genetics2 2

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What is the study of chromosome abnormalities?: cytogenetics
Cell with normal chromosome number: euploid
Cell with missing or extra chromosomes: aneuploid
Is missing or adding genetic material more deleterious?: missing
centromere in middle of chromosome: metacentric
centromere near tip of chromosome: acrocentric
centromere between end and middle of chromosome: submetacentric
short arm of acrocentric chromosome: "p" arm
long arm of acrocentric chromosome: "q" arm
one homologue is missing: monosomy
one extra chromosome: trisomy
When does nondisjunction usually occur?: oogenesis in mothers over 35
Trisomy 21: Down Syndrome
Mode of inheritance of Down Syndrome: autosomal
Features of Down Syndrome: -palpebral fissures slant upwards
-flat maxillary region
-short neck
-hypotonia
-increased risk of leukemia
-congenital heart defects
-GI obstructions
-degree of mental retardation
-life expectancy in 50's
Describe possibility of translocation in Down Syndrome: piece of chromosome 21 breaks off and attaches to another chromosome (usually 14)
Trisomy 18: Edwards Syndrome
Features of Edwards Syndrome: -elfin features
-SGA (small for gestational age)
-clenched fist with outer fingers overlapping middle fingers
-heart malformations
VSD (ventricular septal defect)
-1 in 6,000 births
-fatal within first year
Trisomy 13: Patau Syndrome
Features of Patau Syndrome: -cleft palate
-atrial septal defects
-inguinal hernia
-degree of mental retardation
-1 in 1,000 births
What is the test for women of advanced maternal age to rule out chromosomal abnormalities?: 13, 18, 21
oocyte with no chromosomes, fertilized by X: Turner Syndrome 45X
Features of Turner Syndrome: -1 in 2500
-short
-webbed neck
-no secondary female sex characterisitcs
-may be mild retardation
-diagnosed at puberty
-no Barr body in affected cell
-usually due to mosaicism
How can Turner Syndrome be treated if diagnosed early?: estrogen
What is 47XXY?: Klinefelter Syndrome
Features of Klinefelter Syndrome: -tall
-diagnosed when infertility is discovered
-1 in 1000
-body out of proportion
-gynecomastia
-small testes
-degree of learning disabilities
-risk of osteoporosis/breast cancer
Treatment of Klinefelter Syndrome: testosterone if caught early
Characteristics of XXX: mild or none
Characterisitics of XYY: -males with few physical problems
-tall
-minor behavioral problems
Features of Fragile X Syndrome: -X chromosome almost has piece falling off
-large head, elongated face
-prominent ears
-affects boys
-more frequently mother to son
What role does FMR1 have in Fragile X Syndrome?: affects protein product shuttles between nucleus and cytoplasm
What is the term describing a disorder that becomes more severe and more frequent over generations?: anticipation
What nucleotide sequence is repeated in disorders of increasing severity?: CGG
How many nucleotide repeats is considered normal?: 5-50
How many nucleotide repeats is considered a pre-mutation?: 50-200
How many nucleotide repeats is considered an affected individual?: 200-4000
During which cycle would the liklihood of nucleotide repeats occur?: oogenesis
What disorder requires a diet low in protein?: phenylketonuria
What is the treatment of classic galactosemia?: avoid dairy products
Features of classic galactosemia: -failure to thrive
-developmentally delayed
-hepatic insufficiencies
-cataracts
What disorder is characterized by an accumulation of metabolic by-products?: lysosomal disorders
What systems deteriorate in lysosomal disorders?: -cardiovascular
-joints
-hearing/vision
What is an example of a lysosomal disorder?: Hurler syndrome
What is treatment for Hurler's syndrome?: enzymes
What are features of Hurler's syndrome?: -coarse facial features
-crouched stance
What disorder is characterized by a build-up of fatty acids?: MCAD deficiency
What must be remembered when giving someone with MCAD deficiency an IV?: supplement saline with sugar
What are features of MCAD deficiency?: -vomiting
-lethargy
-cerebral edema
-liver/kidney problems
-fatal if not diagnosed
When does MCAD deficiency present?: after period of fasting
What happens one week after fertilization?: migration through fallopian tubes to uterus
What is the term for a zygote at the 2-cell stage?: embryo
What is the term for cells that have the potential to give an entire animal?: totipotent
Up to what cell stage are cells totipotent?: 4-8 cells
When does compaction occur?: during 16-cell stage
What allows cells to communicate with each other?: gap junctions
