that facilitate bending of DNA; bending allows the activator proteins to interact with transcription factors and RNA polymerase. Increases rate of transcription. Can be upstream, downstream, or within introns

Question 2

Leber hereditary optic neuropathy inheritance

Answer 2

mitochondrial

Question 3

Cri-du-chat

Answer 3

Caused by 5p deletion. PResents with weak cry, hypotonia, failure to thrive, developmental delay, microcephaly, low set ears, hypertelorism, broad nasal bridge

Question 4

Quad screen in trisomy 21

Answer 4

Decreased fetal proteins: estriol and AFP

Increased beta-hCG and inhibin A - placental hormones

Question 5

Fragile X

Answer 5

Increased CGG repeats on FMR1 gene causes hypermethylation of cytosine causing FMR1 inactivation

Question 6

Cardiac manifestations of digeorge

Answer 6

tetralogy of fallot, truncus arteriosus

Question 7

Angelman syndrome

Answer 7

Caused by maternal gene deletion + paternal genes silenced

Microcephaly, ataxia, hand flapping, frequent laughter

Question 8

Tuberous sclerosis

Answer 8

Caused by defect in tumor suppressor genes TSC1 and TSC2

Cutaneous angiofibromas, brain hamartomas, cardiac rhabdomyomas

Question 9

Aromatase deficiency

Answer 9

Autosomal recessive.

Female: In female, high androgens and low estrogen results in virilization at birth. Maternal hirsutism in pregnancy distinguishes from 21 hydroxylase def. In puberty, low estrogen causes primary amenorrhea, osteoporosis, talls tature.

Male: Osteoprosis and tall stature without genital abnormalities

Question 10

Pleiotrophy

Answer 10

1 gene mutation causes seemingly unrelated phenotypes in multiple organs

Question 11

Segmented viruses

Answer 11

Orthomyxoviruses, reoviruses, bunyaviruses, arenaviruses

Question 12

Recombination

Answer 12

Crossing over between two dsDNA

Question 13

Phenotypic mixing

Answer 13

Coinfection with two viral strains. Progeny have parental genome from one strain, capsid from other

Question 14

Expression cloning

Answer 14

Type of cloning where signals necessary for transcription and translation included in cloned DNA so that bacteria produce a lot of the protein of interest

Question 15

DNA probes

Answer 15

used for TFs, steroids, thyroid hormone, vit D receptor, retinoic acid receptor, transcription and replication proteins

Question 16

Primary and secondary oocytes: stages of arrest

Answer 16

Primary oocytes arrested in prophase I until ovulation

Secondary oocytes arrested in metaphase II until fertilization

Question 17

Histones

Answer 17

H2 through H4 make up histone core. Negatively charged DNA wraps twice around positively charged histone cores. H1 on outside of histone core binds to linker segments of DNA between nucleosomes, facilitating packaging of nucleosomes into compact structures

Question 18

ras

Answer 18

G protein that cycles betwen active ras-GTP and inactice ras-GDP

Question 19

Tay Sachs

Answer 19

def of hexosaminidase A leading to accumulation of GM2
No HSM

Question 20

Gaucher disease

Answer 20

def of beta-glucocerebrosidase leading to accumulation of glucocerebroside
aseptic necrosis of femur and HSM

Question 21

Fabry disease

Answer 21

def of alpha-galactosidase A leading to accumulation of trihexoside
peripheral neuropathy, CV and renal disease
X-linked recessive

Question 22

Niemann pick

Answer 22

def of sphingomyelinase leading to accumulation of sphingomyelin
progressive neurodegeneration, cherry red spot, HSM

Question 23

Lac operon

Answer 23

expression requires cAMP and lactose

• lactose binds repressory removing it from operator
• cAMP is marker of low glucose and binds to receptor to form cAMP activating protein which facilitates RNA polymerase binding to promotor

lactose increases expression, glucose inhibits expression

Question 24

Myotonic dystrophy type I and II

Answer 24

Type I presents in childhood and includes intellectual disability. Trinucleotide repeat

Type II presents in adulthood with proximal weakness and delayed muscle relaxation. Associated with cataracts and glucose intolerance. Repeat exp (CCTG) of CNBP gene