Cell Reproduction Page #1 Warm Up Where are your genes located?

transcript

Cell ReproductionPage #1

Warm Up

Where are your genes located?

http://people.na.infn.it/~nicodem/research/cell_genes.jpg

•DURING MOST OF THE CELL’S LIFE, DNA FORMS A TANGLED MASS CALLED CHROMATIN.

•CHROMATIN LOOKS LIKE A PLATE OF SPAGHETTI.

•RIGHT BEFORE A CELL DIVIDES, THE CHROMATIN FORMS INTO CHROMOSOMES

(X-SHAPED).

MOST OF THE TIME ONCE IN A WHILE

CHROMATIN CHROMOSOMES

Cell Division

• Chromosomes = Tightly coiled, rod-shaped DNA• Chromosomes are made of chromatin• Human body produces 2 trillion cells per day & 25

million per second• Cells are formed by cell division of older cells

1. When a cell divides, DNA is first copied & then distributed

2. Each cell ends up with a complete set of DNA

Chromosome Number

• Each human somatic cell has 2 copies of 23 different chromosomes – Total 46– Somatic = any cell that is NOT a sex cell– (also called body cells or autosomes)

Sets of Chromosomes

• Each pair is made up of 2 homologous chromosomes– Homologous chromosomes = chromosomes that are similar

in size, shape, & genetic content

– Each homologue comes from one of the parents• One from mom

• One from dad

Cells Can Be Diploid or Haploid

• Diploid = a cell that contains 2 sets of chromosomes (2n)

• Haploid (monoploid) = a cell that contains only 1 set of chromosomes (1n or n)

Chromosomes Determine Your Gender

• Humans have 23 pairs of chromosomes

• 22 pairs are autosomes (chromosomes NOT directly involved in determining sex)

• 1 pair are sex chromosomes (contain genes that WILL determine the sex)– X & Y chromosomes

X & Y Chromosomes

• Male = XY• Female = XX• Male (dad) can donate an X or a Y to

offspring• Female (mom) can ONLY donate an X

So-Which parent determines the sex of the baby?

MALEXY

Gametes

• Gametes are reproductive cells– Males = sperm (n = 23)– Female = egg (n = 23)

• Combine in fertilization to make a: – Zygote (2n = 46)

Haploid VS Diploid

Page #2

““UnderstandingUnderstandingthe concepts ofthe concepts of

Haploid and Haploid and Diploid”Diploid”

Haploid and DiploidHaploid and Diploid

Introducing VocabularyIntroducing Vocabulary

Diploid= DIH – Diploid= DIH – ploydployd

Haploid= HA – Haploid= HA – ploydployd

Let’s take a look at the terms first….Let’s take a look at the terms first….

Diploid= Diploid= Di Di Ploid Ploid““DiDi” means “” means “twotwo””

Let’s take a look at the terms first….Let’s take a look at the terms first….

Haploid= Haploid= HaHa Ploid Ploidthink “think “HAHAlf”lf”

haploidhaploid is is half half of diploid.of diploid.

ReviewReview

““DiploidDiploid” means” means

Half Two

ReviewReview

““HaploidHaploid” means” means

Half Two

GOOD JOB !!!GOOD JOB !!!

You’re on the way !!!You’re on the way !!!

Introducing VocabularyIntroducing Vocabulary

Gamete= GA - Gamete= GA - meatmeat

Somatic= So-MA-Somatic= So-MA-tiktik

A A “Gamete”“Gamete” is a is a generic term for a generic term for a

“sex cell”.“sex cell”. An example would be An example would be

a a spermsperm or an or an eggegg..

Gametes areGametes are HaploidHaploid in in

chromosome chromosome number.number.

The The numbernumber of of chromosomes that a chromosomes that a

gamete gamete would contain would contain would be would be described described

as______as______

Haploid Diploid

““Somatic cellsSomatic cells” ” refers to refers to every every otherother cell cell in the in the

body body exceptexcept gametes.gametes.

