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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.
2 22
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)
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