Sec 3 Biology: Cell Structure and Function Worksheet
Important terms:
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Unicellular: consisting of only one cell
Multicellular: consisting of more than one cell/many cells
Prokaryotes: unicellular organisms e.g. yeast, bacteria
Eukaryotes: multicellular organisms e.g. humans
Organelles: specialised subunits within a cell with specific functions
Fluid Mosaic model: Fluid: flexibility of the phospholipid bilayer to move
laterally; Mosaic: random distribution of proteins throughout the cell membrane
Organelles and their functions:
Organelle
Structure
Function
Cell surface membrane
Consists of a
phospholipid bilayer –
made of two layers of
phospholipids, with
hydrophilic heads
pointing outwards and
hydrophobic tails
pointing inwards
Controls the movement of
substances into and out of
the cell
Cytoplasm
Refers to all the
organelles and cytosol
within the cell membrane
(except the nucleus)
Nuclear envelope
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Made up of a
continuous double
membrane, which is
also continuous with
the endoplasmic
reticulum membrane
Presence of nuclear
pores
Separates the contents of
the nucleus from the
cytoplasm
Nucleus
Largest membranous
organelle in the cell,
appearing as a round
structure under the
microscope
Contains most of the
genetic material found in
the cell and is important
in regulating all cellular
activities
Nucleolus
Dense mass in the centre
of the nucleus
Involved in the synthesis
and assembly of
ribosomes in the cell
Chromatin
In the form of double
stranded DNA present in
the nucleus of the cell
Genetic material of the
cell, carrying all genes
and information of the
cell
Cell wall
Rigid and inflexible
structure consisting
mainly of cellulose
Supporting structure for
plant cells to protect the
cell from damage, and to
prevent lysis or crenation
of plant cells
Chloroplast
Lens shaped organelle,
Site for photosynthesis in
containing the stroma
plants, to produce glucose
together with inner
for the plant
membrane folds,
including thylakoids (one
disc) and granum which
refers to a stack of
thylakoids (plural: grana)
Mitochondria
(mitochondrion)
Spherical in shape, with a
smooth outer membrane
and a highly convoluted
(folded) inner membrane,
with the infoldings
known as cristae
(singular: crista)
Sites for cellular
respiration to produce
energy (ATP) for cell
activity
Vacuole
Animal cells: small,
mobile organelles
Acts as a storage for
organic compounds (e.g.
proteins, carbohydrates)
Plant cells: usually a large
central vacuole
surrounded by a
membrane
Rough endoplasmic
reticulum
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Made of membranous
sheets called cisternae
(singular: cisterna)
Sheet-like appearance,
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and with a “rough”
appearance because of
attached ribosomes on
the surface
Smooth endoplasmic
reticulum
Network of tubules that
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lack ribosomes, hence the
“smooth” appearance
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Golgi apparatus/body
Site of protein synthesis
Proteins synthesized by
rER are usually
transported out of the
cell via transport
vesicles
Synthesis of lipids and
steroids (e.g.
hormones)
Involved in
detoxification of
harmful substances
Consists of a stack of
Involved in modification
flattened discs (cisternae) and packaging of
substances from the ER
for export; the contents
are transported by
vesicles which bud off the
Golgi body
Lysosome
Large vesicles in the
cytoplasm that contain
enzymes
Contains enzymes which
hydrolyse and digest
large molecules or old
and worn out organelles
Ribosome
Consists of two subunits –
large ribosomal unit and
small ribosomal unit,
made up of proteins and
ribosomal RNA (rRNA)
Site for protein synthesis
(free ribosomes usually
synthesise proteins for
use within the cell)