MEIOSIS MEIOSIS Mrs. Kolobaric Mrs. Kolobaric
MEIOSISMEIOSIS
Mrs. KolobaricMrs. Kolobaric
ReviewReview
What is the purpose of mitosis?What is the purpose of mitosis?
__________________________ __________________________
Cells ThemselvesCells Themselves
Every cell has its own life span, all Every cell has its own life span, all cells eventually die, so all of them cells eventually die, so all of them need to replicate (go through need to replicate (go through mitosis)mitosis)
Blood replaces all its cells in about 3 Blood replaces all its cells in about 3 monthsmonths
Lungs will replace themselves in 5 yearsLungs will replace themselves in 5 years Neurons, will neverNeurons, will never
Mitosis As a ReviewMitosis As a Review
Mitosis looks at _______ and _______ Mitosis looks at _______ and _______ of a single organismof a single organism
Also explains ___________ of single Also explains ___________ of single celled organismscelled organisms
An Issue?An Issue?
What is the problem with having What is the problem with having identical cells as organisms?identical cells as organisms?
Do you see a problem with having Do you see a problem with having identical organisms in the identical organisms in the populations?populations?
The Reality of ItThe Reality of It
Imagine a million Niki Minaj’sImagine a million Niki Minaj’s
I like her, she sings and raps well, I like her, she sings and raps well, but is there a problem, but is there a problem,
Is she perfect?Is she perfect? Susceptible to anything? Susceptible to anything?
The ProblemThe Problem
____________________________________________________________________ ____________________________________________________________________
Do we actually find populations that Do we actually find populations that are completely identical to each are completely identical to each other?other?
________________
What is the benefit of not What is the benefit of not being Identical?being Identical?
For ___________, reproduction went For ___________, reproduction went from asexual (mitosis), to sexual from asexual (mitosis), to sexual (which has a great deal of diversity)(which has a great deal of diversity)
__________ of the individual does not __________ of the individual does not matter, but survival of the __________ matter, but survival of the __________ doesdoes
Steps of MitosisSteps of Mitosis
What are the four steps? What What are the four steps? What happens in each?happens in each?
Prophase Prophase
Spindle Fibers Appear and Centrioles begin to Spindle Fibers Appear and Centrioles begin to move to the different polesmove to the different poles
MetaphaseMetaphase
Steps of Mitosis Steps of Mitosis Continued…Continued…
Anaphase Anaphase
TelophaseTelophase
Nuclear envelope reformsNuclear envelope reforms Cells begin to separate and become 2 different Cells begin to separate and become 2 different
identical cellsidentical cells
Cytokinesis Cytokinesis The 2 _________________ move apart and the cycle The 2 _________________ move apart and the cycle
begins againbegins again
Cell HistoryCell History
Historically, mitosis evolved before Historically, mitosis evolved before meiosismeiosis
So how are you created?So how are you created? Well you need a ______ and a _______Well you need a ______ and a _______
But….But….
How can a male with 46 How can a male with 46 chromosomes, and a female with 46 chromosomes, and a female with 46 chromosomes produce a child with 46 chromosomes produce a child with 46 chromosomes?chromosomes?
Half must come from the mother, and Half must come from the mother, and the other half must come from the the other half must come from the father to produce the babyfather to produce the baby
The baby will then grow using The baby will then grow using ______________________
Lets Get StartedLets Get Started
Who can tell me what the purpose of Who can tell me what the purpose of meiosis is?meiosis is?
The production of ________ in male and The production of ________ in male and _____ in female, sex cells are called _____ in female, sex cells are called ___________ ___________
Lets look at the process of creating the Lets look at the process of creating the sex cells happening in both males and sex cells happening in both males and females females
A ComparisonA Comparison
What happens to the genetic info What happens to the genetic info before mitosis begins?before mitosis begins? It is replicated, two identical It is replicated, two identical
chromatids on the chromosomeschromatids on the chromosomes Well the same thing happens in meiosisWell the same thing happens in meiosis
A ComparisonA Comparison
The process of meiosis is a modified The process of meiosis is a modified process of mitosisprocess of mitosis
The First StepThe First Step
We have duplicated genetic info going We have duplicated genetic info going into the first stage of gamete productioninto the first stage of gamete production
What did we call the first stage of mitosis?What did we call the first stage of mitosis? ____________________________
What do you think we are going to call the What do you think we are going to call the first step in meiosisfirst step in meiosis ________________________________________
The First Step…The First Step…
What happens in prophase of mitosisWhat happens in prophase of mitosis The genetic info condenses into visible The genetic info condenses into visible
chromosomes chromosomes The nuclear envelope disappears The nuclear envelope disappears The Centrioles move apart and start to The Centrioles move apart and start to
form spindle fibresform spindle fibres
It happens in meiosis as wellIt happens in meiosis as well
Starts to Disappear
The Second StepThe Second Step
What happens in mitosis during What happens in mitosis during metaphasemetaphase
Chromosomes line up in the equator of the cell Chromosomes line up in the equator of the cell and each chromosome connects to the spindle and each chromosome connects to the spindle fibresfibres
Here is where meiosis starts to changeHere is where meiosis starts to change
If we are talking about a human, how If we are talking about a human, how many spindle fibres do we have in many spindle fibres do we have in mitosismitosis
46, one for each duplicated chromosome46, one for each duplicated chromosome
The Second StepThe Second Step
In meiosis, what are we trying to In meiosis, what are we trying to make?make?
