Transcript Lecture Notes on Cells

Cells, Tissues, Organs and
Systems
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9.1 Introduction to Cells
What are cells?
• Cells are the building blocks of life.
Most animals and plants are made up
of thousands of cells. (Human body made up
of billions of cells)
•
A cell is the smallest unit of life.
•
Basically, there a two types of cells:
- Plant Cells
- Animal Cells
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9.1 Introduction to Cells
What are cells?
• Cells are alive. They do everything that living
things do to stay alive.
• Cells have different parts to do all these
functions.
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9.2 Animal Cells
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9.2 Animal Cells
A more magnified look of an animal cell:
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9.3 Plant Cells
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9.3 Plant Cells
A more magnified look of a plant cell:
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9.4 Functions of different parts of
a cell
Protoplasm
A cell consists of a mass of living matter called
protoplasm.
It includes the cell surface membrane, the nucleus
and the cytoplasm, where numerous reactions take
place.
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9.4 Functions of different parts of
a cell
Nucleus
The nucleus consists of a small spherical mass of
denser protoplasm, the nucleoplasm, surrounded by
a membrane called the nuclear envelope.
It is embedded within the cytoplasm of the cell and
controls the normal cell activities.
Within the cells, there are a network of long threadlike structures called the chromatin, spherical
structures called the nucleoli and a nuclear
envelope.
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9.4 Functions of different parts of
a cell
Nucleus
The chromatin threads contain hereditary
materials, i.e. materials inherited from the parents.
The nucleolus plays a part in building up of
proteins.
A nuclear envelope separates the nuclear content
from the surrounding cytoplasm.
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9.4 Functions of different parts of
a cell
Nucleus
•
Responsible for cell production
•
Needed for the continued life of the cell, as well
as for the repair of worn-out parts.
Without nucleus, a mammal have as short lifespan
and are unable to reproduce.
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9.4 Functions of different parts of
a cell
Cytoplasm
The part of the protoplasm surrounding the nucleus
is called the cytoplasm.
It usually forms the larger part of the cell and is the
place where most life processes occur.
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9.4 Functions of different parts of
a cell
Cytoplasm
Embedded in the cytoplasm are some important
organelles:
•
mitochondria.
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Chloroplast (for plants only)
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Vacuole.
•
Centrioles
•
Ribosome (even smaller than Centrioles).
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9.4 Functions of different parts of
a cell
Cytoplasm - Mitochondria
•
Small spherical or rod-shaped
•
Involved in the release of energy from food
substances during cell respiration.
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9.4 Functions of different parts of
a cell
Cytoplasm – Chloroplast (Plants only)
•
Sites where plants make their food.
•
Combine together carbon dioxide and water, and
using the energy from sunlight to make sugar
(glucose).
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9.4 Functions of different parts of
a
cell
Cytoplasm - Vacuoles
•
A vacuole is a fluid-filled space enclosed by a
membrane.
•
Animal cells may have many small vacuoles but
they are usually not permanent. Vacuoles may
contain water and food substances.
•
A plant cell usually has a large central vacuole
which contains a liquid called cell sap. Cell sap
contains dissolved substances such as sugar,
mineral salts and amino acids. This large vacuole
is enclosed by a membrane called the tonoplast.16
9.4 Functions of different parts of
a cell
Cytoplasm – Cell membrane
•
The cytoplasm is surrounded externally by a cell
membrane (also known as plasma membrane).
•
It is a partially permeable membrane which
controls substances entering or leaving the cell.
•
Similar membranes may also surround large
spaces or vacuoles within the cell.
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9.4 Functions of different parts of
a cell
Cytoplasm – Cell wall
•
In a plant cell, there is a cell wall which encloses
the whole cell.
•
This cell wall is made of cellulose. It protects the
cell from injury.
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9.4 Functions of different parts of
a cell
Cytoplasm – Ribosome
•
Smallest organelles in the protoplasm
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Produces protein from a set of genetic
instructions.
•
Floats freely in the cytoplasm.
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9.5 Similarities between a plant and animal
cells
Similarities between a plant and animal cell:
Both plants and animals cells have the following
structures:
•
Nucleus
•
Cell membrane
•
Cytoplasm
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9.5 Differences between a plant and animal
cells
Differences between a plant and animal cell:
Structure
Animal Cells
Plant Cells
Vacuole
Usually has many
small vacuoles
containing air,
water or food
particles
Has one large
vacuole in the
centre of the cell.
This contains cell
sap, which is
water and
dissolved
substances such
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as sugar and salt.
9.5 Differences between a plant and animal
cells
Differences between a plant and animal cell:
Structure
Chloroplast
Animal
Plant Cells
Cells
Does not
Contains tiny disc-like
contain
structures called
chloroplasts chloroplasts. These
contain the green
pigment chlorophyll
which traps the sunlight
and allows the plant to
photosynthesize (make
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food).
9.5 Differences between a plant and animal
cells
Differences between a plant and animal cell:
Structure
Cell wall
Animal
Cells
Does not
have a cell
wall
Plant Cells
Has a rigid cellulose
cell wall. This supports
the plant cell and gives
it its shape.
