The Cell Cycle & Mitosis
Chapter 5
5.1 – The Cell Cycle
• Key Concept:
– Cells have distinct phases of growth,
reproduction, and normal functions.
The cell cycle has 4 main stages.
• The cell cycle is a regular pattern of growth,
DNA replication, and cell division.
The main stages of the cell cycle are
Gap 1, Synthesis, Gap 2, & Mitosis.
• Gap 1 (G1): cell growth and normal functions,
copy organelles, checkpoint occurs here.
• Synthesis (S): copies DNA
• Gap 2 (G2): additional growth, second
checkpoint occurs.
• Mitosis (M): includes division of the cell nucleus
(mitosis) and division of the cell cytoplasm
(cytokinesis)
– Mitosis occurs only if the cell is large enough and the
DNA undamaged.
Cells divide at different rates.
• The rate of cell division varies with the need for that
type of cell.
• Some cells are unlikely to divide (in Gap 0/G0 of the cell cycle)
– Example: neurons
Cell size is limited.
• Cell volume increases faster than surface
area.
– Cells need to stay small to allow diffusion and
osmosis to work efficiently.
• Surface area must allow for adequate
exchange of materials.
– Cells that must be large have unique shapes.
Stop & Review
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________: cell growth and normal functions, copy organelles
Gap One
__________: copies DNA
Synthesis
_________: additional growth
Gap Two
________: includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis)
M phase (mitosis)
– Mitosis occurs only if the cell is ______ enough and the _____ undamaged.
– Large DNA
The rate of cell division varies with the
.
Need for that type of cell
Volume increases faster than ___________________.
Surface Area
– Cells need to stay ___________ to allow ___________ and __________ to work efficiently.
– Small diffusion osmosis
•
______________________ must allow for adequate exchange of materials.
•
Surface Area
–
Cell growth is coordinated with _____________.
–
Division
– Cells that must be large have unique _____________.
shapes
5.2 – Mitosis & Cytokinesis
• Key Concept:
– Cells divide during mitosis and cytokinesis.
Chromosomes condense at the
start of mitosis.
• Chromosomes: carry genetic information (DNA) that
is passed from one generation of cells to the next.
• DNA wraps around proteins (histones) that
condense it.
• DNA plus proteins is called
chromatin.
• One half of a duplicated
chromosome is a chromatid.
• Sister chromatids are held
together at the centromere.
• Telomeres protect DNA and
do not include genes.
Mitosis and cytokinesis produce two
genetically identical daughter cells.
Box 1: Interphase
• Interphase prepares
the cell to divide.
• During interphase,
the DNA is
duplicated.
• Includes G1, S, and
G2.
Mitosis divides the cell’s nucleus
in four phases.
• Prophase (Box 2)
– Longest phase of mitosis. Chromosomes
condense, spindle fibers form, and the nuclear
membrane disappears
Mitosis divides the cell’s nucleus
in four phases.
• Metaphase (Box 3)
– Chromosomes line up in the middle of the cell
Mitosis divides the cell’s nucleus
in four phases.
• Anaphase (Box 4)
– Sister chromatids are pulled apart to opposite
sides of the cell
Mitosis divides the cell’s nucleus
in four phases.
• Telophase (Box 5)
– Two nuclei form at opposite ends of the cell, the
nuclear membrane reforms, and the
chromosomes uncoil back into chromatin
Cytokinesis differs in animal and
plant cells.
• Cytoplasm separates
– Animal cells: membrane pinches
the two new cells apart
– Plant cells: a cell plate (new cell
wall) separates the two new cells
Cell Cycle and Mitosis Video
• https://www.youtube.com/watch?v=gwcwSZI
fKlM
Stop & Review
•
Chromosomes ____________ at the start of mitosis.
•
Condense
•
DNA wraps around proteins (____________) that condense it.
•
Histones
•
DNA plus proteins is called ______________.
•
Chromatin
•
One half of a duplicated chromosome is a _______________.
•
Chromatid
•
Sister chromatids are held together at the ________________.
•
Centromere
•
_____________ protect DNA and do not include genes.
•
Telomere
Stop & Review (cont)
•
______________ prepares the cell to divide and is when the DNA is duplicated.
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Interphase
•
_____________ is when chromosomes condense, spindle fibers form, and the nuclear membrane
disappears
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Prophase
•
_______________ is when chromosomes line up in the middle of the cell
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Metaphase
•
_____________ is when sister chromatids are pulled apart to opposite sides of the cell
•
Anaphase
•
_____________ is when two nuclei form at opposite ends of the cell, the nuclear membranes reform, and
the chromosomes uncoil back into chromatin
•
Telophase
•
__________ is when the cytoplasm separates
•
Cytokinesis
–
___________ cells: membrane pinches the two new cells apart
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Animal
–
___________ cells: a cell plate (new cell wall) separates the two new cells
–
Plant
5.3 – Regulation of the Cell Cycle
• Key Concept:
– Cell cycle regulation is necessary for healthy growth.
Internal and external factors
regulate cell division.
External Factors
Internal Factors
• Include physical and
chemical signals
• Kinases and cyclins
– Cell to cell contact: when one
cell touches another, they
stop growing
– Growth factors: chemical
signals released by cells that
tell other cells to grow
• Trigger internal factors,
which affect the cell cycle
– Kinases: enzymes in cells,
help control the cell cycle –
are activated by cyclins
– Cyclins: proteins that are
made and destroyed during
the cell cycle; activate
kinases
• Both help to advance a cell
to different parts of the cell
cycle
Cell division is uncontrolled in cancer.
