Search for notes by fellow students, in your own course and all over the country.
Browse our notes for titles which look like what you need, you can preview any of the notes via a sample of the contents. After you're happy these are the notes you're after simply pop them into your shopping cart.
Title: Cells and microscopes
Description: This document will provide with information about cells, microscopes and life functions
Description: This document will provide with information about cells, microscopes and life functions
Document Preview
Extracts from the notes are below, to see the PDF you'll receive please use the links above
Topic 1
...
5nm Virus: 100nm
μm
÷ 1000
10
–9
10
–12
nano
pico
nm
pm
÷ 1000
Bacteria: 1μm
Organelle: 10μm
Cell: 100μm
Microscopes
Objects that are too small for the naked eye may be visualized with microscopes
Light Microscopy
•
Views living specimens in natural colour
•
Has a lower resolution and magnification
Electron Microscopy
•
Views dead specimens in monochrome
•
Has a higher resolution and magnification
Light Microscope
Electron Microscope
Light Microscopy
Bacteria
Plant Cells
Animal Cells
Muscle Tissue
Use of a light microscope to investigate the structure of cells and tissues, with drawings of cells
Electron Microscopy
Bacteria
Plant Cells
Virus (green), bacteria (red), animal cell (blue)
Electron microscopes have a much higher resolution than light microscopes (1
...
2
(height width length
number of boxes)
SA:Vol ratio
(surface area volume)
125
Cells / tissues may increase their
surface area to optimise transfer
6
(e
...
microvilli = ⬆︎ SA:Vol ratio)
Multicellular Organisms
Multicellular organisms form when groups of individual cells function together
These organisms are capable of completing new functions (emergent properties)
due to the collective action of many cells combining to create synergistic effects
Cell
Tissue
Organ
System
cardiac
heart
cardio
vascular
(muscle)
Multicellular organisms have properties that emerge from the interaction of their cellular components
Cell Differentiation
All cells in a multicellular organism share an identical set of genetic instructions
•
Individual instructions (called genes) form a totality called the genome
The activation of different instructions in specific cells will cause these cells to
differentiate and become specialised (possessing distinctive functionality)
Gene A expressed
Identical
cells
Gene B expressed
Specialised tissues can develop by cell differentiation in multicellular organisms
Gene Packaging
Within the nucleus, active genes are packaged in an
expanded and accessible form called euchromatin
The inactive genes are packaged in a condensed
and inaccessible form called heterochromatin
Differentiated cells will have different regions of
DNA packaged according to their specific function
Differentiation involves the expression of some genes and not others in a cell’s genome
Stem Cells
Stem cells are unspecialised cells that possess two key qualities:
•
Self-Renewal – They can continually divide and replicate
•
Potency – They have the capacity to differentiate into specialised cell types
Embryonic stem cells (totipotent / pluripotent) can form any cell type, whilst adult
stem cells (multipotent / unipotent) have a limited capacity for differentiation
Self-Renewal
Potency
The capacity of stem cells to divide and differentiate is necessary in embryonic development
Stem Cell Therapy
Stem cells can be used to replace damaged or diseased
cells with healthy, functioning ones
•
Harvest
Stem cells are extracted from an appropriate source
(embryos, umbilical cord blood, certain adult tissues)
•
Biochemical solutions trigger cell differentiation
•
New cells are implanted into the host’s tissue
•
Immune system is suppressed to prevent rejection
•
New cells monitored to ensure they are not cancerous
Differentiate
Implant
The capacity of stem cells to divide and differentiate makes them suitable for therapeutic use
Examples of Stem Cell Therapy
Stargardt’s Disease
•
An inherited form of juvenile macular degeneration that leads to blindness
•
Treated by replacing dead cells within the retina with functioning ones
Parkinson’s Disease
•
A degenerative disorder caused by the death of dopamine-secreting cells (CNS)
•
Treated by replacing dead cells in the midbrain with functioning ones
Use of stem cells to treat Stargardt’s disease and one other named condition
Ethics of Stem Cell Use
Harvesting
Potency
Tumor Risk
Limitations
Embryos
Are specially
created (SCNT)
Highest
Higher
Involves destruction
of an embryo
Umbilical
Cord Blood
Easy to extract
cells from cord
Lower
Lower
Cells must be stored
from birth at cost
Adult
Tissues
Cells obtainable
at any life stage
Lowest
Lower
May be difficult to
extract (and painful)
Ethics of the therapeutic use of stem cells from embryos, umbilical cord blood (newborn) & adult tissues
Topic Review
Can you do the following?
•
List the functions of life
•
State the cell theory (and exceptions)
•
Contrast light and electron microscopes
•
Calculate magnification of images
•
Explain how SA:Vol ratio limits cell size
•
Outline the process of cell differentiation
•
Describe stem cell use (ethics and examples)
Title: Cells and microscopes
Description: This document will provide with information about cells, microscopes and life functions
Description: This document will provide with information about cells, microscopes and life functions