Bell Work: Bell Work:

1/30/121/30/12Draw the Draw the three pictures three pictures and explain and explain why the third why the third picture is picture is correct.correct.

Objectives• Describe the relationship among genes, Describe the relationship among genes,

chromosomes, and inherited traits. chromosomes, and inherited traits. (SPI 0707.4.3) (SPI 0707.4.3)

• Sequence a series of diagrams that Sequence a series of diagrams that depict chromosome movement during depict chromosome movement during plant cell division. (SPI 0707.1.4)plant cell division. (SPI 0707.1.4)

• Classify methods of reproduction as Classify methods of reproduction as sexual or asexual. (SPI 0707.4.1) sexual or asexual. (SPI 0707.4.1)

Mitosis ReviewMitosis Review1.1. Interphase- DNA is copiedInterphase- DNA is copied

2.2. Prophase- Chromatin (DNA wrapped Prophase- Chromatin (DNA wrapped around protein) forms into chromatids around protein) forms into chromatids (rods)(rods)

3.3. Metaphase- Chromatids line up in the Metaphase- Chromatids line up in the middle of the cellmiddle of the cell

4.4. Anaphase- Chromatids separateAnaphase- Chromatids separate

5.5. Telophase- two new nuclei form around the Telophase- two new nuclei form around the chromatin (separated chromatids)chromatin (separated chromatids)

6.6. Cytokinesis- two new cells formCytokinesis- two new cells form

MitosisMitosis: : process of a process of a

somatic (body) cell somatic (body) cell dividing to produce dividing to produce

an exact copy of an exact copy of itselfitself

MitosisMitosisInterphaseInterphaseDNA copies DNA copies

itself itself (chromosomes (chromosomes are copied)are copied)

Centrioles copy Centrioles copy

MitosisMitosisProphaseProphaseDNA condenses into DNA condenses into

chromatids (rod-like chromatids (rod-like structures), held structures), held together by together by centromerescentromeres

Spindle fibers begin Spindle fibers begin to formto form

Centrioles move to Centrioles move to opposite sidesopposite sides

Nuclear membrane Nuclear membrane breaks apartbreaks apart

MitosisMitosisMetaphaseMetaphase

Chromatids Chromatids (chromosomes) (chromosomes) line up across line up across the center of the the center of the cellcell

Spindle fibers Spindle fibers attach to the attach to the centromerecentromere

MitosisMitosisAnaphaseAnaphase

Spindle fibers Spindle fibers pull the pull the chromatids to chromatids to opposite ends opposite ends of the cellof the cell

MitosisMitosisTelophaseTelophase

Nucleus forms Nucleus forms around the around the chromatidschromatids

Chromosomes Chromosomes unwindunwind

MitosisMitosisCytokinesisCytokinesisDivision of Division of

the the cytoplasm cytoplasm and the rest and the rest of the cellof the cell

FYI: ChromosomesFYI: Chromosomes Human body cells have 46 Human body cells have 46

chromosomes, or 23 pairs chromosomes, or 23 pairs of chromosomes.of chromosomes.

Each chromosome contains Each chromosome contains certain types of genes. certain types of genes.

For example, chromosome For example, chromosome 21 codes for Down 21 codes for Down Syndrome, or Trisomy 21. Syndrome, or Trisomy 21.

A sex cell is produced with an A sex cell is produced with an extra copy of chromosome 21; extra copy of chromosome 21; the gamete thus has 24 the gamete thus has 24 chromosomes. When combined chromosomes. When combined with a normal gamete from the with a normal gamete from the other parent, the embryo now other parent, the embryo now has 47 chromosomes, with three has 47 chromosomes, with three copies of chromosome 21.copies of chromosome 21.

MeiosisMeiosisIn In sexual reproductionsexual reproduction, two , two parent cells join together to parent cells join together to

form offspring that are form offspring that are different from both parents.different from both parents.These parent cells are called These parent cells are called

sex cells sex cells (sperm & egg).(sperm & egg).Sex cells are made during Sex cells are made during

meiosismeiosis..

MeiosisMeiosisprocess of a cell process of a cell

dividing to produce dividing to produce 44 cells with half the cells with half the genetic materialgenetic material

Why do the cells produced in Why do the cells produced in meiosis only need half of the genetic meiosis only need half of the genetic

material?material?

MeiosisMeiosisInterphase IInterphase IDNA DNA copiescopies

itself itself (chromosomes (chromosomes are copied)are copied)

CentriolesCentrioles copy copy

MeiosisMeiosisProphase IProphase I

DNA DNA condenses condenses into into chromatidschromatids, , held together by held together by centromeres and centromeres and attach to the attach to the membranemembrane

Spindle fibers begin Spindle fibers begin to formto form

Centrioles move to Centrioles move to opposite sidesopposite sides

Nuclear membraneNuclear membrane breaks apartbreaks apart

MeiosisMeiosisMetaphase IMetaphase IChromatids Chromatids line line

upup on each side on each side of the of the centercenter of of the cellthe cell

Spindle fibers Spindle fibers attach to the attach to the centromerecentromere

Meiosis is a bit different because there something called crossing-over happens with the DNA.

This crossing over is an exchange of genes. The genes are mixed up, not resulting in a perfect duplicate like mitosis.

