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Foundations > Genetics > Flashcards

Genetics Flashcards

1
Q

How many chromosomes in human cells and how many pairs?

A

46 chromosomes

23 pairs

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2
Q

Define autosome

A

any chromosome that is not a sex chromosome - 22 pairs

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3
Q

Describe haploid number

A

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

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4
Q

Describe diploid number

A

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

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5
Q

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

A

p=short arm

q=long arm

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6
Q

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

A

4 spermatozoa - each is haploid (n)

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7
Q

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

A

1 haploid ovum (n)

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8
Q

Describe codominance

A

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

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9
Q

Describe incomplete dominance

A

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

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10
Q

Describe penetrance

A

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

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11
Q

Describe expression

A

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

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12
Q

Describe anticipation

A

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

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13
Q

Describe balance translocation

A

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

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14
Q

Describe inversion

A

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

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15
Q

Describe Robertsonian translocation

A

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

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16
Q

What kind of disease is Huntington’s Disease?

A

Autosomal dominant

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17
Q

Describe Autosomal dominant

A 
vertical pattern
multiple generations affected
variable expressivity
reduced penetrance
males and females affected equally
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18
Q

What kind of disease is cystic fibrosis?

A

Autosomal recessive

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19
Q

Describe autosomal recessive

A 
25% of human monogenic disorders
rare
horizontal inheritance
consanguinity
single generation affected
males and females affected equally
20
Q

Describe x-linked

A

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

21
Q

What kind of disease is Fragile X syndrome?

A

x-linked dominant

22
Q

What kind of disease is Duchenne muscular dystrophy?

A

X-linked recessive

23
Q

What is the most common chromosomal abnormality in live births?

A

Trisomy 21

24
Q

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

A

maternal serum AFP, estriol, hCG, inhibin-alpha

Nuchal translucency

25
Q

What is Edwards Syndrome?

A

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

26
Q

What is Patau syndrome?

A

Trisomy 13
severe intellectural disability
polydactyly
lethal mutation

27
Q

Describe Cri-du-Chat syndrome

A

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

28
Q

Describe Klinefelter’s syndrome

A 
extra X chromosome, 47XXY
affects males
hypogonadism
infertility
gynecomastia
reduced hair
29
Q

What is the most common sex chromosome aneuploidy in males?

A

Klinefelter’s syndrome

47 XXY

30
Q

Describe Turner syndrome

A 
45X 
Monosomy
Affects development in females
gonadal dysgenesis (non-functional ovaries)
short stature
broad chest
webbed neck
amenorrhea
infertility
cardiovascular abnormalities
31
Q

Describe Huntington’s disease

A 
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
32
Q

Describe Alzheimer’s disease

A 
neurodegenerative disease
loss of acetylcholine
formation of plaques and tangles
several gene mutations cause predisposition to AD
2 forms: familial and sporadic
33
Q

What is the only human disorder of complete dominance?

A

Huntington’s diseasse

34
Q

Describe Familial Alzheimer’s Disease

A

early onset AD
rare -<5%
autosomal dominant

35
Q

Describe Sporadic Alzheimer’s Disease

A

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

36
Q

What are the 2 major breast and ovarian cancer genes?

A

BRCA1 - chromosome 17 and BRCA2 - chromosome 13

autosomal dominant

37
Q

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

A

diet, exercise, smoking, obesity

in small portion of people it is genetic predisposition

38
Q

Describe Familial Adenomatous Polyposis (FAP)

A

<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

39
Q

Describe Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

A

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

40
Q

Describe Chronic Myelogenous Leukemia

A

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

41
Q

Describe Hemophilia

A

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

42
Q

What does a mutation in F8 gene cause?

A

Factor VIII deficiency -> hemophilia A (classic hemophilia)

43
Q

What does a mutation in F9 gene cause?

A

Factor IX deficiency -> hemophilia B (Christmas Disease)

44
Q

Describe Sickle Cell Disease

A

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

45
Q

Describe Cystic Fibrosis

A

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

46
Q

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

A

pulmonary disease

47
Q

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

A

S. aureus, P. aeruginosa, Aspergillus

Foundations (3 decks)

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