Introduction to Cells

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Slide 1

Introduction to Cells

Topic 2: Investigating Cells

Standard Grade Biology

Slide 2

Magnification

Cells can be seen more clearly using

Microscopes _ the cells

Microscopes may have two or

three

and one _.

microscopes

objective lenses

magnify

eyepiece lens

Slide 3

Calculating Magnification

To work out Total Magnification use the following formula

TOTAL = x

MAGNIFICATION

magnification of eyepiece lens

magnification of objective lens

Slide 4

Since microscopes magnify cells we have a new unit of measurement.

These new units are called

_.

1mm = 1000 µm

1 = 1 µm

1000

microns

Slide 5

Measuring Cell Size

We can use microscopes to estimate the size of cells we are looking at

e.g. if we know the diameter of the field of our field of view we can then estimate the size of the cells

Slide 6

if the field of view = 1mm

then onion cells are

mm

or (µm) in length

1mm (1000 µm)

Field of view

Onion cell

0.5

500 microns

Slide 7

if the field of view = 0.5mm or 500µm

then these cheek cells would be

mm or µm in length

0.5 mm (500 µm)

Human cheek cell

500

5

100

Slide 8

4000

1000

500

Slide 9

Staining Cells

Animal and plant cells can be

_

so that the

can be

stained

structures within cells

seen more clearly

Slide 10

_ stains the

_ of onion

cells and also its

_.

cell wall

nucleus

Iodine

Slide 11

_ is

used to stain the

_ of

.

Methyl Blue

nucleus

human cheek cells

Slide 12

_ is used to

stain the _

present in the nucleus of cells which are

about to divide.

Acetic orcein

chromosomes