MBG 2400 Midterm Exam 2025 Rated A+
- ANSWER-- two mice that are homozygous for this Avy gene are crossed
-if the mother is fed a 'normal' mouse diet, you end up with mice that have mostly brown
coats for the F1
-if you end up feeding an altered diet to the mother, you end up with mice that have the
yellow coat appearance
-if you feed yellow mice a normal diet when crossing them, they will still give rise to
offspring with a normal coat appearance
-therefore you are what your mother eats
Briefly describe homologous chromosome pairing - ANSWER--in meiosis 1,
homologous chromosomes align
-once paired, a crossing-over occurs between non-sister chromatids by the formation of
a chiasma
-homologous=identical or same
Briefly describe meiotically heritable epigenetics - ANSWER--sometimes called
transgenerational epigenetics
-these are events that are passed through the germline, does not follow Mendelian
inheritance
-phenomena tend to be called epigenetic events
Briefly describe Mendel's first principle.
Is Mendel's second principle true if genes are linked? What is linkage?
What are Mendel's factors? - ANSWER-1) the two members of a gene pair (alleles)
segregate equally into the gametes, so that 1/2 gametes carry one allele and half the
gametes carry the other allele
=segregation of homologous chromosomes
=also illustrated by a test cross
2) NO
-linkage is the tendency of different genes to be inherited together because they are
located on the same chromosome; genes that do not show independent assortment
3)Mendel's factors are pairing, segregation, independent assortment
Briefly describe methyl groups - ANSWER--methyl donors are things like B12, folic acid,
etc
-involvement in the DNA methyl donor pathway eventually leads to a DNA transferase
putting a methyl group on a CpG island
Briefly describe sex determination in vertebrates. - ANSWER--not all vertebrates show
the same system
-correlation exists between male:female body size ratio and XY or ZW system
-XY: larger male to female body size ratio
-ZW: larger female to male body size ratio
,-climate change could impact on species having ESD (environmental sex determination)
Briefly describe the central dogma and explain why it has had to change. - ANSWER--
DNA is transcribed into RNA
-three different types of RNA (mRNA, rRNA, tRNA)
-they all get together to build the ribosomes
-mRNA is translated into protein
-the central dogma has had to change because small RNA molecules (miRNA, siRNA,
and piRNA) violate the central dogma; they're encoded by genes that are transcribed,
but they are not involved in the synthesis of protein- their function is at an RNA level
Compare and contrast gene expression in the Callipyge vs normal lambs both before
and after birth. - ANSWER--looking at fetal lambs vs lambs
-the expression of PEG11 results in two different phenotypes: homozygous normal, and
lambs that contain the callipyge allele coming from the paternal background
-these are significantly different in terms of expression levels of PEG11
-day 150-230 are lambs, and prior to that are fetal lambs
-at days 80-100 the levels of normal and callipyge are the same, levels drop off but are
still the same at 120
-following birth, all of a sudden there are different levels of PEG11 expression
-hardly any PEG11 expression in normal lambs, but extremely high PEG11 expression
in callipyge lambs
-the only DLK1 expression is occurring in the callipyge lambs
-fairly high levels of expression of Gtl2 is primarily in callipyge, and same with meg8
-two genes where there is no difference between the normal lambs and callipyge lambs
Compare and Contrast siRNAs and miRNAs briefly - ANSWER--siRNAs and miRNAs
both come from very different types of DNAs
-siRNAs from repetitive DNA, miRNAs from genes; both go through double-stranded
step, and have the same sorts of targets, and same sorts of functions
Define and describe meiotic recombination.
What is it called if there is no gene linkage?
What is a test cross? - ANSWER-1) any meiotic process that generates a haploid
product with a genotype that differs from the two haploid genotypes that constituted the
meiotic diploid
-the product of meiosis so generated is called a recombinant
2) inter chromosomal recombination: always produces a recombinant frequency of 50
percent
3) when a homozygous recessive genotype is crossed to another genotype to
determine if a group exhibiting a dominant trait is heterozygous or homozygous for that
trait
Define and Describe segregation.
