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Std.7 Meiosis ReviewDescribe the steps to meiosis I and meiosis 2. What types of cells are produced?
Provide examples and identify the location of gametes. How does fertilization restore chromosome number (hint: n →2n)
Word List: Fill in the blanks to make each statement correct. Some words may be used more than onceDiploid crossing-over egg fertilization four (4) gametes haploid homologous sperm tetrad unique zygote
Meiosis produces what type of cells: ___________________ Examples: _______________ cells & __________ cells
Meiosis results in ______ (#) __________________(n) cells that are genetically ______________________
During prophase I of meiosis _____________________ (pairs) chromosomes come together to form a ____________
and exchange segments of genes. This process is called _________________________ and results in unique gametes
During _______________________ 2 ________________ gametes come together to form a _____________ zygote.
Question AnalysisThe diagram below shows a cellular process that occurs in organisms. This process is known as: __________________
Cells produced are (circle one): haploid diploid
Write True/False for each statement about meiosis. Correct false statements.
______ Cells divide only once during meiosis.
______ Meiosis does not occur in reproductive cells.
______ The cells produced at the end of meiosis are genetically identical to the parent cell.
______ The cell produced at the end of meiosis contain half the number of chromosomes as the parent cell.
Write True/False for each statement about meiosis. Correct false statements.
______ It is carried out in all tissues that require cell replacement.
______ It occurs only in the reproductive structures of organisms
______ It happens in all tissues except the brain and spinal cord.
______ It is the first stage of mitosis
Explain why diploid chromosome number is even (see table)
Write an equation for what happens to chromosome # during fertilization:
______ (haploid) + _______ (haploid) = ________ (_________________)
This process is called
_________________________ &
_______________ are exchanged
during meiosis making gametes genetically unique.
Label: gametes &homologous chromosomes
Sperm cell
Egg cellzygote
Std.7 Meiosis Study GuideI. Meiosis *Results in formation of gametes → sex cells (sperm/ eggs)
Results in 4 , genetically unique gametes Two cell divisions (cytokinesis/ cytokinesis II) Gametes - are haploid (n) in chromosome #
o Single set of chromosomes (no pairs) Location = Gonads – testicles and ovaries
o gametes → sperm cells and eggs cells
II. Phases of Meiosis*Meiosis I
Prophase I – chromosomes condenseo Homologous chromosomes line up & form
tetrado Crossing over – homologous
chromosomes exchange pieces of genetic information Crossing over results in genetically unique
gametes
Metaphase I – homologous chromosomes align at center of cell
Anaphase I – homologous chromosomes separate
Telophase I – Nuclear membrane forms followed by cytokinesis Io Following telophase I and cytokinesis I,
chromosome number is reduced to haploid* Meiosis I results in 2 haploid (n) daughter cells
*Meiosis II
Prophase II – chromosomes condense
Metaphase II – chromosomes align in center of cell
Anaphase II – sister chromatids separate & move to opposite ends of the cell
Telophase II & cytokinesis II– Nuclear membrane reforms resulting in 4 haploid cellso After telophase II and cytokinesis II each
haploid cell has a single copy of each gene
End Result of Meiosis: o 4 haploid, genetically unique gametes
Sperm cells (4 sperm) Egg Cells (1 egg + 3 polar bodies)
III. Fertilization
* fertilization restores chromosome number from haploid to diploid (n → 2n)
Haploid gametes come together → form diploid zygote
Meiosis I
Meiosis II