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Genetics > Lecture 10 > Flashcards

Lecture 10 Flashcards

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1
Q

What is mitochondrial inheritance?

A

idea that mitochondria contain their own genes and transcription takes place in the mitochondria independent of the nucleus

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2
Q

Where is mitochondria located?

A

in the cytoplasm- only genetically passed by mom

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3
Q

What disease does mutation in the mitochondrial DNA cause?

A

Leber’s hereditary optic neuropathy - progressive vision loss in 3rd decade of life

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4
Q

What pattern does mitochondrial inheritance follow?

A

pattern of x-linked inheritance– common only in males

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5
Q

What is uniparental disomy?

A

an individual inherits both homologs of a chromosomes pair from only one parent

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6
Q

What did mendel’s experiment establish?

A

that the phenotupe is the same whether a given allele is inherited from the mom or dad

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7
Q

define imprinting

A

the process of gene silencing when a normal individual has only one transcriptionally active copy of a gene

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8
Q

What is an example of a disease due to imprinting?

A

Prader- Willi syndrome

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9
Q

What is Prader-Willi Syndrome

A

deletion inherited from the father of chromosome 15

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10
Q

Features of PWS?

A

short stature, hypotonia (poor muscle tone), small hands and feet, obesity, mild to moderate mental retardation, hypogonadism

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11
Q

What symdrom develops when a child received the chromosome 15 deletion from mom?

A

Angelman syndrome

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12
Q

Characteristics of Angelman syndrome?

A

severe mental retardation, seizures, ataxic gait, perpetually smiling facial expression

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13
Q

What is Angelman’s syndrome?

A

a neuro-genetic disorder characterized by intellectual and developmental delay, sleep disturbance, jerky movements, “happy puppet syndrome”

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14
Q

What is the most common genetic defect leading to Angelman’s syndrome

A

defect on chromosome 15 passed from mom

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15
Q

What does someone look like who has hermaphroditism?

A

ambiguous genitals, ovarian and testicular tissues present in gonadal region

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16
Q

What is the genotype of someone with Hermaphroditism?

A

genotype is 46XX and one X has genes of Y chromosome due to illegitimate crossing over during meiosis 1

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17
Q

What is male pseudohermaphroditism due to?

A

androgen insensitivity- testicular feminization syndrome

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18
Q

What is the genotype of someone with pseudohermaphroditism?

A

46 XY with ambiguous female genitalia

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19
Q

Where are the testes located in someone with pseudohermaphroditism?

A

inguinal canal- vagina ends blindly without uterus and fallopian tubes

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20
Q

WHat happens to the androgen receptors in pseudohermaphroditism?

A

absent in the target organs leading to blockage of masculinizing effect- coded by X chromosome, which has suffered deletion/point mutation

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21
Q

Describe female pseudohermaphroditism

A

46XX, external genitalia are virilized so that they either resemble those of a normal male or are ambiguous

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22
Q

WHat is the most common cause of female pseudohermaphroditism?

A

congenital adrenal hyperplasia- autosomal recessive

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23
Q

What happens in congenital adrenal hyperplasia?

A

hormone synthesis switches from the manufacture or cortisol and aldosterone to the androgen pathway leading to striking virilization of a female fetus

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24
Q

What are hemoglobinopathies?

A

disorders produced by abnormalities of hemoglobin structure

25
Q

What are the alpha and beta globin proteins in hemoglobinopathies?

A

the alpha and beta proteins contained in functional hemoglobin tetramers are derived from gene clusters- alpha is on chromosome 16 and beta is on chromosome 11

26
Q

What is Thalassemias the result of?

A

abnormalities in hemoglobin synthesis that affects both alpha and beta clusters

27
Q

Symptoms of Thalassemias?

A

anemia- fatigue, pallor, breathlessness

28
Q

What is thalassemia minor?

A

individuals heterozygous for B thalassemia have thalassemia minor

29
Q

What is thalassemia major?

