CIE IGCSE Biology

Revision Notes

2.1 Cell Structure & Organisation

Cell Structures: Basics

  • Cytoplasm is found inside the cell and contains all the other cell structures
  • The large nucleus is surrounded by a nuclear membrane to separate it from the cytoplasm
  • The cell membrane surrounds the cell
  • The cell wall is made of cellulose and surrounds the cell membrane in plant cells
  • Chloroplasts are organelles found in the cytoplasm that are packed with the pigment chlorophyll and so are green in colour
  • Vacuoles are large vesicles that take up a large part of the interior of plant cells

 

An animal and plant cell as seen under a light microscope, IGCSE & GCSE Biology revision notes
An animal and plant cell as seen under a light microscope

 

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Cell Structures

Within the cytoplasm, the following organelles are visible in almost all cells except prokaryotes when looking at higher magnification (ie using an electron microscope):

  • Mitochondria (singular: mitochondrion) are organelles found throughout the cytoplasm
  • Ribosomes are tiny structures that can be free within the cytoplasm or attached to a system of membranes within the cell known as Endoplasmic Reticulum
  • Endoplasmic reticulum studded with ribosomes looks rough under the microscope; this gives rise to its name of Rough Endoplasmic Reticulum (often shortened to R.E.R.)
  • Vesicles can also be seen using a higher magnification – these are small circular structures found moving throughout the cytoplasm

 

Structures in an animal cell visible under a light microscope & an electron microscope, IGCSE & GCSE Biology revision notesStructures in an animal cell visible under a light microscope and an electron microscope

 

Structures in a plant cell visible under a light microscope & an electron microscope, IGCSE & GCSE Biology revision notesStructures in a plant cell visible under a light microscope and an electron microscope

 

Functions of Cellular Structures: Basics

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Functions of Subcellular Structures

Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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