sex cells, but when fertilization takes place, sex cells, but when fertilization takes place, the genetic material is donated half from the genetic material is donated half from mom, and half from dad, so we are trying to mom, and half from dad, so we are trying to make cells with half the genetic materialmake cells with half the genetic material
So how many spindle fibres form in a So how many spindle fibres form in a
meiotic cellmeiotic cell ____________
Lets back track a BitLets back track a Bit
Because the spindle is forming with Because the spindle is forming with 23 fibres only, and in a human cell 23 fibres only, and in a human cell there are 46 chromosomes, the 46 there are 46 chromosomes, the 46 need to pair up the chromosomesneed to pair up the chromosomes
They do this with their "look alike They do this with their "look alike partner“partner“
What do you think i mean by the What do you think i mean by the words “look alike” partner?words “look alike” partner?
Why You Look Like ThatWhy You Look Like That
Every sexually reproducing organism Every sexually reproducing organism gets _____of its genetic information from gets _____of its genetic information from one parent, and _____ from the otherone parent, and _____ from the other
So which parent gives you the information for So which parent gives you the information for hair color?hair color?
Eye colour?Eye colour? Height?Height?
In actuality, you get this from both In actuality, you get this from both parents equallyparents equally
Why You Look Like ThatWhy You Look Like That
If that comes from both parents, we If that comes from both parents, we need some genetic information from need some genetic information from dad, and one from mom, dad, and one from mom,
Does it have to be the same Does it have to be the same information?information?
Why You Look Like ThatWhy You Look Like That Example, what if mom’s genes says blue, Example, what if mom’s genes says blue,
and dad’s genes said brown eyes?and dad’s genes said brown eyes?
The information can be different, but its The information can be different, but its still information about eye colour. still information about eye colour.
So the “look alike” partners have So the “look alike” partners have information about the _______ _______, information about the _______ _______, but do not necessarily have the same but do not necessarily have the same identical information, they talk about the identical information, they talk about the same wordssame words
The Look AlikesThe Look Alikes
Look alike partners actually have a Look alike partners actually have a proper name proper name
______________ _______________________________ _________________
What does that mean?What does that mean?
What does that Mean?What does that Mean?
What does “homo” mean in Greek? What does “homo” mean in Greek? It means the ________It means the ________
What does “logos” mean in Greek?What does “logos” mean in Greek? It means ________It means ________
Homologous = the same words (or Homologous = the same words (or information)information)
Homologous Homologous ChromosomesChromosomes
Homologous chromosomes contain __________ Homologous chromosomes contain __________ information information
We can think of the genetic material as ____ We can think of the genetic material as ____ pairs of chromosomespairs of chromosomes
Each pair containing the _________ information. Each pair containing the _________ information.
___ is therefore called the _______ number___ is therefore called the _______ number
___ is called the _________ number ___ is called the _________ number
This will be important later on in our This will be important later on in our discussionsdiscussions
Back To ProphaseBack To Prophase
The “look alike” partners find each The “look alike” partners find each other, or the __________ chromosomes other, or the __________ chromosomes pair and they form what is called a pair and they form what is called a ____________
The process of coming together is The process of coming together is called _______, so when the process of called _______, so when the process of synapsis takes place, it forms tetradssynapsis takes place, it forms tetrads
Time for a Bio Break…for Time for a Bio Break…for MathMath
Lets pause for a second we need to Lets pause for a second we need to do some mathdo some math
lets take a look at an organisms that lets take a look at an organisms that has one pair of chromosomes has one pair of chromosomes
How many ways can u arrange the 2 How many ways can u arrange the 2 chromosomes when they pair up, chromosomes when they pair up, lets call one mom and one dad?lets call one mom and one dad?