MeiosisMeiosisAnaphase IAnaphase ISpindle fibers Spindle fibers

pull the pull the chromosome chromosome pairs pairs apartapart to to oppositeopposite ends of the ends of the cellcell

MeiosisMeiosisTelophase ITelophase INucleusNucleus forms forms

around the around the chromosomeschromosomes

MeiosisMeiosisCytokinesisCytokinesisDivisionDivision of of

the the cytoplasmcytoplasm and the rest and the rest of the cellof the cell

MeiosisMeiosisInterphase IIInterphase IICell restsCell restsDNA DOES DNA DOES

NOTNOT duplicateduplicate

Centrioles Centrioles duplicateduplicate

MeiosisMeiosisProphase IIProphase IIDNA condenses DNA condenses into into

chromatidschromatids, held , held together by together by centromerescentromeres

Spindle fibers begin Spindle fibers begin to formto form

Centrioles move to Centrioles move to opposite sidesopposite sides

Nuclear membrane Nuclear membrane breaks apartbreaks apart

MeiosisMeiosisMetaphase IIMetaphase IIChromosomeChromosomes s

line up across line up across the center of the center of the cellthe cell

Spindle fibers Spindle fibers attach to the attach to the centromerecentromere

MeiosisMeiosisAnaphase IIAnaphase IISpindle fibers Spindle fibers

pullpull the the chromatids chromatids to opposite to opposite ends of the ends of the cellcell

MeiosisMeiosisTelophase IITelophase IINucleusNucleus forms forms

around the around the chromatidschromatids

Chromosomes Chromosomes unwindunwind

MeiosisMeiosisCytokinesisCytokinesisDivisionDivision of of

the the cytoplasmcytoplasm and the rest and the rest of the cellof the cell

Mitosis vs. MeiosisMitosis vs. Meiosis

Mitosis Meiosis

•Both are processes of cell division•Both reproduce new cells•Both go through Interphase, Prophase, Metaphase, Anaphase, Telophase, & Cytokinesis

•Asexual cell reproduction (only one parent cell is needed)•Produces an exact copy of itself with 46 chromosomes•Reproduces two new cells•Somatic cells: body cells (skin cells, blood cells, bone cells, muscle cells)

•Sexual cell reproduction (two parent cells are needed)•Produces cells with half as many chromosomes (23)•Reproduces four new cells•Sex cells (sperm & egg)

Sex Chromosome:Sex Chromosome:Chromosome 23 (XX or XY)Chromosome 23 (XX or XY)

xx

Determining the Sex or Gender of Offspring

• Sex chromosomes carry genes that determine the sex or gender of offspring.

• In humans, females have two X chromosomes and males have one X and one Y chromosome.

• During meiosis, one of each of the chromosome pairs ends up in a sex cell.

• Baby boy= XY• Baby girl= XX• Example:

Living Things Reproduce

2 Types of Reproduction:2 Types of Reproduction:

AsexualAsexual- a single parent produces an - a single parent produces an offspring identical to the parentoffspring identical to the parent

SexualSexual- two parents produce an - two parents produce an offspring with traits of both parentsoffspring with traits of both parents

Challenge QuestionsChallenge Questions1.1. When animals go through sexual When animals go through sexual

reproduction, what type of cell division reproduction, what type of cell division are they going through?are they going through?

– meiosismeiosis

2.2. When animals go through asexual When animals go through asexual reproduction, what type of cell division reproduction, what type of cell division are they going through?are they going through?

– mitosismitosis

Types of Asexual Reproduction In Animals

• BuddingBudding: happens : happens when a part of the when a part of the parent organism parent organism pinches off and forms pinches off and forms a new organism.a new organism.

• The new organism The new organism separates from the separates from the parent and lives parent and lives independently.independently.– Jellyfish & hydraJellyfish & hydra

Types of Asexual Reproduction In Animals

• FragmentationFragmentation: : parts of the parts of the organism break organism break off and a new off and a new organism grows organism grows identical to the identical to the parent. parent.

– Worms & Worms & starfishstarfish

Types of Asexual Reproduction In Animals

• RegenerationRegeneration: : organism loses a organism loses a body part and body part and that part may that part may develop into a develop into a new organism.new organism.

– Sea starSea star

Asexual Reproduction in Other Organisms

• Binary fission Binary fission is a is a method of asexual method of asexual reproduction in reproduction in which an organism which an organism splits into two. splits into two.

• This occurs in This occurs in bacteriabacteria and other and other single-celled single-celled organismsorganisms

Asexual Reproduction in PlantsAsexual Reproduction in Plants

• Some plants can reproduce asexually Some plants can reproduce asexually when they are cut or damaged. These when they are cut or damaged. These plants can sprout new growth from plants can sprout new growth from their their roots, stems, and leavesroots, stems, and leaves. .

• In wild strawberry plants, stems are In wild strawberry plants, stems are capable of arching downward and capable of arching downward and taking root in the ground, resulting in taking root in the ground, resulting in the formation of a new plant. This is an the formation of a new plant. This is an example of example of asexual reproductionasexual reproduction. .

3-2-1 Reflection3-2-1 Reflection

3 differences between mitosis and 3 differences between mitosis and meiosismeiosis

2 different types of asexual reproduction2 different types of asexual reproduction

1 way this relates to your life (real world) 1 way this relates to your life (real world)