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5.1 The Cell Cycle
Chapter 5 : Cell Growth and Division
KEY CONCEPT - Section 5.1
Cells have distinct phases of growth, reproduction,
and normal functions.
• The ___________ is a regular pattern of growth, DNA
replication, and cell division.
5.1
The
Cell
Cycle
• The
main
stages
of the cell cycle are :
– ______ (G1): cell growth
and normal functions
– ____________ (S): copies DNA
– ________ (G2): additional
growth
– _________ (M): division of
the cell nucleus (mitosis)
– _____________: division of
the cell cytoplasm
• Mitosis occurs only if the cell is large enough and the DNA
undamaged.
5.1 The Cell Cycle
• The rate of ______________ varies with the need for
those types of cells.
5.1 The Cell Cycle
• Cell volume increases faster than cell surface area
– limits the _______ of cells
– materials have to be able to reach all parts of cell
efficiently
5.1
The
Cell Cycle
KEY
CONCEPT
- Section 5.2
Cells divide during mitosis and cytokinesis.
Chromosomes are formed at the start of mitosis.
• DNA becomes _______________- easier to organize
DNA double
helix
DNA and
histones
Chromatin
Supercoiled
DNA
5.1 The Cell Cycle
• DNA plus proteins is called _____________
• One half of a duplicated
chromatid
chromosome is a chromatid.
• Sister chromatids are held
together at the centromere.
• ____________ protect DNA and
do not include genes.
centromere
telomere
Condensed, duplicated chromosome
5.1 The Cell Cycle
cells spend _____ of the cell cycle in interphase
• cell grows, prepares
to divide
• _____is duplicated
Parent cell
centrioles
spindle fibers
centrosome
nucleus with
DNA
5.1 The Cell Cycle
• Mitosis divides the cell’s nucleus in four steps:
– ____________ : chromosomes condense and
spindle fibers form.
5.1 The Cell Cycle
– ___________ : chromosomes line up in the middle of
the cell.
5.1 The Cell Cycle
– ___________ : sister chromatids separate to
opposite sides of the cell.
5.1 The Cell Cycle
– __________: the new nuclei form and chromosomes
begin to uncoil.
5.1 The Cell Cycle
• ____________- splitting of cytoplasm and organelles
between two new cells
– In _______cells, the
membrane pinches
closed between two
cells
– In ______ cells, a
cell plate forms new
cell walls between
the two new cells
5.1
Cell Cycle
KEYThe
CONCEPT
- Section 5.3
Cell cycle regulation is necessary for healthy
growth.
Internal and external factors regulate _______________
• External factors include physical and chemical ________
• Growth factors are proteins that stimulate cell division.
– Most mammal cells form a single layer in a culture
dish and stop dividing once they touch other cells.
5.1 The Cell Cycle
• External factors trigger internal factors, which affect the
cell cycle.
• Two of the most important internal factors are ________
and ___________
• Cell growth is balanced by cell death in healthy organisms
• _____________ = programmed cell death.
– a normal feature of healthy organisms
– caused by a cell’s production of self-destructive
enzymes
– occurs in development of infants
5.1
The
Cell Cycle
Cell
division
is uncontrolled in cancer - “immortal cells”
• _________cells form disorganized clumps called tumors.
– Benign tumors remain clustered and can be removed.
– _______________ metastasize, or break away, and can
form more tumors.
• Cancer cells do not carry out necessary functions.
• Cancer cells come from normal cells with damage to
____________ involved in cell-cycle regulation.
• Carcinogens are substances known to promote cancer.
- examples : ____________, tobacco, asbestos,
exposure to environmental poisons
• Standard cancer treatments typically kill both cancerous
and healthy cells.
5.1 The Cell Cycle
• ________________ must allow for adequate exchange of
materials.
– Cell growth is coordinated with ___________
– Cells that must be large have unique shapes so that
materials can still be exchanged with the
environment efficiently
5.1
The
Cell Cycle
KEY
CONCEPT
- Section 5.4
Many organisms reproduce by cell division.
________________ is similar in function to mitosis.
• Asexual reproduction is the creation of offspring from a
single parent.
– Binary fission produces _____daughter cells genetically
identical to the parent cell.
– method of reproduction in
parent cell
______________
DNA
duplicates
cell begins
to divide
daughter
cells
5.1 The Cell Cycle
• Environment determines what form of reproduction is most
advantageous.
– __________ reproduction is an advantage in
consistently favorable conditions.
– __________ reproduction is an advantage in changing
conditions.
Some eukaryotes reproduce through mitosis.
• __________ forms a new organism from a small
projection growing on the surface of the parent.
• ______________: splitting of the parent into pieces that
each grow into a new organism.
• _____________________ forms a new plant from
the modification of a stem or underground structure
on the parent plant - type of asexual reproduction
5.1
The
Cell Cycle
KEY
CONCEPT
- Section 5.5
Cells work together to carry out complex functions.
Multicellular organisms depend on interactions among
different cell types.
• _______________ are groups of cells that perform a
similar function.
• ___________ are groups of tissues that perform a
specific or related function.
• ___________________ are groups of organs that
carry out similar functions.
5.1 The Cell Cycle
Specialized cells perform specific functions.
• Cells develop into their mature forms through the process
of ____________________
• Cells differ because different combinations of genes are
expressed.
• A cell’s location in an embryo helps determine how it will
differentiate.
Outer: skin cells
Middle: bone cells
Inner: intestines
5.1 The Cell Cycle
___________ are unique body cells.
• Stem cells have the ability to
– divide and renew themselves
– remain undifferentiated in form - they can “turn into”
other types of cells
– develop into a variety of specialized cell types
5.1 The Cell Cycle
• Stem cells are classified into _______________.
– totipotent, or growing into ______ other cell type
– pluripotent, or growing into __________ but a totipotent
cell
– multipotent, or growing into cells of a closely related cell
family
5.1 The Cell Cycle
• Stem cells come from adults and ____________
– Adult stem cells can be hard to isolate and grow.
– The use of adult stem cells may prevent transplant
rejection.
– The use of embryonic
stem cells raises
________ issues
– Embryonic stem cells
are pluripotent and
can be grown indefinitely
in culture.
First, an egg is fertilized by a sperm cell in a petri dish. The egg divides, forming
an inner cell mass. These cells are then removed and grown with nutrients.
Scientists try to control how the cells specialize by adding or removing certain
molecules.
5.1 The Cell Cycle
• The use of stem cells offers many currently realized and
potential benefits.
– used to treat leukemia and _______________
– may cure disease or replace damaged organs.
– may revolutionize the ________________________