Developmental Malformations Flashcards
Every individual is said to be unique in every aspect and this is determined by the?
genes in the chromosomes
is hereditary when the defect of one parent is transmitted in the gametes through the generations
defect
simply imply that the individual is born with the defect and has no reference
to it being hereditary or no
congenital defects
not all defects are hereditary
True or False
True
all congenital defects have a genetic
origin
True or False?
False, Not All.
not all hereditary defects are congenital, for some are made
manifest later in life of the individual
such as those inborn errors of
metabolism
True or false?
True
showed that although some traits are transmitted to generation of offspring in an unchanged state, the physical expression of a trait differed
from genetic constitution
Mendel
a unit of genetic information (gene) is transmitted unchanged from generation to generation
first law
alternate forms of the gene must segregate during gamete formation and recombine independently in the offspring to provide a 1:2:1ratio
second law
This alternate form of gene was later called? and its transmission outlined
the concepts of dominance and
recessivity
allele
non-allelic traits do not segregate but assort randomly and recombine with a probability representing the product of their independent probabilities
Third law
There are three modes of genetic defect transmission in animals and these includes;
✓ mutant genes of large effect
✓ change in number or morphological state
✓ additive effects of many genes of small effects but influenced by environmental factors
is the most commonly reported genetic defects in domestic animal species, compared to humans where autosomal dominant inheritance was reported to account for most cases
autosomal recessive inheritance
individual contains a pair of identical alleles of a given gene
homozygous
if a heterozygote affected animal mates with a homozygote animal; each offspring has 50% risk of being
affected
Assuming that both parents
are heterozygote affected, the risk
that the offspring produced are
affected increases to how many percent?
75%
Cases reported in farm animals that are expressed by autosomal dominant inheritance include?
idiopathic epilepsy and familial convulsion in cattle
male of the species carries the?
XY chromosomes
the female of the species carry the
XX chromosomes
If
the defect is X-linked, an affected
female (XX) is mated to anormal
male (XY), there is 50% chances that
the female offspring will carry the
defect, and 50% of the male will inherit the maternal X chromosomes
containingthe defect.
an individual with possessing only one allele
hemizygous
However, if the allele is recessive
to the normal allele, the affected female carrying the allele will not express the defect, but the male who has only one X chromosome been hemizygous for the trait and will not carry any normal allele and would express the defect
diploid number of chromosomes in
somatic cells, e.g., in human the
diploid number is
46
In gametes however, the haploid number is
23
The karyotype for a species is writtenas the diploid number of chromosome and the sex
chromosome, for instance 46,XY to
denote a human male
chromosomal abnormalities, there
occur two types:
✓ numerical abnormality
✓ structural abnormality
Abnormalities in the number of
chromosomes are called?
heteroploidy
When an individual is born and carries with its multiples of the haploid number of its chromosomes,
the condition is called?
Polyploidy
involves either an increase or decrease in the normal number of chromosomes without regard to completion of full haploid set
aneuploidy
If there are three sex chromosomes instead of two (e.g.,XXY, or XYY), the condition is called
trisomy
if only one sex chromosome occur (e.g., OX, OY), the condition is called
monosomy
occur as a result of non disjunction of chromosomes during the anaphase stage in meiosis of germ cells or in mitosis at the zygote, and result to
heteroploidy
