From Mendel to the future (30 hours)
Characteristics are passed on from one generation to the next. In sexual reproduction both parents contribute to the features of the offspring. Information, embedded in the DNA molecules
that make up the chromosomes in the sperm and ovum nuclei, determines these features through the production of specific proteins. There are a variety of patterns by which this information
is transmitted. Knowledge of these patterns, the way in which genes are expressed and the genome has led to human intervention in the characteristics that may be expressed in crops and
domestic animals and possible applications in human reproduction.
Key Concepts:
1. Cells are the functioning units of all living things.
4. Changes in the living world occur in different scales of time and space.
6. There are mechanisms by which characteristics of individuals in one generation are passed on to the next generation.
UNIT ORGANISATION
Main Focus
Key
Ideas
Where it began
22
Suggested Learning Experiences
Possible Student Activity
Understand why Mendel’s work was a success
because it was based on the Scientific Method
although he was a man before his time.
Library research on the life of
Mendel
Work out genetic questions
that are based on different
types of crosses. Use
computer simulations on
various organisms (e.g. fruit
flies and peas).
Cross this with this and
that and what is likely to
happen
22, 23
Define the terms alleles, dominant and recessive traits.
Describe monohybrid and dihybrid crosses and ratios,
test crosses. Realise that the principals and laws in
these crosses underlie genetics.
Where are genes found?
2, 23
Link the concepts of the structure of DNA, genes and
chromosomes with genetics.
When Mendel’s ideas do
not hold – what is going
on?
22
Realise that Mendel’s ideas were limited to peas and
this does not hold in the wider world. Consideration of
codominance, intermediate dominance, multiple
alleles, continuous variation and other forms.
I don’t have the disease
but my son does. How can
this be?
22, 23
Investigate sex determination and sex linked diseases
e.g. haemophilia, along with other diseases such as
sickle cell anaemia and cystic fibrosis.
Genes are linked if they
are on the same
chromosome
22, 23
Continue the concept of genes on chromosomes but
extend to show linkage, crossing over and mapping of
chromosomes
How do genes affect me?
2, 23
Relate the chemical structure of DNA of the genes to
their role in protein production – from the nucleus to
cell organelle to the individual.
Investigate the different types
of inheritance that do not
follow the Mendelian pattern.
Grow peas and barley to show
lethal genes, monohybrid ratio
and intermediate dominance.
Use computer simulations to
map genes on a chromosome
using linkage and crossing
over
Skills
4, 6
Objectives
Text Reference
UB
Ch. 1.4 20.1
UB, IB
Ch 20.1
UB
Ch. 21.1, 21.2
UB, IB
Ch. 20.2
UB
Ch. 20.3
UB, IB
Ch. 20.4
UB
Ch. 21.3
From Mendel to the future
UNIT ORGANISATION
Main Focus
Continued
Key
Ideas
Suggested Learning Experiences
10, 24
Investigate chromosomal abnormalities like Down
Syndrome (numerical defect) or Fragile X Syndrome
(structural defect), gene abnormalities that can be
autosomal or sex-linked, dominant, recessive or point
mutations like sickle cell anaemia. Understand that
these are diseases and are considered disadvantageous
to humans but some mutations may give organisms an
advantage or be neutral at that time and/or place.
When things go wrong,
how are they detected?
10, 18
Pull together the concepts of: causes of genetic
diseases and their early detection methods using
ultrasound scanning, amniocentesis, chorionic villus
sampling, karyotyping, DNA analysis, gene probes,
family pedigrees etc.
Who do I see for genetic
counselling?
22
Understand the need for genetic counselling and
locate where this is available near them.
18
Research different types and methods of gene therapy
that are currently available or under research.
What are the ways in
which new variations can
occur?
Can gene therapy help?
Possible Student Activity
Each student is to locate one
disorder and the class will pool
the investigations to prepare a
table on Genetic Disorders,
including the type and cause of
the disorder, and a description of
the affected person. This should
lead into, and be used in, the next
topic.
Use second-hand data to
determine the pattern of
inheritance of a genetic trait in
families.
Arrange for a genetic counsellor
to give a talk on their career and
work.
Do an internet search and
prepare notes on current ideas.
Visit a research centre.
Present a justified solution to a
hypothetical situation.
Skills
Objectives
Text Reference
UB, IB
Ch. 21.4
UB, IB
Ch. 19.3, 20.5
UB
Ch 20.5.2
UB, IB
Ch. 24.3.4
EBI