Alterations in Chromosome Structure and Number

developmental disability

lifelong disability due to mental/physical impairment

what can a developmental disability be caused by

social, environmental, or physical factors

trisomy

three copies of chromosome

down syndrome

• extra copy of chromosome 21

• trisomy 21

non disjunction

occurs when homologous chromosomes dont separate during anaphase I/II

what results from non disjunction

gametes w missing or extra chromosomes

although there is no known cause of non disjunction, there is a correlation with what

woman’s age, the higher it is, the greater the chance of non disjunction

mutation

change to DNA

T or F: all mutations occur on all lvls of chromosomes

F, some only change one or few base pairs

translocation

fragment of one chromosome attaches to nonhomologous chromosome

deletion

fragment of chromosome lost

T or F: small deletions have a great harm

F, no harm

duplication

part of chromosome repeated

how many duplications must there be to have developmental delays

3 or more

inversion

reverses fragment of original chromosome

how does inversion affect meiosis

causes problems w synapsis of chromosomes in meiosis

those w inversion struggle to what

conceive

carrier testing

determines if person has copy of mutation that kids could inherit

presymptomatic testing

based off of family’s genetic history, this tests to see if you’re likely to dev it

diagnostic genetic testing

confirms diagnosis when symptoms are present

which testing method is used to conditions appearing after birth

presymptomatic testing

prenatal testing

detects small-scale mutations in fetus

newborn screening

detects genetic disorders at birth

amniocentesis

type of prenatal screening at 14 to 20 wks where amniotic fluid is extracted for karyotyping

chorionic villus testing

type of prenatal screening at 8 to 10 wks where chorionic villus is extracted for karyotyping

autosome

first 22 pairs of chromosomes

how are autosomes organized

based on banding patterns and centromere position from largest to smallest