CH 2
CH 2
USING THE BRAILLE
SCIENCE CODE
THE BRAILLE SCIENCE CODE FOR SCHOOLS
This document is intended for use by all those who are involved with the
teaching of Science to students who use Braille as their main medium for
communication. The document is based on the Braille code used in the
United Kingdom for transcribing Science from print text into Braille, and
includes advice about various transcription issues. The official statement of
the UK Science code is contained in the BAUK document “Braille Science
Notation” which may be obtained from the BAUK web site, www.bauk.org.uk,
or in hard copy from RNIB.
The document contains examples of most of the common units and chemical
symbols found in the Key Stage 3, Key stage 4, AS and A2 curricula.
The examples are not meant to be exhaustive but should act as a guide to
solving the common problems which occur when transcribing Science
notation into Braille. There is also a section for those wishing to transcribe
the notation found in Genetics. The code in this section is one that has been
used successfully but has never been adopted as a standard by BAUK.
The document was produced by the following members of the RNIB/VIEW
Science Curriculum Group.
Frances Betts, Norman Brown, Rowena Curley, Susan Epstein, Susan
Parker, Cath Smith and Hillary Unwin.
We would like to thank the staff at RNIB New College and the members of
RNIB/VIEW Science Curriculum Group for their comments during the
drafting of this document.
1
CONTENTS
1. Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Key stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mass and force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Key stage 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Radiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AS and A2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Compound units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additional useful units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chemical symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chemical formulae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ionic symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Atomic structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Subatomic particles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronic structure/configuration . . . . . . . . . . . . . . . . . . . . . . . . . .
Chemical equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
State symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reversible reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Covalent bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AS and A2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Organic chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shorthand for organic chemistry . . . . . . . . . . . . . . . . . . . . . . . . . .
Molecular formulae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Structural formulae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Graphical display formulae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochemical shorthand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. Physics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Key stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit diagram symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GCSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit diagram symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5. Genetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
3
3
3
4
4
5
5
5
5
6
6
6
6
7
7
7
7
8
9
10
10
11
13
14
14
15
16
18
19
20
21
21
22
22
22
23
24
25
26
26
26
27
27
29
UNITS
For details of layout see the Braille Science Notation and Braille
Mathematics Notation booklets.
Units are coded according to the print by placing a dot 6 before each
capital letter.
Dot 5,6 is only required:
1. Before a lower case or upper case single letter unit symbol
(eg m or T), standing alone or with just an index or punctuation.
2. Before the abbreviation for second in combined unit, where
necessary to avoid ambiguity.
3. Before a lower case letter which is followed by an upper case letter
at the beginning of an abbreviation.
The following are examples of the most commonly used symbols at KS 3,
KS 4 and AS and A2 levels.
Key Stage 3
Length
Print
Braille
Examples
mm (millimetres)
Mm
9 mm
#i mm
#d1e mm
4.5 mm
cm (centimetres)
Cm
#c cm
3 cm
150.5 cm
m (metres)
km (kilometres)
;m
Km
6m
#aej1e cm
#f ;m
12 m
#ab ;m
1.5 m
#a1e ;m
20 km
#bj km
12.25 km
3
#ab1be km
Area
Print
Braille
Examples
mm2 (millimetres2)
Mm+2
9 mm2
#i mm+2
#d1e mm+2
4.5 mm2
cm2 (centimetres2)
Cm+2
#c cm+2
3 cm2
150.5 cm2
m2 (metre2)
km2 (kilometres)
;m+2
Km+2
#aej1e cm+2
#f ;m+2
6 m2
1.5 m2
#a1e ;m+2
20 km2
#bj km+2
12.25 km2
#ab1be km+2
Volume
Print
Braille
Examples
mm3 (millimetres3)
Mm+3
9 mm3
#i mm+3
#d1e mm+3
4.5 mm3
cm3 (centimetres3)
Cm+3
#c cm+3
3 cm3
150.5 cm3
m3 (metre3)
l (litre)
;m+3
;l
or
#aej1e cm+3
#f ;m+3
6 m3
12 m3
#ab ;m+3
1.5 m3
#a1e ;m+3
20 l
#bj ;l
12.25 l
#ab1be ;l
L (Litre)
;,l
50 L
#ej ;,l
ml (millilitre)
Ml
50 ml
#ej ml
4
Time
Print
Braille
Examples
s (second)
;s
6s
min (minute)
M9
3 min
Print
Braille
Examples
g (gram)
;g
6g
kg (kilogram)
Kg
3 kg
N (Newton)
;,n
15.5 N
#f ;s
#c m9
Mass and force
#f ;g
#c kg
#ae1e ;,n
Temperature
Print
Braille
Examples
°C (degrees celsius)
0,c
6°C #f0,c
Note the unit is unspaced.
