Download PPT NOTES_AP Biology Chapter 12 Notes

AP Biology Chapter 12 Notes
Mitosis
What you need to know…
• The structure of the replicated _________________________.
• The stages of __________________.
• The role of _____________________ and ________________________ in the regulation of the
cell cycle.
Cell Cycle
• In ________________________ organisms, division of one cell reproduces the entire organism
• Multicellular organisms depend on cell division for:
– __________________________ from a fertilized cell
– _______________________
– _______________________
Concept 12.1: Cell division results in genetically identical daughter cells
• Most cell division results in daughter cells with ___________________________________, DNA
• A special type of division (_____________________ - ch 13) produces nonidentical daughter cells
(gametes, or sperm and egg cells)
• All the DNA in a cell constitutes the cell’s ___________________
• genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of
DNA molecules (common in eukaryotic cells)
• DNA molecules in a cell are packaged into ________________________
• __________________________________ (nonreproductive cells) have two sets of chromosomes
• _________________________ (reproductive cells: sperm and eggs) have half as many
chromosomes as somatic cells
• Chromosomes
• Eukaryotic chromosomes consist of ______________________, a complex of DNA and
protein that condenses during cell division
• Each duplicated chromosome has two ________________________, which separate during
cell division
• The _________________________ is the narrow “waist” of the duplicated chromosome,
where the two chromatids are most closely attached
• Label the Picture
•

Eukaryotic cell division consists of:
o ______________________, the division of the nucleus
o ______________________, the division of the cytoplasm
Concept 12.2: The mitotic phase alternates with interphase in the cell cycle
 The cell cycle consists of
o ______________________ (M) phase (mitosis and cytokinesis)
o ______________________ (cell growth and copying of chromosomes in preparation for
cell division)
 Interphase (about 90% of the cell cycle) can be divided into subphases:
o ____________________ (“first gap”)
o ____________________ (“synthesis”)
o ____________________ (“second gap”)
 The cell grows during all three phases, but chromosomes are duplicated only during the S phase
 Label the Picture


5 Phases of Mitosis:
o Prophase
 __________________ becomes more tightly coiled into discrete chromosomes.
 Nucleoli disappear.
 Mitotic ____________________ (consisting of microtubules extending from the 2
centrosomes) begin to form in cytoplasm.
o Prometaphase
 _______________________ beings to fragment, allowing ____________________
to attach to chromosomes.
 2 ________________________ of each chromosome are held together by protein
kinetochores in centromere region.
 Microtubules will attach to kinetochores.
o Metaphase
 _______________________ move the chromosomes to the metaphase plate at the
__________________ of the cell. Microtubule complex is referred to as the spindle.
 _______________________ have migrated to opposite poles in the cell, riding
along the developing spindle.
o Anaphase


o Sister ______________________ begin in separate, pulled apart by motor molecules
interacting with kinetochore microtubules.
o The cell elongates, as the nonkinetochore microtubules ratchet apart, again with the help of
motor molecules.
o By the end of anaphase, the _____________________ ends of both cell contain complete
and ______________ sets of chromosomes
o Telophase
 The nuclear envelopes _____________________ around the sets of chromosomes
located at opposite ends of the cell.
 The chromatin fiber of the chromosomes becomes ______________ condensed.
 _________________________ begins, during which the cytoplasm of the cell is
divided. In animal cells _______________________________ forms that
eventually divides the cytoplasm; in plant cells, a _________________________
forms that divides the cytoplasm.
Mitotic Spindle:
o an apparatus of __________________________ that controls chromosome movement
during mitosis
o During prophase, assembly of spindle microtubules begins in the ____________________,
the microtubule organizing center
o The centrosome ___________________, forming two centrosomes that migrate to opposite
ends of the cell, as spindle microtubules grow out from them
o
Binary Fission:
o ______________________________ (bacteria and archaea) reproduce by a type of cell
division
o In binary fission, the chromosome _______________________ (beginning at the origin of
replication), and the two daughter chromosomes actively move apart
12.3 The Eukaryotic Cell Cycle is Regulated by a moleculuar control system
 Label the Picture


Checkpoints:
o For many cells, the _________ checkpoint seems to be the most important one

o If a cell _____________________ a go-ahead signal at the G1 checkpoint, it will usually
complete the S, G2, and M phases and divide
o If the cell does not _______________ the go-ahead signal, it will exit the cycle, switching
into a nondividing state called the _________________________
Cyclins and Cyclin Dependent Kinases
o Two types of regulatory proteins are involved in cell cycle control:
____________________ and cyclin-dependent kinases (______________)
o ______________ (maturation-promoting factor) is a cyclin-Cdk complex that triggers a
cell’s passage past the G2 checkpoint into the M phase
o Label the Picture
o
o Some external signals are ______________________________, proteins released by
certain cells that stimulate other cells to divide
o For example, _______________________________________________________ (PDGF)
stimulates the division of human fibroblast cells in culture
o Another example of external signals is _________________________________________,
in which crowded cells stop dividing
o Most animal cells also exhibit _________________________________, in which they
must be attached to a substratum, like the extracellular matrix of a tissue, in order to divide
o Loss of Cell Cycle Controls = Cancer
 Cancer cells do not respond normally to the body’s control mechanisms
 Cancer cells may not need _____________________________ to grow and divide:
 They may make their own growth factor
 They may convey a growth factor’s signal without the presence of the
growth factor
 They may have an abnormal cell cycle control system