ch 2&3: genetic diseases Flashcards
what are the 3 main categories with genetic disease?
- chromosomal abnormalities
- mutations
- epigenetic modifications
what is chromosomal abnormality? what phase does this occur in?
- prophase
- non-dividing DNA formation
- chromatin attaches to histone proteins
what is a nucleosome? what makes it up?
DNA (chromatin) + histone
what is the histone’s role? what is a histone?
- protein
- organize chromatin, condense, and make chromatids
what is a chromatid? what makes it up?
- chromosome
- 2 chromatids + centromere
what are autosomes? what does homologous mean?
- first 22 pairs out of 23
- two members are virtually identical
what are sex chromosomes? in females? males?
- 23rd pair
- homologous pair (XX)
- non-homologous pair (XY)
what is an euploid cell? what are gametes? somatic cells?
- normal number of chromosomes
- haploid
- diploid
what is a disjunction?
failure of sister chromatids to separate normally
what is the main cause of chromosomal abnormalities?
disjunction
what can a disjunction cause?
- polyploid
- aneuploidy
what is a polyploid cell? triploidy? tetraploidy? what % end in miscarriages?
- when an euploid cell has more than the diploid number
- zygote having 3 copies of each chromosome (3n=69)
- four copies of each (4n=92)
- 10%
what an aneuploidy cell? trisomy? partial trisomy? monosomy?
- a somatic cell that does not contain a multiple of 23 chromosomes
- cell contains 3 copies of a chromosome
- cell contains only portions of the chromosomes are copied
- only one copy of any chromosome
is monosomy lethal?
- can be
- depends on the certain chromosome
is the loss of chromosomes more serious than the duplication of chromosomes?
yes
what is autosomal aneuploidy? sex aneuploidy?
- somatic cell doesn’t have a euploid formation somewhere from chromosomal pairing 1-22 (serious)
- disorder where the 23rd pair doesn’t have euploid formation (less serious)
what is down syndrome AKA? what type of aneuploidy is it? how often does it occur? what are the s&s? what age does the risk go up for this?
- trisomy 21
- autosomal
- 1:800 live births
- mental retardation (IQ 20-70), low nasal bridge, epicanthal folds, protruding tongue, poor muscle tone, and cardiovascular problems
- > age 35
who does turner syndrome occur with? what type of aneuploidy is it? what are the s&s? how is it treated?
- female with only 1 X chromosome
- sex chromosome aneuploidy
- no ovaries (sterile), short, small boobs, wide nipples, neck webbing, and edema
- treat with GH and estrogen
who does klinefelter syndrome occur with? what type of aneuploidy is it? what are the s&s? what increases the risk?
- individuals with at least 2 Xs and 1 Y chromosome
- sex chromosome aneuploidy
- male appearance, develop female breasts, small testes, sparse body hair, long limbs
- older age
what happens with chromosomal breakage? what does the telomere relationship turn to?
- physiologic mechanisms usually repair the break but heals in a way of altering the structure of the chromosome
- apoptosis and cancer
what disease happens with material is deleted? which chromosome is deleted? what are the s&s?
- cry of the cat
- chromosome 5
- low birth weight, mental retardation, and microcephaly
is it better to have more or less genetic material?
more
what is an inversion? what is this from?
- two breaks of a chromosome
- from a break that gets reversed when being repaired
what are translocations? what is reciprocal translocation? what is robertsonian translocation?
- interchanging of material between non-homologous chromosomes
- two chromosomes break and rejoin at an abnormal location
- when fusion occurs at the centromere, creating a single chromosome
what are fragile sites? what can they cause? example of this?
- areas that develop distinctive breaks or gaps when cells are cultured
- inheritable mutations
- fragile x syndrome
what is fragile x syndrome? s&s? who is it most common in?
- fragile site on the x chromosome
- large forehead and ears with an intellectual disability
- males
what is a single gene disorder? what does this lead to? why is this very serious?
- mutations
- inheritable alterations to the DNA that can occur during mitosis or meiosis
- lead to changes in amino acids sequences and therefore proteins functionality
- serious because of homeostatic life functions of cellular replications, cellular division, transcription, and translation
what are the 3 types of mutations?
- base pair substitutions: one base pair is substituted for another
- frameshift mutation: insertion or deletion of one or more base pairs
- chromosome aberrations
what is genetic inheritance determined by?