K (Kelvin)
;,k
8K
#h ;,k
Electrical
Print
Braille
Examples
V (Volt)
;,v
6V
#f ;,v
A (Ampere)
;,a
3A
#c ;,a
mA (milliamp)
;m,a
5 mA
#e ;m,a
5
For KS 4 add the following
Electrical
Print
Braille
Examples
Ω (Ohm)
_w
6Ω
#f _w
W (Watt)
;,w
3W
#c ;,w
MW (megawatt)
,,mw
6 MW
#f ,,mw
J (Joule)
;,j
4.2 J
#d1b ;,j
kJ (kilojoule)
;k,j
35 kJ
#ce ;k,j
Note the use of the capital Greek letter sign (dots 4,5,6)
Radiation
Print
Braille
Examples
λ (lambda)
.l
6λ
Hz (Hertz)
,hz
50 Hz
α (alpha)
.a
α-particle
.a-"picle
β (beta)
.b
β-particle
.b-"picle
γ (gamma)
.g
γ-particle
.g-"picle
#f .l
#ej ,hz
Note the use of the lower case Greek letter sign (dots 4,6)
Time
Print
Braille
Examples
ms (milliseconds)
ms
50 ms
6
#ej ms
For AS and A2 add the following
Length
Print
Braille
Examples
μm (micrometre)
.mm
6 μm
#f .mm
nm (nanometres)
Nm
3 nm
#c nm
Print
Braille
Examples
μl (microlitre)
.ml
6 μl
dm3 (decimetre3)
Dm+3
3 dm3
Print
Braille
Examples
Pa (Pascals)
,pa
6000 Pa
kPa (kilopascals)
;K,pa
6 kPa
MPa (megapascals)
,m,pa
2.5 MPa
Volume
#f .ml
#c dm+3
Pressure
7
#fjjj ,pa
#f ;k,pa
#b1e ,m,pa
COMPOUND UNITS
Print
Braille
Examples
Nm
(Newton metres)
,n'm
3 Nm
#c ,n'm
g/l (grams
per litre)
;g_/l
10 g/l
#aj ;g_/l
gl-1 (grams
per litre)
;g'l+;-1
5 gl-1
#e ;g'l+;-1
m/s metres
per second
;M_/s
30 m/s
ms-1 (metres
per second)
;M's+;-1
20 ms-1
#bj ;m's+;-1
m/s2 (metres
per second2)
;m_/s+2
25 m/s2
#be ;m_/s+2
ms-2 (metres
per second2)
;M's+;-2
25 ms-2
#be ;m's+;-2
Nm-2 (Newtons
per metre squared)
,n'm+;-2
25 Nm-2
#be ,N'm+;-2
N/m2 (Newtons
per square metre)
,n_/m+2
25 N/m2
#be ,n_/m+2
mph (miles
per hour)
;mph
60 mph
kph (kilometres
per hour)
;kph
35 kph
or
#cj ;m_/s
or
or
or
#fj ;mph
#ce ;kph
Note the use of a dot 3 separator where the oblique sign is not used.
8
Additional useful units
Print
Braille
Examples
pH
;p,h
pH 7
molarity
,m
2M
;p,h #g
#b,m
pH can be spaced or unspaced from a following number, according to print.
