Module 5
in a triploid plant, the probability that meiosis will produce a gamete that is perfectly haploid or diploids is, where n is the number of chromosomes in a set. Thus, the high probability of aneuploid gametes makes triploid plants sterile.
(1/2)^n-1
The banding pattern of eukaryotic chromosomes is useful to
- detect changes in chromosome structure- to distinguish between chromosomes of the same size- to assess evolutionary relationships between species
Spontaneously aborted human embryos have been found to contain every trisomy except that of chromosome
1
List the steps of comparative genomic hybridization in order.
1. Isolate DNA from human breast cancer cells and normal breast cells. 2. Label the breast cancer DNA with a green fluorescent molecule and the normal DNA with a red fluorescent molecule 3. Mix together heat-denatured fluorescent;u labeled DNA and metaphase chromosomes from white blood cells 4. Allow the fluorescently labeled DNA to hybridize to the metaphase chromosomes. 5. Visualize the chromosomes with a fluorescent microscope. Analyze the amount of green and red fluorescence along each chromosome with a computer.
Match the type of meiotic segregation of a reciprocal translocation to its correct description
1. alternate segregation- chromosomes on opposite sides of the translocation cross segregate into the same cell; two gametes have normal chromosomes; two have balanced translocations 2. Adjacent -1 - segregation - Adjacent chromosomes (on of each type of centromere) sort into the same cell; four gametes are genetically unbalanced 3. Adjacent 2-segregation - Centromeres do not segregate as they should; one daughter cell received both copies of the centromere on chromosome one, and the other receives both copies of the centromere on chromosome 2; four gametes are genetically unbalanced
the globin gene family is dispersed on chromosome ____ and chromosome ________
11, 16
the three most common autosomal trisomies in humans are those involving what chromosome
13, 18, 21
Consider an animal with a normal diploid chromosome number of 20. A monosomic cell would have ____ chromosomes.
19
consider an animal with a normal diploid chromosome number of 20. A monosomic cell would have __________ chromosomes
19
The house mouse mus musculus has a diploid number of 40 chromosomes. Suppose that the first meiotic division of a germ cell is normal, but a single dyad in one of the two daughter cells undergoes nondisjunction in meiosis II. How many chromosomes would be present in each of the four gametes that result from that meiosis
20, 20, 21, 19
Species A and species B are closely related. Both are diploid with A having 2n=12 and B having 2n=14. How many chromosomes will an allotetraploid have?
26
The newly-discovered organism Yawle nhoj, has a diploid chromosome number of 56. Suppose that one of the chromosome pairs fails to disjoin properly during Meiosis I. How many chromosomes will be present in each of the four gametes that result from that meiosis? Assume meiosis II is normal.
27, 27, 29, 29
During mitosis of a particular diploid cell, a single chromosome undergoes nondisjunction. What will be the chromosome number in the resulting daughter cells?
2n+1, 2n-1
During mitosis of a particular diploid cell, a chromosome loss event occurs. What will be the chromosome number in the resulting daughter cells?
2n, 2n-1
Normal somatic cells of a human have a total of ____ chromosomes, whereas those of a fruit fly contain a total of ____ chromosomes.
46 8
what percentage of spontaneous abortions are due to the changes in chromosome number
50%
In Drosophila melanogaster, 2n=8. A triploid fly would have ___ chromosomes, while a monosomic fly would contain ___ chromosomes.
9, 7
Copy number variations are relatively common in genomes of which of the following
Animals Plants
Unlike trisomy for autosomes, trisomy X is often without serious phenotypic consequences. This is due to the fact that the additional X chromosome is converted to a(n) _____ _____ in the somatic cells of the adult.
Barr body
The haploid determining system of sex determination is used by which of the following?
Bees Ants
Match the syndrome to its appropriate description.
Down-21 Edwards-18 Patau-13
Copy number variations may involve which of the following?
Duplications Deletions
Which of the following statement is about polyploidy is true?
It is more common in plants
__________is specialized to bind and store oxygen in the muscle while ____________ is specialized to bind and transport oxygen in the red blood cells
Myoglobin Hemoglobin
which of the following are due to a deletion in chromosome 15
Prader-Willi syndrome Angelman syndrome
This figure highlights a change in chromosome structure. The chromosome on top is derived from human chromosome 1, while that on the bottom is derived from human chromosome 21. What chromosomal structural change has produced these two chromosomes?
Reciprocal Translocation
A person with 44 autosomes, one X chromosome and no Y chromosome is said to have _______________ syndrome
Turner
Complete nondisjunction during the first meiotic division would result in which of the following gametes at the end of meiosis II
Two diploid gametes
What proportion of inversions cause phenotypic consequences?
Very few of them
Nonallelic homologous recombination between two chromosomes leads to
a chromosome carrying a duplication and another carrying a deletion.
chromosome loss during mitosis of a diploid cell produces
a normal and a monosomic daughter cell
Mitotic nondisjunction in a diploid cell produces
a trisomic and monosomic daughter cell
abnormalities in chromosome number in human rise with an increase in the --- of either parents
age
An organism that possesses sets of chromosomes from at least two different species is termed
alloploid
An organism that has at least two set of chromosomes from two or more different species is best described as a
allopolyploid
Aneuploidy causes an abnormal phenotype due to
an imbalance of gene products
Changes in the number of individual chromosomes such that are the total number of chromosomes is not an exact multiple of a set results in a condition called
aneuploid
An individual has multiple sets of chromosomes from the same species is best described as
autopolyploid
This figure best illustrates
autopolyploidy
Reciprocal translocations are called _______ translocations, because they do not change the total amount of genetic material.
balanced
a cell has a normal diploid chromosome number of 4. the phenomenon shown in this diagram is
chromosome loss during mitosis
The drug ___________ is often used to promote polyploidy because it binds to the microtubule spindle apparatus and thus disrupts normal chromosome segregation during cell division
colchicine
In meiosis, if all of the chromosomes fail to separate normally, and end up migrating to one of the other two daughter cells, the result is that all four cells are abnormal. This event is known as
complete nondisjunction
an alloploid is an organism that
contains sets of chromosomes from two or more different species
Individuals with chromosome 5 that is missing part of its short arm may have a disease called _______________ syndrome.
cri-du-chat
During meiosis I in an individual carrying a reciprocal translocation, the homologous chromosomes synapse with each other via the formation of a structure that contains four pairs of sister chromatids. This unusual structure is called a translocation
cross
Which of the following can cause reciprocal translocations to occur
crossover between nonhomologous chromosomes Chromosomal breakage and DNA repair
A change in chromosome structure where a portion of the chromosome is missing is called a
deletion
Cri-du-chat syndrome is caused by a
deletion in the short arm of chromosome 5
This figure shows a ____________ chromosome
dicentric
a chromosome that possesses two centromeres is called a ___________ chromosome
dicentric
The region of a chromosome that links two centromeres is called a
dicentric bridge
A change in chromosome structure where a portion of the chromosome is repeated is called
duplication
A chromosome in which the number of copies of a gene increases from one to two is said to have gene _________
duplication
Considering the homologous chromosomes in this figure, The bracket circle is used to highlight a gene _______________
duplication
Liver cells of humans may be triploid (3n), tetraploid (4n), or even octaploid (8n). This phenomenon is best described as
endopolyploidy
A ____________ organism is one with a chromosome number that is an exact multiple of chromosome set
euploid
in this figure, the blue and red chromosomes represent chromosome number 14 and 21, respectively. an individual with the circled chromosomes has---- -----syndrome.
familial down
A collection of two or more genes in a particular species that are similar to each other is known as a gene ___________
family
Paralogs are homologous ______.
genes in the same species
One of the most important examples of gene families in humans is the _______ gene family, whose protein products play roles in oxygen binding.
globin
This karyotype depicts the ___________ chromosome of an ___________.
homeologous, allodiploid
The process which involved the formation of a double-stranded DNA molecule from a single-stranded DNA molecule of two different samples is termed
hybridization
the dna from one source forms a double-stranded region with the DNA from another source during what process
hybridization
Consider a chromosome that has broken into two places to produce three chromosomal fragments. The middle fragment is lost and degraded. The rejoining of the two outer fragments will create a chromosome with a(n) _____ deletion.
interstitial
A chromosomal structural change in which a segment of DNA is rotated 180o is referred to as a(n) ___
inversion
A reversal of the order of genes along a chromosomes is termed
inversion
an individual with the following chromosomes is best described as an
inversion heterozygote
an individual that carries one copy of a normal chromosome and one copy that contains an inverted segment is described by the term
inversion heterozygote.