ReviewReview

SpermSperm or or EggEgg = = GametesGametesAll All Other Other cells = cells = SomaticSomatic

CellsCells

Gamete or Somatic Cell ?Gamete or Somatic Cell ?

A Liver CellA Liver Cell

GameteSomatic

A Sperm CellA Sperm Cell

GameteSomatic

A Brain CellA Brain Cell

GameteSomatic

A Lung CellA Lung Cell

GameteSomatic

An EggAn Egg

GameteSomatic

A Skin CellA Skin Cell

GameteSomatic

Keep Going !!!Keep Going !!!

HAlf way There !!!HAlf way There !!!

Somatic Cells Somatic Cells areare DiploidDiploid in in chromosome chromosome

number.number.

The The numbernumber of of chromosomes that a chromosomes that a somatic cell somatic cell would would contain would be contain would be described as______described as______

Haploid Diploid

ReviewReview

Gametes =Gametes = haploid haploidSomatic Cells = Somatic Cells =

diploiddiploid

Mathematically SpeakingMathematically Speaking

if if haploid=nhaploid=n,,then then diploid=2ndiploid=2n

Mathematically Mathematically SpeakingSpeaking

or… or… haploid is haploid is ½½ of of diploiddiploid

or… or… diploid is diploid is 2x2x haploid haploid

ReviewReview

SpermSperm or or EggEgg = = GametesGametes==HaploidHaploid==nnAll All Other Other Cells = Cells = SomaticSomatic CellsCells==DiploidDiploid==2n2n

Humans have Humans have 4646 chromosomes in their chromosomes in their somatic cellssomatic cells. These . These

cells are cells are ____________

Haploid Diploid

Humans have Humans have 2323 chromosomes in their chromosomes in their gametesgametes. These cells . These cells

are are ____________

Haploid Diploid

IfIf humans humans diploiddiploid number = number = 4646, what , what

is the is the haploidhaploid number?number?

IfIf humans humans haploidhaploid number = number = 2323, what , what

is the is the diploiddiploid number?number?

IfIf chimps chimps diploiddiploid number = number = 4848, what , what

is the is the haploidhaploid number?number?

IfIf chimps chimps haploidhaploid number = number = 2424, what , what

is the is the diploiddiploid number?number?

Review AgainReview Again

Sperm or Egg = Gametes=Haploid= Sperm or Egg = Gametes=Haploid= nnAll Other Cells = Somatic Cells=Diploid= All Other Cells = Somatic Cells=Diploid= 2n2n

IfIf humans humans diploiddiploid number = number = 4646,, How many How many

chromosomes in achromosomes in a liverliver cell ? cell ?

chromosomes in a chromosomes in a spermsperm cell ? cell ?

chromosomes in achromosomes in a brainbrain cell ? cell ?

chromosomes in achromosomes in a lunglung cell ? cell ?

chromosomes in an chromosomes in an eggegg cell ? cell ?

chromosomes in achromosomes in a skinskin cell ? cell ?

Up so far !!!Up so far !!!

ALMOST THERE !!!ALMOST THERE !!!

Review Last RoundReview Last Round

Sperm or Egg = Gametes=Haploid= Sperm or Egg = Gametes=Haploid= nnAll Other Cells = Somatic Cells=Diploid= All Other Cells = Somatic Cells=Diploid= 2n2n

If If chimp’schimp’s haploid haploid number = number = 2424,, How many How many

chromosomes in achromosomes in achimp’schimp’s liverliver cell ? cell ?

If If chimp’schimp’s haploid haploid number = number = 2424,, How many How many

chromosomes in achromosomes in achimp’schimp’s eggegg cell ? cell ?

If If Horse’sHorse’s diploid diploid number = number = 6464,, How many How many

chromosomes in achromosomes in aHorse’sHorse’s liverliver cell ? cell ?

