genetics 2 Flashcards
how does studying inheritance help
- preventative treatment
- early intervention
- tracking disease in populations
- family planning
- fertility treatment
what did Karl Landsteiner discover and in what year
1900 - ABO blood groups
what did Archibald Garrod find and in what year
1902 - described alkaptonria as the first inborn error of metabolism
what did Wilhelm johannsen discover and in what year
1909- term gene to denote the basic unit of heredity
define a gene
discrete factor of inheritance
define an allele
different form of a gene
define a genotype
combination of alleles
define a phenotype
appearance of a trait
describe dominant
phenotype that suppresses another trait
describe recessive
phenotype that is suppressed by a dominant phenotype
what is mendels first law
- segregation
- each inherited trait is defined by a gene pair
what is mendels second law
- independent assortment
- genes for different traits are sorted separately so inheritance of one trait is not dependent on another
what is mendels third law
- dominance
- organisms with alternate forms of a gene present only dominant phenotypes
what is the characteristics of autosomal dominance
- affected person has a parent who is affected
- 50% offspring affected
- affects males and females equally
what is Huntington disease and the symptoms
- 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
what is Marfan syndrome and what are the symptoms
- autosomal dominant
- affects the connective tissue
symptoms - vision problems, aorta defects - bulge in the wall, arotic value to leak, tearing aorta layers
what are the characteristics of x-linked dominant
- 50% offering affected from mother
- no male offspring affected but all female offspring affected from father
what is fragile X syndrome and what are the symptoms
- x-linked dominant
- symptoms: learning disabilities, cognitive impairment, anxiety, hyperactive, attention disorder
- long and narrow face and large ears
what are the treatments for fragile X syndrome
special eduction, speech, occupational an sensory integration training and behavioural modification programs
what is cystic fibrosis and what are the treatments
- autosomal recessive
- build up of thick, sticky mucus
- medicines for lung problems
- exercise
- airway clearance techniques
- lung transplant
what is sickle cell anaemia and what are the symptoms
- 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
what is tay-sacks disease and what are the symptoms
- 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
what is haemophilia and what are the complications and treatments
- 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
what are the two types of haemophilia and what are the deficiency’s
haemophilia A - factor VIII deficiency
haemophilia B - factor ix deficiency - Christmas disease
what is fabry disease and what are the symptoms
- 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
what are obligate carriers
- known from a pedigree analysis to posses a disease causing gene
- may not be affected with the disease phenotype
what is incomplete penetrance
- some disease gene carries not exhibiting the phenotype
- variable expressivity, calculated by looking at family histories
what is age dependent penetrance
- phenotype in older age
- increase frequency in population
eg. Huntingtons disease
what is mitochondrial inheritance
- inherited from other via egg
- affected mothers children all affected
what are the symptoms and progression of
Leber hereditary optic neuropathy (LHON
- 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)
what are the symptoms of Neuropathy, ataxia & retinitis pigmentosa
(NARP)
- 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
what are the consequences of matting between relations
- 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
what are the consequences of incest
- Little data
- Offspring affected by serious disease (often mental impairment)
what is pseudodominance
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
what is complementation
different mutations that produce the same trait
what is mosaicism
more than one genetically distinct cell line in the body
- mutation occurs in cell and is passed onto daughter cells
what are gremlin mutations
mutation in sperm and egg used to carry on to later generations
what are somatic mutations
mutations in other cells - organs and tissues
what is uniparental disomy
- inherited both genes from one parent
- errors in the formation of sperm or ovum
- elimination of extra chromosome
