Di - Cell + Molecular Exam Ii: Human Genetics

Front 1

In addition to transposase, what among the following is usually a component of the active transposase complex of a bacterial transposon?

A. transposon DNA, minus the transposase gene
B. short direct repeats of target DNA
C. complete transposon DNA including inverted repeats
D. RNA intermediate
E. DNA polymerase and helicase

Back 1

C. complete transposon DNA including inverted repeats

Front 2

What is an Allele?

Back 2

nature of the gene (e.g. wild-type vs mutant)

Front 3

What are the Sources of human genetic variability/individuality?

Back 3

Segregation of alleles
Independent assortment
Homologous recombination
Mutation

Front 4

What is Mendel’s Law of segregation?

Back 4

alleles of homologous genes separate from each other at meiosis

Front 5

What is Mendel’s law of independent assortment?

Back 5

an allele on one chromosome will be distributed to the gametes independently with regard to alleles on non-homologous chromosomes

Front 6

Genetic linkage is a _________ term not a physical one

Back 6

“statistical”

Front 7

What is synteny?

Back 7

Genes are physically located near each other on a chromosome

Front 8

True/False?
Most mutations that occur in the Human genome are NOT harmful and have no effect on a physiological phenotype

Back 8

True

Front 9

Most mutations result from what?

Back 9

uncorrected DNA replication errors

Front 10

Ratio of sperm:egg mutations is about

Back 10

2:1

Front 11

What are the different types of mutations and their frequencies?

Back 11

Chromosome misegregation: 10-2/cell division

chromosome rearrangement: 6x10-4/cell div.

base pair change:10-10/bp/cell div

Front 12

red-green color blindness is an example of __________ recombination

Back 12

Non-reciprocal

Front 13

Incidence of Human Chromosome Abnormalities...

Back 13

50% of 1st trimester miscarriages (96% of these are aneuploidies)
2% of fetuses of mothers >35 years of age (85% of these are aneuploidies)
~0.6% (1/160) of all live births (60% of these are aneuploidies)

Front 14

What is taurodontism?

Back 14

dental pulp occupies a greater area than normal.  This results in a thinner layer of the hard enamel which leads to an increased risk of tooth decay

Front 15

Trisomy 13 causes...

Back 15

Patau Syndrome – avg postnatal survival = 3 months

Front 16

Trisomy 18 causes...

Back 16

Edwards Syndrome – avg postnatal survival = 6 months

Front 17

partial deletion of chromosome 5 results in ...

Back 17

cri du chat syndrome

Front 18

Down Syndrome can arise from either trisomy 21 or __________

Back 18

a Robertsonian translocation event between chromosomes 14 and 21 (about 3-4% of cases)

Front 19

What are the Common Dental Manifestations of Down Syndrome?

Back 19

Enamel hypoplasia (primary dentation)
High prevalence (90%) of periodontal disease (both early onset and advanced adult type chronic inflammatory periodontitis
Cranio-facial abonormalities incl narrow/short palate
Irregular and delayed dental eruption
Hypodontia (missing teeth) frequent, esp. 2nd & 3rd molars, lateral incisors
Taurodontism (enlargement of the pulp cavities and the reduction of the roots)
Malocclusion (crossbites and openbites common)

Front 20

genes on the X chromosome that have alleles on the Y chromosome are called what?

Back 20

pseudoautosomal genes

Front 21

True/False?
Both Somatic mosaicisms and germline mosaicisms are inheritable

Back 21

False.
Somatic mosaicisms are not inheritable; germline mosaicisms are inheritable

Front 22

The Genetic map of human mitochondrial DNA has how many base pairs?

Back 22

16,500bp

Front 23

What is an Epigenetic factor?

Back 23

any factor that can affect the phenotype without changing the genotype
i.e. imprinting

Front 24

Describe imprinting

Back 24

For a paternally imprinted gene: Mother removes imprint from the gene in her eggs; father puts imprint on both gene copies in his sperm.