If If Alligators’sAlligators’s diploid diploid number = number =

3232,, How many How many chromosomes in achromosomes in aAlligators’sAlligators’s liverliver

cell ?cell ?

If If Dog’sDog’s diploid diploid number = number = 7878,, How many How many

chromosomes in achromosomes in aDog’sDog’s spermsperm cell ? cell ?

http://www.goldiesroom.org/http://www.goldiesroom.org/Shockwave_Pages/REG-15-Shockwave_Pages/REG-15-haplodvdiploid.htmhaplodvdiploid.htm

Mitosis Animation Mitosis Animation

http://www.goldiesroom.org/http://www.goldiesroom.org/Shockwave_Pages/REG-14-tnm--Shockwave_Pages/REG-14-tnm--celldivision.htmcelldivision.htm

Page #3 Karyotype

• Karyotype = a photo of the chromosomes in a dividing cell that shows the chromosomes arranged by size.

Karyotype cont’d

• Each of an individual’s 46 chromosomes has thousands of genes so the presence of all chromosomes is essential for normal functioning– Humans who are missing a chromosome don’t

survive– Humans with more than two copies of a

chromosome, called trisomy, may survive but will not develop properly.

What is wrong?

The Cell Cycle

• Repeating sequence of cell growth and division during an organism’s life

• 90% of cell life is spent in INTERPHASE

• Then it may go into MITOSIS & CYTOKINESIS

INTERPHASE(divided into mini-phases)

• G1(first growth) phase = Cell grows rapidly

• S (synthesis) phase = DNA copied

• G2 (2nd growth) phase = Nucleus prepares to divide

http://publications.nigms.nih.gov/insidethecell/ch4_interphase_big.html

AFTER INTERPHASE

• Mitosis

• Cytokinesis

• http://www.cellsalive.com/cell_cycle.htm

Mitosis and Meiosis

WARM UP

Females are X___Males are X___

Having 3 copies of a chromosome is called a ______________

Mitosis and Meiosis

• Mitosis:-division of somatic (body) cells- results in two daughter cells that are identical

• Meiosis-division of gametes (sex cells)

Mitosis

• Interphase

• Prophase

• Metaphase

• Anaphase

• Telophase

The Cell Cycle is Carefully Controlled

• Key check points which feedback signals from the cell will delay the next step

• Controlled by proteins!

1. Cell Growth CHECKPOINT (G1) – Start – Nerve/muscle cells stop here

2. DNA Synthesis CHECKPOINT (G2) – Enzymes

3. Mitosis CHECKPOINT – Back to G1 phase

Page #4When Control is Lost -- Cancer

• Cancer = Cell growth is uncontrolled - does not respond to control mechanisms.

• Causes: Mutations that cause over-production of growth molecules – (accelerator) or by in-activating proteins that slow or stop the cell cycle (brakes)

• Tobacco and UV radiation linked to increased cancer risk.

Change in Chromosome Number

• Trisomy = humans with more than 2 copies of chromosomes – improper development

• Karyotype = a photo of the chromosomes in a dividing cell.

• Disjunction = when egg/sperm cells form – each chromosome and homologue separate – sometimes one or more chromosomes fail to separate - unequal distribution.

• Down Syndrome - 3 copies of chromosome 21- NONDISJUNCTION

Change in Chromosome Structure

• Mutation – A change in an organism’s chromosomal structure.

• Deletion = piece of chromosome breaks off completely – lacks of a set of genes – fatal

• Duplication = chromosome fragment attaches to its homologous chromosome –two copies of a gene set

• Inversion = chromosome piece reattaches to original chromosome, but in reverse orientation.

• Translocation = chromosome piece reattaches to a nonhomologous chromosome.

Interphase

• Interesting things happen!1. Cell preparing to divide2. Genetic material doubles

Prophase

• Chromosome pair up!1. Chromosomes thicken and shorten

-become visible-2 chromatids joined by a centromere

2. Centrioles move to the opposite sides of the nucleus

3. Nucleolus disappears

Metaphase

• Chromosomes meet in the middle!