M is always unspaced from a preceding number.
9
CHEMICAL SYMBOLS
A single letter symbol is preceded by dot 6.
A two letter symbol is preceded by dot 5.
Examples:
Level
Print
Braille
All levels
H
,h
C
,C
O
,O
Na
"na
Mg
"Mg
Al
"Al
Note that, as with units and elsewhere, a single letter symbol possibly
followed by a subscript number, standing alone in ordinary text requires a
dots 5,6 also.
Example
Print
Braille
H
;,h
(when standing alone)
10
Chemical formulae
All two letter symbols must be preceded by dot 5.
Dot 6 only needs to be used at the start of the formula if the first symbol is a
one letter symbol. It does not have to be repeated in the middle of a formula.
Subscripts are written in the lower case.
Key Stage 3
Print
Braille
H 2O
,H2O
CO2
,CO2
MgO
"MgO
KCl
,K"Cl
CaCl2
"Ca"Cl2
CuSO4
"CuSO4
(no need for dot 6)
CaCO3
"CaCO3
(no need for dot 6)
CO
,co
CoO
"coo
(no need for dot 6)
11
Formulae with brackets
Round brackets ( ), use maths brackets (gh and ar contractions).
Square brackets [ ], use maths brackets (of and with contractions).
Level
Print
Braille
Key Stage 3
Ca(OH)2
"Ca<oh>2
Key Stage 4
(NH4)2SO4
<,nh4>2so4
Cu(NO3)2
"Cu<no3>2
(CH3)3OH
<,ch3>3oh
[Fe(OH)3(H2O)3]
("fe<oh>3<h2o>3)
A Level
12
Ionic symbols
Use the appropriate number of + or – signs unspaced from the symbol.
Level
Print
Braille
Key Stage 4
H+
,h;6
K+
,k;6
Zn2+
"Zn;66
Al3+
"Al;666
F-
,f;-
O2-
,o;--
N3-
,n;---
NH4+
,nh4;6
OH-
,oh;-
SO42-
,so4;--
[Fe(H2O)6]2+
("fe<h2o>6);66
[Cr(OH)6]3-
("cr<oh>6);---
A Level Complex ions
N.B. The Braille Science Code includes the alternative notation for ionic
charges of +/- 2 or greater using a superscript number followed by
a + ;6 or – ;- sign.
Print
Braille
Mg2+
"Mg+#b;6
Al3+
"Al+#c;6
SO42-
,so4+#b;-
The notation using the appropriate number of + or – signs is preferred by
teachers.
Braille producers for examinations can use the alternative!
13
Atomic Structure
Atomic mass numbers and atomic numbers are given as superscript + and
subscripts * respectively in front of the symbol. Use lower case numbers.
Level
Print
Braille
Key Stage 4 and A Level
4 He
2
+4*2"he
27
13 Al
+27*13"al
Subatomic particles
Use lower case letters.
Level
Print
Braille
Key stage 4
p (proton)
;p
e (electron)
;e
e- (electron showing charge)
;e;-
n (neutron)
;n
1p
1
+1*1;p
–0 e
–1
+0*;-1;e
1n
0
+1*0;n
A Level
14
Electronic Structure/configuration
Key Stage 4
Print
Braille
Na (2,8,1)
"na <#b#h#a>
Ca (2,8,8,2)
"ca <#b#h#h#b>
A Level
No need to use lower case letter sign except in front of “d” (this avoids
confusion with the number 4) . Keep unspaced throughout.
1s22s22p4
#as+2#bs+2#bp+4
1s22s22p63s23p63d74s2
#as+2#bs+2#bp+6#cs+2#cp+6#c;d+7#ds+2
15
Chemical equations
Use + (;6) unspaced from the following item.
The Æ spaced on both sides is preferred to = unspaced from the
following item.
Print
Braille
Æ
3o
Word equations
Here are some examples.