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9.5 Differences between a plant and animal
cells
Differences between a plant and animal cell:
Structure
Cytoplasm
Animal
Plant Cells
Cells
Most of the Has a thin lining of
cell is filled cytoplasm
with
cytoplasm
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9.6 Level of Organisations
Differences between cells, tissues, organs, etc:
Many cells will make up a Tissue
Many tissues working together will make
an Organ
Many organs working together will form an
Organ system
Many organ systems will form a Organism
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9.7 Tissues of Plant
What is a tissue?
A tissue is a group of cells which have a common
origin and a similar structure, which enables them
to perform a particular function.
Tissues in Plants:
Some examples of plant tissues:
• Epidermal tissue (also known as epidermis)
• Xylem tissue
• Phloem tissue
• Photosynthetic tissue (also known as mesophyll)
• Palisade tissue
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9.7 Functions of Tissues of Plant Cells
Epidermal Tissue
• Also known as epidermis
• Protects the underlying cells of a leaf by
preventing water loss and acts as a barrier to
fungi and other invaders.
Xylem Tissue
• Transports water and dissolved mineral salts to
the leaf.
Phloem Tissue
•
Phloem transports the manufactured food away
from the leaf to other part of the plants.
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9.7 Functions of Tissues of Plant Cells
Photosynthetic Tissue
• Also known as Mesophyll
• Carries out photosynthesis.
• Palisade Mesophyll Tissue
 Long cylindrical cells that occur at right
angle to the epidermis.
 Contains numerous chloroplasts for
photosynthesis.
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9.7 Functions of Tissues of Plant Cells
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9.8 Tissues of Animal
Tissues in Animal:
Some examples of animal tissues:
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Epithelial tissues
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Muscle tissues
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Connective tissues
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Nerve tissue
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Glandular tissue
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9.8 Functions of Tissues of Animal
Epithelial Tissue
• Also known as epithelium
• This is a sheet of cells which covers the internal
and external surfaces of an organ.
• This tissue lines both the outside (skin) and the
inside cavities of an animal.
•
Functions include secretion, absorption,
protections, trancellular transport, sense of
touch.
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9.7 Functions of Tissues of Animal Cells
Muscle Tissue
• Divided into 3 main groups
 Smooth muscle tissue
Smooth muscle controls slow, involuntary
movements such as the contraction of the
smooth muscle tissue in the walls of the
stomach and intestines.
 skeletal muscle tissue
Skeletal muscles function in pairs to bring
about the co-ordinated movements of the limb,
trunk, jaws, eyeballs, etc.
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9.7 Functions of Tissues of Plant Cells
Muscle Tissue
• Divided into 3 main groups
 cardiac muscle tissue
Cardiac muscle tissue plays the most
important role in the contraction of the atria
and ventricles of the heart.
Refer to handouts !
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9.7 Functions of Tissues of Animal Cells
Connective Tissue
• Divided into 4 main groups
 Dense connective tissue
Forms ligaments and tendons. It is densely
packed and have great tensile strength.
 Loose connective tissue
Holds organs in place.
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9.7 Functions of Tissues of Animal Cells
Connective Tissue
 Reticular connective tissue
This is a network of reticular fibers (fine
collagen) that form a soft skeleton to support
the lymphoid organs (lymph nodes, bone
marrow and spleen).
 Adipose tissue
Used for cushioning, thermal insulation and
energy storage.
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9.8 Functions of Tissues of Animal
Nerve Tissue
• Make up the nervous system that carry
information within the body.
Glandular Tissue
• Forms gland that produces substances to secrete
hormones or sweat.
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9.9 Organs of Plant
What is an organ?
An organ is a structure made up of different tissues
working together for a specific function.
Organs in Plants:
Some examples of plant organs:
• Leaf
 An organ of photosynthesis (contains
photosynthetic tissues).
• Stem
 Contains Xylem and phloem tissues and
supporting tissues
 Provide support and transport food to other
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parts of the plants.
9.9 Organs of Plant
Organs in Plants:
Some examples of plant organs:
• Roots
 Contain xylem and phloem tissues.
 These tissues take in the nutrients from the
soil and transport them to other parts of
the plant.
 Roots serve to anchor the plants to the soil
and absorb water and minerals.
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9.9 Animal Organs
Organs in Animals:
Some examples of animal organs:
• Stomach
 Consist of glandular tissues which secrete
digestive juices to digest food
 Muscle tissue which causes stomach to
contract and relax and mix the food well
with the digestive juices
 Connective tissue which helps to connect
the other tissues.
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9.9 Animal Organs
Organs in Animals:
Some examples of animal organs:
• Heart
 Circulates blood around the body
 Consist of blood tissue
 Muscle tissue which causes heart to
contract and expand to circulate blood
 Connective tissue which helps to connect
the other tissues.
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9.10 Organs systems of human body
What is an organ system?
An organ system consists of several organs working
together to perform a special function, e.g.the
digestive system.
Organ systems in Human:
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Respiratory system
 Lungs, windpipe, nose and mouth.
 Supplies the body with oxygen and remove
carbon dioxide.
 Allows animal to breathe in order to carry out
respiration.
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9.9 Organs of Animal
Organs in Animals:
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Digestive system
Breaks down
food into smaller
and soluble
substances that
can be absorbed
by the blood.
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9.9 Organs of Animal
Organs in Animal:
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Circulatory system
 Made up of heart, capillaries, arteries and
veins.
 Allows animal to circulate blood around
the body so that different parts of the body
will receive food, oxygen,
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