Bio 351 Module 2 Exam with
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precise detailed answers |! |!
5 unique stages of prophase - Correct answer ✔Leptotene -> Zygotene -
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>Pachytene->Diplotene->Metaphase I and Diakinesis |! |! |!
Leptotene - Correct answer ✔Means "thin thread"
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DNA replication has occurred - cell is now 4N
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Each chromosome consists of 2 chromatids
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Chromatin is stretched out thinly, not condensed, can't identify individual
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chromosomes
Telomeres have attached along the nuclear membrane
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Zygotene - Correct answer ✔Homologous chromosomes pair side by side, this
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is synapsis
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Characteristic of meiosis, not in mitosis |! |! |! |! |!
Requires formation of synaptonemal complex
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Configuration formed by the 4 chromatids and the synaptonemal complex is
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referred to as a bivalent or tetrad
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Synaptonemal Complex - Correct answer ✔Requires a nuclear membrane to
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be present|!
,Ladder-like structure made of protein with central elements and two lateral
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bars
Chromatin is associated with the two lateral bars and the chromosomes are
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then joined together and to the nuclear membrane
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Pachytene - Correct answer ✔Means "thick thread"
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Chromatids thicken and shorten |! |! |!
Individual chromatids can now be distinguished by light microscopy
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Crossing-over may occur and continues into diplotene |! |! |! |! |! |!
Diplotene - Correct answer ✔Crossing-over continues into this stage
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Synaptonemal complex breaks down and the two homologous chromosomes
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start to separate
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Chiasmata: regions at which crossing over is occuring
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This only occurs between regions of homologous genes
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Metaphase I and Diakinesis - Correct answer ✔Means "moving apart"
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Kinetochores move away from one another |! |! |! |! |!
Chromosomes remain joined only at the tips of the chromatids |! |! |! |! |! |! |! |! |!
Last stage of meiotic prophase I
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Ends with the breakdown of the nuclear membrane and migration of
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chromosomes from the metaphase plate |! |! |! |!
, Nondisjunction of homologous chromosomes in meiosis I - Correct answer |! |! |! |! |! |! |! |! |! |!
✔All gametes will be abnormal or aneuploid
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Half of the gametes will contain neither member of the chromosome pair
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Half of the gametes will contain both homologous chromosomes
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Nondisjunction of sister chromatids in meiosis II - Correct answer ✔Only two |! |! |! |! |! |! |! |! |! |! |!
of the four gametes will be abnormal
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One gamete will have an extra chromosome and one will have an absence of
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the chromosome
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Trisomy 18 - Edwards Syndrome - Correct answer ✔Children born with this
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syndrome have: |! |!
kidney and heart defects, omphalocele (intestines protruding outside the
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body), esophageal atresia, intellectual disability, growth deficiency, generally
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die within first year of life
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Spermatogenesis - Correct answer ✔Production of haploid sperm from |! |! |! |! |! |! |! |! |!
spermatogonial stem cells |! |!
Spermiogenesis - Correct answer ✔Maturation of haploid spermatids into |! |! |! |! |! |! |! |! |!
fully motile spermatozoa
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Begins at the end of meiosis |! |! |! |! |!
Sertoli Cells - Correct answer ✔Nourish and protect developing sperm cells
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Differentiate from epithelial cells lining the sex cords embryonically |! |! |! |! |! |! |! |!
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precise detailed answers |! |!
5 unique stages of prophase - Correct answer ✔Leptotene -> Zygotene -
|! |! |! |! |! |! |! |! |! |! |!
>Pachytene->Diplotene->Metaphase I and Diakinesis |! |! |!
Leptotene - Correct answer ✔Means "thin thread"
|! |! |! |! |! |! |!
DNA replication has occurred - cell is now 4N
|! |! |! |! |! |! |! |!
Each chromosome consists of 2 chromatids
|! |! |! |! |!
Chromatin is stretched out thinly, not condensed, can't identify individual
|! |! |! |! |! |! |! |! |! |!
chromosomes
Telomeres have attached along the nuclear membrane
|! |! |! |! |! |!
