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Bio 111 Test 3
Chapter 11
41
Biology
Undergraduate 3
11/10/2013

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Term
What does meiosis produce?
Definition
Gametes. (Egg cells and sperm cells)
Term
Adult body cells (somatic) are ________, containing ____ sets of chromosomes.
Definition
diploid. 23
Term
Gametes are ________. Containing __ set of chromosomes.
Definition
haploid. 1.
Term
What is sexual reproduction?
Definition
Includes the fusion of gametes to pro due a diploid zygote.
Term
What is the fusion of gametes?
Definition
Fertilization
Term
What state dominates in humans?
Definition
Diploid state
Term
_______ first undergoes meiosis to produce _________ cells.
Definition
Zygote. Diploid.
Term
Later in the life cycle, some of these diploid cells undergo meiosis to produce ___________ gametes.
Definition
haploid.
Term
How many rounds of division are there in meiosis?
Definition
2
Term
What is the first division in meiosis called?
Definition
The reduction division
Term
What does the reduction division result in?
Definition
daughter cells that contain ONE homologue from each chromosome pair.
Term
Does DNA replication occur between meiotic divisions?
Definition
no
Term
What does the 2nd meiotic division do?
Definition
DOES NOT reduce the number of chromosomes. Separates the sister chromatids from from each homologue.
Term
Do meiotic cells go through interphase?
Definition
Yes
Term
What are the steps of Meiosis I?
Definition
1.) Prophase I
2.) Metaphase I
3.) Anaphase I
4.) Telophase I
Term
What happens during prophase I?
Definition
-Chromosomes coil tightly
-Spindle forms
-Each consisting of 2 sister chromatids
Term
What is the synapsis during prophase I?
Definition
When crossing OVER occurs between non sister chromatids. Remain attached @ their chiasmata which then moves to the end of the chromosome arm before metaphase 1.
Term
What is the synaptonemal complex?
Definition
Formation also caled tetrad or bivalents. Occurs when crossing over happens.
Term
What is crossing over?
Definition
Genetic recombination between non sister chromatids.
Term
What is a chiasmata?
Definition
Site of crossing over.
Term
When are the homologues separated?
Definition
Anaphase 1.
Term
What happens during metaphase I?
Definition
-Microtubules from opposite poles attach to each HOMOLOGUE not each sister chromatid. Then they align at the metaphase plate side-by-side. Orientation of each pair on the spindle is random.
Term
What is the difference in separation of genetic material in mitosis and meiosis I?
Definition
Meiosis = PAIRS pulled
Mitosis = Sister chromatids separated
Term
Independent assortment allows what?
Definition
Genetic variety.
Term
What happens during anaphase I?
Definition
-Microtubules of the spindle shorten, chiasmata break.
-Homologues are separated from each other.
-Sister chromosomes remain attached to each other at their centromere.
Term
After anaphase I, how many chromosomes does each pole have?
Definition
A haploid set. One member of each homologous pair.
Term
What happens during telophase I?
Definition
-nuclear envelope forms
-each nucleus is now haploid
-sister chromatids are no longer identical because of crossing over
-Cytokinesis may or may not occur after
-Meiosis II follows
Term
What does meiosis II resemble?
Definition
A mitotic division.
Term
What happens during prophase II?
Definition
Nuclear envelopes dissolve and new spindle apparatus forms.
Term
What happens during metaphase II?
Definition
Chromosomes align on metaphase plate.
Term
What happens during anaphase II?
Definition
Sister chromatids are separated from each other.
Term
What happens during telophase II?
Definition
Nuclear envelope reforms around 4 haploid daughter chromosomes and cytokinesis follows.
Term
What happens to the daughter cells in animal vs plant cells?
Definition
Animal - directly into gametes
Plant - divide mitotically to produce more gametes
Term
What is nondisjxn?
Definition
Failure of chromosomes to move to opposite poles during either meiotic division. Failure to move from metaphase plate correctly.
Term
What are aneuploid gametes?
Definition
Gametes with missing or extra chromosomes
Term
What is the most common cause of spontaneous abortion in humans?
Definition
Aneuploid gametes
Term
What are the 4 characteristics of meiosis?
Definition
1.) Synapsis and crossing over
2.) Sister chromatids remain joined at their centromeres through meiosis I
3.) Kinetochores of sister chromatids attach to same pole during meiosis 1.
4.) DNA replication is suppressed between meiosis I and II.
Term
Meiosis produces __ _______ cells that are _____ genetically identical.
Definition
4 haploid. non.
Term
How do genetic differences occur in meiosis?
Definition
- crossing over
- random alignment of homologues during metaphase I.
- mate selection
Term
Mitosis produces __ ________ _________ cells.
Definition
2 geneticaly identical
Term
Sperm + Egg = ? -> ?
Definition
Zygote -> Gametes
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