3. PARTS OF A TYPICAL ANIMAL CELL
AND THEIR FUNCTIONS:
• NUCLEUS: It controls all the activities of the cell,
including cell repair.
• CHROMOSOMES: They are thread-like structures
and are made of DNA and proteins .
• GENES: They are part of chromosomes which
store information to be passed down from one
generation to another.
• CELL MEMBRANE : It is a partially permeable layer
that controls the movement of materials into and
out of the cell.
4. • CYTOPLASM: It almost fills the entire animal cell.It is
jelly-like and contains other cell parts. New
materials are being made and broken down here.
• VACUOLES: They are small and numerous in an
animal cell. They contain food,water and waste
material and other substances.
6. A TYPICAL PLANT CELL AND ITS
FUNCTIONS
• A large central vacuole, a water-filled volume enclosed
by a membrane known as the tonoplast that maintains
the cell's turgor, controls movement of molecules
between the cytosol and sap, stores useful material
and digests waste proteins and organelles.
• A cell wall composed of cellulose and hemicellulose,
pectin and in many cases lignin, is secreted by the
protoplast on the outside of the cell membrane. This
contrasts with the cell walls of fungi (which are made
of chitin), and of bacteria, which are made of
peptidoglycan.
7. • Plastids, the most notable being the chloroplast, which
contains chlorophyll, a green-colored pigment that absorbs
sunlight, and allows the plant to make its own food in the
process known as photosynthesis. Other types of plastids
are the amyloplasts, specialized for starch storage,
elaioplasts specialized for fat storage, and chromoplasts
specialized for synthesis and storage of pigments. As in
mitochondria, which have a genome encoding genes,
plastids have their own genomes of about unique genes
and, it is presumed, arose as prokaryotic endosymbionts
living in the cells of an early eukaryotic ancestor of the land
plants and algae.
9. CELL DIVISION
• Cell division is the process by which a parent cell divides into
two or more daughter cells. Cell division usually occurs as part
of a larger cell cycle. In eukaryotes, there are two distinct type
of cell division: a vegetative division, whereby each daughter
cell is genetically identical to the parent cell (mitosis), and a
reductive cell division, whereby the number of chromosomes
in the daughter cells is reduced by half, to produce haploid
gametes (meiosis). Both of these cell division cycles are
required in sexually reproducing organisms at some point in
their life cycle, and both are believed to be present in the last
eukaryotic common ancestor Prokaryotes also undergo a
vegetative cell division known as binary fission, where their
genetic material is segregated equally into two daughter cells.
All cell divisions, regardless of organism, are preceded by a
single round of DNA replication.
