Edexcel IGCSE Biology 复习笔记 2.2.2 Specialised Cells

Edexcel IGCSE Biology 复习笔记 2.2.2 Specialised Cells

Cell Differentiation & Specialised Cells

 

  • The structural differences between different types of cells enables them to perform specific functions within the organism
  • Cell differentiation is an important process by which a cell changes to become specialised
  • As an organism develops, cells differentiate to form different types of cells
  • Almost all of the cells in a multicellular organism will contain the same genetic information (the same genes or alleles), but depending on what role a particular cell needs to have, only some of the genes in a particular cell are used/expressed to control its development
  • When a cell differentiates, it develops a structure and composition of subcellular structures which enables it to carry out a certain function
    • For example, to form a nerve cell the cytoplasm and cell membrane of an undifferentiated cell must elongate to form connections over large distances

     

 

 

1.1.4-Differentiation

 

Diagram showing the possible differentiation of a human cell into two different cell types

 

 

 

Differentiation and development

  • As a multicellular organism develops, its cells differentiate to form specialised cells
    • In an animal, most cells differentiate at an early stage of development
    • As a result, animal cells lose their ability to differentiate  early in the life of the organism

     

  • Specific cells in various locations throughout the body of an animal retain the ability to differentiate throughout the life of the animal
    • These undifferentiated cells are called adult stem cells and they are mainly involved in replacing and repairing cells (such as blood or skin cells)

     

  • Plants differ from animals in that many types of plant cells retain the ability to fully differentiate throughout the life of a plant, not just in the early stages of development

 

 

Specialised cells in animals and plants

  • Specialised cells are those which have developed certain characteristics in order to perform particular functions. These differences are controlled by genes in the nucleus
  • Cells specialise by undergoing differentiation: this is a process by which cells develop the structure and characteristics needed to be able to carry out their functions
  • Some examples of specialised animal and plant cells are shown in the table and images below

 

 

 

Examples of Specialised Cells in Animals Table

 

 

Examples-of-specialised-cells-in-animals-table 

 

Ciliated-Cells

 

Ciliated epithelial cells

 

 

Nerve-Cell

 

A nerve cell

 

 

Red-Blood-Cells

 

Red blood cells

 

 

 

Sperm-Cell

 

Sperm cell

 

 

Egg-Cell

 

Egg cell

 

 

 

Examples of Specialised Cells in Plants Table

 

 

Examples-of-specialised-cells-in-plants-table 

 

Root-Hair-Cell

 

Root hair cell

 

 

Palisade-Mesophyll-Cell

 

Palisade mesophyll cell

转载自savemyexam

更多IGCSE课程
翰林国际教育资讯二维码