1. Chromosomes arrange at equator of cell

2. Become attached to spindle fibres by centromeres

3. Homologous chromosomes do not associate

Anaphase

• Chromosomes get pulled apart1. Spindle fibres contract pulling

chromatids to the opposite poles of the cell

Telophase

• Now there are almost two!1. Chromosomes uncoil2. Spindle fibres disintegrate3. Centrioles replicate

Cytokinesis

• Cell splits

http://www.cellsalive.com/mitosis.htm

Metaphase

Telophase

Prophase

Anaphase

http://www.youtube.com/watch?v=HV5kPiDYC3M

Cell Reproduction Cell Reproduction Page #5Page #5

Warm UpWarm Up

List the stages of mitosis in orderList the stages of mitosis in order

IPMATIPMAT

MeiosisMeiosis

Meiosis = Meiosis = Cell divisionCell division that produces only that produces only haploid cells (half the number of haploid cells (half the number of chromosomes)chromosomes)Sex cells or gametesSex cells or gametesSpermatogenesisSpermatogenesisOogenesisOogenesis

Meiosis Occurs in Two StagesMeiosis Occurs in Two Stages

Meiosis IMeiosis I

Meiosis IIMeiosis II

Follows the same order as MITOSIS, but it Follows the same order as MITOSIS, but it does it does it TWICETWICE

Meiosis IMeiosis I

Homologous chromosomes Homologous chromosomes are separated into are separated into separate separate cells.cells.

Interphase IInterphase I

Cell doubles its DNA and Cell doubles its DNA and then doubles it againthen doubles it again

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Prophase IProphase I

Chromosomes formChromosomes formCrossing over takes placeCrossing over takes place

Crossing OverCrossing Over

Exchanging corresponding segments of Exchanging corresponding segments of DNADNA

Important because it gives a new Important because it gives a new combination of combination of genes.genes.

Crossing OverCrossing Overhttp://waynesword.palomar.edu/images/cross3.jpghttp://waynesword.palomar.edu/images/cross3.jpg

Metaphase IMetaphase I

Chromosomes line up Chromosomes line up in the in the middlemiddle..

Anaphase IAnaphase I

Chromosomes Chromosomes separateseparate

Telophase ITelophase I

Cell begins to divide Cell begins to divide & 2 new cells form & 2 new cells form (cytokinesis)(cytokinesis)

Each cell has Each cell has chromosomeschromosomes

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/Meiosis6.html

Meiosis IIMeiosis II

ChromatidsChromatids of each chromosome are of each chromosome are separated into separate cellsseparated into separate cells

http://botit.botany.wisc.edu/images/130/Meiosis/Lilium_microsporogenesis/Meiosis_II.html

Prophase IIProphase II

Chromosomes form in Chromosomes form in both cellsboth cells

Metaphase IIMetaphase II

Chromosomes line up Chromosomes line up along middle of cellalong middle of cell

Anaphase IIAnaphase II

Chromosomes Chromosomes separate and are separate and are pulled apart into pulled apart into chromatidschromatids

http://www.scq.ubc.ca/filter/wp-content/uploads/2007/10/sister-chromatid.gif

Telophase IITelophase II

Chromatids gather at Chromatids gather at ends of cellsends of cells

Cytokinesis occurs – Cytokinesis occurs – (cell splits apart)(cell splits apart)

End Result of Meiosis & End Result of Meiosis & CytokinesisCytokinesis

44 new cells each with new cells each with half as much half as much geneticgenetic info as the parentinfo as the parent

http://www.cellsalive.com/meiosis.htm

SpermatogenesisSpermatogenesis

http://www.soc.ucsb.edu/sexinfo/images/12-06-spermatogenesis.gif

OogenesisOogenesis

http://img.sparknotes.com/content/testprep/bookimgs/sat2/biology/0003/oogenesis.gif

Cell Reproduction Page #1 Warm Up Where are your genes located?

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