Magnesium + oxygen Æ magnesium oxide
magnesium ;6oxyg5 3o magnesium oxide
Calcium carbonate + hydrochloric acid Æ calcium chloride +
carbon dioxide + water
calcium c>bonate ;6hydro*loric acid
3o calcium *loride ;6c>bon dioxide
;6wat]
Carbon dioxide + water
(chlorophyll, light)
glucose + oxygen
c>bon dioxide ;6wat] 3o+<*lorophyll1
li<t> glucose ;6oxyg5
See pages 19 and 20 for more information about words above and below
the arrow.
16
Symbol equations
Equations should begin in cell 5, with runovers in cell 7.
If a runover is needed, finish the previous line with a dot 5.
All Levels
C + O2 Æ CO2
,c ;6,o2 3o ,co2
2NH4OH + H2SO4 Æ (NH4)2SO4 + 2H2O
#b,nh4oh ;6,h2so4 3o <,nh4>2so4"
;6#b,h2o
or:
#b,nh4oh ;6,h2so4 3o"
<,nh4>2so4 ;6#b,h2o
17
State symbols in equations
Write after the formula, leaving one space.
Key Stage 4 and A Level
Print
Braille
(s) (solid)
7;s7
(l) (liquid)
7;l7
(g) (gas)
7;g7
(aq) (aqueous)
7aq7
C(s) + O2(g) Æ CO2(g)
,c 7;s7 ;6,o2 7;g7 3o ,co2 7;g7
2H2(g) + O2(g) Æ 2H2O(l)
#b,h2 7;g7 ;6,o2 7;g7 3o"
#b,h2o 7;l7
NaOH(aq) + HCl(aq) Æ NaCl(aq) + H2O(l)
"naoh 7aq7 ;6,h"cl 7aq7 3o"
"na"cl 7aq7 ;6,h2o 7;l7
H+(aq) + OH-(aq) Æ H2O(l)
,h;6 7aq7 ;6,oh;- 7aq7 3o"
,h2o 7;l7
Mg(g) Æ Mg2+(g) + 2e-
"mg 7;g7 3o "mg;66 7;g7 ;6#b;e;Cl(g) + e- Æ Cl-(g)
"cl 7;g7 ;6e;- 3o "cl;- 7;g7
18
Reversible reactions/equilibrium
The arrow should be spaced on both sides.
Key Stage 4 and A Level
Print
Braille
53e
N2 + 3H2
2NH3
,n2 ;6#c,h2 53e #b,nh3
Information above/below arrows
Key Stage 4 and A Level
Use superscript sign (+) immediately after the arrow. Use round brackets to
enclose two or more items of information.
H 2S
400°C
º
H2 + S
,h2s 53e+#djj0,c ,h2 ;6,s
N2 + 3H2
400°C, 200 atm
º
2NH3
,n2 ;6#c,h2 53e+<#djj0,c1
#bjj atm> #b,nh3
19
If there is information above and below the arrow in print, Braille entirely as
superscript.
400°C, 200 atm
N2 + 3H2
Haber Process
2NH3
,n2 ;6#c,h2 53e+<#djj0,c1
#bjj atm1 hab] process> #b,nh3
Covalent bonds
Key Stage 4 and A Level
Bond
Print
Braille
Single
H—H
,h@h
Double
O
,o^o
Triple
N≡N
O
,n_n
20
A Level Chemistry
Example
Print
Braille
delta +
δ+
.d;6
Enthalpy change
ΔH
_d,h
Enthalpy of formation
ΔHf
_d,h*f
Enthalpy of combustion
ΔHc
_d,H*c
Equilibrium constants
Kc
,k*c
Kp
,k*p
Kw
,k*w
Ka
,k*a
Rate constant
k
;k
Standard reduction potential
E
,e+0
(n.b. this is not an agreed
convention but is an acceptable
match to the print)
21
Acceptable shorthand for Organic Chemistry
Example
Print
Braille
Alkyl radical
R
,R
Aryl group, C6H5
Ar
"Ar
(n.b. this is only in the context of Organic
Chemistry and must not be confused with the
symbol for the element argon, Ar)
Methyl group, CH3
Me
"me
Ethyl group, C2H5
Et
"et
Molecular formulae
Follow the rules for chemical formulae.
