Ch. 1 Flashcards
What is a phenotype?
expression of a genotype
What are autosomes?
pairs of chromosomes that are not sex-determining
What is a mitochondrial chromosome? What genes does it encode for?
small circular chromosomes in mitochondria; encodes for all tRNA, rRNA, and proteins involved in oxidative metabolism
How are mitochondrial chromosomes passed down?
from cytoplasm of fertilized ovum = maternal in origin
What is somatic mutation?
mutation that occurs AFTER conception
What is chromosomal aberration?
change in physical structure of chromosome
What is aneuploidy?
extra or less than 46 chromosomes
What are the 3 types of aneuploidy?
monosomy, trisomy, and polysomy
What is monosomy?
one chromosome of a pair is present = missing other pair = incomplete (ie: X0)
What is trisomy?
a chromosome pair has 1 extra chromosome = 3 chromosomes
What is polyploidy?
there is 4+ copies of a chromosome
What is translocation?
rearrangement of chromosome arms
What is inversion?
chromosomal region reoriented 180 degrees
What is a degenerate?
amino acid corresponds to more than 1 codon
What is a truncated protein?
protein isn’t full length or proper form = cannot fully function properly
What are 6 health problems associated with Down’s Syndrome?
heart defects | GI issues | vision | hearing | infections | intellectual
What is mosaicism?
person has two or more genetically different sets of cells in their body
Why is Trisomy 21 considered mosaic?
affected individuals have both trisomic (42,XX/Y and XXX) and euploid (44,XX/Y)cell lines.
What is the life expectancy of Down Syndrome?
55 yrs
What is the screening done for a newly pregnant woman for Down Syndrome?
blood test either 1st trimester w/ cell free DNA or 2nd trimester
What is Klinefelter syndrome?
when an XX ovum is fertilized with a Y sperm = XXY = sterile male
What is Turner Syndrome?
monosomy disorder with a sex-empty ovum (0) gets fertilized with a sperm (X) = X0 = female appearance and sterile
What is penetrance?
how much of the genotype is phenotypically showing
What is variable expressivity?
same genes but differ in characteristics or symptoms displayed with varying intensity or presentation (ie: same painter’s palette, different pictures)
What is consanguinity?
both partners descended from a common ancestor
What is the definition Mendelian?
phenotypes due to alterations at a single gene
What is Mendelian disorders?
monogenic human diseases
What is inborn errors of metabolism?
autosomal recessive phenotypes associated with deficient activity of an enzyme
What is Mendelian genetics?
genes passed from generation to generation ; dominance vs recessive alleles; heterozygous vs homozygous
What is a missense mutation?
changes to a different protein by changing a single nucleotide
What is a nonsense mutation?
codes for a premature stop codon
What is a silent mutation?
changes the codon but no effect on protein product
What is a frameshift mutation?
deletion or insertion of an amino acid = shifts the sequence = codons read differently
What type of mutation is observed in Edward’s syndrome?
trisomy 18 and is a germinal mutation
What is mitochondrial inheritance?
comes from maternal mitochondria
What kind of diseases do mitochondrial inheritance commonly entail?
affecting oxidative metabolism
What is cytogenetics?
studying chromosomes via light microscopy
Explain fluorescence in situ hybridization
obtain gene –> make a probe (tag) for a specific target sequence –> tag finds target sequence –> match = glow
What is fluorescence in situ hybridization used for?
localization of genes on specific chromosomes
What is the limitations of karyotyping?
identifies sex NOT gender ; atypical/mutated genes are not visualuzed
What is karyotyping?
staining chromosomes –> rearranged from longest to shortest
What is karyotyping used for?
observing chromosome structure and quantity
What is DNA analysis?
understanding gene expression via study of DNA sequences on chromosomes
What test is used for DNA analysis?
Polymerase Chain Reaction
What is PCR?
amplifies gene of interest
What is PCR used for?
observing a gene of interest via amplification
Simple steps of PCR
denature = open up DNA –> primers bind = Taq polymerase copies template || NEED control DNA to compare and determine if sample has disease of interest
What is biochemical analysis?
determine presence/absence of certain protein ; looks for enzymatic defects
Phenylketonuria (PKU)
disorder = inability to convert phenylalanine into tyrosine
What causes PKU?
absence/defect of enzyme phenylalanine hydroxylase (PAH)
What effect does PKU have on an affected individual?
severe intellectual disability unless treated in infancy and childhood by a low-phenylalanine diet
What are the 3 stages of embrology?
pre-embryonic; embryonic, and fetal
