Chapter 3.cell structures and fuctions

Prayer
Heavenly Father up above
Please give us wisdom, strength and love
Keep us always in the right track
And open Your door every time we knock
This wisdom is for our study sake
The strength is for the trials that we will take
Your love is to everyone to share
This can keep us away from life nightmare.
AMEN.

THE CELLS
(Plant Cell & Animal Cell)
Structure and Functions

Terminologies
• Organelles
- internal compartments
- discrete structures of specific
functions
- provide a “division of labor” that
makes a plant more efficient
- examples: nucleus, vacuole

Terminologies….
• Cytoplasm
- the materials inside the cell membrane
but outside the nucleus
• Cytosol
- the semifluid matrix that surrounds
and bathes the organelles outside the
nucleus

Terminologies…
• Protoplast
- the entire plant cell from the cell
membrane inward
• Cell Wall
- assembles from cellulose and other
polymers produced by the plant cell
(cell product)
- considered to be extracellular; outside
the protoplast

Plant Cell Structures and Functions
• The Cell Membrane
- a highly remarkably changeable and
multipurpose membrane
- supports and defines the plant cell
protoplast
- regulates the flux of molecules into
and out of the cell interior
- selectively permeable

- receives chemical and environmental
signals from outside the cell
which can change cellular
activities
- accepts raw materials from the
membranes inside the cell and
directs the assembly of these
materials into cell walls

• The Nucleus
- surrounded by a double membrane called the
nuclear envelope which has pores to allow
passage of materials in and out of the
nucleus
- contains most of the cell’s DNA
(chloroplasts and mitochondria contain some
DNA), which occurs with proteins in
threadlike structures called
chromosomes

Chromosomes – contain genes, which
are sequences of DNA; that
directs most of the activities of the
cells via the synthesis of RNA.

• Endoplasmic reticulum (smooth and rough)
- rough ER is a major region of protein
synthesis in a cell
- smooth ER helps make phospholipids
and assemble new membranes
- extends from the nucleus through
cytoplasm in any one cell and from
one cell to the next
throughprotoplasmic connections
(plasmodesmata)

Plant Cell Structures and
Functions
• Golgi Bodies (Dictyosomes)
- concerned with cellular secretions
- their activity is associated with
new cell walls when they are laid
down as a partition between two
newly divided cells

• Vacuoles
- help regulate the water content of the
plant cells and contain numerous enzymes
and pigments
- its membrane is called tonoplast
- as plant cell grows, most of their
enlargement results from the absorption
of water by vacuoles

- pigments in vacuoles such as red and
blue anthocyanins impart bright colors
to flowers, fruits and other plant
parts
- some plant vacuoles harbor toxic
chemicals that will deter insects
and other animals from eating plants
that contain them

• Ribosomes
- the workbench for protein synthesis
- very small and consist of
approximately equal amounts of and
RNA
- unlike nucleus and other organelles
ribosomes are not surrounded by
membranes thus some biologists do not
considered them as organelles

• Mitochnodria
- organelles of energy conversion needed for
cellular metabolism
- considered as the powerhouse of the cell
because it converts energy stored in the
sugars produced during photosynthesis to
ATP that powers much of the work of the
cell
- contains a small amount of DNA and RNA
and ribosomes that synthsize some of the
enzymes specific to each organelle
- grow and divide on their own

• Chloroplasts
- an organelle of energy conversion
- sites of photosynthesis in plant cells
- the chlorophylls in them trap the light
to fix (capture and integrate) carbon
dioxide into sugars
- use light energy to make amino acids
and fatty acids from carbon fixed via
photosynthesis

• Lysosomes
- contains various enzymes
- act as cellular scavengers, digesting
cytoplasmic particles such as
mitochondria which have passed
usefulness
- they may also bring about dissolution
of entire cells

• The Cytoskeleton
- forms a network and support system
within the cell
- performs the following:
a. help maintain organelle position and
organization within the cell; direct cell
expansion and control the movement
of chromosomes during nuclear division;
b. transports large molecules within the cell
(for some filaments)

Plant Cell Structures and
Functions
Centriole
- found only in animal cells
- associated with spindle fiber formation
or organization during cell division
- synthesis microtubules of cilia and
flagella may produce spindle in animal
cells.

Activity
Given the following words in the box. Put
each word in the Venn Diagram that
correspond to the correct answer.
Cell Wall Endoplasmic Reticulum Golgi Complex
Centrioles Chloroplast Cell Membrane
Lysosome Cytoplasm Vacoule
Ribosomes Mitochondria Nucleus

Evaluation
A. Choose the letter of the best answer. Write the
chosen letter on a ½ crosswise sheet of paper.
1. Where is the site of protein synthesis?
a. Nucleus c. ribosome
b. lysosome d. mitochondria
2. Plant cells often have a box-like shape because of
the
a. nucleus c. cytoplasm
b. cell wall d. cell membrane

3. Which of the following is found in the
nucleus?
a. vacuoles c.
mitochondria
b. chloroplasts d. chromosomes
4. Digestive enzymes or hydrolytic enzymes are
terms associated with
a. ribosomes c. golgi apparatus
b. lysosomes d. smooth ER
5. What site regulates what goes in and out of
the cell?
a. cell wall c. cell
membrane

B. Draw and label the different part of the
cell either plant cell or animal cell.

Assignment
Thought Questions:
1. What is the selective advantage of the small
size of cells compared to the large size of
organisms?
2. What is the evolutionary advantage of
secondary cell walls?

Prepared by
Joy Clearth A. Padro
BSEd 3.02 – Biological Sciences

Chapter 3.cell structures and fuctions

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