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39 Cards in this Set

  • Front
  • Back
an individual who is heterozygous at a given genetic locus for a recessively inherited disorder
a gene located on either sex chromosome; most are on x chromosome
sex linked gene
a human genetic disease resulting in the absence of one or more blood clotting proteins
-what kind of disease?
-sex-linked recessive
one or more chromosomes are present in extra copies or are deficient in number
-example = polyploidy
lies along the nuclear envelope in cells of female mammals
-represents what?
Barr body
-inactivated x chromosome
-men don't have these
diploid cell that has three copies of a particular chromosome instead of the normal two
an organism possesses more than two complete chromosome sets
trisomy vs triploidy
trisomy = one extra copy of a chromosome
triploidy = three complete sets of chromosomes
a human genetic disease characterized by developmental delays and heart and other defects that are generally treatable and not life threatening
-caused by?
down syndrome
-trisomy of chromosome 21
each gene has its own position in sequence on a chromosome
okay okay
the x chromosome has some genes that the y chromosome doesnt
key concept!
a male will always inherit his y chromosome from?
percentage of having a girl versus a boy
50 50
describe the x-0 system
males have no y chromosome, instead they simply have nothing
so females = XX
males = X
some insects including roaches and grasshoppers
describe the z-w system
opposite of XY
females = ZW
males = ZZ
-egg determines sex
-true in birds, some fishes and insects
describe the haploid diploid system
-in bees and ants
-diploid = females
-haploid = males
when does an embryo determine sex
8 weeks old
what does SRY stand for?
sex-determining region of Y
what does gene SRY code for?
the development of testes, codes for a protein that regulates many other genes
x chromosome linkage can skip the son because he receives his x chromosome from his mother, and will pass it on to his daughter
examples of recessive x-linked diseases
color blindness, hemophilia, duchenne muscular dystrophy
x-linked recessive gene characterized by progressive weakening and a loss of muscle tissue
duchenne muscular dystrophy
-if father is infected, he must have recessive x
-if son is infected, mother must have been at least a carrier
okay okay
most common childhood muscular disease
duchenne muscular dystrophy
y-linked inheritance is common where?
among populations of India
y-linked chromosomes - only males can get them from fathers
makes sense
a mutational loss of one or more nucleotide pairs from a gene
an aberation in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated
an aberation in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated
an aberration in chromosome structure resulting from an attachment of a chromosomal fragment to a non homologous chromosome
reciprocal translocation
result of nondysjunction
males with an extra x chromosome
klinefelter syndrome
= 44 + XXY = 47
females missing an x chromosome
turner syndrome (monosomy x)
= 44 + X = 45
males with an extra y chromosome
speck syndrome
= 44 + XYY = 47
down syndrome
trisomy 21
= 3 #21 = 2N = 47
females with an extra x
trisomy x
= 44 + XXX = 47
chances of down syndrome increase with?
mother's age