Describe the Principle of Segregation briefly in meiosis 1. Make note of the important
step. - ANSWER-1) the separation of paternal and maternal chromosomes from each
,other at meiosis; the separation of alleles from each other in heterozygotes; the
occurrence of different phenotypes among offspring, resulting from chromosome or
allele separation in their heterozygous parents; Mendel's 1st principle of inheritance
-the segregation of alleles corresponds to the disjunction (separating) of paired
chromosomes in the anaphase of the first meiotic division
2) -begins with one gene pair: a maternally and paternally inherited chromosome
-metaphase 1: replicated chromosomes that have paired move to the cell's equator
-**anaphase 1: maternal and paternal chromosomes disjoin, and the alleles A and a
segregate from each other**
-telophase 1: chromosomes and alleles are segregated into different cells
-telophase 2: each allele is recovered in half the products of meiosis
Define genetic variation - ANSWER-heritable differences in genetic constitution that
result in observable differences in phenotype
Define hemizygous.
Where is hemizygosity found? - ANSWER-1) a word meaning 'half zygous' when
referring to a gene, such that only one chromosome in a chromosome pair contains a
copy (allele) of that specific gene
2)for sex-linked traits
-when genetically-engineering plants and animals use a foreign gene
-when the deletion of an allele occurs; this is sometimes termed pseudo dominance if a
dominant allele is deleted since the normally recessive allele is 'unmasked'
Since only one allele is present in a hemizygous situation, a recessive allele when
present in a hemizygous state will not be masked by a dominant allele in a diploid
organism
Define Isomorphic.
Define Heteromorphic.
Describe the basic life cycle found in Viridiplantae: Alternation of Generations -
ANSWER-1) similar morphology for the n and 2n phases (some algae)
2) different morphology for the n and 2n phases (most algae, all land plants)
3) -in Viridiplantae, species show either an isomorphic or heteromorphic alternation of
generations
-For Viridiplantae that show a heteromorphic alternation of generations, either the n or
2n phase is dominant (i.e. larger and exists over a longer period of time)
-n phase is dominant in most algae and non-vascular plants
-2n phase is dominant for vascular plants and kelp
-only angiosperms show double fertilization
Define parthenogenesis and describe the two types.
What are some general examples of species that show either of these types of
parthenogenesis? - ANSWER-a form of asexual reproduction in which an embryo
develops from an unfertilized egg; genetic diversity decreases, but a mate is not
required to reproduce
, 1) apomictic parthenogenesis:
-parthenogenesis without meiosis by the female, and thus progeny are genetically
identical (full clones) to the mother and female (aphids are an exception); aphids
produce both female and males owing to their XO sex determination system-in
apomictic males one X chromosome is lost or inactivated giving the male XO genotype.
2) Automictic parthenogenesis:
-parthenogenesis involving meiosis by the female, and thus progeny are not genetically
identical-they will be a half clone of the mother; usually diploidy is restored-if so,
progeny will be all female for animals that use the XY sex determination system or male
and female if the XO sex determination system is used (e.g. some sharks)
some snails, flatworms, some crustaceans, komodo dragon, some snakes
Define the following:
x:
2x:
Aneuploidy:
Euploidy:
n:
2n:
Autopolyploidy:
Allopolyploidy:
What is autopolyploidy generally characterized by? - ANSWER-1) basic number of
chromosomes in a species
2) normal somatic complement
3) deviations from 2x having + or - one or more chromosomes
4) conditions where an entire chromosome set (x) deviates from the 2x condition
5) haploid or gametic number of chromosomes
6) zygotic or somatic number of chromosomes (with somatic number only equalling the
euploid number, 2n=2x, for diploids)
7) multiple sets of chromosomes that are identical in origin
8) multiple sets of chromosomes from different ancestors
9) an increase in size of vegetative parts of the plant resulting in a more vigorous
appearance than the diploid version
Describe (briefly) synteny between pig and human chromosomes - ANSWER--direct
homology between pig (sc1-sc18) and human chromosomes (hs1-hs22)
-18 pig and 22 human autosomal chromosomes
Describe alleles in coupling phase.
Describe alleles in repulsion phase.