• Cancer cells form disorganized clumps called
tumors.
– Benign tumors remain clustered and can be
removed.
– Malignant tumors metastasize, or break away,
and can form more tumors.
Apoptosis is programmed cell death.
• Some cells need to grow and divide but other
cells need to die.
• Apoptosis is the process of programmed cell
death.
– Normal feature in healthy organisms
– Caused by a cell’s production of self-destructive
enzymes
– Occurs during fetal development
(responsible for separation of
fingers and toes)
• Cancer cells do not carry out normal cell
functions.
• Cancer cells come from normal cells with
damage to genes involved in cell-cycle
regulation.
• Carcinogens are substances known to cause
cancer (they damage those genes)
– Chemicals, tobacco smoke, X-rays, UV rays
• Standard cancer treatments typically kill both
cancerous and normal, healthy cells.
Video on Cell Cycle and Cancer
• https://www.youtube.com/watch?v=lpAa4TW
jHQ4
Stop & Review
•
____________ _____________: Include physical and chemical signals such as cell to cell contact:
when one cell touches another, they stop growing and growth factors: chemical signals released
by cells that tell other cells to grow
•
External Factors
•
___________ ______________: examples are kinases and cyclins. Kinases: enzymes in cells,
some of which help control the cell cycle – those that do are activated by cyclins. Cyclins: proteins
that are made and destroyed during the cell cycle; activate kinases
•
Internal Factors
•
Both help to advance a cell to different parts of the cell ___________.
•
Cycle
•
Cancer cells form disorganized clumps called __________________.
•
Tumors
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_________________ tumors remain clustered and can be removed.
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Benign
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_________________ tumors metastasize, or break away, and can form more tumors.
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Malignant
•
__________________ is the process of programmed cell death.
•
Apoptosis
5.4 – Asexual Reproduction
• Key Concept:
– Many organisms reproduce by cell division.
Binary fission is similar to mitosis.
• Asexual reproduction is the
creation of offspring from a
single parent.
– Binary fission produces two
daughter cells genetically
identical to the parent cells.
– Binary fission occurs in
prokaryotes.
Environment determines which form
of reproduction is most advantageous
• Asexual reproduction is an advantage in
consistently favorable conditions.
• Sexual reproduction is an advantage in
changing conditions.
Some eukaryotes reproduce by
mitosis.
• Budding forms a new organism
from a small projection growing
on the surface of the parent.
• Fragmentation is the splitting of
the parent into pieces that each
grow into a new organism.
• Vegetative reproduction forms a
new plant from the modification
of a stem or underground
structure on the parent plant.
Stop & Review
•
_______________ _______________ is the creation of offspring from a single parent.
•
Asexual Reproduction
•
___________ _______________ is asexual reproduction in prokaryotes and produces two daughter cells
genetically identical to the parent cells.
•
Binary Fission
•
Asexual reproduction is an advantage in consistently
•
Favorable
•
Sexual reproduction is an advantage in
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Changing
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Asexual Reproduction In Eukaryotic Organisms
•
_____________ forms a new organism from a small projection growing on the surface of the parent.
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Budding
•
__________________ is the splitting of the parent into pieces that each grow into a new organism.
•
Fragmentation
•
____________ _________________ forms a new plant from the modification of a stem or underground
structure on the parent plant.
•
Vegetative Reproduction
conditions.
conditions.
5.5 – Multicellular Life
• Key Concept:
– Cells work together to carry out complex
functions.
Multicellular organisms depend on
interactions among different cell types.
• Tissues are groups of cells that perform a similar
function.
• Organs are groups of tissues that perform a specific
or related function.
• Organ systems are groups of organs that carry out
similar functions.
Specialized cells perform specific
functions.
• Cells develop into their mature forms through
the process of cell differentiation.
• Cells differ because different combinations of
genes are expressed.
• A cell’s location in an embryo helps determine
how it will differentiate.
Specialized cells develop from a
single zygote. A zygote is the union
of an egg and sperm
red blood cell
•
nerve cell
Organisms are made up of specialized cells.
• Zygotes first divide into embryonic stem cells. Stem cells
can become any of 200 types of cells in the human body.
• Stem cells develop in
two stages.
– determination, or
committing to
become one cell
type
– differentiation, or
acquiring
specialized
structures and
functions
Specialized cells function together in
tissues, organs, organ systems, and
the whole organism.
• Specialized cells perform
specific tasks.
• Tissues are groups of
similar cells working
together.
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epithelial tissue
connective tissue
muscle tissue
nervous tissue
cell
tissue
• There are 11 major organ systems in the human body.
Ted Ed Video
http://ed.ted.com/lessons/making-sense-ofhow-life-fits-together-bobbi-seleski
STOP & REVIEW
•
Specialized cells develop from a single _______.
•
zygote
•
Zygotes first divide into embryonic ____________.
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Stem cells
•
Stem cells develop in two stages.
–
___________, or committing to become one cell type
–
determination
–
____________, or acquiring specialized structures and functions.
–
differentiation
•
The five levels of biological organization are (in order)
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Cells
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Tissue
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Organ
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Organ System
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Organism