Two ways first one can be mom, and then Two ways first one can be mom, and then dad, the second can be dad and then momdad, the second can be dad and then mom
Time for a Bio Break…for Time for a Bio Break…for MathMath
Now, lets double Now, lets double the number of the number of chromosomes to chromosomes to two pairstwo pairs
How many ways How many ways can you arrange 2 can you arrange 2 pairs?pairs?
mom dadmom dad
mom dadmom dadmom dadmom dad
dad momdad mom
dad momdad mom
dad momdad momdad momdad mom
mom dadmom dad
Time for a Bio Break…for Time for a Bio Break…for MathMath
What about 3 sets of chromosomesWhat about 3 sets of chromosomes 8 different ways8 different ways
What is the relationship?What is the relationship? # of combinations = 2# of combinations = 2nn
(n=number of chromosome pairs)(n=number of chromosome pairs)
Time for a Bio Break…for Time for a Bio Break…for MathMath
How many different combinations How many different combinations are there for 23 pairs?are there for 23 pairs?
222323
222323 = 8,388,608 = 8,388,608
Well hold on a second, its not a big Well hold on a second, its not a big number. How many people do we number. How many people do we have on the planet?have on the planet?
The TrickThe Trick
6.5 billion, and I will bet, that no two 6.5 billion, and I will bet, that no two individuals are identical except for individuals are identical except for identical twins, triplets etc, and there identical twins, triplets etc, and there are not that many of themare not that many of them
So variation in the genetic information So variation in the genetic information can not only be due to the way the can not only be due to the way the chromosomes line up, there must be a chromosomes line up, there must be a way to mix up the genetic information way to mix up the genetic information furtherfurther
The TrickThe Trick
We have to look closer at the tetradWe have to look closer at the tetrad As the chromosomes of the tetrad As the chromosomes of the tetrad
come together in synapsis, is there a come together in synapsis, is there a possibility that the 2 chromatids that possibility that the 2 chromatids that are on the inside may lie across each are on the inside may lie across each other?other?
YES! That is a possibilityYES! That is a possibility
The TrickThe Trick Well what if identical Well what if identical
segments from dad and segments from dad and moms chromosomes moms chromosomes were exchanged?were exchanged?
Now you have ________ Now you have ________ diversity, this event is diversity, this event is called a ____________called a ____________
It is a physical exchange It is a physical exchange of identical piecesof identical pieces
Where it happensWhere it happens
Does it have to happen at the same Does it have to happen at the same place?place?
EpiphanyEpiphany No wonder we have so many No wonder we have so many
different people on the planet with different people on the planet with different genetic make ups.different genetic make ups.
We can have hundreds of thousands We can have hundreds of thousands of cross over spots which gives us a of cross over spots which gives us a lot more variationlot more variation
MetaphaseMetaphase Lets move on to Lets move on to
metaphase, metaphase, How many spindle fibres How many spindle fibres
did we say will form?did we say will form? 23, one for each pair of 23, one for each pair of
pair homologous pair homologous chromosomes, chromosomes,
Unlike metaphase of Unlike metaphase of mitosis, the chromosomes mitosis, the chromosomes line up as _________ pairs, line up as _________ pairs, not in single filenot in single file
AnaphaseAnaphase What happens in anaphase What happens in anaphase
of mitosis?of mitosis? the individual chromatids are the individual chromatids are
pulled apart by the pulled apart by the shortening of the spindle shortening of the spindle fibresfibres
Think about a rope tug of Think about a rope tug of war between the 2 war between the 2 CentriolesCentrioles
Homologous pairs lined up Homologous pairs lined up in meiosis are pulled apart in meiosis are pulled apart to opposite ends of the cellto opposite ends of the cell
Daughter CellsDaughter Cells
How many chromosomes does each How many chromosomes does each daughter cell have?daughter cell have?
______________________________________________________________
Remember the diversity, tons of Remember the diversity, tons of combinations, but what we have done is combinations, but what we have done is taken 46 chromosomes and created 2 taken 46 chromosomes and created 2 cells with 23 cells with 23 duplicatedduplicated chromosomes, chromosomes,
The major StepThe major Step
Since 46 chromosomes Since 46 chromosomes became 23 became 23 duplicated duplicated chromosomes, this chromosomes, this particular process is particular process is going to be called the going to be called the _________ ________ after _________ ________ after telophase is completedtelophase is completed
Telophase is the same Telophase is the same as in mitosisas in mitosis
Are We Done?Are We Done?