Print
Braille
C 2H 6
,c2h6
C3H7OH
,c3h7oh
CH3COCl
,ch3co"cl
C2H5COOCH3
,C2H5COOCH3
22
Structural formulae
Follow the rules for chemical formulae.
Print
Braille
CH3CH3
,CH3CH3
CH3CHOHCH3
,CH3CHOHCH3
CH3CHClC(CH3)2CH3
,CH3CH"CLC<CH3>2CH3
Structural formulae showing bonds
Use code for bonds.
Print
Braille
CH3—CH3
,CH3@CH3
CH3—CH2—Br
,CH3@CH2@"BR
—O
(CH3)2C—
<,CH3>2C^O
23
Displayed graphical formulae
Whilst this is covered in para 19 onwards in the Chemistry section of the
Braille Science Notation, for school use these are best done using raised
diagrams with the bonds represented by solid lines. For double and triple
bonds the gap between the lines should be no less than 3mm.
Key Stage 4 and A Level
Print
Braille
,H
H
H
C
H
,H
,C
,H
H
,H
H
H
C
,H
,H
C
,C
H
,C
H
,H
H
C
C
H
,H
24
,H
,C
,C
,H
Electrochemical cell shorthand
A Level
There is no agreed Braille convention for this. The following is only a
suggestion which bears some resemblance to the print layout.
Print
Zn(s) ⎮ Zn2+(aq)
Cu2+(aq) ⎮ Cu(s)
Suggested Braille:
_ unspaced to the right to represent vertical line
Use __ unspaced to the right to represent double, dashed vertical lines
Use
"zn 7;s7 _"zn;66 7aq7 __"cu;66 7aq7
_"cu 7;s7
25
PHYSICS
Circuit diagrams
The following symbols are used to produce raised circuit diagrams.
Where a symbol is thought to be unfamiliar the name of the component is
often added in Braille under the symbol.
Key Stage 3
Print
Braille
Switch (open)
Cell
Resistor
Variable resistor
Lamp
Lamp (alternative version)
26
Print
Braille
V
Voltmeter
,v
A
Ammeter
,A
M
Motor
,m
All of these symbols will need to be enlarged by a factor of at least two
before they can be used by a student working by touch alone.
For GCSE
Print
Braille
Fuse
Battery
Diode
27
For GCSE (continued)
Print
Braille
Capacitor
Thermistor
Light emitting
diode (LED)
Light dependent
resistor (LDR)
These examples are not exhaustive but they should give a good idea of how
the majority of symbols can be enlarged and presented in a tactile form.
Where there might be doubt about a particular example the name can be
provided below the symbol in Braille.
Mathematical formulae used in Physics should follow the advice given in the
Braille Mathematics Notation (BAUK).
28
GENETICS
The study of Genetics requires students to solve problems which require a
standard code in print. There is at present no Braille equivalent but the
following has been used successfully with students working towards GCSE
and A level examinations.
The key to the code involves the use of the dot 6 capital letter sign to
identify upper case letters in the code and the dots 56 letter sign to identify
the lower case letters. Genetics problems have a particular layout which
forms part of the assessment criteria. The following examples use Braille but
have the layout that is used in print. This means that students’ answers can
be easily transcribed and anyone with a limited amount of Braille knowledge
can follow the steps used by the student to solve the problem.
In each example the print translation is provided as a guide to both content
and layout.
The first example shows the steps used in a standard Mendel monohybrid
cross. This type of cross is found in the syllabi for GCSE.
29
Example 1
The original parents are from two pure breeding strains where the dominant
allele codes for a tall individual and the recessive allele codes for a dwarf
individual. The dominant allele is represented by T and the recessive allele
by t.
P>5ts
tall
Parents
tall
G5otypes
,T,T
Genotypes
TT
Gametes
,T
Gametes
T
;8
x
dw>f
dwarf
;t;t
tt
;t
t
(fspr+
,T;t
Offspring
Tt
All (fspr+ >e tall 2c ;,T is dom9ant
6;t4
All offspring are tall because T is dominant to t.
