Cell Structure
and Organelles
SBI4U—2016/10/14
Inside the cell
These are generalizations, not rules!
Everything inside the cell membrane besides the
nucleus is called the cytoplasm;
◦ The liquid is known as cytosol.
Source: http://www.yourgenome.org/
Plant vs Animal Cells
Plant
Chloroplast
Central vacuole
Cell wall
Animal
Lysosomes
Many small vesicles
Nucleus
Contains and replicates DNA (genetic information):
◦ DNA is stored as chromatin and, during replication, as
chromosomes.
Has its own membrane, the nuclear envelope:
◦ The envelope has nuclear pores which regulate nutrient and
macromolecule movement.
The densest part of the nucleus is called the nucleolus,
which is used to synthesize ribosomes;
The rest of the nucleus is filled with nucleoplasm.
Source: http://0.tqn.com/
Mitochondria
The mitochondria breaks down certain molecules to release
energy;
Has a smooth external membrane, but a folded inner
membrane;
Also plays a role in regulating apoptosis (self-destruction);
Mitochondria has some DNA of its own!
Source: https://micro.magnet.fsu.edu/
Chloroplast
Permits cells to conduct photosynthesis;
Light is absorbed by the photosynthetic pigment
chlorophyll:
◦ This light helps convert water and carbon dioxide into high
energy molecules.
The chlorophyll is contained in the membranes of diskshaped thylakoids:
◦ A stack of thylakoids forms a granum.
Not found in animal cells (but rather plant and algal cells).
Source: http://images.tutorvista.com/
Which is more important?
Nucleus, mitochondria or chloroplast?
Endoplasmic reticulum
Part of the endomembrane system;
Two types of endoplasmic reticulum (ER), rough & smooth;
Rough ER contains ribosomes:
◦ It is attached to the nucleus;
◦ It synthesizes proteins (for the membrane or export).
Smooth ER does not contain ribosomes:
◦ It synthesizes lipids;
◦ Also provides other services, such as detoxing alcohol.
Source: http://image.tutorvista.com/
Golgi apparatus
Part of the endomembrane system;
New proteins and lipids are transported from the rough and
smooth ER to the Golgi apparatus
The Golgi apparatus sorts, packs and distributes these
proteins and lipids;
Also, the Golgi apparatus produces lysosomes.
Source: https://media1.britannica.com
Endomembrane system
Nuclear envelope;
Endoplasmic reticulum:
◦ Rough;
◦ Smooth.
Golgi apparatus;
Vesicles.
Source: https://qph.ec.quoracdn.net/ & Texbook p. 61
Lysosomes and peroxisomes
Lysosomes and peroxisomes break down large, harmful and
useless molecules;
They perform similar functions but through different
processes and on different molecules;
Lysosomes are not found in plant cells.
Source: http://www.gridgit.com/
Vesicles and vacuoles
Vesicles are sacs used to store and transport nutrients
throughout the cell;
◦ E.g. Transport form the ER to the Golgi apparatus
Vacuoles are very large sacs and replace many small
vesicles;
Vacuoles are not found in animal cells.
Source: http://waynesword.palomar.edu
Cytoskeleton and cell wall
The cytoskeleton is a network of filaments and other
anchors that give structure to the cell and its organelles;
A cell wall is composed of cellulose and give the cell rigidity;
The cell wall is not found in animal cells.
Source: http://plantcellcrk.weebly.com/
Cilia and flagella
Cilia and flagella are appendages that extend outside
of the cell;
Flagella are few and long, generally used for
movement;
Cilia are short and many, used for a variety of physical
tasks.
Source: http://www.microbiologyinfo.com
Parts of the Cell
Nucleus
Contains DNA
Mitochondria
Converts certain molecules into usable energy
Chloroplasts
Absorbs light energy, conducts photosynthesis
Endoplasmic reticulum
Part of protein and lipid synthesis
Golgi apparatus
Processes proteins and lipids
Vesicles and vacuoles
Storage and transport of resources (also provides structure, in plants)
Lysosomes and peroxisomes
Break down molecules
Cytoskeleton and cell wall
Provides structure
Cilia and flagella
Mobility and other physical functions
Activity: ____ is like…
Nucleus
Contains DNA
Mitochondria
Converts certain molecules into usable energy
Chloroplasts
Absorbs light energy, conducts photosynthesis
Endoplasmic reticulum
Part of protein and lipid synthesis
Golgi apparatus
Processes proteins and lipids
Vesicles and vacuoles
Storage and transport of resources (also provides structure, in plants)
Lysosomes and peroxisomes
Break down molecules
Cytoskeleton and cell wall
Provides structure
Cilia and flagella
Mobility and other physical functions