We have taken the diploid number We have taken the diploid number ____, and reduced it to the haploid ____, and reduced it to the haploid number___number___
Do you see any issues with these 2 Do you see any issues with these 2 product cells?product cells?
Each of the chromosomes is still Each of the chromosomes is still _________, and contains _______the _________, and contains _______the genetic information, therefore we genetic information, therefore we must separate the copies.must separate the copies.
Another DifferenceAnother Difference
Meiosis has to go through the Meiosis has to go through the process again to _________ the process again to _________ the __________ in each chromosome.__________ in each chromosome.
All we do is repeat prophase, All we do is repeat prophase, metaphase, anaphase and telophase metaphase, anaphase and telophase the same as mitosis, except with half the same as mitosis, except with half the number of chromosomesthe number of chromosomes
The Second PhaseThe Second Phase
The Second PhaseThe Second Phase
How we distinguish How we distinguish
MEIOSIS 1MEIOSIS 1 MEIOSIS 2MEIOSIS 2
Prophase 1Prophase 1 Prophase 2Prophase 2
Metaphase 1Metaphase 1 Metaphase 2Metaphase 2
Anaphase 1Anaphase 1 Anaphase 2Anaphase 2
Telophase 1Telophase 1 Telophase 2Telophase 2
The Final TallyThe Final Tally
Mitosis produces _____ _________ Mitosis produces _____ _________ daughter cells (_________), daughter cells (_________),
Meiosis 1 produces ___ daughter cells Meiosis 1 produces ___ daughter cells with __ _____________ chromosomeswith __ _____________ chromosomes
Meiosis 2 _________ the duplicated Meiosis 2 _________ the duplicated chromosomes to a total of ___daughter chromosomes to a total of ___daughter cells with a _________ # of cells with a _________ # of chromosomeschromosomes
But aren't there 2 Kinds?But aren't there 2 Kinds?
All organisms produce 2 types of sex All organisms produce 2 types of sex cells, male produces ______ and cells, male produces ______ and female, ______.female, ______.
There are differences in the two There are differences in the two processes that produces these 2 processes that produces these 2 types of gametes, lets look at themtypes of gametes, lets look at them
SpermatogenesisSpermatogenesis Proceed through meiosis stage 1 and Proceed through meiosis stage 1 and
2 as described and at the end, 2 as described and at the end, we end up with 4 haploid cells that we end up with 4 haploid cells that
are all the same _____ that contain are all the same _____ that contain _____ the number of chromosomes _____ the number of chromosomes
Due to cross over they are ____ Due to cross over they are ____ different, different,
SpermatogenesisSpermatogenesis
These cells will then These cells will then continue to mature inside the continue to mature inside the _______ _______ growing a _____ for propulsion, growing a _____ for propulsion, a mid piece containing ________ a mid piece containing ________
to provide the energy for to provide the energy for movement, movement,
Package of ________ at the tip Package of ________ at the tip called the _________ which called the _________ which allows the sperm to penetrate allows the sperm to penetrate the outer layers of the egg and the outer layers of the egg and form a tunnel, for fertilizationform a tunnel, for fertilization
Oogenesis Oogenesis
Oogenesis is different in the sense Oogenesis is different in the sense that an ____ has to go through a that an ____ has to go through a large number of divisions before it large number of divisions before it _______ in the uterus and receives _______ in the uterus and receives nutrients from the mothernutrients from the mother
The egg must be ______ and contain The egg must be ______ and contain a large quantity of _________. a large quantity of _________.
OogenesisOogenesis The first difference occurs in __________, The first difference occurs in __________,
there is an _______ split of the cytoplasm there is an _______ split of the cytoplasm where one of the 2 cells gets the where one of the 2 cells gets the majority (_____) and the other cell gets majority (_____) and the other cell gets __________
even though the small cell has correct even though the small cell has correct genetic information, it does not have genetic information, it does not have enough _______ to become an eggenough _______ to become an egg
It is called a _______ ________ It is called a _______ ________
OogenesisOogenesis
These two cells go through meiosis 2 These two cells go through meiosis 2 The polar body splits into 2 small polar The polar body splits into 2 small polar
bodiesbodies
The large cell splits unevenly to The large cell splits unevenly to produce the egg and one polar bodyproduce the egg and one polar body
The egg matures just like the sperm The egg matures just like the sperm did, but in the ovary and released did, but in the ovary and released during ovulationduring ovulation