A

in severe situation mutations in both maternal and paternal beta globin genes lead to loss of normal amount of beta globulin protein

30
Q

What is sickle cell disease due to?

A

abnormal HB- defective gene located on chromosome 11- mutated gene is HBA, autosomal recessive

31
Q

What is sickle cell disease caused by?

A

a point mutation in hemoglobin that causes abnormal shapes of fragile RBCs which may undergo hemolysis resulting in anemia

32
Q

What is heterozygote advantage?

A

when heterozygous individuals do not have symptoms and yet are resistant to malaria

33
Q

Symptoms of someone with sickle cell?

A

hemolytic anemia, vaso-oclusive process, splenic enlargement/infarction, aplastic crisis due to B 19 infection, all lead to shortened life span

34
Q

What is homocystinuria?

A

an autosomal recessive inherited disorder in which enzyme deficiency leads to defective metabolism of methionine

35
Q

What is homocystinuria characterized by?

A

accumulation of homocysteine in serum and increased excretion of homocysteine in urine

36
Q

What does homocysteinuria lead to?

A

multi systemic dosorder of the connective tissue, muscles, CNS, and cardiovascular system- infants appear normal

37
Q

What does someone with homocysteinuria look like?

A

tall, thin built, long limbs, high-arched feet, knock-knees, mental retardation, seizures

38
Q

Medication for someone with homocysteinuria

A

vitamin B6 diet, restriction of methionine in diet

39
Q

WHat is galactosemia?

A

a metabolic disorder that affects an individual’s ability to metabolize the sugar galactose properly - autosomal recessive

40
Q

What does galactosemia result in?

A

enlarged liver, cirrhosis, renal failure, cataracts, brain damage, ovarian failure

41
Q

Treatment for galactosemia

A

eliminating lactose and galactose from diet

42
Q

What is phenylketonuria

A

deficiency of enzyme phenylalanine hydroxyls

43
Q

What is phenylalanine necessary for?

A

metabolizing the amino acid phenylalanine to the amino acid tyrosine which is essential for melanin formation.

44
Q

Where is PAH gene located?

A

chromosome 12

45
Q

What will someone with phenylketonuria look like?

A

may have blond hair, blue eyes, fair skin, musty odor in sweat and urine- if not treated they may develop microcephaly, mental retardation and seizures

46
Q

Who is phenylketonuria common in ?

A

caucasians of western europe

47
Q

How is PKU detected?

A

using the HPLC test/Guthrie test

48
Q

Treatment for PKU?

A

restriction of phenylalanine rich foods (meat, chicken, fish, eggs, nuts, cheese) and supplementing with starches- potatoes, bread, pasta, corn

49
Q

What is glucose-6-phosphate dehydrogenase deficiency?

A

X linked hereditary disease characterized by low levels of glucose 6-phosphate dehydrogenase

50
Q

Who is G6PD common in?

A

african, middle east and south asian populations

51
Q

What is a beneficial effect of G6PD?

A

protects against malaria

52
Q

What is the primary symptom of G6PD?

A

mostly asymptomatic- primary symptom is non-immune hemolytic anemia

53
Q

What is hemolysis caused by?

A

infection/by some drugs, antibiotics, anti-malarials/by eating broad beans

54
Q

SYmptoms in severe cases of G6PD?

A

hemolytic anemia, kernicteus, kidney damage

55
Q

What is alkaptonuria

A

inherited condition that causes urine to turn black when exposed to air

56
Q

What is the characteristic cause of alkaptonuria?

A

buildup of dark pigment in connective tissues and skin

57
Q

Characteristics of someone with alkaptonuria?

A

develop arthritis, particularly in spine and large joints

58
Q

Where is the mutation in alkaptonuria?

A

mutation of HGD gene- cause an enzyme deficiency which is involved in phenylalanine and tyrosine metabolism which results in accumulation of acid- autosomal recessive

Genetics (12 decks)

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