1. Tutorial for module BY1101: Joe Colgan (tcolgan@tcd.ie)
BY1101 Introduction to Molecular and Cellular Biology
Tutorial for module BY1101:
Cells & organelles
Joe Colgan

2. Tutorial objectives Define and describe major cell groups
BY1101 Introduction to Molecular and Cellular Biology
Tutorial objectives
Define and describe major cell groups
Examine organelles and their functions
Examine mechanisms of transport in and out of the cell

3. Which cell is which and why?
BY1101 Introduction to Molecular and Cellular Biology
What is a cell?
Basic structural or functional unit of an organism
Prokaryotic cell
Eukaryotic cell
(Plant)
Eukaryotic cell
(Animal)
Which cell is which and why?

4. Prokaryotic cell Which organisms have prokaryotic cells?
BY1101 Introduction to Molecular and Cellular Biology
Prokaryotic cell
Which organisms have prokaryotic cells?
Prokaryotes: Bacteria and Archaea
Fimbriae/pili
Chromosome
Plasma membrane
Cell wall
Capsule
Nucleoid
Ribosome
Flagella

5. Prokaryotic cell – organelles functions
BY1101 Introduction to Molecular and Cellular Biology
Prokaryotic cell – organelles functions
Name the organelles responsible for each of the following functions:
Function
Organelle
Propels the cell
Flagella
Appendages that allow a bacterium to stick to a surface
Frimbriae/pili
Rigid structure that surrounds, supports, and protects the cell
Cell wall
Acts as a selective barrier, allowing passage of oxygen, nutrients, and wastes
Plasma membrane
Site of protein synthesis
Ribosome
Contains the genes that control the cell
Nucleoid

6. Animal Eukaryotic cell
BY1101 Introduction to Molecular and Cellular Biology
Animal Eukaryotic cell
Nuclear envelope
Nucleolus
Chromatin
Flagellum
Nucleus
Smooth endoplasmic
reticulum
Plasma membrane
Cytoskeleton
Microfilaments
Interm. filaments
Microtubules
Rough endoplasmic
reticulum
Ribosomes
Microvilli
Golgi apparatus
Peroxisome
Mitochondrion
Centrioles
Lysosome

7. BY1101 Introduction to Molecular and Cellular Biology
Plant eukaryotic cell
Nuclear envelope
Nucleolus
Chromatin
Rough endoplasmic
reticulum
Nucleus
Smooth endoplasmic
reticulum
Golgi apparatus
Ribosomes
Central vacuole
Mitochondrion
Microfilaments
Interm. filaments
Microtubules
Peroxisome
Plasma membrane
Cytoskeleton
Chloroplast
Cell wall
Plasmodesmata

8. Eukaryotic cell – organelles functions
BY1101 Introduction to Molecular and Cellular Biology
Eukaryotic cell – organelles functions
Name the cellular structures responsible for each of the following functions:
Cell support and movement
Synthesis of secretory proteins and membranes
3. Lipid synthesis, detoxification, and calcium storage
Modifies, stores, and repackages products of the ER, mostly for secretion
Protein synthesis
6. Support the cytoplasm
7. Carries out cellular respiration
Selective barrier, allowing passage of oxygen, nutrients, and wastes
Break down toxins in the cell-detoxify
10. Stores the cell's DNA and coordinates the cell's activities
11. Serves as tracks along which other organelles can move
12. Processes and packages proteins after their synthesis
Cytoskeleton/Microfilaments
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Golgi apparatus
Ribosomes
Cytoskeleton
Mitochondrion
Plasma membrane
Peroxisome
Nucleus
Microtubules
Golgi apparatus

9. PLANT Eukaryotic cell – organelles functions
BY1101 Introduction to Molecular and Cellular Biology
PLANT Eukaryotic cell – organelles functions
Name the 4 structures that are only present in plant eukaryotic cells?
Central vacuole
Chloroplast
Cell wall
Plasmodesmata
Match the function to the correspondent structure:
a. Connect the cytoplasmic fluid of one cell to neighbouring plant cells
b. Storage, waste disposal, protection and growth
c. Carries out photosynthesis / where chlorophyll traps solar energy
d. Maintain cell shape and protects from mechanical stress
Plasmodesmata
Central vacuole
Chloroplast
Cell wall

10. ANIMAL Eukaryotic cell – organelles functions
BY1101 Introduction to Molecular and Cellular Biology
ANIMAL Eukaryotic cell – organelles functions
Name the 2 structures that are only present in animal eukaryotic cells?
Centrioles
Lysosome
Match the function to the correspondent structure:
a. Important in breaking down food and recycling
b. Compression girders of the cytoskeleton
Lysosome
Centrioles

11. BY1101 Introduction to Molecular and Cellular Biology
Tour of the cell

12. Nucleus BY1101 Introduction to Molecular and Cellular Biology
Function: The “brains” of the cell. The nucleus directs cell activities and contains genetic material called chromosomes made of DNA. Storage, replication and transcription of DNA.
Match the function to the correspondent structure:
1. Allows ribosomal subunits and mRNA transcribed off genes in the DNA to leave the nucleus, enter the cytoplasm, and participate in protein synthesis
2. Involved in the assembly of ribosomal subunits
3. Separates nucleus from the cytoplasm
4. DNA and proteins that make up the chromosomes
Nuclear pores
Nucleolus
Nuclear envelope
Chromatin