Imprint can either be maternal or paternal, but not both. In paternal imprinting, mother can pass dominant deadly allele on to offspring that will be turned on in the offspring. Happens sometime during meiosis. The imprint is reset in the germline, so that in the next generation, the active copy of the gene depends on the parent of origin, not on whether that copy was active in the parent.

Front 25

sickle cell disease, PKU and Tay-Sachs are examples of _______ ________ genetic disorders

Back 25

Autosomal Recessive

Front 26

What is a "phenocopy" in relation to PKU?

Back 26

If the mother has PKU, and has a high intake of phenylalanine, the fetus may not be able to process all the phenylalanine because its own enzymes won't be functioning yet. In this case, fetus is phenocopy.

Front 27

Is the sickle cell allele: recessive, incompletely recessive or co-dominant?

Back 27

Depends on how you look at it:
At level of gene expression it is co-dominant
At level of physiological function it is incompletely recessive (and wild-type allele can be said to be incompletely dominant).
At clinical level (disease or not?) it is recessive.

Front 28

What is the biochemical malfunction responsible for Tay-Sachs?

Back 28

Cannot convert GM2 ganglioside to other normal lipids and the buildup of the lipid causes nerve damage.

Front 29

Tay-Sachs is 100X more common in people of ________ ________descent than in general population

Back 29

Ashkenazi Jewish

Front 30

Huntington disease, Marfan syndrome and Neurofibramatomous 1 are examples of _____________ __________ genetic disorders.

Back 30

Autosomal Dominant

Front 31

What is Neurofibromatosis type 1 (NF-1)?

Back 31

autosomal dominant genetic disorder that causes tumors to grow on the covering of the nerves anywhere in the body at any time.

Front 32

What are the Clinical Manifestations of Marfan Syndrome?

Back 32

Skeletal, cardiovascular, ocular, pulmonary,
skin manifestations
Skeletal manifestations include long & lanky stature, long limbs, arachnodactyly, scoliosis, bowed or funnel chest, thin & narrow face, narrow palate

Front 33

Huntington’s Disease has what degree of penetrance?

Back 33

100% penetrant

Front 34

What does the Mutant Huntington protein do?

Back 34

Reduces acetylation of histones
Interacts with some transcription factors causing their inactivation

Front 35

Lesch-Nyhan syndrome, Hypohydrotic ectodermal dysplasia and Classic red-green color blindness are examples of ___________ genetic disorders.

Back 35

X-linked

Front 36

Hypoxanthine-Guanine Phosphoribosyl Transferase inactivity causes a build up of _____ ______

Back 36

Uric Acid


Uric acid build up can destroy developing neurons in the CNS

Front 37

Lesch-Nyhan is caused by Null mutations in the gene for what enzyme?

Back 37

HGPRT

Activity of enzyme is < 1.6% of normal

Front 38

clinical manifetations of Hypohydrotic Ectodermal Dysplasia may include:

Back 38

Hypotrichosis, alopecia or fine silky hair
Small pointed incissors and absent teeth
Absent sweat glands
Corneal dystrophy; alacrima or lacrimal gland hypoplasia
Short stature; possible degree of mental retardation

Front 39

What does the term “proband” refer to?

Back 39

the individual who has brought the condition in question to medical attention

Front 40

What is Consanguinity?

Back 40

“inbreeding”

Front 41

What is a Polymorphism?

Back 41

the existence of two or more variants (alleles, phenotypes, sequences) each at significant frequencies (>1%) in the population

Front 42

What is the Hardy-Weinberg equation?

Back 42

p^2 + 2pq + q^2 = 1

p + q = 1


p2 is frequency of homozygotes for the allele with frequency p; q2 is frequency of homozygotes for the other allelle; 2pq is frequency of heterozygotes

Front 43

In many cases, Recurrence Risk can be estimated as...

Back 43

√f where f is prevalence in the general population

Front 44

Of the ~3 billion base pairs in the haploid genome, how many code for proteins?

Back 44

<2%