8.1
Cell division: when two identical daughter cells are
genetically identical to eachother and the parent cell
Chromosomes: the structure that contains most of the
cell’s genetic information in the form of DNA
• Many multicellular organisms can reproduce
asexually. For example, some sea star species and
many house plants
• The production of gametes involve a particular type
of cell division that occurs only in the reproductive
organs (testes and ovaries). (WHICH IS MEIOSIS)
• A gamete has half as many chromosomes as the
individual parent cell.
• All of the trillions of cells in your body arose via
repeated cell division that began in your mother’s
body with a single fertilized egg cell.
• After an organism is fully grown, cell division
continues to function to repair itself, and replacing
cells that die normally
Checkpoint 8.1
What function does cell division play in an
amoeba (a single-celled protist)? What
functions does it play in your body?
• Reproduction; development, growth and repair
8.2
Prokaryotes: single celled organisms that go through asexual reproduction
Prokaryotes reproduce by a type of cell division called binary fission, which means it
divides in half. In most prokaryotes, most genes are carried on one circular DNA
molecule that with the association of proteins, constitutes the organism’s single
,chromosome.
• Prokaryotic chromosomes are much shorter than eukaryotic chromosomes, so this
makes dividing them in half into two daughter cells a hard task.
• For example, when stretched out, the chromosome of the bacteria, E. Coli, is 500x
longer than the cell itself, you wouldn’t know this because its coiled up inside the cell.
In the image 8.2A, it is showing binary fission in a
prokaryote
1. The chromosomes duplicate
2. The cell starts to get larger
3. The cell has reached twice its initial size, and the
plasma membrane pinches inward and more cell
wall is made, eventually causing the divide of the
parent cell into two daughter cells as was stated
earlier
Checkpoint 8.2
Why is binary fission classified as asexual
reproduction?
Because the genetically identical offspring inherited DNA from a single parent
8.3
Eukaryotic cells are more complex than prokaryotic cells. Eukaryote cells have many
more genes and units of information that specific an organism’s inherited traits.
• For example, human cells carry under 21,000 genes and the average bacteria only
contains 3,000.
• Genes are found in the nucleus grouped into multiple chromosomes (The exceptions
include genes on the small DNA molecules within mitochondria and in plants, within
chloroplasts)
• Each eukaryotic species has a specific # of chromosomes in each cell nucleus. Ex:
human body cells each have 46 chromosomes while the cells of a dog each have 78,
and a hedgehog having 90.
,Each eukaryotic chromosome have one long DNA molecule, bearing hundreds to
thousands of genes and a certain # of protein molecules which are attached to the
DNA. The proteins help maintain the chromosomes structure and control the activity of
the genes. Together, it is called a chromatin.
Chromatin: the complex of DNA and protein
that make up eukaryotic chromosomes.
Chromatin exists as long, thin fibers that if
stretched out, would be too long to fit the
nucleus.
As a cell prepares to divide in mitosis its
chromatin coils up, forming distinct
chromosomes.
The chromosomes of a eukaryotic cell duplicate
and the cell divides. Each chromosome now
consisted of two copies called sister
chromatids.
Checkpoint: When does a chromosome consist of two identical chromatids?
When the cell is preparing to divide and has duplicated its chromosomes, but before
the duplicates actually separate from each other
8.4
• The process of cell division is a key factor in the cell cycle: a cell is first formed from a.
Dividing parent cell until its own division into another two cells. The cell cycle consists
of two main stages: Interphase, when the cell duplicates DNA and everything in the
cytoplasm, and the mitotic phase (PMAT).
• Most of the cell cycle is spent in Interphase, the cell’s metabolic activity is very high as
it performs normal functions. For ex: a cell in your small intestine might release
digestive enzymes and absorb nutrients. Your intestinal cell may grow in size during
interphase, making more cytoplasm and increasing its supply of digestive proteins
and creating organelles like ribosomes and mitochondria.
• Interphase lasts at least 90% of the total time required for the cell cycle
, • G1: about to start
• S: DNA replication
• G2: is prepared completely for cell division
• Calling the G phases “gaps” is a misnomer,
cells are actually active and grow throughout
all three subphases of interphase
• In mitosis, the nucleus and its contents and
duplicated chromosomes, divide and are
distributed into two daughter nuclei. During
cytokinesis, the cytoplasm divides in two.
Checkpoint:
A researcher treats cells with a chemical that
prevents DNA synthesis from starting. This treatment would trap the cells in which
part of the cell cycle?
G1 because its before DNA replication even starts, its not stopping DNA synthesis, its
stopping the START of DNA synthesis
8.5
5 stages of mitosis: Prophase, Prometaphase, metaphase, anaphase, and telophase.
