Chapter 10
Sexual Reproduction and Genetics
Chapter 10.1
Meiosis
Chromosomes


Structures that contain the genetic
material that is passed from
generation to generation of cells.
Homologous Chromosomes – make
up a pair.



Human body cells have 46
chromosomes, each parent contributes
23 chromosomes.
23 pairs of chromosomes per cell.
Carry genes that control the same
inherited traits.

Genes – segments on the DNA that
determine the characteristics and functions
of the cell.
Haploid vs. Diploid Cells

Gametes – sex cells that have half
the number of chromosomes


Haploid (n) Cells – cells with only
one set of chromosomes


In humans this would be 23
Diploid (2n) Cells – cells with 2n
number of chromosomes


This is done to maintain the same
number of chromosomes from
generation to generation.
In humans this would be 46
Fertilization – process in which a
a haploid gamete combines with
another haploid gamete.
Sexual v. Asexual Reproduction
Read the section Sexual Reproduction v. Asexual Reproduction on p. 276. Compare and
contrast these types of reproduction by recreating the table in your notebook.
Sexual Reproduction
Asexual Reproduction
Sexual v. Asexual Reproduction
Read the section Sexual Reproduction v. Asexual Reproduction on p. 276. Compare and
contrast these types of reproduction by recreating the table in your notebook.
Sexual Reproduction
• Two parents
• Offspring are genetically different
from parents
• Genetic variation each generation
• Most Plants & Animals
Asexual Reproduction
• One parent
• Offspring are genetically identical
to parent
• Bacteria (and most protists)
Meiosis


Process in which gametes are formed.
Type of cell division that reduces the number of
chromosomes; called a reduction division.




Reduces chromosome number by the separation of
homologous chromosomes.
2n
n
Occurs in the reproductive structures of organisms that
reproduce sexually.
Involves two consecutive cell divisions called meiosis I
and meiosis II
Animations

http://www.biostudio.com/d_%20Meiosis.htm


http://www.stolaf.edu/people/giannini/flashanimat/celldivision/meiosis
.swf


http://www.sumanasinc.com/webcontent/animations/content/meiosis
.html


http://www.cellsalive.com/meiosis.htm


http://www.johnkyrk.com/meiosis.html

http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072
437316/120074/bio16.swf::Unique Features of Meiosis
Meiosis I
Interphase and Meiosis I
Meiosis II
Crossing over

During prophase, the homologous chromosomes
exchange segments of DNA
Mitosis and Meiosis
Mitosis
Meiosis
One division
Two divisions (meiosis I and II)
DNA replication during interphase
DNA replication during interphase
Homologous chromosomes do NOT
pair up
Homologous chromosomes pair up
Daughter cells are genetically identical
Daughter cells are not genetically
identical (crossing over occurs)
Mitosis occurs in body cells only
Meiosis occurs in reproductive cells
Mitosis involved in growth and repair
Meiosis involved in producing gametes
and increasing genetic variation