Section 6-2
“Meiosis”
Write everything that is
underlined
6.2 Process of Meiosis
KEY CONCEPT
During meiosis, diploid cells undergo
two cell divisions that result in haploid
cells
6.2 Process of Meiosis
A. Cells go through two rounds of division in
meiosis
1. Meiosis reduces chromosome
number and creates genetic
diversity
6.2 Process of Meiosis
2. Meiosis I and meiosis II each have four phases,
similar to those in mitosis
– Pairs of homologous chromosomes
separate in meiosis I
– Homologous chromosomes are similar but not identical
– Sister chromatids divide in meiosis II
– Sister chromatids are copies of the same chromosome
homologous chromosomes
sister
chromatids
sister
chromatids
6.2 Process of Meiosis
• Meiosis I occurs after DNA has been
replicated
• Meiosis I divides homologous
chromosomes in four phases
6.2 Process of Meiosis
• Meiosis II divides sister chromatids in four phases
• DNA is not replicated between meiosis I and
meiosis II
6.2 Process of Meiosis
Listen Up!
• http://www.youtube.com/watch?v=nML6q8u_58&safety_mode=true&persist_safety_mode=
1
• Follow along on a sheet Miss Walsh will pass out.
• Goofy? Yes. Helpful? Absolutely!!!!!
6.2 Process of Meiosis
Hands On!
• Each table will receive 5 pieces of yarn- one big
piece, tied into a circle, and 4 little pieces, which
represent homologous chromosomes.
• Miss Walsh will call out a step of meiosis I- using
your textbook (page 174) and pieces of yarn,
demonstrate each step.
• Miss Walsh will call out the phases of meiosis II- use
your textbook (page 175) and yarn to demonstrate
each step. (…You are going to need scissors for
Meiosis II)
6.2 Process of Meiosis
3. Meiosis differs from mitosis in significant ways
– Meiosis has two cell divisions; mitosis has one
– In mitosis, homologous chromosomes never
pair up
– Meiosis results in haploid cells; mitosis results
in diploid cells
6.2 Process of Meiosis
B. Haploid cells develop into mature gametes
1. Gametogenesis is the
production of gametes
2. Gametogenesis differs between
females and males
– Sperm become streamlined and
motile
– Sperm primarily contribute DNA to
an embryo
– Eggs contribute DNA, cytoplasm,
and organelles to an embryo
– During meiosis, the egg gets most
of the contents; the other cells
form polar bodies
6.2 Process of Meiosis
The Fate of the 4 Haploid
Cells…
• If it is from the male parent,
all 4 will become sperm cells
• If it is from the female
parent, 1 will be an egg and
the other 3 gametes die
6.2 Process of Meiosis
Pick 1 of the 3 below:
-Draw and label the following
picture
-Write a paragraph about what
is happening in the pictures
-Write a rap about what is
occurring in the pictures
Diploid
Parent
Cell
DNA
copies
itself
1st meiotic
division
(haploid)
2nd meiotic
division (haploid)