-mendelian genetics:; predictable patterns of inherited with garden peas
what is the locus? allele?
- locus is the position the gene has on the chromosome
- allele is the nucleotide sequence for each locus
what is a genotype? phenotype?
- “what they have”
- “what they demonstrate”
what is dominant? recessive?
- D: allele that is observable
- r: allele that is hidden
what is a homozygous dominant? heterozygote? homozygous recessive?
- RR
- Rr
- rr
what is huntington disease? when does it effect someone? which chromosome is effected? what are the s&s?
- autosomal dominant
- delayed age onset (40 years old)
- chromosome 4
- neurologic disorder, progressive dementia, uncontrolled limb movements, and seizures
what is retinoblastoma? where does it effect someone? which chromosome is effected? what are the s&s?
- autosomal dominant
- incomplete penetrance
- malignant eye tumor in children
- chromosome 13: tumor suppressor
- pupil leukocoria, decreased vision, irritation, redness, and strabismus
what is neurofibromatosis? where does it effect someone? which chromosome is effected? what are the s&s?
- autosomal dominant
- demonstrates expressively variations
- chromosome 17: tumor suppressant
- cafe-au-spots, neurofibromas, scoliosis, seizures, neuromas, hypertension, learning disorders
what is cystic fibrosis? where does it effect someone? which chromosome is effected? what are the s&s?
- autosomal recessive
- chromosome 7: defective transport of chloride ions
- respiratory problems, malnutrition
- death from lung disease or heart failure by 30 years old in half of cases
what is phenylketonuria? where does it effect someone? which chromosome is effected? what are the s&s?
- autosomal recessive
- 1 out of 15,000 births
- chromosome 12: liver enzymes
- untreated leads to mental retardation, microcephaly, and delayed speech
- diet must be restricted
- routinely screened in newborns
who are sex x linked disorder more common in? is this dominant or recessive? can males transmit this to sons?
- males
- recessive
- no
what is duchenne muscular dystrophy? what is it caused by? what are the s&s?
- x-linked recessive disorder
- 1 out of 3500 males
- dysfunction of protein dystrophin
- caused by frameshift deletion
- unable to walk by 10-12 years old
- death by respiratory or cardiac failure by 20
what is epigenetic?
chemical modifications altering the expression of genes
what diseases are related to epigenetic mutations?
- fragile x syndrome
- cancer
- muscular dystrophy
what are some congenital disorders?
- cleft lip or palate
- clubfoot
- congenital heart disease
- pyloric stenosis
what are some diseases that may occur later in life?
- cancer
- diabetes
- hypertension
- schizophrenia
- coronary artery disease
what mutation is responsible for insertion or deletion of one or more base pairs?
frameshift
which type of mutation alters a single amino acid and is considered a silent mutation?
missense
how many chromosomes do somatic cells contains?
- 46 chromosomes
- 23 pairs
what is it called when you have a normal number of chromosomes?
euploid
what is it called when you have too many chromosomes?
polyploidy
what is it called when you have 3 times chromosomes? 4 times?
- triploidy
- tetraploidy
does having too many chromosomes effect a neonate?
they are rarely carried to term
what is it called when you have subtraction or addition of a particular chromosome or a set of them?
aneuploidy
what is it called when you have 3 copies of one single chromosome?
trisomy
what is it called when you have only one single copy of any chromosome?
monosomy
what is an abnormal separation of chromosomes?
disjunction
what usually causes a disjunction?
aneuploidy
autosomal aneuploidy is common on which chromosomes?
- 13
- 18
- 21
what is the best known example of aneuploidy? what is it aka?
- down syndrome
- trisomy 21
a male presents at a clinic complaining of breast development. after you examen you also document that his testes are underdeveloped and he has overly long limbs. what do you suspect?
klinefelters
what can cause changes in the chromosomal structure?
- breaks
- deletion
- duplication
- inversion
- translation
- fragile sites
cri du chat or “cry of the cat” causes low birth weight, mental retardation, and microcephaly and is due to which abnormality?
deletion
what is robert sonian translocation?
an abnormality that occurs when chromosomes fuse at the centromere forming a single chromosome
what is a gene?
a single area on a chromosome
what is a genotype? phenotype?
- a person’s genetic material
- a person’s physical or observable traits
what is an allele? what is it called when it is observable? how about when it is hidden?
- one member of a pair of genes located on a chromosome
- dominant
- recessive