What gives rise to the entire embryo?: inner cell mass
What are the cells surrounding the embryo that don't give rise to any part of the embryo?: trophoblast
T or F - The inner cell mass is pluripotent: T
What needs male influence to form?: trophoblast
Which part of the embryo implants into endometrial lining?: trophoblast
What secretes enzymes to break down tissue of endometrium?: synctiotrophoblast
What two parts is the trophoblast separated into?: 1. daughter cells
2. cytotrophoblast
Describe the daughter cells of the trophoblast: syncytium
What does the cytotrophoblast give rise to?: cellular portion of fetal placenta, chorion
What is the inner cell mass called when it flattens into a layer of tissue?: epiblast
How does the epiblast form the amnion?: edges roll up to form a dome
What is the process of the epiblast becoming three layers?: gastrulation
What are the three germ layers?: 1. ectoderm
2. mesoderm
3. endoderm
What does the ectoderm form?: skin, hair, nails
What does the mesoderm form?: muscle, bone, cardio
What does the endoderm form?: lining of gut from mouth to anus
At what age is the embryo considered a fetus and displays facial features?: 8 weeks
What is the rod of mesodermal cells that forms the brain and spinal cord?: notochord
What controls which genes do/don't get transcribed and is in the receiving cell?: transcription factors
What happens when the notochord is removed?: no further development
What happens when an extra notochord is inserted?: two embryos
Describe the limb bud: ectodermal jacket around mesoderm
What is the pile of ectoderm at the tip of the limb bud?: apical ectodermal ridge
What happens when the AER is removed?: development stops
What is in the posterior region of the mesoderm and determines the polarity of digits?: zone of polarizing activity
What happens when the ZPA is removed?: AER goes away and development stops
What instructs the tissue as to what it will be?: diffusable morphogen
Where is the diffusable morphogen more concentrated?: closer to the source
What forms a pattern under control of diffusable signal?: positional information
What is a teratogen that pregnant women should avoid?: retinoic acid
What does retinoic acid mimic?: diffusable morphogen
In salamanders, when a limb is severed what grows over the stump?: ectocap
What happens to tissue under the ectocap?: de-differentiates to regeneration blastema
What happens when the severed limb of a salamander is treated with retinoic acid?: new limb grows
What eminates from the AER?: FGF (fibroblast growth factor)
What are freely diffusable signaling molecules?: secreted ligands
What is at the root of telling cells what to become?: sonic hedgehog (shh)
Where is Shh?: ZPA, notochord
What is the homeotic gene that is 180 base pairs long and is the code for DNA binding proteins?: Hox
What tweaks the protein into specific shape to bind to DNA and chooses which genes are read?: homeodomain
What is caused by a mutation in Shh?: holoprosencephaly
What gene is found in everything and determines basic differentiation?: Hox
What maintains stem cells?: Hox
What is an increased number of cells without obvious change to tissue?: hyperplasia
What is increased cell growth with obvious change to cell?: dysplasia
What is spreading and invasiveness of changing cells?: cancer
one cell is transformed and all tissue of tumor is descendant of that one cell: monoclonal
What is epithelial cancer?: carcinoma
What is connective tissue/muscle cancer?: sarcoma
What is lymph cancer?: lymphoma
What are three features of transformed cells?: 1. lack contact inhibition
2. angiogenesis
3. don't drop out of cell cycle
What is a mitosis promotion factor?: cdk (cyclin-dependant kinase)
How does cyclin work when mutated growth factors?: Cdk on all the time and cells divide
What are normal genes for normal growth factor?: proto-oncogenes
What are mutated genes that signal unlimited cell division?: oncogenes
What are factors that stop growth in the case of chromosome abnormalities?: tumor suppressors
What occurs if DNA repair is not possible?: apoptosis
What initiates inhibition of cdk-cyclin?: p53
T or F - Most cancer cells are aneuploid: T
What is the term for aging of the cell?: senesence
What is the end of the chromosome that repeats to protect DNA?: telomere
How does senesence occur?: as DNA is copied, telomeres shorten, which doesn't allow ends to tuck over to protect DNA
What is secreted by tumors, placental cells that allows telomere lengthening?: telomerase

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