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Cell Division: Mitosis and Meiosis
Chromosomes are structures that contain ____________________ material
When Eukaryotes are not dividing, DNA and Proteins are in a mass called:
When the cell divides, it condenses and becomes identifiable as individual ___________
Humans have _____ chromosomes in their body or ______________________________ cells
This is the normal number and these cells are called _________________ - noted as (2n)
These cells undergo ____________________ to replicate/divide
Sex cells or _______________ have _____ chromosomes which is half the number
These cells are called _______________, are noted as (n), and undergo ______________
Mitosis
This is how unicellular cells reproduce; resulting in identical copies of the cell.
In multicellular organisms it is the simple cell division necessary for:
New cells can only come from pre-existing cells.
Cells cannot get too big – need ________ surface area to volume ratio for transport & efficiency
Mitosis ensures that all new cells get the proper number of:
Cell Cycle – the phases in the life of a cell – Interphase and Cell Division
Interphase – occurs when the cell is:
Longest phase in the cell cycle, divided into three stages
G1 = Named for Gap 1 but the cell is really performing its function and ______________
Some cells stop in this stage and do not divide – for example ____________ cells
_________________________ are needed to move on to each new level
If they are not there, the cell will not move on and will not divide
S = Named for ___________________________________ or DNA Replication
Chromosomes copy themselves so that:
At the beginning of Interphase, each chromosome is made of 1 ______________
After Replication, each chromosome is made of ___________________________
They are called sister because they are:
The 2 chromatids are connected by a ____________________
DRAW
G2 = Named for Gap 2 but the cell is getting ready to _______________
Store up proteins and ATP, replicate ____________________
If there are no growth factors, some cells like muscle cells stay in this stage
Cell Division –
Includes karyokinesis = division of the ____________________ during Mitosis
And cytokinesis = division of the ____________________ during Cytokinesis
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Stages of Mitosis
Prophase
Chromatin condenses around _______________ proteins so chromosomes are visible
______________________________ and ____________________ disappear
____________________ fibers form from the cell wall in plants and fungi
and the _________________________ in animal cells. In animal cells, the
spindle apparatus radiates out from the centriole and is called an __________
DRAW
Prometaphase
The _________________________ attaches the centromere to the spindle fibers
Metaphase
The chromosomes align on the:
DRAW
Anaphase
The centromeres divide resulting in daughter chromosomes made up of
_____ chromatid and _____ centromere
The spindle lengthens to push the poles of the cell further apart
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Telophase
_________________________ break down
_________________________ and ____________________ reform
The chromosomes relax into chromatin
Each daughter cell has the ____________________ number of chromosomes
Cytokinesis occurs with ____________________ and is the division of the _________________
In animal cells, actin filaments pull in the membrane between the cells, forming a:
In plant cells, the golgi apparatus produces new cell wall called a:
DRAW
Bacteria do a similar but much more simple type of cell division called ____________________
The circular DNA copies itself and the cell splits
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Meiosis
This is the process of making ____________________ for sexually reproducing organisms
They must be _______________ or _______________.
If not then the cells would __________ in chromosome number with each generation
when a sperm fertilizes an egg to make a _______________
Meiosis reduces the chromosome number from diploid to haploid in a special way
to make sure the right chromosomes are passed on
Each diploid cell has _____ chromosomes, _____ from the sperm and _____ from the egg
There are _____ pairs of chromosomes, called __________________________________
1 member of the pair is ____________, 1 member of the pair is ______________
Each member of the pair has the gene that codes for the same genetic trait
Eye color from Dad, Eye color from Mom = combination makes You
It is on the exact same location on both chromosomes
When you go to make your gametes, you can only pass down _____ member of the pair
Meiosis makes sure that the homologous pairs __________________ so this happens
Meiosis is similar to Mitosis – the names of the stages are the same
Interphase occurs before Meiosis – just like before Mitosis the chromosomes replicate
Each member of the homologous pair has _____ chromatids
And different – there are _____ stages to Meiosis and the daughter cells will not be identical
Stages of Meiosis I
Prophase I
Chromosomes condense, nuclear envelope and nucleolus break down, spindle forms
Homologous Pairs find each other by undergoing ____________________ and forming a
____________________ - named because of the four chromatids together
Non-sister chromatids may become entangled and exchange genetic material
This process is called _________________________, and the place where it
takes place is called a ____________________
Since the genes code for the same trait, no genes are lost and the chromosome is not
damaged but the sister chromatids are no longer ____________________
DRAW
(You do not need to know about Prometaphase in Meiosis. I have no idea why.)
