ESSENTIAL CELL BIO CHAPTER #19
STUDY GUIDE EXAM QUESTIONS AND
ANSWERS
Bivalents are very (stable or not stable) and remain associated throughout the long
(prophase, metaphase, or anaphase) of meiosis 1 - ANSWER-They are stable
prophase
What are the steps to 2 sister chromasomes crossing over? - ANSWER-1. Double
stranded breaks by recombination proteins
2. nuclease digests 5' end
3.crossover
4. dna synthesis
5. move closer/ capture other chromosome
6. additional synthesis
7. dna ligation
8. cutting certain points
Crossing over is facilitated by?
A) chiasma
B) Synaptonemal Complex
c) Chismata Complex
D) Recombination complex - ANSWER-B) Synaptonemal Complex
What helps to hold the bivalent together and align the homologs so that crossing over
can occur?
A) Chiasma
B)Chismata Complex
C) Synaptonemal Complex
D) Recombination Complex - ANSWER-C) Synaptonemal Complex
Cross over creates chiasmata between each non sister chromatid in each bivalent. True
or False - ANSWER-True.
- Also most bivalents contain more than 1 chiasma
- Means multiple crossovers exist
How are the sister chromatids held together?
A) DNA
B) Cohesin proteins - ANSWER-B) Cohesin Proteins
Independent assortment during Meiosis 1 produces 2^x different haploid gametes. What
is x - ANSWER-x= 23
, In humans, each meiosis requires that the starting cell keep track of ___ chromosomes(
23 pairs, each of which has duplicated
A) 2
B) 23
C) 24
D) 92
E) 4 - ANSWER-D) 92
What is Nondisjunction? - ANSWER-homologs fail to separate properly.
-haploid cell have more than one copy or lack a particular chromosome
Down syndrome is caused by? - ANSWER-an extra copy of chromosome 21
- the resulting embryo contains 3 copies of chromosome 21 instead of 2
Nondisjustion occurs in what % of the meiosis in human oocytes? - ANSWER-10%
Aneuploidy means that an EGG contains the WRONG number of chromosomes. True
or false? - ANSWER-True
If meiosis goes wrong in male cells what happens? - ANSWER-1. A cell cycle
checkpoint is activated
2. arrest meiosis
3. Apoptosis
Nondisjunction is thought to be one reason for the high rate of miscarriages
(spontaneous abortions). T or F - ANSWER-True
What is Loss of Function mutations - ANSWER-mutations that reduce or eliminate the
activity of genes
Is loss of function mutations dominant or recessive? - ANSWER-Usually recessive
What is Gain of Function mutations? - ANSWER-Mutations that INCREASE the activity
of genes or its product, or result in the gene being expressed in inappropriate
circumstances
Is Gain of Function dominant or recessive? - ANSWER-Usually Dominant
What are mutagens? - ANSWER-Agents that can damage DNA
In the mutagenized cells experiment,
When colonies are placed into COLDER temperature (23C), do the colonies divide? -
ANSWER-Yes, they divide at the PERMISSIVE TEMPERATURE
In the mutagenized cells experiment,
STUDY GUIDE EXAM QUESTIONS AND
ANSWERS
Bivalents are very (stable or not stable) and remain associated throughout the long
(prophase, metaphase, or anaphase) of meiosis 1 - ANSWER-They are stable
prophase
What are the steps to 2 sister chromasomes crossing over? - ANSWER-1. Double
stranded breaks by recombination proteins
2. nuclease digests 5' end
3.crossover
4. dna synthesis
5. move closer/ capture other chromosome
6. additional synthesis
7. dna ligation
8. cutting certain points
Crossing over is facilitated by?
A) chiasma
B) Synaptonemal Complex
c) Chismata Complex
D) Recombination complex - ANSWER-B) Synaptonemal Complex
What helps to hold the bivalent together and align the homologs so that crossing over
can occur?
A) Chiasma
B)Chismata Complex
C) Synaptonemal Complex
D) Recombination Complex - ANSWER-C) Synaptonemal Complex
Cross over creates chiasmata between each non sister chromatid in each bivalent. True
or False - ANSWER-True.
- Also most bivalents contain more than 1 chiasma
- Means multiple crossovers exist
How are the sister chromatids held together?
A) DNA
B) Cohesin proteins - ANSWER-B) Cohesin Proteins
Independent assortment during Meiosis 1 produces 2^x different haploid gametes. What
is x - ANSWER-x= 23
, In humans, each meiosis requires that the starting cell keep track of ___ chromosomes(
23 pairs, each of which has duplicated
A) 2
B) 23
C) 24
D) 92
E) 4 - ANSWER-D) 92
What is Nondisjunction? - ANSWER-homologs fail to separate properly.
-haploid cell have more than one copy or lack a particular chromosome
Down syndrome is caused by? - ANSWER-an extra copy of chromosome 21
- the resulting embryo contains 3 copies of chromosome 21 instead of 2
Nondisjustion occurs in what % of the meiosis in human oocytes? - ANSWER-10%
Aneuploidy means that an EGG contains the WRONG number of chromosomes. True
or false? - ANSWER-True
If meiosis goes wrong in male cells what happens? - ANSWER-1. A cell cycle
checkpoint is activated
2. arrest meiosis
3. Apoptosis
Nondisjunction is thought to be one reason for the high rate of miscarriages
(spontaneous abortions). T or F - ANSWER-True
What is Loss of Function mutations - ANSWER-mutations that reduce or eliminate the
activity of genes
Is loss of function mutations dominant or recessive? - ANSWER-Usually recessive
What is Gain of Function mutations? - ANSWER-Mutations that INCREASE the activity
of genes or its product, or result in the gene being expressed in inappropriate
circumstances
Is Gain of Function dominant or recessive? - ANSWER-Usually Dominant
What are mutagens? - ANSWER-Agents that can damage DNA
In the mutagenized cells experiment,
When colonies are placed into COLDER temperature (23C), do the colonies divide? -
ANSWER-Yes, they divide at the PERMISSIVE TEMPERATURE
In the mutagenized cells experiment,
