Topic 2a. Biology Organisation of life : Name: _________________________________________________
Structure of Plant & Animal cell (for core section)
NB: you should know how to draw & label
parts of plant and animal cell plus state the
functions of the parts given in this
document
In all eukaryotic cells:
Cell membrane; selectively controls what enters or leaves cytoplasm;
Genetic material = nucleic acids (DNAs & RNAs)
cytoplasm is a jelly-like substance in which everything else in the cell is suspended in & chemical reactions take place;
Eukaryotes have membrane bound specialised regions within cytoplasm:
These are organelles “organs of the cell”
Examples of organelles:
1. Nucleus protects genetic information (DNA);
2. mitochondrion; aerobic respiration occurs here to release energy currency molecule called ATP;
cells with high metabolism rates (very active cells) normally have lots of mitochondria,
to offer sufficient energy; examples: muscle cells, root hair cells, liver cells & neurons;
NB:
Plants have some extra structures such as:
3. cell walls; structurally supports the cell; & prevent bursting due to osmosis;
4. Chloroplast – Site of photosynthesis in plant cells
5. permanent vacuole called sap vacuole,
 Stores/isolates harmful material
 Stores small nutrients
 Maintains water balance
 Structural support for plant cells via turgor pressure
NB: animal cells have small temporary ones.
NB: the above diagram & parts are only sufficient for the core part of syllabus!
extended course wants you to know the following two extra structures:
6. Ribosomes;
site of protein synthesis (translation stage of protein synthesis)
NB: - later you will learn that initial stage of protein synthesis is transcription = copying a gene which is
along DNA to make a copy (transcript) called messenger RNA, mRNA;
- Some ribosomes are freely floating in cytoplasm; - synthesis proteins used within the cell;
- some ribosomes are attached to ER
7. Endoplasmic reticulum (ER); tubular membranes made of extensions of outer membrane of nucleus;
NB: Rough endoplasmic reticulum (rER); has ribosomes on its surface so it looks “rough”;
ribosomes on ER synthesise proteins that eventually go to form part of cell
surface membrane or proteins that are transported out of cell by exocytosis;
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Extended students should be comfortable with the following diagram!
Summary of Levels of organisation
Cell – The smallest structural and functional unit of an organism
Tissue – Group of cells with similar structures working together to perform a shared function
Examples – blood (a fluid tissue), epithelium, palisade, epidermal, xylem, phloem, bone
Organ – Structure made up of a group of tissues, working together to perform specific functions
Examples:- root, stem, leaf, heart, liver, lung, leg, hand, eye etc
Organ system – Group of organs with related functions, working together to perform body functions;
Some Multicellular organisms (plants & animals) are made of several Organ systems working together;
Development in plants & animals involves formation of specialised cells & tissues;
Remember Development in some multicellular organisms involves:
 Is increase in complexity
 Caused by differentiation of cells & tissues to perform specialised functions;
 Differentiation involves,
 Switching some genes on while switching off other genes;
 This results in structural & physiological changes in cells;
 In plants & animals this results in formation of tissues &
organs;
Examples of specialised cells in plants & animals you need to
know by the end of the syllabus;
1.
2.
3.
4.
5.
6.
7.
Ciliated cells
Root hair cells
Xylem vessels
Palisade cells
Nerve cells
Red blood cells
Sperm and egg cells
Each of the things above will be covered in more detail in other topics in the syllabus and therefore should not be covered here;
But use the following worksheet named “specialised cells – worksheet” to remind yourself since the same were covered in lower secondary.
End
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