Notes On Biology Concepts

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Biology Concepts
Chapter 1: Cells in Action
Different types of cells
Cell theory
Types of microscopes LM, TEM, SEM
Cell size
Chapter 2: Cell Structure & Function
Prokaryotes
Eukaryotes
Cell theory
Plasma membrane
Diffusion
Osmosis
Active transport
Bulk transport
Cell walls
Cellular organelles structure and function
Cells, tissues, organs, organ systems
Chapter 3: Composition of Cells
Water
Organic compounds – CHO, Proteins, Lipids, Nucleic acids
Minerals
Vitamins
Enzyme structure and specificity
Cellular respiration

Functions: Plasma membrane, nucleus, ribosomes, mitochondrion, endoplasmic reticulum, Golgi complex
Difference of the electron and light microscopes
How staining helps in viewing an image
Process of exocytosis and endocytosis
Functions: Diffusion, osmosis, active transport, cell organelles
Know the microscopic pictures

Chapter 1 – Cells in Action
Cells and Microscopes: an introduction
Cells are the basic structural and functional units of all living things
Most cells are too small to be seen with the naked eye, therefore microscopes provide enlarged images with great detail of cells and the structures they contain
Cells : a historical overview
Robert Hooke, English scientist discovered cells in 1665
Recognising the pattern: the cell theory
The cell theory (Schleiden, Schwann, Virchow):
All living things consists of one or more organised structures that are called cells or of products of cells
Cells are the basic functional unit of life
New cells are produced from existing cells
Spontaneous generation: idea that living things could arise from non-living or dead matter
Another idea: living things developed and gathered to form a compact mass, then becoming organised cells
Life span of Cells
The life span of cells in multicellular organism varies
Cells are constantly being replaced by new ones
The average life span of some human cells are
Stomach cells: 2 days
Mature sperm cells: 2-3 days
Skin cells: 20-35 days
Red blood cells: about 120 days
Unit of measure used in relation to cell size is the micrometre (μm)
Tools for viewing cells
Light Microscope (LMs):
Uses visible light that illuminates  (shows arrangement of an internal structure of cells) and passes through a specimen
Simple Light Microscope:
Has one lens
Similar to a magnifying glass
Compound Light Microscope (CLM):
Has at least 2 sets of lenses  objective lens and ocular (eyepiece) lens
Most have several objective lenses, each with a different magnification
Magnification powers of both the eyepiece and lens is used to enlarge the image
Characteristics of the lenses also influence a microscope’s resolution
Resolution is the ability to distinguish two points that are close together as two separate points
Cells are virtually colourless, therefore staining is used so that it’s easier to observe under a LM, however they are often toxic and distort cell features
Phase Contrast Microscope:
Developed to observe unstained intact living cells
Image developed has highly contrasting light and dark areas
Fluorescence Microscope:
Uses ultraviolet (UV) light to reveal compounds that have been stained with fluorescent dyes that bind to particular parts in a cell – shows chemical substances present
Scanning confocal Microscope:
Sort of a cross between a light microscope and an electron microscope
Uses laser light and special optics to allow a viewer to look at successively deep layers of an object without having to cut it into thin sections
3D images can be produced through a computer
Electron Microscopes:
Transmission Electron Microscopes (TEM):
A beam of electrons with shorter wave lengths than light passes through and illuminates specimens
Electromagnets are used to control the beam of electrons instead of glass lenses (electromagnetic field)
Shorter wavelengths = greater resolving power
Shows the internal structure of specimens
Scanning Electron Microscope (SEM):
Electrons are
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