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