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Here, we will talk about the process of meiosis(cell division) and homologous chromosomes. Meiosis is a special type of cell division of germ cells in sexually-reproducing organisms used to produce the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately result in four cells with only one copy of each chromosome.
1.
Warm Up- 11/6
Who do you receive more genes from:
Mom or Dad?
3.
Test Corrections- Advocate or After
School this week only!
Extra Credit- Tissues
4.
Warm Up- 11/7
What biomolecule made of carbon, hydrogen,
and oxygen is used to make energy (ATP)?
7.
Meiosis I
Stage Events Photo
Chromosomes
Interphase I replicate
Chromosomes
Prophase I become visible
Sister chromatids
Metaphase I form tetrads at the
equator
Homologous
Anaphase I chromosomes move
AWAY to the poles
Chromosomes
Telophase I reach ENDs of cells
at poles
8.
Meiosis II
Stage Events Photo
Nuclear membrane forms
Interkinesis No replication of chromosomes
No Picture
o e s bet
a t d w
Wh ter een
In ? ?
an ?
m e
9.
Meiosis II
Stage Events Photo
Nuclear membrane forms
Interkinesis No replication of chromosomes
No Picture
Prophase II Spindle forms
10.
Meiosis II
Stage Events Photo
Nuclear membrane forms
Interkinesis No replication of chromosomes
No Picture
Prophase II Spindle forms
Chromosomes align at the
Metaphase II equator
NOW …
equator single file
line
11.
Meiosis II
Stage Events Photo
Nuclear membrane forms
Interkinesis No replication of chromosomes
No Picture
Prophase II Spindle forms
Chromosomes align at the
Metaphase II equator
Anaphase II Sister chromatids separate
12.
Meiosis II
Stage Events Photo
Nuclear membrane forms
Interkinesis No replication of chromosomes
No Picture
Prophase II Spindle Forms
Chromosomes align at the
Metaphase II equator
Anaphase II Sister chromatids separate
Chromatids arrive at ends
Telophase II Cytokinesis begins
13.
Meiosis – one more time
Meiosis is a two-part cell division
process….
14.
Meiosis II – one more time
… which results in 4 gametes with
one half the number of
chromosomes of the parent cell.
15.
Mitosis vs. MEIOSIS
mitosis meiosis
• Takes place to create somatic • Takes place to create
cells gametes
• Creates 2 cells • Creates 4 cells
• Creates diploid cells • Creates haploid cells
• Daughter cells are identical to • Daughter cells are NOT
parent cell identical to parent cells
• Used in ASEXUAL reproduction • Used in SEXUAL
• 1 division reproduction
• Homologous chromosomes line • 2 divisions
up in a single file line in • Homologous chromosomes
metaphase line up in a single file line
in metaphase II
• Chromosomes duplicate in
Interphase
• Both a type of cell division
• Both requiredhttp://www.pbs.org/wgbh/nova/miracle/divi_flash.htm
to sustain life
16.
Meiosis creates
4 haploid cells
Spermatogenesis (meiosis
of sperms cells) takes
about 64 days. All 4 sperm
will survive.
Oogenesis (meiosis of egg
cells) is complete when a
female is born. Only 1 egg
of the 4 will become viable.
17.
Warm Up- 11/8
What process happens in the
mitochondria and what does it
produce?
20.
Crossing Over
To make things more
interesting, crossing
over can occur during
Prophase I.
During metaphase I,
the homologous
chromosomes line up
together and form
tetrads. Remember??
21.
Crossing Over
Crossing over takes
place when two
chromosomes, break
and then reconnect
but to the different
end piece.
Crossing over
increases the number
of variations that can
exist in offspring.
22.
Crossing Over
Which of the following did crossing over ONLY take place?
23.
Nondisjunction
Although the events of meiosis usually proceed accurately,
sometimes an accident occurs and the chromosomes fail to
separate correctly. This is known as nondisjunction.
24.
The zygote that has been created will have an extra
or missing chromosome. This would result in an
inherited genetic disorder.
o In most cases, the presence of an additional
chromosome or missing chromosome results in the
death of the zygote.
25.
The zygote that has been created will have and
diploid number of chromosomes plus the extra
chromosomen+1 = 47 chromosomes.
Monosomy - the presence of only one chromosome from
a pair in a cell's nucleus.
Trisomy – the presence of three chromosomes instead of
2 in a cell’s nucleus.
26.
When you are born, doctors take a sample of your
blood and create a karyotype. This will enable the
doctor to see if you have any additional or missing
chromosomes.
A karyotype is a standardized arrangement of all the
chromosomes of a cell.
27.
Homologo
us
chromoso
mes are
paired up,
then they
are put in
order from
the
LARGEST
chromoso
me pair to
the
smallest.
28.
2xc
hrom
o
= somes
GIRL
29.
Every
thing
Karyotypes okay
here?
r? ?
d e
en
t g
h a
W 2 different sized sex chromosomes = ma
30.
Every
thing
okay
Down’s syndrome here
•decreased muscle tone at birth
•asymmetrical or odd-shaped skull
•round head with flat area at the back of
the head
•slanting eyes
•small mouth with protruding tongue
•single crease on the palm
•slowed growth and development
•delayed mental and social skills
31.
Warm Up- 11/9
Draw a phospholipid and label the
HYDROPHILIC and HYDROPHOBIC
ends.
33.
Down’s
Kleinfelters
Turner’s
Patau’s
34.
Every
thing
okay
Turner’s syndrome here
short stature (affects almost all girls with
Turner, to different degrees)
failure of ovaries to develop (90-95% of
girls)
webbed neck (25%) or short neck (40%)
abnormal fingernails and toenails (70%)
hearing disorders (50-90%)
frequent ear infections in childhood (75%)
36.
Every
t h ing
okay
Kleinfelter’s syndrome here
37.
Kleinfelter’s syndrome
No symptoms - some men are unaware they have an
extra chromosome
Enlarged male breasts - only severe in about 10% of
cases
Sparse facial hair
Sparse body hair
Inability to produce sperm
Tallness - more likely to be taller than non-XXY males.
Thinness
Normal intelligence
Language impairment
Delayed language
38.
Kleinfelter’s syndrome
39.
Every
t h ing
okay
Patau’s syndrome here
40.
Patau’s Syndrome
Mental retardation, severe
Seizures
Small head
Scalp defects (absent skin)
Small eyes (microphthalmia)
Cleft lip and/or palate
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