Guidelines For Using Your Microscope:: © Pearson Education Ltd 2008 This Document May Have Been Altered From The Original

Guidelines for using your microscope: • Always use the same microscope • Always carry it by the handle and the base • Always start with the smallest objective lens • Switch the light on and ensure you can see a white light before starting • When observing specimens always start with the stage and the objective close to each other and move them away • Use the coarse focus first then try and improve the clarity of the image with the fine focus

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Criteria Cost

Light Microscope £100 - £500

Electron Microscope £ 1000000

Flexibility of Use

Portable

Large – requires a specialist room

Specimen Preparation

Quick Specimen may be alive

Time consuming Specimen must be dead

Specimen Colour

Natural colours can be seen

Image in black and white unless false colour added

Magnification

X 2000

X 500000

Stains

Stains often needed

Must use a heavy metal

Operation

Uses light

Uses Electrons

Image

2D

2D (TEM)/3D(SEM)

Resolution

Low

High © Pearson Education Ltd 2008 This document may have been altered from the original

SEM of blood SEM of blood – false colour Light Microscope of blood sample © Pearson Education Ltd 2008 This document may have been altered from the original

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© Pearson Education Ltd 2008 This document may have been altered from the original

Week 3 (a) Phospholipid molecule enlarged and (b) layer of phospholipids at the surface of water

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Week 3 The fluid mosaic model

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Passive Transport includes: • • •

Diffusion Facilitated diffusion Osmosis

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Passive Transport includes: • • •

Diffusion Facilitated diffusion Osmosis

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Active Transport:

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Exocytosis:

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Endocytosis:

Electromicrograph of endocytosis

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Plant Cells: Make sure you use the key terms of turgid and plasmolysed

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Animal Cells: Make sure you use the key terms of haemolysed and crenated (mainly used to refer to erthrocytes)

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M is nuclear division (mitosis) and cytokinesis (cleavage of cytoplasm)

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Interphase of the cell cycle: During interphase: DNA doubles New organelles are formed No chromosomes are visible as chromatin is dispersed throughout the nucleus in a diffuse form

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© Pearson Education Ltd 2008 This document may have been altered from the original

Stem Cells: Stem cells are cells that have the ability to differentiate and develop into other cell types There are 5 main types: 1. Early embryonic stem cells 2. Blastocyst embryonic stem cells 3. Fetal stem cells 4.Umbilical Cord stem cells 5. Human stem cells (in bone marrow and blood)

erythrocytes

Epithelial cells

Other specialised cells:

neutrophils

Palisade cell

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Tissue

Key Info

Squamous epithelial

Cells are flattened and so very thin. Forms a thin, smooth, flat surface. Lines the inside of blood vessels and forms thin walls of alveoli (short diffusion pathway for gaseous exchange). Cells are held in place by the basement membrane (collagen and glycoproteins). Attaches Made up of columnshaped cells. epithelial connective Found on cells innerto surface of the tissue. trachea, bronchi, bronchioles, in

Ciliated epithelial

the uterus and the oviducts. Covered with tiny projections called cilia, some of which produce mucus.