• Mitotic Spindle: made of microtubules and guides the separation of the two sets of
daughter chromosomes
• Centrosomes: microtubule-organizing regions in the cytoplasm of eukaryotic cells
Cell division: when two identical daughter cells are
genetically identical to eachother and the parent cell
Chromosomes: the structure that contains most of the
cell’s genetic information in the form of DNA
• Many multicellular organisms can reproduce
asexually. For example, some sea star species and
many house plants
• The production of gametes involve a particular type
of cell division that occurs only in the reproductive
organs (testes and ovaries). (WHICH IS MEIOSIS)
• A gamete has half as many chromosomes as the
individual parent cell.
• All of the trillions of cells in your body arose via
repeated cell division that began in your mother’s
body with a single fertilized egg cell.
• After an organism is fully grown, cell division
continues to function to repair itself, and replacing
cells that die normally
Checkpoint 8.1
What function does cell division play in an
amoeba (a single-celled protist)? What
functions does it play in your body?
• Reproduction; development, growth and repair
8.2
Prokaryotes: single celled organisms that go through asexual reproduction
Prokaryotes reproduce by a type of cell division called binary fission, which means it
divides in half. In most prokaryotes, most genes are carried on one circular DNA
molecule that with the association of proteins, constitutes the organism’s single
,chromosome.
• Prokaryotic chromosomes are much shorter than eukaryotic chromosomes, so this
makes dividing them in half into two daughter cells a hard task.
• For example, when stretched out, the chromosome of the bacteria, E. Coli, is 500x
longer than the cell itself, you wouldn’t know this because its coiled up inside the cell.
In the image 8.2A, it is showing binary fission in a
prokaryote
1. The chromosomes duplicate
2. The cell starts to get larger
3. The cell has reached twice its initial size, and the
plasma membrane pinches inward and more cell
wall is made, eventually causing the divide of the
parent cell into two daughter cells as was stated
earlier
Checkpoint 8.2
Why is binary fission classified as asexual
reproduction?
Because the genetically identical offspring inherited DNA from a single parent
8.3
Eukaryotic cells are more complex than prokaryotic cells. Eukaryote cells have many
more genes and units of information that specific an organism’s inherited traits.
• For example, human cells carry under 21,000 genes and the average bacteria only
contains 3,000.
• Genes are found in the nucleus grouped into multiple chromosomes (The exceptions
include genes on the small DNA molecules within mitochondria and in plants, within
chloroplasts)
• Each eukaryotic species has a specific # of chromosomes in each cell nucleus. Ex:
human body cells each have 46 chromosomes while the cells of a dog each have 78,
and a hedgehog having 90.
,Each eukaryotic chromosome have one long DNA molecule, bearing hundreds to
thousands of genes and a certain # of protein molecules which are attached to the
DNA. The proteins help maintain the chromosomes structure and control the activity of
the genes. Together, it is called a chromatin.
Chromatin: the complex of DNA and protein
that make up eukaryotic chromosomes.
Chromatin exists as long, thin fibers that if
stretched out, would be too long to fit the
nucleus.
As a cell prepares to divide in mitosis its
chromatin coils up, forming distinct
chromosomes.
The chromosomes of a eukaryotic cell duplicate
and the cell divides. Each chromosome now
consisted of two copies called sister
chromatids.
Checkpoint: When does a chromosome consist of two identical chromatids?
When the cell is preparing to divide and has duplicated its chromosomes, but before
the duplicates actually separate from each other
8.4
• The process of cell division is a key factor in the cell cycle: a cell is first formed from a.
Dividing parent cell until its own division into another two cells. The cell cycle consists
of two main stages: Interphase, when the cell duplicates DNA and everything in the
cytoplasm, and the mitotic phase (PMAT).
• Most of the cell cycle is spent in Interphase, the cell’s metabolic activity is very high as
it performs normal functions. For ex: a cell in your small intestine might release
digestive enzymes and absorb nutrients. Your intestinal cell may grow in size during
interphase, making more cytoplasm and increasing its supply of digestive proteins
and creating organelles like ribosomes and mitochondria.
• Interphase lasts at least 90% of the total time required for the cell cycle
, • G1: about to start
• S: DNA replication
• G2: is prepared completely for cell division
• Calling the G phases “gaps” is a misnomer,
cells are actually active and grow throughout
all three subphases of interphase
• In mitosis, the nucleus and its contents and
duplicated chromosomes, divide and are
distributed into two daughter nuclei. During
cytokinesis, the cytoplasm divides in two.
Checkpoint:
A researcher treats cells with a chemical that
prevents DNA synthesis from starting. This treatment would trap the cells in which
part of the cell cycle?
G1 because its before DNA replication even starts, its not stopping DNA synthesis, its
stopping the START of DNA synthesis
8.5
5 stages of mitosis: Prophase, Prometaphase, metaphase, anaphase, and telophase.
• Mitotic Spindle: made of microtubules and guides the separation of the two sets of
daughter chromosomes
• Centrosomes: microtubule-organizing regions in the cytoplasm of eukaryotic cells
