Genetics Exam test queries and
answers graded A+
Must contain hundreds to thousands of genes - ANS✅✅each species of organism
a few dozen chromosomes - ANS✅✅Yet most species have at most
will violate Mendel's law of independent assortment - ANS✅✅The transmission of genes close to
one another on the same chromosome
genetic linkage - ANS✅✅is the phenomenon that genes close together on a chromosome tend to
be transmitted as a unit, which influences inheritance patterns
synteny - ANS✅✅s when two or more genes are located on the same chromosome...so syntenic
genes are physically linked to each other.
chromosomes - ANS✅✅are called linkage groups-They contain a group of genes that are linked
together
number of types of chromosomes of the species-For example, in humans•22 autosomal linkage
groups - ANS✅✅the number of linkage groups is the
may independently assort from each other-This is due to crossing over - ANS✅✅Genes that are far
apart on the same chromosome
a chromosome contains a group of genes that are physically linked together. -
ANS✅✅Chromosomes are linkage groups because
equals the number of chromosome types. - ANS✅✅the number of linkage groups
However, Bateson and Punnett had a surprise result in a cross between flower color and pollen
shape.They looked at a true breeding Purple flower (PP) and long-shaped pollen (LL) and a true
breeding red flower (pp) and round-shaped pollen (ll).All of the F1 generation was Purple-Long
(PpLl). In the F2 generation, the proportion of the parent phenotypes (purple long) and (red round)
, went up. - ANS✅✅In 1905, William Bateson and Reginald Punnett conducted a cross in sweet pea
involving two different traits-Flower color and pollen shape•This is a dihybrid cross that is expected
to yield a 9:3:3:1 phenotypic ratio in the F2 generation-However, Bateson and Punnett obtained
surprising results
That Did Not Assort Independently - ANS✅✅Bateson and Punnett Discovered Two Traits
Bateson and Punnett did not realize at the time that the coupling was due to linkage of the flower
color and pollen shape genes on the same chromosome. - ANS✅✅this was because transmission
of these two characters were somehow coupled and not easily sorted in an independent manner.
linkage can be altered during meiosis as a result of crossing over•Crossing over-Occurs during
prophase I of meiosis •replicated sister chromatid homologues associate as bivalents-Non-sister
chromatids of homologous chromosomes exchange DNA segments - ANS✅✅in diploid eukaryotic
species,
thomas hunt morgan - ANS✅✅The first direct evidence of linkage came from studies conducted by
that followed an X-linked pattern of inheritance in Drosophila - ANS✅✅Morgan investigated
several traits
Linkage was revealed when the F1 were crossed and the F2 were examined. - ANS✅✅he looked at
X chromosomes and found that crossing over occurs on them as well. He conducted a three-factor
analysiWild type is a gray body (y+), red eyes (w+) and long wings (m+) as opposed to the recessive
yellow body (yy), white eyes (ww) and short wings (mm). He crossed a yywwmm female with a
y+w+m+ male. In the F1 generation he got a Xy+w+m+ Xywmfemale and a Xywm Y male.
hat crossing over did not occur between the X and Y chromosome and that these three genes were
not found on the Y chromosome. - ANS✅✅Morgan concluded that crossing over between
homologous chromosomes was consistent with his data and
homologous X chromosomes (in the female) can exchange pieces of chromosome and produce new
(recombinant) patterns of alleles and recombinant patterns of traits. - ANS✅✅His hypothesis then,
is
1. The genes for body color, eye color and wing length are all located on the X-chromosome•The
alleles will tend to be inherited together-
answers graded A+
Must contain hundreds to thousands of genes - ANS✅✅each species of organism
a few dozen chromosomes - ANS✅✅Yet most species have at most
will violate Mendel's law of independent assortment - ANS✅✅The transmission of genes close to
one another on the same chromosome
genetic linkage - ANS✅✅is the phenomenon that genes close together on a chromosome tend to
be transmitted as a unit, which influences inheritance patterns
synteny - ANS✅✅s when two or more genes are located on the same chromosome...so syntenic
genes are physically linked to each other.
chromosomes - ANS✅✅are called linkage groups-They contain a group of genes that are linked
together
number of types of chromosomes of the species-For example, in humans•22 autosomal linkage
groups - ANS✅✅the number of linkage groups is the
may independently assort from each other-This is due to crossing over - ANS✅✅Genes that are far
apart on the same chromosome
a chromosome contains a group of genes that are physically linked together. -
ANS✅✅Chromosomes are linkage groups because
equals the number of chromosome types. - ANS✅✅the number of linkage groups
However, Bateson and Punnett had a surprise result in a cross between flower color and pollen
shape.They looked at a true breeding Purple flower (PP) and long-shaped pollen (LL) and a true
breeding red flower (pp) and round-shaped pollen (ll).All of the F1 generation was Purple-Long
(PpLl). In the F2 generation, the proportion of the parent phenotypes (purple long) and (red round)
, went up. - ANS✅✅In 1905, William Bateson and Reginald Punnett conducted a cross in sweet pea
involving two different traits-Flower color and pollen shape•This is a dihybrid cross that is expected
to yield a 9:3:3:1 phenotypic ratio in the F2 generation-However, Bateson and Punnett obtained
surprising results
That Did Not Assort Independently - ANS✅✅Bateson and Punnett Discovered Two Traits
Bateson and Punnett did not realize at the time that the coupling was due to linkage of the flower
color and pollen shape genes on the same chromosome. - ANS✅✅this was because transmission
of these two characters were somehow coupled and not easily sorted in an independent manner.
linkage can be altered during meiosis as a result of crossing over•Crossing over-Occurs during
prophase I of meiosis •replicated sister chromatid homologues associate as bivalents-Non-sister
chromatids of homologous chromosomes exchange DNA segments - ANS✅✅in diploid eukaryotic
species,
thomas hunt morgan - ANS✅✅The first direct evidence of linkage came from studies conducted by
that followed an X-linked pattern of inheritance in Drosophila - ANS✅✅Morgan investigated
several traits
Linkage was revealed when the F1 were crossed and the F2 were examined. - ANS✅✅he looked at
X chromosomes and found that crossing over occurs on them as well. He conducted a three-factor
analysiWild type is a gray body (y+), red eyes (w+) and long wings (m+) as opposed to the recessive
yellow body (yy), white eyes (ww) and short wings (mm). He crossed a yywwmm female with a
y+w+m+ male. In the F1 generation he got a Xy+w+m+ Xywmfemale and a Xywm Y male.
hat crossing over did not occur between the X and Y chromosome and that these three genes were
not found on the Y chromosome. - ANS✅✅Morgan concluded that crossing over between
homologous chromosomes was consistent with his data and
homologous X chromosomes (in the female) can exchange pieces of chromosome and produce new
(recombinant) patterns of alleles and recombinant patterns of traits. - ANS✅✅His hypothesis then,
is
1. The genes for body color, eye color and wing length are all located on the X-chromosome•The
alleles will tend to be inherited together-
