genetics 2 Flashcards

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1
Q

how does studying inheritance help

A
  • preventative treatment
  • early intervention
  • tracking disease in populations
  • family planning
  • fertility treatment
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2
Q

what did Karl Landsteiner discover and in what year

A

1900 - ABO blood groups

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3
Q

what did Archibald Garrod find and in what year

A

1902 - described alkaptonria as the first inborn error of metabolism

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4
Q

what did Wilhelm johannsen discover and in what year

A

1909- term gene to denote the basic unit of heredity

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5
Q

define a gene

A

discrete factor of inheritance

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6
Q

define an allele

A

different form of a gene

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7
Q

define a genotype

A

combination of alleles

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8
Q

define a phenotype

A

appearance of a trait

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9
Q

describe dominant

A

phenotype that suppresses another trait

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10
Q

describe recessive

A

phenotype that is suppressed by a dominant phenotype

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11
Q

what is mendels first law

A
  • segregation
  • each inherited trait is defined by a gene pair
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12
Q

what is mendels second law

A
  • independent assortment
  • genes for different traits are sorted separately so inheritance of one trait is not dependent on another
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13
Q

what is mendels third law

A
  • dominance
  • organisms with alternate forms of a gene present only dominant phenotypes
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14
Q

what is the characteristics of autosomal dominance

A
  • affected person has a parent who is affected
  • 50% offspring affected
  • affects males and females equally
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15
Q

what is Huntington disease and the symptoms

A
  • progressive brain disease
  • autosomal dominant
    adult onset - irritability/ depression , jerking or twitching, poor coordination, trouble learning and making decisions
    juvenile - movement problems, mental and emotional changes, slurred speech and drooling, seizures and progresses quickly
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16
Q

what is Marfan syndrome and what are the symptoms

A
  • autosomal dominant
  • affects the connective tissue
    symptoms - vision problems, aorta defects - bulge in the wall, arotic value to leak, tearing aorta layers
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17
Q

what are the characteristics of x-linked dominant

A
  • 50% offering affected from mother
  • no male offspring affected but all female offspring affected from father
18
Q

what is fragile X syndrome and what are the symptoms

A
  • x-linked dominant
  • symptoms: learning disabilities, cognitive impairment, anxiety, hyperactive, attention disorder
  • long and narrow face and large ears
19
Q

what are the treatments for fragile X syndrome

A

special eduction, speech, occupational an sensory integration training and behavioural modification programs

20
Q

what is cystic fibrosis and what are the treatments

A
  • autosomal recessive
  • build up of thick, sticky mucus
  • medicines for lung problems
  • exercise
  • airway clearance techniques
  • lung transplant
21
Q

what is sickle cell anaemia and what are the symptoms

A
  • autosomal recessive
  • group of disorders affecting haemoglobin
    symptoms:
  • sickle shaped red blood cells
  • anaemia
  • fatigue
  • episodes of pain
  • repeated infections
  • shortness of breathe
  • delayed growth/ development
22
Q

what is tay-sacks disease and what are the symptoms

A
  • progressive nerve cell degradation
  • brain and spinal cord damage
    symptoms: - 3-6 months old
  • slow development
  • weakened muscles
  • loss of motor skills
  • startle reaction to loud noises
  • red cherry spot in eye
23
Q

what is haemophilia and what are the complications and treatments

A
  • x-linked recessive
  • slow blood clotting and prolonged bleeding following an injury
    complications - bleeding in joints, muscles, brain and internal organs
    treatment - artificial clotting factors
24
Q

what are the two types of haemophilia and what are the deficiency’s

A

haemophilia A - factor VIII deficiency
haemophilia B - factor ix deficiency - Christmas disease

25
Q

what is fabry disease and what are the symptoms

A
  • x-linked recessive
  • cellular build up of globotriaosylceramine fats
    symptoms:
  • episodes of pain
  • clustered small, dark red spots on skin
  • decreased ability to sweat
  • cloudiness in eyes
  • gastrointestinal problems
  • tinnitus
26
Q

what are obligate carriers

A
  • known from a pedigree analysis to posses a disease causing gene
  • may not be affected with the disease phenotype
27
Q

what is incomplete penetrance

A
  • some disease gene carries not exhibiting the phenotype
  • variable expressivity, calculated by looking at family histories
28
Q

what is age dependent penetrance

A
  • phenotype in older age
  • increase frequency in population
    eg. Huntingtons disease
29
Q

what is mitochondrial inheritance

A
  • inherited from other via egg
  • affected mothers children all affected
30
Q

what are the symptoms and progression of
Leber hereditary optic neuropathy (LHON

A
  • mitochondrial mutation
  • Symptoms:
  • Painless rapid vision failure
  • 95% lose vision before 50
  • More common in males
    Progression:
    1) Blurring and clouding
    2) Colour vision lost over time
    3) Central scotoma (blind spot)
31
Q

what are the symptoms of Neuropathy, ataxia & retinitis pigmentosa
(NARP)

A
  • mitochondrial mutation
    Symptoms:
  • Numbness, tingling or pain in the arms and legs
  • Muscle weakness
  • Coordination problems
  • Vision loss

Also: Seizures, hearing loss and cardiac conduction defects

32
Q

what are the consequences of matting between relations

A
  • Often produce offspring with genetic diseases (autosomal recessive disorders)
  • Rare recessive diseases prevalent
  • Uncle-niece and first cousins marriages are regular in some countries (20% to 50%)
  • Marriages often prohibited
33
Q

what are the consequences of incest

A
  • Little data
  • Offspring affected by serious disease (often mental impairment)
34
Q

what is pseudodominance

A

Homozygous for an autosomal recessive disorder (rr) Mating with a Heterozygous carrier the same disease (Rr
- 50 % chance offspring have the disease
- all offspring are carriers

35
Q

what is complementation

A

different mutations that produce the same trait

36
Q

what is mosaicism

A

more than one genetically distinct cell line in the body
- mutation occurs in cell and is passed onto daughter cells

37
Q

what are gremlin mutations

A

mutation in sperm and egg used to carry on to later generations

38
Q

what are somatic mutations

A

mutations in other cells - organs and tissues

39
Q

what is uniparental disomy

A
  • inherited both genes from one parent
  • errors in the formation of sperm or ovum
  • elimination of extra chromosome
40
Q
A