Metaphase I
Homologous Pairs ____________________ line up at the metaphase plate
This process is called ______________________________
and also ensures that the daughter cells are not identical
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Anaphase I
The Homologous Pairs or _______________ separate and each moves towards a pole
Note that the chromosomes still have 2 ____________________ but they are no longer
sister chromatids because they are no longer ____________________
DRAW
Telophase I
This stage does not always occur, but if it does it proceeds just as Telophase of Mitosis
The difference is that there are now _______________ and they are _______________
If ____________________ occurs, then there may be a resting phase called:
But the nuclei may not re-form, the spindle may not break down, etc…
DRAW
Stages of Meiosis II
Prophase II
Chromosomes condense, nuclear envelope and nucleolus break down, spindle forms
Each daughter cell has _______ chromosomes. The cells are ____________________,
but each chromosome has _________________________
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Metaphase II
Chromosomes line up ____________________ on the metaphase plate
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Anaphase II
___________________ divide, _____________ sets of chromosomes move to the poles
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Telophase II
Spindle fibers break down, nucleus and nucleolus reform, chromosomes relax
______________________ occurs along with Telophase II, creating _____ daughter cells
Daughter cells are _______________ and genetically _______________ from the parent
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The Human Life Cycle
Requires both ____________________ and ____________________
In males, __________ is formed via ______________________________, which results in ___
sperm cells per round of meiosis
In this process, a ____________________ spermatocyte with 46 chromosomes divides
into a ____________________ spermatocyte in Meiosis I
It continues to divide into 4 spermatids with _____ chromosomes during Meiosis II.
Males produce sperm for a great deal of their lifetime while females have all of their
eggs by the time they are a three month old fetus.
In females, __________ are formed via _________________________
In this process, the primary ____________________ divides unequally to form a larger
____________________ oocyte and a smaller __________ body.
Females have unequal cytokinesis because females supply the zygote with all of the
other organelles while the males only supply the nuclear formation. These other
organelles help the embryo sustain itself until the ____________________ is formed.
The secondary oocyte goes into Meiosis II and stops at Metaphase II.
If the egg is fertilized by the sperm, it is sent through the rest of __________________,
resulting in a ____________________ egg and 2 more __________ bodies.
The end result is _____ egg cell and _____ polar bodies.
The polar bodies are a way to get rid of ____________________ chromosomes.
Why Meiosis and Why Sex?
Meiosis allows for a way to keep chromosome number constant in a species while continuing
the ______________________________
Meiosis gives us genetic variance through __________________ and ____________________
Sex allows for _________________________ which increases genetic variability even more
We must have variability in the genotype in order to react to variations in the environment
Cancer and the Cell Cycle
____________________ must be present for a cell to move on to Mitosis
This is how cell growth and division is regulated
Occasionally, the growth factors will not work properly and the cell is ______________
This results in uncontrolled growth and a mass of cells called a:
Cancer causing genes called _______________ code for these _______________ growth factors
______________________________ genes create proteins that combine with certain growth
factors to prevent the cancer from occurring
The immune system tries to get cancerous cells to die in a process called:
Cancerous tumors that are easily removed or treated are called:
Cancer may spread throughout the body in a process called _______________________
We call this cancer: