Download Human Genetics - Antelope Valley College

Genetics
 Various
forms of a gene at a given locus are
called:
 Alleles
 Mendel chose …… plants as his test
subject.
 Pea
 If A is
dominant to a, the genotypes AA and
Aa have the same:
 Phenotype.
 The F2 phenotypic ratio of a monohybrid
cross is:
 3:1
 The phenotypic ratio of a testcross is:
 1:1
 The
F2 phenotypic ratio of a dihybrid cross
is :
 9:3:3:1
 B is dominant to b, The cross Bb X bb is
called:
 Testcross.
PKU TEST
 This
disease is known to be caused by an:
 Autosomal recessive gene.
DMD: Duchenne Muscular Dystrophy
 How
a boy with
DMD rises
 DMD is an ……….
trait in humans.
 X-linked recessive.
 What is the genotype
of a normal man
whose brother has
DMD?
X (D) Y
 Can this man be a carrier?
 NO
 If he marries a normal woman X (D) X (D),
what is the probability that their children
will have DMD?
 O%

Pedigree of DMD, an X-linked gene
The Royal Hemophilia Pedigree:
Hemophilia is an ……...trait
Nicolas, Czar of Russia (right), married Alexandra (left),
granddaughter of Victoria of England (1819-1901). Alexis
inherited the hemophilia allele and suffered serious bleeding.
Colorblindness
 Colorblindness
is an …...trait in humans.
 X-linked
 A colorblind
woman has the following
genotype (the gene is designated by D):
 X(d) X (d)
 If this woman marries a normal man:
 their ……. will be colorblind, …… will be
carriers.
Down Syndrome:Trisomy 21 was first
described in 1866 by J. Langdon Down
 Syndrome
means:
 A set of symptoms that occur together.
 The sex chromosome composition of a
person with Klinefelter syndrome is:
 XXY
 The sex chromosome composition of a
person with Turner syndrome is:
 XO
Correlation between maternal age and
the incidence of Down syndrome
 As
women age,
the chances they
will bear a child
with Down
syndrome increase
 A chromosome’s
gene sequence that was
ABCDEFGH before damage and ABCFG
H after is an example of:
 Deletion
 A chromosome’s
gene sequence that was
ABCDEFGH before modification and
ABCDLMNOP afterward is an example of:
 Translocation
 A chromosome’s gene sequence that was
ABCDEFGH before modification and
ABCDCDCDEFGH afterward is an
example of:
 Duplication
 A chromosome’s
gene sequence that was
ABCDEFGH before damage and
ABFEDCG H after is an example of:
 Inversion
 Bacteriophages
are:
 Viruses
 In
DNA, complementary base pairing
occurs between:
 Adenine and thymine, guanine and cytosine
A-T pairs and G-C pairs
 If cytosine makes up 15% of the bases in a
DNA molecule. The base A makes up what
proportion of the bases?
 35%
 In
the pairing of two nucleotides within the
double helix:
 Hydrogen bonds are used.
 The base order of one strand of a DNA
molecule is: 5’ G A A T T C 3’ what is the
most likely sequence of the other strand?
 3’ C T T A A G 5’
 If
the codon that specifies an amino acid is
AUA, the base sequence of the anticodon is:
 UAU
 Genetic information flows:
 DNA
RNA
Protein

Transcription
Translation
 A change
in the sequence of DNA bases
(mutation) results in a change in the
sequence of bases in mRNA, which can
result in a change in the sequence of amino
acids in a polypeptide chain. These changes
can destroy the functions of proteins
(products of genes).