1. Unit 2 Cells
2.3 Eukariotic cells
IB Biology SFP - Mark Polko

2. IB Biology SFP - Mark Polko
2.3.1 Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell.
The diagram should show free ribosomes, rough endoplasmic reticulum (rER), lysosome, Golgi apparatus, mitochondrion and nucleus.
The term Golgi apparatus will be used in place of Golgi body, Golgi complex or dictyosome.
2.3.2 Annotate the diagram from 2.3.1with the functions of each named structure.
2.3.3 Identify structures from in electron micrographs of liver cells.
2.3.4 Compare prokaryotic and eukaryotic cells.
Differences should include:
Naked DNA versus DNA associated with proteins
DNA in cytoplasm versus DNA enclosed in a nuclear envelope
No mitochondria versus mitochondria
70S versus 80S ribosomes
eukaryotic cells have internal membranes that compartmentalize their functions.
2.3.5 State three differences between plant and animal cells.
2.3.6 Outline two roles of extracellular components.
The plant cell wall maintains cell shape, prevents excessive water uptake, and holds the whole plant up against the force of gravity.
Animal cells secrete glycoproteins that form the extracellular matrix. This functions in support, adhesion and movement.
Assessment statements
IB Biology SFP - Mark Polko

3. IB Biology SFP - Mark Polko
Introduction
Eukaryotic organisms have cells that contain a nucleus. Animals, plants, fungi and protoctist all have eukaryotic cells.
They all have organelles which can only be fully appreciated while observed with an electron microscope.
Note that the image on the left is a highly schematic illustration. It compares some possible structures of both animal and plant cells.
IB Biology SFP - Mark Polko

4. IB Biology SFP - Mark Polko
2.3.1 Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell.
The diagram should show :
Free ribosomes
Rough endoplasmic reticulum (rER),
Lysosome,
Golgi apparatus,
Mitochondrion
Nucleus.
The term Golgi apparatus will be used in place of Golgi body, Golgi complex or dictyosome.
IB Biology SFP - Mark Polko

5. IB Biology SFP - Mark Polko
2.3.2 Annotate the diagram from 2.3.1with the functions of each named structure.
Cell organelle
Structure
Function
(free) ribosome
made of two subunits, both made of protein and RNA
free ribosomes make proteins that are used in the cell site of protein synthesis (see Topic 3.5)
IB Biology SFP - Mark Polko

6. IB Biology SFP - Mark Polko
2.3.2 Annotate the diagram from 2.3.1with the functions of each named structure.
Cell organelle
Structure
Function
rough endoplasmic
reticulum - RER
RER is membrane with ribosomes attached. RER makes proteins that are exported via exocytosis in order to be used outside the cell
free ribosomes make proteins that are used in the cell site of protein synthesis (see Topic 3.5)
IB Biology SFP - Mark Polko

7. IB Biology SFP - Mark Polko
2.3.2 Annotate the diagram from 2.3.1with the functions of each named structure.
Cell organelle
Structure
Function
lysosome
contains hydrolytic enzymes e.g. lysozymes which can break down substances in the cell
fuses with and digests old cell organelles and
material taken in via endocytosis intracellular
digestion); it also can burst and cause autolysis of a cell
IB Biology SFP - Mark Polko

8. IB Biology SFP - Mark Polko
2.3.2 Annotate the diagram from 2.3.1with the functions of each named structure.
Cell organelle
Structure
Function
Golgi apparatus
stack of flattened, membrane-bound sacs, forming an extensive network in the cell
intracellular transport, processing and packaging of proteins
IB Biology SFP - Mark Polko

9. IB Biology SFP - Mark Polko
2.3.2 Annotate the diagram from 2.3.1with the functions of each named structure.
Cell organelle
Structure
Function
mitochondrion
the link reaction and the Krebs cycle take place in the matrix; the electron transport chain is found on the cristae of the inner membrane
Involved in the release of energy from inorganic molecules
IB Biology SFP - Mark Polko

