Cell Division Chapter 2 Section 3

Cell Division

• The Regular sequence of growth and division that cells undergo is known as the_______________.

• The three main stages of the cell cycle are:• Interphase • Mitosis • Cytokinesis

Cell Cycle

The Cell Cycle

Interphase

• What three things occur during Interphase?

• The cell grows• The cell makes a copy of its DNA• The cells prepares to divide into two cells.

Replication of DNA

• What is replication?• The process by which

the cell makes an exact copy of the DNA inside of the nucleus.

Chromatin

Cell Division

• The second stage of the cell cycle during which the cell's nucleus divides int two new nuclei is called ______________.Mitosis

Mitosis

• Mitosis is divided into the following four phases:

Prophase Metaphase Anaphase Telophase

Mitosis - Prophase

______________ condenses and coils – looks like rods.

Chromatin

Mitosis - Prophase

Chromatid

Chromatid

Centromere

Each doubled rod of condensed chromatin is called a _______________ and held together by a _______________.

Each single strand of the chromosome is called a ____________.

Chromosome

Centromere

Chromatid

Mitosis - Prophase

• The __________________ beaks down• Spindle fibers from a bridge (attached to the

centrioles).

nuclear envelope

Centrioles

Spindle fibers Nuclear envelope

Mitosis - Metaphase

• ______________ line up across the center of the cell.

• Each chromosome attaches to a spindle fiber at its ___________

centriole

Spindle fibers

Chromosome

Chromosomes

centromere

Mitosis - Anaphase

• _____________ split. • Two __________ separate.• _____________ move to

the opposite ends of the cell.

• Cell stretches out.

centriole

Spindle fibers

Separating chromatids

Centromeres

ChromatidsChromatids

Mitosis - Telophase

• ____________ unwind and lose their rod-like appearance

• New ______________ forms around each region of chromosomes

• Cell membrane starts to pinch inward.

Chromosomes

nuclear envelopes

New nuclear membrane forms

Chromosomes unwind

Cell membrane pinches inward

Cell Division – Final Stage

• The final stage of the cell cycle that follows mitosis is called _____________.

• _____________ are distributed between the two new cells, called daughter cells

• At the end of cytokinesis, new cells enter _____________ and the cycle begins again.

cytokinesisorganelles

Interphase

Cytokinesis in animal vs. plant cells

• In animal cells:• The _______________ squeezes together

around the middle of the cell and the ___________ pinches into two new cells.

• In Plant cells• A ___________ forms across the middle of

the cell and develops into new cell membrane.• Then new ____________ form around the cell

membrane

cell membrane

cytoplasm

cell plate

cell walls

Cytokinesis

Animal Cell Plant Cell

Mitosis Animation

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

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html

Length of the cell cycle

• Varies for different organisms.

• Can range from ____hours to ____ hours.

• Nerve, heart, and _______ cells never divide. They remain in interphase for as long as they live.

• Cancer cells divide rapidly.

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brain

DNA Structure

• DNA replication ensures that:• The replication process ensures that each

new daughter cell will have a complete set of DNA which it needs to carry out all the cell’s activities.

The Discovery of the Structure of DNA

James Watson and Fransis CrickRosalind Franklin

DNA Structure

• DNA looks like a twisted ladder and is often called a ________________.double helix

DNA Structurea. The sides of the ladder are made up of molecules

of ______________ called ______________ that are alternating with molecules of phosphate.

sugar deoxyribose

DNA Structure

• Ladder rungs are made up of a pair of molecules called nitrogen bases (containing nitrogen and other elements). The four nitrogen bases are:

o ____________________(A)o ____________________(T)o ____________________(G)o ____________________(C)

Adenine

Thymine

Guanine

Cytosine

DNA Structure

• How do the nitrogen bases pair up to make the rungs of the DNA ladder?

o ______________ pairs only with _______________

o ______________ pairs only with _______________

Adenine Thymine

Cytosine Guanine

Nitrogen Base Pairing

DNA Replication

• DNA molecule unwinds and separates between the nitrogen bases on each rung.

• ____________________ that are floating in the nucleus pair up with each half (A with T and G with C)

• Two new DNA molecules are formed• The order of nitrogen bases in each new

DNA molecule will exactly match the order in the original DNA molecule.

Nitrogen bases

DNA Replication

http://www.youtube.com/watch?v=hfZ8o9D1tus

Cancer• Cancer is a disease in which:

• Cells grow and divide uncontrollably, damaging the parts of the body around them.

• Cancer can occur when something damages a portion of DNA in a chromosome. This damage causes a change in DNA called _____________.mutation

Cancer

• Abnormal cells that develop uncontrollably may form a mass of abnormal cells which is called a _________________.

• Treatment for cancer include _____________, ________________ and or ____________________

tumor

surgery radiation

Drugs (chemotherapy)