Cell Cycle / Mitosis
• The cell cycle is the cycle of growth, DNA
replication and cell division in eukaryotic
• Cell Cycle Animation
• Interphase – Normal cell processes and
growth of cell, DNA replication, and more
growth. Cells spend most of their time in
• Mitosis is the part of the cell cycle where the
replicated DNA (sister chromatids) separates equally
to both sides of the cell. Mitosis produces two identical
nuclei within the cell usually in preparation for cell
division (cytokinesis).
There are 4 steps to mitosis:
Prophase – Nuclear membrane disappears
Metaphase – Sister chromatids line up in the center
of the cell.
Anaphase – Sister chromatids split into chromosomes
and migrate to opposite sides of the cell
Telophase – Nuclear membranes form around the
two sets of chromosomes forming two nuclei.
• Cytokinesis is the part of the cell cycle where
the cytoplasm and cellular organelles are divided
and the cell divides into two separate cells. In
animal cells the cell membrane pinches in (forms
a cleavage furrow) to separate the cells. In plant
cells, a cell plate forms to divide the cell into two
separate cells.
Mitosis & Cytokinesis Animation
• Monday, October 30, 2006
6A. Read the section of the textbook
Write the definitions, understand and
memorize the following terms
• Asexual Reproduction
Binary Fission – not in text.
Sexual Reproduction
• Asexual reproduction involves only one
parent and produces offspring genetically
identical to that parent. It is most common in
single celled or simple organisms and in plants.
Asexual reproduction involves mitosis.
• Sexual reproduction involves combining the
genetic material from two parent organisms to
produce genetically unique offspring. Meiosis is
the process by which the gametes are formed in
the parents and fertilization is the process by
which a gamete from each parent combines to
produce the offspring.
Asexual Reproduction Examples
• Binary Fission occurs in bacteria (prokaryotes) and in most single celled
eukaryotes (protists). The cell divides in half to form two identical (or almost
identical) daughter cells.
• Budding occurs in eukaryotes (such as yeast) through mitosis (to create
two identical nuclei) and the formation of a bud (a small protrusion of the
cell membrane). The new cell formed is smaller than the parent cell.
Multicellular organisms (such as plants and hydra) also bud to produce
offspring genetically identical to the parent.
• Spores are specialized cells that act similar to seeds but are produced
asexually. Spores have protective coats that allow them to endure hot, dry,
or cold conditions. When conditions are good for growth, the spore grows
into a new organism genetically identical to the parent. Ferns, bread mold,
and mushrooms produce spores.
• Regeneration occurs through mitotic cell division to reproduce parts of an
organism which are damaged, lost, or injured. Many organisms display
varying degrees of regenerative ability. Some organisms such as planaria
and certain starfish can produce multiple offspring by regeneration.
• Write the definitions, understand and memorize
the following terms (p93, 208, 298)
– Gamete
– Egg
– Sperm
– Fertilization
– Zygote
– Haploid
– Diploid
– Conjugation (Read Page 173)
Sexual Reproduction
• Gametes are the specialized sex cells formed by meiosis
in each parent which combine during fertilization to form
the offspring.
Egg (Ovum) cells are female gametes
Sperm cells are male gametes
Gametes are haploid because they only have one copy of
each chromosome
Parents are diploid if they have two copies of each
Meiosis is the process that makes haploid gametes from
diploid cells.
During fertilization, two haploid gametes combine to
form a diploid zygote.
A zygote is a fertilized cell – the offspring
Meiosis I
Meiosis II
• Draw and label a color diagram of an eukaryotic
cell cycle on white unlined paper with no holes.
• State what happens at each phase. Label the
parts that are mitosis.
• Draw and label a color diagram of meiosis on white unlined paper
with no holes.
Prophase I
Metaphase I
Anaphase I
Telophase I
Cytokinesis I
Prophase II
Metaphase II
Anaphase II
Telophase II
Cytokinesis II
• State what happens at each phase.
• Due Wednesday
NYS Core Curriculum
• 2.1a Hereditary information is contained in genes. Genes are
composed of DNA that makes up the chromosomes of cells.
• 2.1b Each gene carries a single unit of information. A single
inherited trait of an individual can be determined by one pair or by
many pairs of genes. A human cell contains thousands of different
• 2.1c Each human cell contains a copy of all the genes needed to
produce a human being.
• 2.1d In asexual reproduction, all the genes come from a single
parent. Asexually produced offspring are genetically identical to the
• 2.1e In sexual reproduction typically half of the genes come from
each parent. Sexually produced offspring are not identical to either
NYS Core Curriculum
• 4.1a Some organisms reproduce asexually. Other organisms
reproduce sexually. Some organisms can reproduce both sexually
and asexually.
• 4.1b There are many methods of asexual reproduction, including
division of a cell into two cells (binary fission), or separation of part
of an animal or plant from the parent (budding), resulting in the
growth of another individual.
• 4.1c Methods of sexual reproduction depend upon the species. All
methods involve the merging of sex cells (gametes) to begin the
development of a new individual. In many species, including plants
and humans, eggs and sperm are produced.
• 4.1d Fertilization and/or development in organisms may be internal
or external.
NYS Core Curriculum
• 4.2a The male sex cell is the sperm. The female
sex cell is the egg. The fertilization of an egg by
a sperm results in a fertilized egg (zygote).
• 4.2b In sexual reproduction, sperm and egg
each carry one-half of the genetic information
for the new individual (haploid). Therefore, the
fertilized egg contains genetic information from
each parent (diploid).
NYS Core Curriculum
• 4.4a In multicellular organisms, cell division is responsible for growth,
maintenance, and repair. In some one-celled organisms, cell division is
a method of asexual reproduction.
• 4.4b In one type of cell division (mitosis), chromosomes are duplicated
and then separated into two identical and complete sets to be passed
to each of the two resulting cells. In this type of cell division, the
hereditary information is identical in all the cells that result.
• 4.4c Another type of cell division (meiosis) accounts for the production
of egg and sperm cells in sexually reproducing organisms. The eggs
and sperm resulting from this type of cell division contain one-half of
the hereditary information.
• 4.4d Cancers are a result of abnormal cell division.