Transcript Survey of variation

Year 10 – Genetics and Biotechnology (Biology)
Variation Survey
Year 10 – Genetics and Biotechnology (Biology)
• By the end of the lesson I will be able to:
– State the difference between inherited and
acquired variation
– Describe how variation can be classified and
give examples
– Complete diagrams to show genetic crosses.
Year 10 – Genetics and Biotechnology (Biology)
Classifying variation
 A feature that can be measured
and given a value from a range
of values shows continuous
variation.
 A feature that cannot be
measured but is one of a few
distinct options shows
discontinuous variation.
Which type of variation are eye colour and height?
Year 10 – Genetics and Biotechnology (Biology)
Answers:
• Continuous variation
• Discontinuous
• Height is an example of
• Eye colour is an example of
Year 10 – Genetics and Biotechnology (Biology)
What type of variation?
Year 10 – Genetics and Biotechnology (Biology)
Pairing of chromosomes
• A human sperm and
egg each have 23
single chromosomes.
• Each chromosome
from the sperm
pairs up with its
‘partner’ from the
egg, making 23 pairs
in the zygote.
Zygote
Year 10 – Genetics and Biotechnology (Biology)
Pairing of genes
• This brings the 2 sets
of genes together.
1 Blonde hair
colour gene 1
brown
2 blue eyed gene
• They are now called
Homologous pairs.
• The genes for hair
colour pair up, genes for
skin colour pair up etc.
• These different forms
of the same gene are
called alleles.
father
Mother
Year 10 – Genetics and Biotechnology (Biology)
• What genes you have from your parents
are said to be your genotype e.g BB or
bb or Bb
• What people see on the outside is your
phenotype e.g. Blue /brown
• So your genotype
determines your
phenotype!
Year 10 – Genetics and Biotechnology (Biology)
Task 2: Questions
1. How many single chromosomes does a
sperm and egg cell have?
2. What happens to this number when
the sperm and egg fertilise?
3. What is an Allele?
4. Name 2 alleles for eye colour?
5. What is genotype?
6. What is phenotype?
Year 10 – Genetics and Biotechnology (Biology)
Ear lobes
• Free earlobes
(dominant trait) hang
below the point of
attachment to the
head.
• Attached ear lobes
(recessive trait) are
attached directly to
the side of the head.
Year 10 – Genetics and Biotechnology (Biology)
Thumbs
• Straight thumbs
(dominant trait) can be
seen as nearly a straight
line and may contain a
slight arch when viewed
from the side as in the
illustrations.
• Curved thumbs
(recessive trait) can be
seen as part of a circle.
Year 10 – Genetics and Biotechnology (Biology)
Technology
Center for Innovation in Engineering and
Science Education
Pinky
Bent pinky (dominant
trait) vs. Straight
pinky (recessive trait):
1. Hold your hands together
as if you are covering your
face.
2. If the tips of the pinkies
(or baby fingers) point
away from one another,
the pinkies are bent
(recessive trait).
Year 10 – Genetics and Biotechnology (Biology)
Forelock
• A White Forelock
(dominant trait) is a
patch of white hair,
usually located at the
hairline just above the
forehead. The photo to
the left clearly shows an
exaggerated white
forelock.
• No White Forelock is
the recessive trait.
Year 10 – Genetics and Biotechnology (Biology)
Task 3: Design a survey
• Design a survey table that could be used to
ask the class about their traits.
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Ear lobes
Thumbs
Pinky
Forelock
Height
Shoe size
Eye colour
If we are sensible we
could carry this out for
small groups
Year 10 – Genetics and Biotechnology (Biology)
My survey
Year 10 – Genetics and Biotechnology (Biology)
• Make a note of this info
• Draw a diagram or picture
• Discuss
• Think
• Investigate
Watch
Answer question