13. Appear in two cytoplasmic locales (i.e. Locations)
BY1101 Introduction to Molecular and Cellular Biology
Ribosomes
What is the function of the ribosomes?
Function: Main sites of protein synthesis
Appear in two cytoplasmic locales (i.e. Locations)
Free ribosomes
Suspended in the cytosol
Bound ribosomes
Bound to nuclear envelope or endoplasmic reticulum
Proteins remain in the cytosol
Proteins inserted in membranes, packed into specialised organelles or exported (secreted)

14. What are the two sections?
BY1101 Introduction to Molecular and Cellular Biology
Endoplasmic reticulum (ER)
Function: Biosynthesis of a number of macromolecules
What are the two sections?
Smooth ER
Portion of the ER free of ribosomes
Roles:
Synthesis of lipids
Drug detoxification
Calcium storage
Rough ER
Portion of ER studded with ribosomes
Roles:
Site of secretory proteins
Membrane proteins
Smooth ER
Cisternae
Lumen
Rough ER
Nucleus
Ribosomes

15. Golgi apparatus What is the function of the golgi apparatus?
BY1101 Introduction to Molecular and Cellular Biology
Golgi apparatus
What is the function of the golgi apparatus?
Function: Processes and packages proteins after their synthesis

16. Lysosome What is the function of the lysosome?
BY1101 Introduction to Molecular and Cellular Biology
Lysosome
What is the function of the lysosome?
Function: Degradation of host and foreign macromolecules into individual monomers

17. Endomembrane BY1101 Introduction to Molecular and Cellular Biology RER
Golgi apparatus
1. A secretory protein is synthesized inside the RER and migrates through it, and exits inside a vesicle
2. The transport vesicle moves through the cytoplasm to the Golgi apparatus

18. Endomembrane BY1101 Introduction to Molecular and Cellular Biology RER
Golgi apparatus
3. The Golgi modifies the protein as it moves from cis face to trans face
4. The protein is dispatched from the Golgi in a transport vesicle that then fuses with the plasma membrane, releasing the protein to the outside of the cell

19. What are the powerhouses of the cell?
BY1101 Introduction to Molecular and Cellular Biology
What are the powerhouses of the cell?

20. Mitochondria BY1101 Introduction to Molecular and Cellular Biology
Function: Conversion of oxygen and nutrients into adenosine triphosphate (ATP)

21. Chloroplast BY1101 Introduction to Molecular and Cellular Biology
Chloroplast contains thylakoid vesicles
Thylakoid vesicles are stacked together to form structures known as grana
Thylakoids contain chlorophyll and are the site of photosynthesis
Soluble matter (stroma) fixes carbon dioxide

22. Plasma membrane BY1101 Introduction to Molecular and Cellular Biology
Function: Selective barrier, allowing passage of oxygen, nutrients, and wastes
Carbohydrate
Extracellular matrix
Glycolipid
Glycoprotein
Phospholipids
Cholesterol
Cytoskeleton
Extracellular matrix
Protein

23. Selective permeability
BY1101 Introduction to Molecular and Cellular Biology
Selective permeability
Hydrophobic interior of the bilayer
Hydrophobic molecules (soluble in lipids) can move through
Certain molecules, such as hydrophilic molecules or ions, move slowly through or cannot pass at all.
How do they get through?

24. BY1101 Introduction to Molecular and Cellular Biology
Transport proteins
Specific membrane transport proteins in the plasma membrane form a channel through which water molecules of a specific solute can pass

25. Transport across the membrane What are the two types of transport
BY1101 Introduction to Molecular and Cellular Biology
Transport across the membrane
What are the two types of transport
Passive transport
Active transport

26. Diffusion BY1101 Introduction to Molecular and Cellular Biology
What is diffusion?
Tendency for particles of any kind to move from where they are more concentrated to less concentrated
Molecules are also said to move along their concentration gradient.
What is the concentration gradient?
A region along which the density of a chemical substance increases or decreases

27. Facilitated diffusion
BY1101 Introduction to Molecular and Cellular Biology
Facilitated diffusion
What is facilitated diffusion?
Spontaneous passage of molecules and ions, bound to specific transport proteins, across a biological membrane down their concentration gradients

28. Active transport BY1101 Introduction to Molecular and Cellular Biology
Active transport – Requires ATP input
Cells need to expel sodium and intake potassium
Sodium ions bind to the transport protein.
ATP transfers a phosphate group that changes the shape of the protein, the sodium ions are pushed across the membrane and released

29. Active transport BY1101 Introduction to Molecular and Cellular Biology
4. Potassium ions now bind to the protein and the phosphate group is released.
5. The release of the phosphate group causes the protein to revert to its original shape, releasing the potassium ions into the cell. The process can be repeated.

30. BY1101 Introduction to Molecular and Cellular Biology
2 types of exocytosis
Requires a sorting signal (clathrin coat) and an increase in intracellular calcium

31. 3 types of endocytosis – uptake material into cell
BY1101 Introduction to Molecular and Cellular Biology
3 types of endocytosis – uptake material into cell
Large particles
Cell changes shape
e.g. bacteria
“Cellular drinking”
Dissolved in water
Invagination
Small particles
Receptor-ligand interaction
e.g. Metabolism of cholesterol

32. Past paper questions Exam 2010
BY1101 Introduction to Molecular and Cellular Biology
Past paper questions
Exam 2010

33. Chapter 6: Tour of the cell Chapter 7: Membrane structure and function
BY1101 Introduction to Molecular and Cellular Biology
Questions
Further reading:
Campbell
Chapter 6: Tour of the cell
Chapter 7: Membrane structure and function