Zygotene - Correct answer ✔Homologous chromosomes pair side by side, this
|! |! |! |! |! |! |! |! |! |!
is synapsis
|! |!
Characteristic of meiosis, not in mitosis |! |! |! |! |!
Requires formation of synaptonemal complex
|! |! |! |!
Configuration formed by the 4 chromatids and the synaptonemal complex is
|! |! |! |! |! |! |! |! |! |! |!
referred to as a bivalent or tetrad
|! |! |! |! |! |!
Synaptonemal Complex - Correct answer ✔Requires a nuclear membrane to
|! |! |! |! |! |! |! |! |! |!
be present|!
,Ladder-like structure made of protein with central elements and two lateral
|! |! |! |! |! |! |! |! |! |! |!
bars
Chromatin is associated with the two lateral bars and the chromosomes are
|! |! |! |! |! |! |! |! |! |! |! |!
then joined together and to the nuclear membrane
|! |! |! |! |! |! |!
Pachytene - Correct answer ✔Means "thick thread"
|! |! |! |! |! |!
Chromatids thicken and shorten |! |! |!
Individual chromatids can now be distinguished by light microscopy
|! |! |! |! |! |! |! |!
Crossing-over may occur and continues into diplotene |! |! |! |! |! |!
Diplotene - Correct answer ✔Crossing-over continues into this stage
|! |! |! |! |! |! |! |!
Synaptonemal complex breaks down and the two homologous chromosomes
|! |! |! |! |! |! |! |! |!
start to separate
|! |!
Chiasmata: regions at which crossing over is occuring
|! |! |! |! |! |! |!
This only occurs between regions of homologous genes
|! |! |! |! |! |! |!
Metaphase I and Diakinesis - Correct answer ✔Means "moving apart"
|! |! |! |! |! |! |! |! |!
Kinetochores move away from one another |! |! |! |! |!
Chromosomes remain joined only at the tips of the chromatids |! |! |! |! |! |! |! |! |!
Last stage of meiotic prophase I
|! |! |! |! |!
Ends with the breakdown of the nuclear membrane and migration of
|! |! |! |! |! |! |! |! |! |! |!
chromosomes from the metaphase plate |! |! |! |!
, Nondisjunction of homologous chromosomes in meiosis I - Correct answer |! |! |! |! |! |! |! |! |! |!
✔All gametes will be abnormal or aneuploid
|! |! |! |! |! |!
Half of the gametes will contain neither member of the chromosome pair
|! |! |! |! |! |! |! |! |! |! |! |!
Half of the gametes will contain both homologous chromosomes
|! |! |! |! |! |! |! |!
Nondisjunction of sister chromatids in meiosis II - Correct answer ✔Only two |! |! |! |! |! |! |! |! |! |! |!
of the four gametes will be abnormal
|! |! |! |! |! |! |!
One gamete will have an extra chromosome and one will have an absence of
|! |! |! |! |! |! |! |! |! |! |! |! |! |!
the chromosome
|!
Trisomy 18 - Edwards Syndrome - Correct answer ✔Children born with this
|! |! |! |! |! |! |! |! |! |! |! |!
syndrome have: |! |!
kidney and heart defects, omphalocele (intestines protruding outside the
|! |! |! |! |! |! |! |! |!
body), esophageal atresia, intellectual disability, growth deficiency, generally
|! |! |! |! |! |! |! |!
die within first year of life
|! |! |! |! |!
Spermatogenesis - Correct answer ✔Production of haploid sperm from |! |! |! |! |! |! |! |! |!
spermatogonial stem cells |! |!
Spermiogenesis - Correct answer ✔Maturation of haploid spermatids into |! |! |! |! |! |! |! |! |!
fully motile spermatozoa
|! |!
Begins at the end of meiosis |! |! |! |! |!
Sertoli Cells - Correct answer ✔Nourish and protect developing sperm cells
|! |! |! |! |! |! |! |! |! |!
Differentiate from epithelial cells lining the sex cords embryonically |! |! |! |! |! |! |! |!
