CHAPTER 21: MEIOSIS & SEXUAL REPRODUCTION

21-1: MEIOSIS

I.                  Another Kind of Cell Division

Sexual Reproduction:

Fertilization:

Zygote:

              Egg (n) + Sperm (n) = Zygote (2n)

II.              Diploid and Haploid Chromosome Number

Homologous Chromosomes –

III.            Stages of Meiosis

A.    Prophase I

·         

·        

·             

·        

·        

·        

B.   Metaphase I

·         

C.   Anaphase I

·         

·        

D.   Telophase I

·         

·        

·        

E.   Prophase II

·        

·        

F.    Metaphase II

·        

G.  Anaphase II

·        

·        

·        

H.   Telophase II

·        

·        

·        

IV.         Comparing Mitosis and Meiosis

CHROMOSOME STRUCTURE

·       Chromosomes are a ___________________ information

·       Consist of one long strand of _____wrapped around __________________________

·       Each chromosome contains ______________________

Chromatids –

Centromere –

CHROMOSOME NUMBER AND ANALYSIS

·       You have ___________ of chromosomes (46 total), “___________________ Chromosomes”

·       In each pair, one chromosome is from your __________, one from your ___________

Karyotype –

Chromosomes are ____________ under the ____________, a ____________ is taken of the cell, and ________________ ________________________________________________ on a “karyotype” form.

Autosomes – Chromosome _______________. They contain all of the __________ that determine who you are. ____________________________.

Sex Chromosomes – Chromosome ___________ (__, __).  These chromosomes _______________________.

Notation for Normal __________ Karyotype = ___________

Notation for Normal __________ Karyotype = ___________

______ of a child is determined by the ___________! (mom always gives X, dad gives X or Y)

KARYOTYPE ¯ Is this a male or female?

CHROMOSOMAL DISEASES

1.           Down Syndrome (Trisomy 21) 47,XX+21 or 47,XY+21

·       Have an extra chromosome #____

·       Phenotype (_____________________________):

-

·       Most common genetic cause of mental retardation

·       Occurs in _________ live births

·       Higher incidence in ____________________ years old

2.           Turner Syndrome 45,X

·       ___________________________________

·       Phenotype:

-

·       Occurs in __________ live births

3.           Klinefelter Syndrome 47,XXY or 47,XXXY or 47,XXXXY

·       _________________________________

·       Phenotype:

-

·       Occurs in __________ live births

21-2: SEXUAL REPRODUCTION IN SIMPLE ORGANISMS

I.                 Advantages of Sexual Reproduction

·       Ensures __________________ by providing ________ _____________ through “crossing over”

·       Allows certain individuals in a population to _________ _____________________

II.              Conjugation & Mating Types

·        

·       Occurs between 2 different ___________à __ or __ (biochemical differences exist)

·       A _____________________ forms between two cells, and a ______________ takes place through the bridge

A.          Conjugation in Bacteria

·        

·        

·         

·       Amount of DNA exchanged depends on the amount of time conjugation lasts

B.          Conjugation in Spirogyra (green algae with threadlike filaments made of haploid cells)

·       _______________ of opposite mating types (________________) come to lie side by side

·       _______________ are formed on the sides of neighboring cells

·       ________________, and the walls where the projections meet break down, forming a ________________ between the cells of the 2 filaments

·       ___________________ à conjugation tube à ______________ = _______________

·       Zygotes secrete a thick protective wall and become a ________________.

·       Original filaments decay, releasing zygospores

·       Zygospore ____________________, forming ____________________

·        

C.          Conjugation in Paramecia

·       Takes place between _____ mating types

·       2 ___________________ at their oral groove

·       ___________________ forms between them

·       Macronucleus disappears, _______________ _______________________

·       2 of the resulting haploid micronuclei remain (others disappear)

·        

·       _______________ contain a ________________________

·       _______________________

·       New micronuclei undergo several mitotic divisions

·       ____________________________ without nuclear division

·       _________________________ produced

21-3: SEXUAL REPRODUCTION IN ANIMALS

I.                 Reproductive Systems

Gonads:

Testes à

Ovaries à

II.              Separation of Sexes and Hermaphroditism

A.           Separate Sex organisms have either __________ OR _____________

B.          Hermaphrodites Have BOTH _________________

·       Usually ______________ or are _____________ to a surface

·        

·       Self-fertilization can happen (not likely though)

·       Ex:

III.            Gametogenesis –

A.           Oogenesis –

·       _____________________, are surrounded by a follicle, or sac in which it develops.

·       Oogonia = ________________

·       Oogonia ________________________________ ______________ à stops at _________

·       Baby is ____________________________ she will ever have

·       By 3^rd month of development, oogonia develop into __________________________

·        

·       ______________ one of the _______________ finishes meiosis and ______________________  _________________

·       ______________________________

B.          Spermatogenesis –

·       ____________________________ = immature sex cells

·       Spermatogonia _____________ _________during childhood

·       At ___________, __________________________

·       Other spermatogonia continually divide

·        

·       Each diploid _____________________________ _______________________________

IV.         Sperm vs. Egg

V.             Fertilization and Zygote Formation

Fertilization: _______    +   _______     à   _________

                      _______    +   _______    à    _________

                         ___                  ___                      ___

Fertilization restores the ___________________________.

During Fertilization:

·       ________ comes into _________ with _______

·       _____________ (covering on head of sperm) _______ ____________________________________ through membranes of the __________

·       Nucleus in head of _________________________

·        

·       Fertilization membrane forms around egg after sperm enters. It functions in

à

à

VI.         Internal vs. External Fertilization

Parthenogenesis –