ch 14 - forms of inheritance Flashcards
mutation def
any change in the DNA
autosomal dominant def
only takes 1 copy to have the trait
ex: huntingtons, hypercholesterolemia, breast cancer
autosomal recessive def
need 2 copies of allele to express trait
ex: CF, CKU, taysachs, albinism
x-linked dominant def
all daughters of affected male will have trait, all sons of a homozygous affected female will have trait
ex: fragile X
x-linked recessive def
all sons of affected female and 1/2 sons of a carrier female will express the trait; all daughters of affected male will be carriers
ex: hemophilia, color blindness, DMD
do mitochondria have double-stranded DNA? what is it called?
yes; mtDNA
mitochondrial trait def
passes only from the mother because the sperm’s mitochondria is in the tail which disintegrates during fertilization
affected female passes to all children, affected males do not to any
ex: mitochondrial myopathy
mtDNA (maternal inheritance) def
mother gives trait to all children, males won’t pass it on
to determine pattern of inheritance in pedigree for sex-linked trait
if there are way more males than females affected
if child is different from both parents-
label child homozygous recessive and parents heterozygous
if child is shaded and parents are not-
pedigree is tracing autosomal recessive trait
if parents are shaded and child is not-
pedigree is tracing autosomal dominant trait
genetic anticipation def
onset of symptoms and severity increases with successive generations. due to genes where the number of triplets increase when passed to child (trinucleotide repeats)
ex: huntington’s disease, fragile X, myotonic dystrophy
in genetic anticipation, the more repeats-
the earlier the onset and the more severe the disease
which trinucleotide repeats in huntington’s?
CAG
which trinucleotide repeats in fragile X?
CGG
which trinucleotide repeats in myotonic dystrophy?
CTG
what are 2 main types of mutations?
gene mutations and chromosome mutations
gene mutation def
happens during DNA replication, due to point mutations or frameshift from an insertion or deletion affecting all the codons that come after the error
ex: cystic fibrosis, dwarfism, sickle cell anemia
DNA replication def
a change to the original DNA sequence
point mutations def
1 base change
chromosome mutation def
happen during meiosis, changes the number or location of genes
ex: down syndrome, klinefelters syndrome, turners syndrome
chromosomal errors def
deflects are due to errors in a large piece of the chromosome
deletion def
large section of the chromosome is lost
duplication def
broken piece attaches to the homolog
inversion def
a broken section reattaches in reverse order (some harmless
translocation
broken pieces swap positions on different chromosomes can cause trisomies, tumors, miscarriages, philidelphia chromosome (translocation of #9 and #22 leading to leukemia
mutations of chromosomes:
deletion, duplication and deletion, inversion, reciprocal translation between 2 different chromosomes
can some single gene mutations be due to more than one reason?
yes
ex: SCIDS
nonfunctional protein
Nonsense mutations result in a polypeptide chain that is shorter and is non-functional.
A nonsense mutation
results in the addition of an incorrect amino acid, but can still lead to a functional protein
huntingtons disease
half the people in a Venezuelan village affected
a large pedigree was conducted of 10,000 people by Nancy Wexler; lead to the identification of the gene at the tip of chromosome 4
transposons def
jumping genes - segment of RNA that can move from 1 chromosome location to another
ex: corn bacteria retroviruses
human genome project def
mapped out the genes on the 24 chromosomes to cure sound 4000 diseases by gene therapy- a diagnosis could alter the patients lifestyle for multifactorial traits
ex: hypercholestromia, autosomal dominant diseases
Germaine gene therapy risks
I/ No consent of future generations
II. Possible fatal flaw
III. Eugenics
the only disease gene therapy has cured
SCIDS
the lac operon gene operon
e coli bacteria synthesizes lactase to break down lactose, which is only made in the presence of lactose. if theres no lactose, the gene is repressed. it lives on whatever the host drinks then- so if u drink milk then that’s what it uses