See the next page for the next stage.
30
If ;! (fspr+ n[ 9t]bre$4
If these offspring now interbreed.
P>5ts
,T;t
;8
Parents
Tt
Gametes
,T & ;t
,T & ;t
Gametes
T and t
T and t
x
,T;t
Tt
(fspr+
Offspring
,T
;t
T
t
,T
,T,t
,T;t
T
TT
Tt
;t
,T;t
;t;t
t
Tt
tt
? gives "o ,T,T & two ,T;t 9dividuals
b !y w 2 tall 9dividuals z ;,T is
dom9ant4 "O ;t;t 9dividual is al
produc$4 ? 9dividual is dw>f4
This gives one TT and two Tt individuals but they will be tall individuals as
T is dominant. One tt individual is also produced. This individual is dwarf.
Please note that the Braille table above is identical to the Punnet square
used by those working in print. Some teachers use arrows to link the
various gametes to form the offspring. This process will not work for
students working in Braille and is confusing for many partially sighted
students. Therefore teachers should be encouraged to use the
Punnet square method.
31
32
rT
and
rt
RT
Gametes
Rt
,R,T ,R;t ;r,T & ;r;t
RrTt
,R;r,T;t
Gametes
Parents
P>5ts
x
;8
RT
Rt
rT
and
rt
,R,T ,R;t ;r,T & ;r;t
RrTt
,R;r,T;t
Let one gene be for flower colour with two alleles, R for red petals and r for white petals. R is dominant to r.
The other gene is for plant height, T for tall and t for dwarf. T is dominant to t. In this example the parents are
heterozygous for both genes ie their genotypes are RrTt.
This second example shows a Mendel dihybrid cross which is found in most A2 level syllabi. Here two genes with
two alleles are involved in the cross.
Example 2
This page has to be in landscape format so that the Braille can fit. Students making notes on standard Braille paper
need to be aware that they will need to conserve space as much as possible.
33
,R,R,T;t
RRTt
,R;r,T,T
RrTT
,R;r,T;t
RrTt
,R;t
Rt
;r,T
rT
;r;t
rt
Rrtt
,R;r;t;t
RrTt
,R;r,T;t
RRtt
,R,R;t;t
RRTt
rrTt
;r;r,T;t
rrTT
;r;r,T,T
RrTt
,R;r,T;t
RrTT
,R;r,T,T
rT
;r,T
rrtt
;r;r;t;t
rrTt
;r;r,T;t
Rrtt
,R;r;t;t
RrTt
,R;r,T;t
rt
;r;t
This gives 9 red flowered tall plants, 3 red flowered dwarf plants, 3 white tall plants and 1 white dwarf plant.
? gives #i r$ fl[]$ tall plants1 #c r$ fl[]$ dw>f
plants1 #c :ite tall plants & #a :ite dw>f plant4
RRTT
RT
,R,R,T;t
Rt
RT
,R,R,T,T
,R;t
,R,T
,R,T
Offspring
(fspr+
Example 3
Some geneticists use a single capital letter to distinguish the gene and a
superscript letter to label the allele. This can be seen in crosses involving
the fruit fly, Drosophila and sometimes in the genetics of the ABO blood
groups. In blood groups the gene is given the letter I and the groups are
labelled as IA, IB and Io. In Braille these would be ,i+,a, ,i+,b
and ,i+;o. This notation takes up considerably more space (especially
in a dihybrid cross). It may be necessary to modify questions to eliminate the
letter for the gene leaving the letters for the alleles which can then be used
as shown earlier.
34
Other titles in this series:
TC20209 Using the Braille French Code
TC20910 Using the Braille German Code
TC20911 Using the Braille Spanish Code
TC21086P Using the Braille Mathematics Code
ISBN
976 1 85878 820 3
TC21085P
2008
Produced by RNIB on behalf of
RNIB/VIEW Science Curriculum Group