Transcript 14-19 Learning Core Development Programme

14-19 Learning Core
Development Programme
Laura Blacoe
Connah’s Quay High School
Aim
To help pupils understand more about the
importance of the increasing knowledge
of genetics and how and why people
inherit genetic disorders.
Lesson Objectives
We are learning:
 That genetic information is found in the nucleus of
every cell in the body and determines characteristics.
 That genetic information is inherited from parents
and that in each pair of chromosomes one is inherited
from the mother and one from the father.
 That diseases and disorders can be inherited.
Lesson Outcomes
What I am looking for:
 TYC describe what DNA, genes and chromosomes
are and how they determine characteristics.
 TYC describe how genetic information is inherited
and use genetic cross diagrams to determine the
possible genotype of offspring.
 TYC describe the symptoms of 4 different genetic
diseases and explain how they are inherited. Also,
predict possible genotype of offspring using genetic
cross diagrams.
Sexual Fertilisation
Zygote
Embryo
Foetus
Human Chromosomes
Using letters to represent alleles
Dominant alleles = Capital letter
Recessive alleles = Lower case letter of
the dominant allele
Black hair allele = B
Red hair allele = b
Genetic Crosses
B
B
B
BB
BB
Black Hair
b
Bb
Black Hair
Black Hair
Bb
Black Hair
Dad’s Genotype
Mum’s Genotype
B
b
B
BB
Bb
b
Bb
bb
Activity 1 – Huntington’s Disease
Huntington’s disease is a fatal disease
that affects the nervous system. It is
caused by a defective allele on
chromosome 4. It affects both men and
women and makes the body shake
uncontrollably.
Faulty allele = H
Normal allele = h
Answers to activity 1
h
h
H
Hh
Hh
h
hh
hh
Extension Activity
John and Karen have both discovered
that they have the genetic disorder
Huntington’s disease.
But, they already have 2 children
together. Explain to them (using genetic
cross diagrams) the possibilities of
their children’s genotype.
Answers to extension activity
H
H
H
H
HH
HH
HH
HH
H
h
H
HH
Hh
h
Hh
hh
H
H
H
HH
HH
h
Hh
Hh
Activity 2 – Cystic Fibrosis
Cystic Fibrosis is a genetic disorder
caused by a recessive faulty allele.
C = Normal allele
c = Faulty allele
Cystic Fibrosis affects the cells
membranes and causes the production
of excess mucus in the respiratory
organs and digestive system.
c
c
C
Cc
Cc
C
Cc
Cc
Activity 3 – Sickle Cell Anaemia
Distribution of Sickle Cell sufferers
S
S
SS
s
Ss
s
Ss
ss
Activity 4 - Haemophilia
Symptoms:
 Main symptom is that blood
does not clot properly.
 Even small cuts and tooth
extractions can be lethal due
to blood loss.
 Small knocks can cause
internal bleeding and big
bruises and joints may also
bleed.
Treatment
 The condition can be treated quite
successfully by regular injections of the
clotting factor – FACTOR 8.
Haemophilia – The sex-linked Gene
• Sex linked means only present in males or
females.
• Haemophilia is only present in males.
• Sex-linked conditions occur when the
there’s a defective allelle on the Xchromosome.
•
Any recessive genes on the man’s Xchromosome will express themselves
because their equivalent gene is missing
form the shorter Y-chromosome.
There are 5 possible combinations for the
blood clotting allele
Normal Male
X HY
Haemophiliac
Male
Normal Female
XhY
Carrier Female
X HX h
X HX H
Zygote does not XhXh
develop
You can’t have a
male carrier without
them having the
disease.
There are no female
sufferers because
the offspring don’t
develop.
H = Normal
h = Haemophiliac
Genetic Cross Diagram for Haemophilia
Parent
Genotypes
XHY
XH
XHXH
XH
Y
Normal
Female
XHXh
XHXh
Carrier
Female
Xh
Haemophiliac
Male
h
XHY Normal X Y
Male