During meiosis I in an inversion heterozygote, the normal chromosome and inversion chromosome can synapse via the formation of a(n) _____ _____. This allows the homologous genes on both chromosomes to align next to each other, regardless of the size of the inverted segment.
inversion loop
A(n) ______ is a micrograph which displays the chromosomes of a cell, usually in descending order of size.
karyotype
In general, having only a single copy of a gene is ______ having three copies.
more harmful than
A misalignment of repetitive sequences on two chromosomes can cause an abnormal crossover to happen. This is called ____________ __________recombination, and it results in one chromatid carrying a duplication and another containing a deletion
nonallelic homologous
Individuals with down syndrome have three copies of chromosome 21. The extra copy is most likely to be due to during meiosis I in the oocyte
nondisjunction
The failure of chromosomes to segregate properly in meiosis or mitosis is called
nondisjunction
The term meiotic __________ refers to the failure of chromosomes to separate normally during meiosis. This result in haploid cells that have too many or too few chromosomes.
nondisjunction
Mosaics are most likely caused by
nondisjunction during mitosis.
A chromosome typically has a short arm (designated by the letter ___) and a long arm (designated by the letter ____).
p q
the figure shows the outcome of a crossover that occurred during prophase I in an individual carrying a ____________ inversion
paracentric
Inversions are classified into two types. In a(n) ______ inversion, the centromere lies within the inverted region of the chromosome, while in a(n) ______ inversion, the centromere is located outside the inverted region.
pericentric paracentric
A ___________ organism that contains three or more sets of chromosomes
polyploid
a gene has been moved from the short arm of chromosome 1 to the long arm of chromosome 5, thus causing a change in the phenotype associated with that gene. this is an example of an -----effect
position
Identical or similar DNA sequences that occur multiple times on a chromosome are called _____ sequences.
repetitive
In this figure, the bracket is used to highlight
segmental duplication
In an individuals carrying a reciprocal translocation, alternate and adjacent-1 segregation patterns typically occur in equal frequency. Since the gametes produces by adjacent-1 segregation are not viable, this leads to a decrease in the reproductive potential of the individual -- a condition called __________
semisterility
translocations can occur in two main ways. The movement of a single piece of chromosome to another chromosome is called an __________ translocation, while the exchange of pieces between two different types of chromosomes is known as ______________
simple reciprocal
Polyploid plants that have an odd number of chromosome sets are usually ______, and those with an even number of chromosome sets are usually ______.
sterile fertile
A cytogeneticist
studies chromosomes microscopically
The ends of eukaryotic chromosomes are called
telomeres.
Consider a normal chromosome that has broken into two separate pieces, one of which is lost because it lacks a centromere. The resultant chromosome is said to have a(n) ______ deletion.
terminal
Inversions are classified based on what characteristics
the position of the centromere
Polyploidy is best defined as the presence of
three or more sets of chromosomes
A change in chromosome structure in which a segment of DNA becomes attached to another part of the same chromosome or to a different chromosome is called ______________
translocation
This figure illustrates a structure called
translocation cross
G banding is a procedure in which chromosomes are
treated with stains to produce dark and light bands dependent on the compaction of their DNA
An organism that has three copies of a particular chromosome instead of the normal two copies is said to be
trisome
The diploid chromosome number of fruit flies is 8. The condition exhibited in this figure is
trisome
If a sperm carrying an extra chromosome fertilizes a normal egg, the zygote that is produced will be
trisomic
Individuals with reciprocal translocations are at risk of having offspring with _____________ translocations, having chromosomes that carry duplications and/or deletions
unbalanced
Genetic differences within individuals of the same species or between different species is referred to as genetic _____________
variation
