Download File

Adaptation
Differentiation of cells
Differentiation
• Definition – give a dictionary definition of the word above.
• Give examples of differentiated cells
• Cellular differentiation is the process by which a less
specialised cell becomes a more specialised cell type
• Examples you need to be aware of are:
• erythrocytes (red blood cells) and neutrophils derived from
stem cells in bone marrow,
• xylem vessels and phloem sieve tubes from cambium;
Lesson 7 - Differentiation
Learning Objectives
• define the term
differentiation, with
reference to erythrocytes,
neutrophils
• describe and explain, how
cells of multicellular
organisms are specialised
for particular functions
• explain the meaning of the
terms tissue, organ and
organ system
Success Criteria
• Produce a resource to show
how each of the cell types is
differentiated
• Describe how the cell’s
differentiation allows it to
fulfill its role
• Produce a flow diagram to
show how blood cells
differentiate
2.1.6 h-l
Spec. Check
• describe and explain, with the aid of diagrams and
photographs, how cells of multicellular organisms are
specialised for particular functions,
•
• with reference to erythrocytes, neutrophils, epithelial cells,
sperm cells, palisade cells, root hair cells and guard cells;
• explain, with the aid of diagrams and photographs, how
cells are organised into tissues, using squamous and ciliated
epithelia, xylem and phloem as examples;
Remember – key definitions
• Cell, tissue, organ, organ system
• Organisation of the work:
• Cells: Animal/Plant - erythrocytes, neutrophils, epithelial cells,
sperm cells, palisade cells, root hair cells and guard cells;
• Tissues: Animal/Plant – epithelial, connective, muscle,
nervous, epidermal, vascular, meristematic, parenchyma, sclerenchyma,
collenchyma
• Organs: Animal/Plant heart, lungs, kidney etc, leaf root,
stem, (flower)
• Organ Systems: Animal/Plant – digestive, nervous, skin
etc, flower
How can cells be adapted?
• The amount of a certain organelle
• The shape of the cell
• The contents of the cell
Why is specialisation and
differentiation needed?
• Single celled organisms have a large SA/V ration, all surfaces
are in contact with the external environment and the division
of labour is determined by the organelles.
• Multicellular organisms are large – have a smaller SA/V ratio.
• The majority of their cells are not in direct contact with the
external environment.
• This means they need specialised cells to carry out particular
functions.
Erythrocyte
Adaptations
Organelles
• No nucleus, mitochondria, Golgi apparatus,
rough endoplasmic reticulum
Shape
• Biconcave discs
Contents
• Contain lots of the protein haemoglobin
Neutrophil
Adaptations
Organelles
• Many lysosomes – enzymes to digest
pathogens
• Multi-lobed nucleus – makes it easier to
squeeze between gaps between cells to enter
tissues
Sperm Cells
Adaptations
Organelles
• Many mitochondria
• Acrosome (lysosome)
Shape
• Streamlined
• Undulipodium
Content
• Half the number of chromosomes
Epithelial Cell
Squamous Epithelial Cell
• Flattened
• Smooth
• Secrete collagen and glycoproteins
Ciliated Epithelial Cell
• Covered in cilia
• Some release mucus
Palisade Cells
Adaptation
• Lots of chloroplasts for photosynthesis
• Laid end on
• Placed at top of leaf
Guard Cell
Adaptations
• Thick cell walls so inner cell wall does not
stretch when changing shape due to water
entry
• Contain chloroplasts to undergo
photosynthesis
Root Hair Cell
Adaptations
• Large surface area