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NadiaA

Introduction to Cell Biology
LO:
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Explain what cells are
Outline the history of cell discovery and the importance of microscopy;
Describe how cells differ in size, structure and function

Basics
Greek for hollow vessel = cell
Prefix =cytoCytology- study of cells
Endocytosis- moving into cells

Cytochemistry- cell chemistry
Suffix= -cyte
Hepatocyte- liver cell
Exocytosis- moving out of cells

What are cells?
Cell
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Smallest living entity
small unit bound by a plasma membrane (or cell wall)
smallest functional component of a multicellular organism
some organisms are unicellular, some are multicellular

Cells contain
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aqueous fluid (cytosol which contains water, proteins, and dissolved ions)
Chemicals (cytoplasm which is the site of some reactions and contains the organelles)
Structural support (cytoskeleton)
Membrane bound organelles (e
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mitochondria, Golgi apparatus)

Tissue- a group of different cells that work together for a particular function
Organ- a group of different tissues that work together for a particular function
Organ system- a group of different organs that work together for a particular function e
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endocrine, reproductive, renal, cardiovascular
Different organ systems work for the survival of the organism
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g
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Thus CELLS are the SMALLEST LIVING ENTITY
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Harness energy (eat and drink)
Respire (take oxygen in, take out carbon dioxide, if a human)
Grow and developReproduce- remember all life comes from pre-existing life
Respond to stimuli

These factors above apply to plant cells too but NOT prions
There is a debate on whether viruses are ‘living’ or not
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3
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b
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g
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g
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g
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g
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Cells specialise/differentiate
 There are approximately 37 trillion cells in the human body
 There are approximately 210 cell types
 These specialise/ differentiate to make up the tissues and organs
Differentiate- to specialise to perform a particular function
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Reproduce by Cell proliferation;
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e
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Mitosis (of somatic cells)

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Remember that some cells divide more often than others e
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hair is every 18 hours
Apoptosis- programmed cell death
Somatic cells- of the body
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g
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youtube
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e
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But some use fluorescence dyes,
antibodies and sometimes organelles can be identified if we use the nucleus as a reference point and
look around it
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See https://www
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com/watch?v=LjXSHn4g3GI
Max resolution: 200nm
Magnification: x1500
There are two types of electron microscopes:
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Scanning electron microscopes
Max resolution: 0
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2nm
Magnification: x500000
Electron beam goes through sample

How do cells differ?
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Shape/ structure
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Size
RBC= 50 micrometers2
Oocyte= 11,308 micrometers2
Sperm= 150 micrometers2
A average man has a sperm that is 50 micrometres, the same as an average whale
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Another example if the sperm of
a fruit fly which is larger than of an average male!

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Function
 Erythrocytes display such features to increase surface area to carry blood and also squeeze
past capillaries
 Neuron’s function is to transmit electrical information
 Keratinocyte – epidermal cell that produces keratin that make up our hair, nails
 Macrophage- does phagocytosis
 Melanocyte- produce melanin, skin pigment

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