Describe coupling (cis) configuration
Describe repulsion (trans) configuration - ANSWER-1) dominant alleles together,
recessive alleles together
2) dominant allele together with recessive allele
- ANSWER-- two mice that are homozygous for this Avy gene are crossed
-if the mother is fed a 'normal' mouse diet, you end up with mice that have mostly brown
coats for the F1
-if you end up feeding an altered diet to the mother, you end up with mice that have the
yellow coat appearance
-if you feed yellow mice a normal diet when crossing them, they will still give rise to
offspring with a normal coat appearance
-therefore you are what your mother eats
Briefly describe homologous chromosome pairing - ANSWER--in meiosis 1,
homologous chromosomes align
-once paired, a crossing-over occurs between non-sister chromatids by the formation of
a chiasma
-homologous=identical or same
Briefly describe meiotically heritable epigenetics - ANSWER--sometimes called
transgenerational epigenetics
-these are events that are passed through the germline, does not follow Mendelian
inheritance
-phenomena tend to be called epigenetic events
Briefly describe Mendel's first principle.
Is Mendel's second principle true if genes are linked? What is linkage?
What are Mendel's factors? - ANSWER-1) the two members of a gene pair (alleles)
segregate equally into the gametes, so that 1/2 gametes carry one allele and half the
gametes carry the other allele
=segregation of homologous chromosomes
=also illustrated by a test cross
2) NO
-linkage is the tendency of different genes to be inherited together because they are
located on the same chromosome; genes that do not show independent assortment
3)Mendel's factors are pairing, segregation, independent assortment
Briefly describe methyl groups - ANSWER--methyl donors are things like B12, folic acid,
etc
-involvement in the DNA methyl donor pathway eventually leads to a DNA transferase
putting a methyl group on a CpG island
Briefly describe sex determination in vertebrates. - ANSWER--not all vertebrates show
the same system
-correlation exists between male:female body size ratio and XY or ZW system
-XY: larger male to female body size ratio
-ZW: larger female to male body size ratio
,-climate change could impact on species having ESD (environmental sex determination)
Briefly describe the central dogma and explain why it has had to change. - ANSWER--
DNA is transcribed into RNA
-three different types of RNA (mRNA, rRNA, tRNA)
-they all get together to build the ribosomes
-mRNA is translated into protein
-the central dogma has had to change because small RNA molecules (miRNA, siRNA,
and piRNA) violate the central dogma; they're encoded by genes that are transcribed,
but they are not involved in the synthesis of protein- their function is at an RNA level
Compare and contrast gene expression in the Callipyge vs normal lambs both before
and after birth. - ANSWER--looking at fetal lambs vs lambs
-the expression of PEG11 results in two different phenotypes: homozygous normal, and
lambs that contain the callipyge allele coming from the paternal background
-these are significantly different in terms of expression levels of PEG11
-day 150-230 are lambs, and prior to that are fetal lambs
-at days 80-100 the levels of normal and callipyge are the same, levels drop off but are
still the same at 120
-following birth, all of a sudden there are different levels of PEG11 expression
-hardly any PEG11 expression in normal lambs, but extremely high PEG11 expression
in callipyge lambs
-the only DLK1 expression is occurring in the callipyge lambs
-fairly high levels of expression of Gtl2 is primarily in callipyge, and same with meg8
-two genes where there is no difference between the normal lambs and callipyge lambs
Compare and Contrast siRNAs and miRNAs briefly - ANSWER--siRNAs and miRNAs
both come from very different types of DNAs
-siRNAs from repetitive DNA, miRNAs from genes; both go through double-stranded
step, and have the same sorts of targets, and same sorts of functions
Define and describe meiotic recombination.
What is it called if there is no gene linkage?
What is a test cross? - ANSWER-1) any meiotic process that generates a haploid
product with a genotype that differs from the two haploid genotypes that constituted the
meiotic diploid
-the product of meiosis so generated is called a recombinant
2) inter chromosomal recombination: always produces a recombinant frequency of 50
percent
3) when a homozygous recessive genotype is crossed to another genotype to
determine if a group exhibiting a dominant trait is heterozygous or homozygous for that
trait
Define and Describe segregation.
