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Cells (What is inside the nucleus? (Chromatin (long thread-like structures…
Cells
What are cells?
the
building
blocks of life
the simplest units
that exhibit the characteristics of life
most cells cannot be
seen by the naked eye
there are
2
types of
microscopes which are
light and electron
microscopes
light microscope:
the images comes out
coloured
electron microscope:
the images are black and
white and can also be
artificially colourised
What does a cell
consist of??
each
living cell consists of a
living material called
protoplasm
there are different types
of cells but they have similar
parts; they only differ in shape,
size and structure
protoplasm are made up of
3
parts
Cell Surface Membrane
a.k.a plasma membrane
surrounds the cytoplasm
of the cell
made up of proteins and lipids
partially permeable membrane
controls substances entering or leaving the cell
Cytoplasm
in between the cell surface membrane and the nucleus
it is where most cell activities occur
contains organelles and enzymes
tiny structures that carry out many functions in the cell
they are not visible under the naked white and light microscope
e.g: mitochondria, centrioles and ribosomes
Nucleus
consists of a small round mass of deeper protoplasm called
nucleoplasm
it controls cell activities such as
cell growth and repairing worn-out cells
it is also essential for cell division
Cell Wall
it is only present in plant cells
it encloses the entire plant cell
made of cellulose
protects the cell from injury
gives the plant cell a fixed shape
fully permeable
What is inside the nucleus?
Nuclear Envelope
separated the contents of the nucleus from the cytoplasm
Nucleolus
plays a part in making the proteins in the cell
Chromatin
long thread-like structures within the nucleus
made up of proteins and
DNA
which stores the hereditary information and also instructions that a cell needs for carrying out its activities
during cell division, chromatin threads condenses to become
chromosomes
Nucleoplasm
dense material within the cell
What are the parts of the cytoplasm?
contains organelles like
Rough Endoplasmic Reticulum [RER]
its surface appears rough under the electron microscope
ribosomes are attached to its outer surface
its outer surface is continuous with the nuclear envelope
transports proteins made by ribosomes to the Golgi Apparatus for secretion out of the cell
Ribosomes
small round structures
they would either lie freely in the cytoplasm or attached to the ER
the ones attached to the ER make proteins that are transported out of the cell
the ones lying freely make proteins that are going to be used within the cytoplasm of the cell
they are needed to synthesise proteins in the cell
Smooth Endoplasmic Reticulum [SER]
connected to the RER
does not have ribosomes attached
synthesises substances such as fats and steroids(e.g: sex hormones)
carries out detoxification
Golgi Apparatus
shaped like a disc
consists of a stack of flattened spaces surrounded by membranes
vesicles fuses with one side of the Golgi apparatus
and pinches off from the opposite side
it modifies chemicals made by the ER chemically
stores the modified substances in vesicles for secretion out of cell
Mitochondria
carries out aerobic aerobic respiration to release energy
energy can be used to perform cell activities like growth
Chloroplasts
only found in plant cells
contains chlorophyll
chlorophyll are essential for photosynthesis
Vacuoles
stores substances within the cell
animal cells: small and many
plant cells : large and only one; contains cells sap