Excursion: Zooming on Cells

1. Excursion: Zooming on Cells GTAC

2. Learning Outcomes • Students recognise that there are different levels of classification – the largest being the five kingdoms which are based on cell structure. • Distinguishing plant cells from animal or fungal cells. • Students compare and contrast the structure of a typical animal cell with the structure of a typical animal cell with the structure of a typical plant cell. • Reflect on the method used to investigate a question or solve a problem, including evaluating the quality of the data collected, and identify improvements to the method (ACSIS146) • Identify organelles within cells (nucleus, cell membrane, mitochondria, cytoplasm, vacuole, plants: chloroplasts, chlorophyll, cell wall) and describing their function. • Organisms consist of one cell only (they are unicellular); while other organisms consist of many cells (they are multicellular). • Identify questions and problems that can be investigated scientifically and make predictions based on scientific knowledge (ACSIS139) • Communicate ideas, findings and solutions to problems using scientific language and representations using digital technologies as appropriate (ACSIS148) • Use scientific knowledge and findings from investigations to evaluate claims (ACSIS234)

3. CELL THEORY Cell theory states that: 1.      All organisms are composed of one or more cells 2.      Cells are ALIVE and are the basic units of function and organisation in organisms. 3.      All cells come from other cells.

4. Cell Theory cont’d. What does alive/living mean – what distinguishes living from non-living things? • Highly organised • Obtain energy from surroundings • Change with time • Respond to their environment • Ability to reproduce

5. CELL STRUCTURE - AN INTRODUCTION • There is a major division in the living world, between organisms that are internally organised into membrane-bound compartments and those that lack such organisation. What are these two types of organism called? Examples?

6. PROKARYOTES PROKARYOTES (pro = before, karyon = nucleus) Size range: Generally 0.2 – 5.0m, Single Celled Organisms  Features: Plasma membrane   Mesosome   Flagella and Pilli   Nucleoid   Ribosomes   Cell wall   Capsule Prokaryotes are much smaller than eukaryotes. Why?

7. Figure 4-3 Structure of a Typical Bacterial Cell

8. PROKARYOTES Cell Wall: Is a stiff non-living wall that surrounds the cell membrane made of cellulose Cytoplasm: Jelly-like material surrounding the organelles Chloroplasts: Involved in photosynthesis Vacuoles: Store waste, nutrients, and water Chlorophyll: This is very important in making the food for plant. This structure takes in sunlight and makes sugar or the plat to eat and become green.

9. EUKARYOTES Have a true NUCLEUS and membrane-bound ORGANELLES.  Sizes: 10 - 100m  Features of eukaryotes: a. Plasma membrane (very similar to prokaryotes)   b. High degree of organisation - COMPARTMENTALISATION. This is a key feature that distinguishes eukaryotic from prokaryotic cells. What does compartmentalisation mean?   How is it achieved?

10. COMPARTMENTS IN EUKARYOTES • CYTOPLASM • NUCLEUS • ORGANELLES: ENDOPLASMIC RETICULUM GOLGI APPARATUS MITOCHONDRION LYSOSOME PEROXISOME CHLOROPLAST VACUOLE

11. EUKARYOTES cont’d. c. Ribosomes: Non-membranous organelles (similar in pro- and eukaryotes).  d. Cytoskeleton (found only in eukaryotes).  e. Cilia and flagella (cilia are found only in eukaryotes; flagella are found in prokaryotes and eukaryotes but they are TOTALLY DIFFERENT structurally).  f. Glycocalyx or cell wall (the bacterial cell wall is TOTALLY DIFFERENT to the structures that surround eukaryotic cells)  g. Multicellularity (Not found in prokaryotes) Why are the advantages of multicellularity?

12. Figure 4-5 A Typical Animal Cell

13. Figure 4-6 A Typical Plant Cell

14. Table 4-1 A Comparison of Some Properties of Prokaryotic and Eukaryotic Cells