Describe the Principle of Segregation briefly in meiosis 1. Make note of the important
step. - ANSWER-1) the separation of paternal and maternal chromosomes from each
,other at meiosis; the separation of alleles from each other in heterozygotes; the
occurrence of different phenotypes among offspring, resulting from chromosome or
allele separation in their heterozygous parents; Mendel's 1st principle of inheritance
-the segregation of alleles corresponds to the disjunction (separating) of paired
chromosomes in the anaphase of the first meiotic division
2) -begins with one gene pair: a maternally and paternally inherited chromosome
-metaphase 1: replicated chromosomes that have paired move to the cell's equator
-**anaphase 1: maternal and paternal chromosomes disjoin, and the alleles A and a
segregate from each other**
-telophase 1: chromosomes and alleles are segregated into different cells
-telophase 2: each allele is recovered in half the products of meiosis
Define genetic variation - ANSWER-heritable differences in genetic constitution that
result in observable differences in phenotype
Define hemizygous.
Where is hemizygosity found? - ANSWER-1) a word meaning 'half zygous' when
referring to a gene, such that only one chromosome in a chromosome pair contains a
copy (allele) of that specific gene
2)for sex-linked traits
-when genetically-engineering plants and animals use a foreign gene
-when the deletion of an allele occurs; this is sometimes termed pseudo dominance if a
dominant allele is deleted since the normally recessive allele is 'unmasked'
Since only one allele is present in a hemizygous situation, a recessive allele when
present in a hemizygous state will not be masked by a dominant allele in a diploid
organism
Define Isomorphic.
Define Heteromorphic.
Describe the basic life cycle found in Viridiplantae: Alternation of Generations -
ANSWER-1) similar morphology for the n and 2n phases (some algae)
2) different morphology for the n and 2n phases (most algae, all land plants)
3) -in Viridiplantae, species show either an isomorphic or heteromorphic alternation of
generations
-For Viridiplantae that show a heteromorphic alternation of generations, either the n or
2n phase is dominant (i.e. larger and exists over a longer period of time)
-n phase is dominant in most algae and non-vascular plants
-2n phase is dominant for vascular plants and kelp
-only angiosperms show double fertilization
Define parthenogenesis and describe the two types.
What are some general examples of species that show either of these types of
parthenogenesis? - ANSWER-a form of asexual reproduction in which an embryo
develops from an unfertilized egg; genetic diversity decreases, but a mate is not
required to reproduce
, 1) apomictic parthenogenesis:
-parthenogenesis without meiosis by the female, and thus progeny are genetically
identical (full clones) to the mother and female (aphids are an exception); aphids
produce both female and males owing to their XO sex determination system-in
apomictic males one X chromosome is lost or inactivated giving the male XO genotype.
2) Automictic parthenogenesis:
-parthenogenesis involving meiosis by the female, and thus progeny are not genetically
identical-they will be a half clone of the mother; usually diploidy is restored-if so,
progeny will be all female for animals that use the XY sex determination system or male
and female if the XO sex determination system is used (e.g. some sharks)
some snails, flatworms, some crustaceans, komodo dragon, some snakes
Define the following:
x:
2x:
Aneuploidy:
Euploidy:
n:
2n:
Autopolyploidy:
Allopolyploidy:
What is autopolyploidy generally characterized by? - ANSWER-1) basic number of
chromosomes in a species
2) normal somatic complement
3) deviations from 2x having + or - one or more chromosomes
4) conditions where an entire chromosome set (x) deviates from the 2x condition
5) haploid or gametic number of chromosomes
6) zygotic or somatic number of chromosomes (with somatic number only equalling the
euploid number, 2n=2x, for diploids)
7) multiple sets of chromosomes that are identical in origin
8) multiple sets of chromosomes from different ancestors
9) an increase in size of vegetative parts of the plant resulting in a more vigorous
appearance than the diploid version
Describe (briefly) synteny between pig and human chromosomes - ANSWER--direct
homology between pig (sc1-sc18) and human chromosomes (hs1-hs22)
-18 pig and 22 human autosomal chromosomes
Describe alleles in coupling phase.
Describe alleles in repulsion phase.
Describe coupling (cis) configuration
Describe repulsion (trans) configuration - ANSWER-1) dominant alleles together,
recessive alleles together
2) dominant allele together with recessive allele