10. IB Biology SFP - Mark Polko
2.3.2 Annotate the diagram from 2.3.1with the functions of each named structure.
Cell organelle
Structure
Function
nucleus
largest cell organelle
contains DNA
controls the activity of the cell by transcribing
certain genes and not others (see Topic 3.5)
IB Biology SFP - Mark Polko

11. IB Biology SFP - Mark Polko
2.3.3 Identify structures from in electron micrographs of liver cells.
Golgi apparatus
An electron micrograph of a liver cell
IB Biology SFP - Mark Polko

12. IB Biology SFP - Mark Polko
2.3.3 Identify structures from in electron micrographs of liver cells.
Endoplasmic reticulum
Mitochondrium
IB Biology SFP - Mark Polko

13. IB Biology SFP - Mark Polko
2.3.3 Identify structures from in electron micrographs of liver cells.
Lysosomes
Nucleus
IB Biology SFP - Mark Polko

14. IB Biology SFP - Mark Polko
2.3.4 Compare prokaryotic and eukaryotic cells.
Feature
Similarities
Differences
Prokaryotes
Eukaryotes
Genetic material
Naked DNA
DNA associated with proteins
Circular DNA
Linear DNA
DNA found in cytoplasm (nucleoid area)
DNA enclosed in nuclear envelope
Protein synthesis
70S (mass and size)
80S(mass and size)
Respiration
no mitochondria but uses plasma membrane and mesosomes
Mitochondria
Ultrastructure
no internal membranes present
compartmentalise the cell into areas with different functions
The differences should include:
Naked DNA versus DNA associated with proteins
DNA in cytoplasm versus DNA enclosed in a nuclear envelope
No mitochondria versus mitochondria
70S versus 80S ribosomes
Eukaryotic cells have internal membranes that compartmentalize their functions
IB Biology SFP - Mark Polko

15. IB Biology SFP - Mark Polko
Protein synthesis
70S (mass and size)
80S(mass and size)
Extra info
Svedberg unit (symbol S, sometimes Sv) is a non-SI unit for sedimentation rate.
It is often used to reflect the rate at which a molecule travels to the bottom of a test tube under the centrifugal force of a centrifuge.
IB Biology SFP - Mark Polko

16. IB Biology SFP - Mark Polko
2.3.4 Compare prokaryotic and eukaryotic cells.
Feature
Plant cell
Animal cell
cell wall
cellulose cell wall and plasma membrane
only plasma membrane
chloroplast
present in photosynthetic cells
absent
vacuole
large, permanent vacuole, filled with cell sap
small, temporary vacuoles may be present
reserve food
carbohydrate stored as starch and also plant oils
carbohydrate storage as glycogen and some
stored as animal fat
IB Biology SFP - Mark Polko

17. IB Biology SFP - Mark Polko
2.3.6 Outline two roles of extracellular components.
Extracellular components are found associated with both plant and animal cells.
Cellulose is the best known example of an extracellular component in plant cells.
Bone, cartilage and connective tissue are examples of tissues with a very important extracellular component in animal cells.
Link to explicative video
IB Biology SFP - Mark Polko

18. IB Biology SFP - Mark Polko
2.3.6 Outline two roles of extracellular components.
The cell wall is a non-living secretion (an extracellular component) of the cell and it serves several purposes:
• The cell wall provides support and mechanical strength for the cell and in turn the tissues of the plant as a whole. It determines the shape of the cell.
• As the plant cell takes up water, the intra-cellular pressure increases. The cell wall will limit the amount of expansion and prevent the plant cell from bursting. The cell will continue to take in water due to osmosis
but the same amount of water will be expelled due to the pressure of the cell wall. The cell is now turgid and mechanically quite stable. Many plants depend to a large extend on turgor to keep them upright.
• Cellulose is a carbohydrate and plants can use the cell wall for carbohydrate storage.
• The cell wall provides a barrier for pathogens (disease causing organisms). Plant cells store specific proteins in the cell wall that recognise pathogens and start a ‘defense response’ to them.
IB Biology SFP - Mark Polko

19. Unit 2 Cells
2.3 Eukariotic cells
IB Biology SFP - Mark Polko