BIO.B.1 Cell Growth and Reproduction
Topic Summary for the Cell Cycle:
Packages of DNA called chromosomes hold a cell’s genetic information.
Prokaryotic chromosomes consist of a single, circular strand of DNA.
Eukaryotic chromosomes are highly organized structures.
• • The DNA winds around histone proteins, forming chromatin.
• • Chromosomes make the precise separation of DNA possible during cell division.
The cell cycle is the series of events in the growth and division of a cell.
In the prokaryotic cell cycle, the cell grows, duplicates its DNA, and divides by pinching in the cell membrane.
The eukaryotic cell cycle has four stages (the first three of which are referred to as interphase):
• • In the G1 phase, the cell grows.
• • In the S phase, the cell replicates its DNA.
• • In the G2 phase, the cell produces organelles and materials for division.
• • In the M phase, the cell divides in two stages--mitosis, the division of the nucleus, and cytokinesis, the division of the cytoplasm.
The division of the nucleus, mitosis, occurs in four stages:
Prophase : a cell’s genetic material condenses, a spindle starts to form, and the nuclear envelope breaks down.
Metaphase : the duplicated chromosomes line up and spindle fibers connect to the centromeres.
Anaphase : sister chromatids separate and move toward the centrioles.
Telophase : the chromosomes begin to unwind and a nuclear envelope reforms.
Division of the cytoplasm differs in plant cells and animal cells.
In animal cells, the cell membrane draws in and pinches off.
In plant cells, a cell plate forms, followed by a new cell membrane, and finally a new cell wall forms.
Dozens of proteins regulate the cell cycle.
Cyclins are proteins that regulate the timing of the cell cycle in eukaryotic cells.
Regulatory proteins work both inside and outside of the cell.
•• Internal regulators allow the cell cycle to proceed when certain events have occurred within a cell.
• • External regulators called growth factors stimulate the cell cycle. Other external regulators cause the cell cycle to slow down or stop.
Apoptosis is programmed cell death that plays a key role in the development of tissues and organs.
Cancer is a disorder in which cells divide uncontrollably, forming a mass of cells called a tumor.
Cancers are caused by defects in genes that regulate cell growth.
Treatments for cancer include:
• • removal of cancerous tumors.
• • radiation, which interferes with the copying of DNA in multiplying cancer cells.
• • chemotherapy, which is the use of chemicals to kill cancer cells.
Topic Summary for the Cell Cycle:
Packages of DNA called chromosomes hold a cell’s genetic information.
Prokaryotic chromosomes consist of a single, circular strand of DNA.
Eukaryotic chromosomes are highly organized structures.
• • The DNA winds around histone proteins, forming chromatin.
• • Chromosomes make the precise separation of DNA possible during cell division.
The cell cycle is the series of events in the growth and division of a cell.
In the prokaryotic cell cycle, the cell grows, duplicates its DNA, and divides by pinching in the cell membrane.
The eukaryotic cell cycle has four stages (the first three of which are referred to as interphase):
• • In the G1 phase, the cell grows.
• • In the S phase, the cell replicates its DNA.
• • In the G2 phase, the cell produces organelles and materials for division.
• • In the M phase, the cell divides in two stages--mitosis, the division of the nucleus, and cytokinesis, the division of the cytoplasm.
The division of the nucleus, mitosis, occurs in four stages:
Prophase : a cell’s genetic material condenses, a spindle starts to form, and the nuclear envelope breaks down.
Metaphase : the duplicated chromosomes line up and spindle fibers connect to the centromeres.
Anaphase : sister chromatids separate and move toward the centrioles.
Telophase : the chromosomes begin to unwind and a nuclear envelope reforms.
Division of the cytoplasm differs in plant cells and animal cells.
In animal cells, the cell membrane draws in and pinches off.
In plant cells, a cell plate forms, followed by a new cell membrane, and finally a new cell wall forms.
Dozens of proteins regulate the cell cycle.
Cyclins are proteins that regulate the timing of the cell cycle in eukaryotic cells.
Regulatory proteins work both inside and outside of the cell.
•• Internal regulators allow the cell cycle to proceed when certain events have occurred within a cell.
• • External regulators called growth factors stimulate the cell cycle. Other external regulators cause the cell cycle to slow down or stop.
Apoptosis is programmed cell death that plays a key role in the development of tissues and organs.
Cancer is a disorder in which cells divide uncontrollably, forming a mass of cells called a tumor.
Cancers are caused by defects in genes that regulate cell growth.
Treatments for cancer include:
• • removal of cancerous tumors.
• • radiation, which interferes with the copying of DNA in multiplying cancer cells.
• • chemotherapy, which is the use of chemicals to kill cancer cells.