Sexual Reproduction / Meiosis
Sexual Reproduction: ________________________________________________________________________
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What determines the traits of the offspring?
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If a gene is not expressed by a parent, can it still be passed on to the offspring? Briefly explain.
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Sexual Reproduction Basics
Each cell contains DNA. The zygote receives a combination of DNA from the gametes.
Remember:
 DNA is a nucleic acid containing 4 different nitrogenous bases (A, T, G, C)
What does DNA do?
 The sequence of bases is called the ___________________________!
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This code tells your cells what to do and determines all of your physical traits
Eg. hair/eye colour, shoe size, determines if you are male or female
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It may also contributes to your personality and natural tendencies
Sorting out the Chromosomes:
Chromatin
Chromosome
Sister Chromatids
How many chromosomes do humans have? __________
If we combine the chromosomes from each parent during sexual reproduction, why doesn’t the chromosome
number double?
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How many chromosomes should each gamete have?
Gametes
46
78
24
Human
Chicken
Rice
Zygote
This means that EACH cell in your body cells has one copy of DNA from your _________________and one copy
of DNA from your ___________________ .
How do gametes get this number of chromosomes? _______________________________________________
Where does this take place? In the sex organs… Male: _________________ Female : _________________
gamete
from mother
gamete
from father
Meiosis divides cells TWICE to get half the normal number of chromosomes. Two cell divisions = 4 new cells!
Meiosis I
Interphase
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(chromosomes
bundled for clarity)
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Prophase I
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Metaphase I
Anaphase I
Telophase I
Meiosis II
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Prophase II
Metaphase II
Anaphase II
Telophase II
Gametes
End Result:
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