Biologist ___________________________
Date ______________
PowerPoint 10-3&4
The Cell Cycle
The controls on cell growth and _____________ can be turned on and off.
For example, when an injury such as a broken bone occurs, cells are stimulated to divide
_____________ and start the healing process. The rate of cell division slows when the healing process
nears completion.
The Discovery of Cyclins
Cyclins are a family of proteins that regulate the _____________ of the cell cycle in eukaryotic
cells.
This graph shows how cyclin _________ change throughout the cell cycle in fertilized clam
eggs.
Regulatory Proteins
Internal regulators are _____________ that respond to events inside a cell. They allow the cell
cycle to proceed only once certain processes have happened inside the cell.
External regulators are proteins that respond to events _____________ the cell. They direct
cells to speed up or slow down the cell cycle.
Growth factors are external regulators that _____________ the growth and division of cells.
They are important during embryonic development and wound healing.
Apoptosis
Apoptosis is a process of programmed cell _____________.
Apoptosis plays a role in development by shaping the _____________ of tissues and organs in
plants and animals. For example, the foot of a mouse is shaped the way it is partly because the toes
undergo apoptosis during tissue development.
Cancer
Cancer is a disorder in which body cells lose the ability to _____________ cell growth.
Cancer cells divide _____________ to form a mass of cells called a tumor.
What Causes Cancer?
Cancers are caused by defects in genes that _____________ cell growth and division.
Some sources of gene defects are smoking _____________, radiation exposure, defective
genes, and viral infection.
A damaged or defective ________ gene is common in cancer cells. It causes cells to lose the
information needed to respond to growth signals.
Treatments for Cancer
Some localized tumors can be removed by _____________.
Many tumors can be treated with targeted _____________.
_____________ is the use of compounds that kill or slow the growth of cancer cells.
From One Cell to Many
All organisms start life as just ________ cell.
Most multicellular organisms pass through an early stage of _____________ called an embryo,
which gradually develops into an adult organism.
During development, an organism’s cells become more differentiated and _____________ for
particular functions.
Defining Differentiation
The process by which cells become _____________ is known as differentiation.
During development, cells differentiate into many different types and become specialized to
perform certain _____________.
Human Development
Biologists say that such a cell is totipotent, literally able to do _____________, to form all the
tissues of the body. (a fertilized egg)
After about ________ days of development, a human embryo forms into a blastocyst, a hollow
ball of cells with a cluster of cells inside known as the inner cell mass.
The cells of the inner cell mass are said to be pluripotent, which means that they are capable
of developing into _____________, but not all, of the body's cell types.
Stem Cells
Stem cells are _____________ cells from which differentiated cells develop.
Embryonic Stem Cells
Embryonic stem cells are found in the inner cells mass of the early _____________.
Embryonic stem cells are _____________.
Researchers have grown stem cells isolated from human embryos in _____________. Their
experiments confirmed that embryonic stem cells have the capacity to produce most cell types in
the human body.
Adult Stem Cells
Adult organisms contain _________ types of stem cells. Adult stem cells are multipotent. They
can produce many types of differentiated cells.
Adult stem cells of a given organ or tissue typically produce only the types of cells that are
_____________ to that tissue.
Potential Benefits
Stem cell research may lead to new ways to _____________ the cellular damage that results
from heart attack, stroke, and spinal cord injuries.
Ethical Issues
Most techniques for harvesting, or gathering, embryonic stem cells cause destruction of the
_____________.
Government funding of embryonic stem cell research is an important political issue.
Groups seeking to protect embryos oppose such _____________ as unethical. Other groups
support this research as essential to saving human lives and so view it as unethical to restrict the
research.