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BIOS 1100 Mitosis and Meiosis
Transcript of BIOS 1100 Mitosis and Meiosis
Mitosis and Meiosis
A Story of Growth
part of the cell cycle
diagram on pg. 30
asexual reproduction of prokaryotes
growth of multicellular organisms
one round of division
two rounds of division
2 daughter cells
4 daughter cells
: meiosis in animal male testes and female ovaries gives gametes used
later for fertilization
1n + 1n = 2n diploid
For both types, DNA is passed on to the "daughter cells" in the form of chromosomes.
form during DNA duplication in interphase of the cell cycle
cell needs to double up the genetic information!
image of DNA
chromosomes move through stages of cell division with help of the "spindle apparatus"
regions at poles of the cell that organize microtubules
Dividing human cell: The centrosomes are shown as gray circles, the chromosomes are in blue, the kinetochores in pink, and the spindle apparatus in green (hairlike strands are microtubules).
Telophase I and Interkinesis
gives sperm (1n)
"when sperm meets egg"
gives eggs (1n)
and useless polar bodies
gives 2n cell that then grows by mitosis
final division of cell to give 2 cells
after the completion of mitosis
similar chromosome pairs
one from mom (maternal)
one from dad (paternal)
in humans, 23 PAIRS of homologous chromosomes
Today, will draw like:
Today, will draw like:
two pairs of
Did you turn in homework from Lab 2?
Extra credit due Oct. 14 (Mon.) and Oct. 15 (Tues.)
Go over Quiz 1 and HW 1
Lab practical in two weeks!
Example stations set up next week.
Review session Friday October 4th at 11:55am-12:55pm in THIS ROOM
science as a verb and as a noun
-Neil deGrasse Tyson interview
facts, definitions, etc.
a way of thinking about
the world, asking questions, etc.
Doing science as a verb will help you remember the facts, definitions, etc.
hereditary material of the cell
b) DNA as chromatin
c) 3-D structure of DNA
a) inside the
G1 of Interphase: growth and prep
S-phase of Interphase
"S" = synthesis, another way to say "duplication"
Why make copies?
Why would a cell
need to grow before
to have something to divide up!
think: cell division vs. ripping a piece of paper in half many times
G2 of Interphase: Growth and Final Prep
Cell is switching gears by making
proteins that help with cell division
Note: DNA still looks like
this during this phase!
first step of interphase after cytokinesis
Remember that each cell will
then go through the cycle again
in plant cells
in animal cells
pro = before
nucleous disappears and chromosomes condense
nuclear membrane gone
frees the chromosomes
meta = mid
chromosomes line up in the
middle of the cell
microtubules, or spindle fibers
attach to the chromosomes
division of cytoplasm
kinesis = movement
ana = upper
sister chromatids pulled apart by spindle fibers
move to opposites ends of the cell
separated sister chromatids now are unduplicated chromosomes
telos = end
spindle apparatus disappears
new nuclear envelope forms
chromosomes will soon
uncondense into chromatin
after crossing over in Prophase I, homologous chromosomes separate and line up at metaphase plate
synapses: homologous chromosomes pair up
crossing over: chromosomes exchange genetic information
duplicated chromosomes still intact with sister chromatids are pulled to opposite ends of cell
completion of Meiosis I
daughter cells have one chromosome from each homologous chromosome pairing
both resulting cells look like this
Telophase II and Cytokinesis
End Meiosis II
Two rounds of division
What is the total number of cells we get from one cell?
2n or 1n cells?
What are they used for?
Where in animals are they made?
cells will not grow in
between Meiosis I and II
n = unique types of chromosomes
1 or 2 tells if haploid or diploid
example for humans
our cells are diploid
2(23) = 46 chromosomes
cells now 1n
one copy of each
line up at metaphase
are pulled to opposite ends of the cell by the spindle fibers
spindle fibers disappear
chromosomes will go back to
Upon the completion of
Meiosis II, cells:
are 1n, haploid
crossing over in Meiosis I!
contributes to genetic
pg. 42- 43 and in HW
(two types: mitosis and meiosis)
the "organized" form of DNA
What to expect for Quiz 3
a chromosome with labels for one chromatid, sister chromatids and the centromere
Be able to draw and explain the phases of mitosis and meiosis in animals and plant cells (draw with difference shapes!)
Be able to recognize ovaries and testes under the microscope.
Use homework, lecture sheet and Prezi
Be able to draw and label: