The concepts pertaining to the structure and function of cells is presented here, with review exercises for students. The sources of illustrative diagrams and figures taken from elsewhere are mentioned.

1. Cell structure and func.on
Concepts and exercises by Arpita Banerjee

2. Learning goals:
• Cells as structural and func.onal units of an organism.
• What defines a cell?
• What cons.tutes a cell? What is the role played by each of the cons.tuents?
• How do cells perform their func.on?
• How do cells connect with other cells to perform a specific func.on?
• How do cells interact with their environment and neighbors to elicit a par.cular
cellular response?
Cell structure and Func7on
Arpita Banerjee

3. 1. Cells are structural and func.onal units of organisms, meaning they are like
building blocks from which organisms are made.
2. Cells collec.vely form .ssues.
3. Tissues in turn form organs or different parts of an organism.
4. Cells have gene.c informa.on (DNA/RNA) encoded within them.
The cell oNen taps into this informa.on for carrying out its func.on and
for regenera.on
Cell structure and Func7on
Warm up
Arpita Banerjee

4. hOp://ssds-science.weebly.com/cells-.ssue-organ-organ-system.html
Cell structure and Func7on
Concept map Arpita Banerjee

5. hOps://www.exploringnature.org/db/view/Connec.ng-the-Cells-to-Tissues-to-Organs-to-Organ-Systems-Diagram
Cell structure and Func7on
Cells vary as per their func.on. For example, cells in muscles would differ from those of lungs as the two organs have different func.ons.
Arpita Banerjee

6. Cell division
Cell structure and Func7on
Cells undergo division to form new daughter cells. The old ageing cells are
discarded and the organism is replenished with new cells. During the
genera.on of new cells by this process, the DNA replicates, and the gene.c
informa.on within a cell gets passed onto its daughter cells.
Arpita Banerjee

7. 1) What defines the boundary of a cell for it to be a separate unit?
2) What is a cell composed of?
3) How does a cell generate energy for running its machinery?
LBQ – Learn by ques.ons
Cell structure and Func7on
Arpita Banerjee

8. Animal Cell
hOps://biologydic.onary.net/animal-cell/
Labeled diagram (Iden.fica.on key not required)
Cell structure and Func7on
Arpita Banerjee

9. Defining the boundary:
Cell membrane or plasma membrane defines the boundary of the cell. It separates
the outside from the inside of the cell. However, it selec.vely allows the passage of
certain materials such as oxygen, carbon dioxide, nutrients, proteins etc. across the
cell for its survival and func.oning.
Each cell has many organelles which carry out specific tasks for smooth and efficient
func.oning of the cell.
Holding the organelles:
Cytoplasm is a gel-like substance which provides a matrix for holding the organelles
in place and allows transit of molecules (such as proteins) within and across the cell.
Microtubule/Intermediate filament/microfilament within the cytoplasm provide
skeletal structure to the cell (they form cytoskeleton) and aids the process of
trafficking materials across the cell. They also play crucial role in cell division and in
mo.lity of the cell.
Cell structure and Func7on
Arpita Banerjee

10. Cell organelles
Nucleus contain DNA (Deoxyribonucleic acid) and/or RNA (Ribonucleic acid) as the
gene.c material that are packed within chroma7n. The informa.on encoded in the
gene.c molecules, oNen expressed as proteins, are required to run the machinery of
the cell. Nucleolus is the region within the cell’s nucleus that is concerned with
produc.on and assembly of ribosomes.
Ribosomes synthesize proteins that helps run the machinery of cells.
Endoplasmic Re7culum are flaOened, interconnected, and membrane-bound sac-like
structures that aid in the synthesis and assembly of protein molecules into their
func.onal form, and is also involved in protein-sor.ng for transport. Protein
synthesis occurs only in rough endoplasmic re7culum that have ribosomes on them,
The synthesized proteins are oNen sent to Golgi apparatus for sor.ng.
Golgi apparatus addi.onally contributes to protein transport by sor.ng the proteins
as per their target site and packaging them within golgi vesicles (similar to vehicles)
accordingly.
Lysosome contain protein degrading enzymes, and (damaged) proteins meant to be
destroyed are sent to this organelle for destruc.on.
Cell structure and Func7on Arpita Banerjee

11. Mitochondria is referred to as the power house of the cell. This organelle
generates the ‘energy molecule’ ATP (Adenosine Tri-Phosphate) which is
required to run the cellular processes such as protein synthesis, sor.ng,
trafficking etc. In some cases (such as human cells), there is liOle gene.c
informa.on contained within the mitochondria too, apart from nucleus.
Centrosome have a crucial role in cell division. This organelle duplicates before
cell division and moves to opposite ends of the cell and organizes the
cytoskeleton to aid the ‘pulling apart’ of the chroma.ds during cell division
so that each daughter cell receives a copy of the gene.c material.
Peroxisome contain enzymes for carrying out (oxida.on) reac.ons on certain
biochemical molecules. The reac.ons produce hydrogen peroxide as a by-
product.
Vacuole is an empty membrane bound space, that sequesters (takes in, stores
away) waste products of the cell. In some animals, the cell’s vacuole may contain
diges.ve enzymes which degrade ingested food materials.
Cell structure and Func7on
Arpita Banerjee

12. Plant Cell
hOps://biologydic.onary.net/animal-cell/
Cell structure and Func7on
Arpita Banerjee

13. Cell wall is an addi.onal layer in the boundary of the plant cell. It provides rigidity
to the cell in varying degrees depending on the plant .ssue type.
Vacuole is large and occupies a huge central space in plants. Not only does it
sequester waste but it also provides rigidity to the cells by holding the right
amount of water within it.
Chloroplast traps energy from sunlight and uses it to synthesize food molecules
(sugar) by a process known as photosynthesis. The capturing of sunlight is aided by
a pigment within chloroplast called chlorophyll that imparts green coloura.on to
leaves.
Amylosplast stores the synthesized food as starch granules.
Cell structure and Func7on
Addi7onal organelles in plant cells
Arpita Banerjee

14. Misconcep7on:
Cells bounded by cell membranes are isolated and can func.on independently.
Cell structure and Func7on
Arpita Banerjee

15. Did you know?
1)There are unicellular organisms.
ie: organisms which are comprised of just one cell such as protozoa, bacteria.
2) Cells within mul.cellular organisms oNen interact with each
other for normal func.oning.
ie: In complex mul.cellular organisms, such as in humans, cells are not
en.rely independent and isolated en..es. They oNen take cues from other
cells to perform their func.on.
Cell structure and Func7on
Arpita Banerjee

16. hOps://6636.stem.org.uk/pathogens5.html
Unicellular Amoeba – a simple protozoa
hOps://www.staff.ncl.ac.uk/t.r.cheek/cellcomm.htm
Unicellular
Cellular communica.on between two cells
cellular response of the target cell gets altered
Mul.cellular
Cell structure and Func7on Arpita Banerjee

17. Ac.vity 1
Label the cell’s organelles and state each of their func.ons
Cell structure and Func7on
hOps://www.pinterest.com/pin/625648573209647195/
Arpita Banerjee

18. Ac.vity 2
Compare and contrast an animal cell with that of a plant cell
Cell structure and Func7on
Arpita Banerjee

19. Check your progress
(Factual ques.on)
1)What is the basic difference between the structure of an animal cell boundary and a plant
cell boundary?
(Conceptual ques.on)
1) Are cell membranes fully permeable or par.ally permeable?
2) What is reason or necessity for this permeability?
(Debatable ques.on)
1) Would the cell wall of a plant’s leaf cell differ from that of a trunk cell?
Cell structure and Func7on
Arpita Banerjee

20. Think, pair and share
Which two on the right contributes to the one on the leN?
Plant cell rigidity
Chloroplast
DNA
Vacuole
ATP
Cell wall
Pair up and explain it to any of your classmates and also to the instructor
Life skills
Cell structure and Func7on
Arpita Banerjee

21. Exercise: Mul.ple Choice ques.ons
1. Where is the gene.c material of an organism stored in the cell?
(a) Mitochondria (b) Nucleus (c) Mitochondria and nucleus (d) Ribosome (e) cell membrane
2. Which organelle in plant cells carry out photosynthesis?
(a) Mitochondria (b) Nucleus (c) Mitochondria and nucleus (d) Chloroplast (e) Endoplasmic Re.culum.
3. Where does protein synthesis occur in cells?
(a) Mitochondria (b) Nucleus (c) cell membrane (d) Chloroplast (e) Endoplasmic Re.culum.
4. How does cell wall differ from cell membrane in plant cells? Check all that are true.
(a) Cell walls are harder and less permeable (b) Cell walls are harder and more permeable (c) Cell
membranes are harder and less permeable (d) Cell membranes are harder and more permeable.
(e) Cell membranes are soNer and less permeable.
5. What will happen to a cell when placed in a salty solu.on? Check all that are true.
(a) The cell will absorb water and swell (b) The cell will release water and contract (c) The cell will absorb
water and contract (d) The cell will release water and swell (e) The cell will remain the same.
Cell structure and Func7on
Arpita Banerjee

22. Exercise: Fill in the blanks
1. ------------ is the barrier between the cell and its environment.
2. Rough Endoplasmic Re.culum has ------------ on it.
3. Protein synthesis occurs in --------- Endoplasmic Re.culum
4. The func.on of a cell would vary as per the --------.
5. Cell divides to form two --------- cells.
Cell structure and Func7on
Arpita Banerjee

23. Exercise: Match the following
Plant cell
Mitochondria
Chroma.n
Unicellular
Cell boundary
Chloroplast
DNA
Bacteria
ATP
Cell membrane
Cell structure and Func7on
Arpita Banerjee

24. Exercise: True or False
1. Cells allow everything from the outside to pass through them.
2. Animal cells contain large vacuoles.
3. ATP (energy molecule) synthesis occur inside the mitochondrion.
4. Nucleolus is the gene.c material mass inside the nucleus.
5. Centrosome has a role in cell division.
Cell structure and Func7on
Arpita Banerjee

25. Cells in different .ssues vary as per their func.on.
The different func.onali.es require cells in the respec.ve .ssues to be
structurally and func.onally different. Think of an unicellular organism with a
single cell, and now think of a mul.cellular organism with different cells
performing different func.ons. To begin with, every cell has a basic structure,
so how does differen.a.on and adapta.on of a cell for a specialized func.on
occur within mul.cellular organisms?
Think like a scien.st - thought provoking ques.on
Cell structure and Func7on
Arpita Banerjee

26. Answer the following:
(Factual ques.ons)
1) Which cell has a large vacuole – plant cell or animal cell?
2) Which organelle produces energy currency of cell?
3) Which is more permeable – cell wall or cell membrane?
4) What is the func.on of Golgi apparatus?
5) Does nucleus has a membrane?
Cell structure and Func7on
Arpita Banerjee

27. Answer the following:
(Conceptual ques.ons)
1) How does water balance in plant vacuoles help maintain rigidity of the cell?
2) What will be the consequence of an impermeable cell membrane?
3) A plant cell is taking up a lot of toxic metals as the plant is growing on a waste land,
where do you think those metal ions would get placed inside the cell?
4) What will be the consequence of pumng a bacteria in pure water (ie: water without
any salt, minerals or other impuri.es)?
5) During cell division, DNA from nucleus is replicated so that each of the daughter
cells gets a copy of the gene.c material. What about the gene.c content in
mitochondria?
Life skills
Cell structure and Func7on
Arpita Banerjee

28. Answer the following:
(Debatable ques.ons)
1) Does protein folding occur in Golgi apparatus?
2) Is the cell mo.le in a mul.cellular animal? If yes, what type of cells
would require to be mo.le and why?
Life skills
Cell structure and Func7on
Arpita Banerjee

29. hOp://iqrasociety.com/animalcell.html
Review worksheet:
Picture based mul.ple choice ques.ons
Study the picture and answer the ques.ons which follow in the next pages
Life skills
Cell structure and Func7on
Arpita Banerjee

30. Suppose the cell in the picture receives a signal from another cell to produce a
par.cular protein in abundance and export the newly synthesized proteins out of the
cell for performing a certain func.on. Now answer the following ques.ons.
1) Where would the cell receive the signal?
(a) Mitochondria (b) cell coat (c) plasma membrane (d) Ribosome (e) Lysosome.
2) Where does the signal needs to be transmiOed to?
(a) Mitochondria (b) cell coat (c) Endoplasmic re.culum (d) Nucleus (e) Lysosome.
3) Where would protein synthesis occur in response to the signal?
(a) Mitochondria (b) Smooth endoplasmic re.culum (c) Rough endoplasmic
re.culum (d) Nucleus (e) Lysosome.
4) Where would protein folding occur?
(a) Cell coat (b) Smooth endoplasmic re.culum (c) Rough endoplasmic re.culum
(d) Golgi apparatus (e) Lysosome.
5) Where would the newly formed protein get trafficked to immediately aNer
synthesis?
(a) Cell coat (b) Smooth endoplasmic re.culum (c) Rough endoplasmic re.culum
(d) Golgi apparatus (e) Ribosome.
Arpita Banerjee

31. 6) Suppose the sor.ng organelle chemically marks the synthesized proteins with XXX
for transport to lysosome, with YYY for transport to cell coat, and with ZZZ for the
proteins to remain in cytoplasm. Which marking do you think the newly synthesized
proteins (for the problem at hand) are going to receive?
(a) XXX (b) YYY (c) ZZZ (d) XXX and ZZZ (d) None.
7) Defects in which of the following do you think is going to have direct adverse
affect on the transporta.on of the proteins?
(a) Mitochondria (b) Microtubules (c) Nucleus (d) lysosome (e) Ribosome
8) What are possibly going to carry the proteins as cargo within them?
(a) Microtubules (b) Nucleus (c) vesicles (d) lysosome (e) Ribosome.
9) Where would the cargo of proteins get finally directed to?
(a) Plasma membrane (b) cytoplasm (c) cell coat (d) Ribosome
(e) Lysosome.
10) Suppose some of the proteins had been detected as misfolded and were
retained within the cell. Where do you think those misfolded proteins would get
directed to?
(a) Plasma membrane (b) cytoplasm (c) Endoplasmic re.culum (d) Ribosome
(e) Lysosome.
Arpita Banerjee

32. Work on a cell from a .ssue of your choice.
1) Find out the structural and func.onal features of the cell which tells it apart
from another cell belonging to any other .ssue.
2) Study how those special features equips the par.cular cell to perform its
designated func.on. Prepare a write-up on your findings and submit to your
instructor.
Project:
Arpita Banerjee

33. Exit 7cket:
Which of the following would a cell membrane be permeable to? Check all that are
true.
(a) Oxygen (b) vesicle-bound protein (c) Large external molecule (d) Micronutrients
(e) Water.
Arpita Banerjee