Genetics

Question 1

How many chromosomes in human cells and how many pairs?

Answer 1

46 chromosomes

23 pairs

Question 2

Define autosome

Answer 2

any chromosome that is not a sex chromosome - 22 pairs

Question 3

Describe haploid number

Answer 3

the number of chromosomes in sex cells/gametes n=23

Question 4

Describe diploid number

Answer 4

the total number of chromosomes in somatic cells 2n=46

Question 5

What arm is the short and what arm is the long in a chromosome?

Answer 5

p=short arm

q=long arm

Question 6

For every one male diploid cell how many spermatozoa do we get?

Answer 6

4 spermatozoa - each is haploid (n)

Question 7

For every one female diploid cell how many ovum do we get?

Answer 7

1 haploid ovum (n)

Question 8

Describe codominance

Answer 8

when two alleles for a trait are equally expressed ex: checkered chickens

Question 9

Describe incomplete dominance

Answer 9

heterozygotes have phenotypes that have both alleles visible as a blend - makes a third phenotype (one allele isn’t expressed over the other) ex red and white flowers -> pink flower

Question 10

Describe penetrance

Answer 10

the probability that individuals in a population who have a particular gene combination will show the condition

Question 11

Describe expression

Answer 11

the components of the phenotype that are exhibited in an individual ex: myotonic muscular dystrophy

Question 12

Describe anticipation

Answer 12

genetic diseases that increase in severity or have earlier onset with each successive generation ex: huntington disease

Question 13

Describe balance translocation

Answer 13

rupture of a chromosome resulting in the pieces “re-sticking” in the wrong combinations

Question 14

Describe inversion

Answer 14

a chromosome piece is lifted out, turned around, and reinserted

Question 15

Describe Robertsonian translocation

Answer 15

tends to arise as an offspring of a balanced carrier
involve any 2 out of chromosomes
results in formation of a “new” chromosome which the bigger chromosome can produce an unbalanced gamete
can produce trisomy 21

Question 16

What kind of disease is Huntington’s Disease?

Answer 16

Autosomal dominant

Question 17

Describe Autosomal dominant

Answer 17

vertical pattern
multiple generations affected
variable expressivity
reduced penetrance
males and females affected equally

Question 18

What kind of disease is cystic fibrosis?

Answer 18

Autosomal recessive

Question 19

Describe autosomal recessive

Answer 19

25% of human monogenic disorders
rare
horizontal inheritance
consanguinity
single generation affected
males and females affected equally

Question 20

Describe x-linked

Answer 20

5% of human monogenic disorders
no male to male transmission is possible
all daughters of an affected male are heterozygous carries

Question 21

What kind of disease is Fragile X syndrome?

Answer 21

x-linked dominant

Question 22

What kind of disease is Duchenne muscular dystrophy?

Answer 22

X-linked recessive

Question 23

What is the most common chromosomal abnormality in live births?

Answer 23

Trisomy 21

Question 24

What is included in the Quad screen? What is other common prenatal test?

Answer 24

maternal serum AFP, estriol, hCG, inhibin-alpha

Nuchal translucency

Question 25

What is Edwards Syndrome?

Answer 25

Trisomy 18 2nd most common autosomal trisomy club foot (Rocker bottom feet) lethal mutation

Question 26

What is Patau syndrome?

Answer 26

Trisomy 13 severe intellectural disability polydactyly lethal mutation

Question 27

Describe Cri-du-Chat syndrome

Answer 27

deletion of part of short arm of chromosome 5 cat-like cry due to abnormal larynx development can be detected in utero with CVS

Question 28

Describe Klinefelter's syndrome

Answer 28

``` extra X chromosome, 47XXY affects males hypogonadism infertility gynecomastia reduced hair ```

Question 29

What is the most common sex chromosome aneuploidy in males?

Answer 29

Klinefelter's syndrome | 47 XXY

Question 30

Describe Turner syndrome

Answer 30

``` 45X Monosomy Affects development in females gonadal dysgenesis (non-functional ovaries) short stature broad chest webbed neck amenorrhea infertility cardiovascular abnormalities ```

Question 31

Describe Huntington's disease

Answer 31

``` neurodegenerative disease autosomal dominant CAG trinucleotide repeat uncontrolled jerky movements (chorea) emotional problems loss of thinking ability changes in personality no treatment from symptom onset to death is 15 years ```

Question 32

Describe Alzheimer's disease

Answer 32

``` neurodegenerative disease loss of acetylcholine formation of plaques and tangles several gene mutations cause predisposition to AD 2 forms: familial and sporadic ```

Question 33

What is the only human disorder of complete dominance?

Answer 33

Huntington's diseasse

Question 34

Describe Familial Alzheimer's Disease

Answer 34

early onset AD rare -<5% autosomal dominant

Question 35

Describe Sporadic Alzheimer's Disease

Answer 35

late onset AD accounts for most cases of AD one gene - Chromosome 19 apolipoprotein E (APOE) gene shown to increase risk

Question 36

What are the 2 major breast and ovarian cancer genes?

Answer 36

BRCA1 - chromosome 17 and BRCA2 - chromosome 13 | autosomal dominant

Question 37

What is the strongest risk factor for colorectal cancer in most people?

Answer 37

diet, exercise, smoking, obesity in small portion of people it is genetic predisposition

Question 38

Describe Familial Adenomatous Polyposis (FAP)

Answer 38

<1% of all colorectal cancers mutation in APC = tumor suppressor gene on chromosome 5 develops in 20's near 100% of getting cancer before age 50 total colectomy is recommended b4 age 20

Question 39

Describe Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

Answer 39

Lynch syndrome 2-3% of all colorectal cancers mutation in one of many genes for DNA repair more rapid transition to cancer than FAP - 30's + 40's 50% in women, 70% in men regular colonoscopy starting age 25 for relatives, upper endoscopy, endometrial/ovarian screening

Question 40

Describe Chronic Myelogenous Leukemia

Answer 40

myeloproliferative disorder translocation bet/w chromosomes 9 & 22 (Philadelphia chromosome) -> enzyme that causes too many stem cells -> WBCs nonfunctional WBC insidious onset, fever, night sweats, fatigue

Question 41

Describe Hemophilia

Answer 41

mutation on F8 or F9 genes X-linked recessive pattern hemarthroses (sponataneous bleeding into a joint), bleeding into muscles, prolonged bleeding

Question 42

What does a mutation in F8 gene cause?

Answer 42

Factor VIII deficiency -> hemophilia A (classic hemophilia)

Question 43

What does a mutation in F9 gene cause?

Answer 43

Factor IX deficiency -> hemophilia B (Christmas Disease)

Question 44

Describe Sickle Cell Disease

Answer 44

mutation on HBB gene autosomal recessive atypical hemoglobin molecules (hemoglobin S) anemia, infections, episodic pain, SOB, fatigue, delayed growth

Question 45

Describe Cystic Fibrosis

Answer 45

autosomal recessive mutation in CFTR gene -cystic fibrosis transmembrane conductance regulator- regulates cl channels in epithelial cells thick sticky mucous in airways and pancreatic ducts failure to thrive meconium ileus - newborn intestinal obstruction

Question 46

What is the most common cause of morbidity associated with CF?

Answer 46

pulmonary disease

Question 47

What are the 3 most common organisms in CF pulmonary system?

Answer 47

S. aureus, P. aeruginosa, Aspergillus