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Inheritance
Lesson 1
Task
With the person next to you, write
down 5 things you have in common
and 5 differences
Lesson 1- learning intention
Variation within a species
Variation: copy
•All members of any species have many
characteristics in common as well as having many
differences
•These differences are called variations
•Variation are due to GENETIC or ENVIRONMENTAL
causes.
What makes organisms different?
Organisms differ because they have different genes.
Humans have human genes
Gerbils have gerbil genes
Bananas have banana genes!
Nobody else in the whole world has the
same DNA as you (unless identical twin)!
Where is the information stored?
•In the nucleus of almost
every one of your body’s
cells are tiny structures
called chromosomes.
•Chromosomes are made
up of really tightly wound
strands of DNA.
•Genes are within the DNA
Sexual Reproduction
•Human sex cells contain 23
chromosomes
•When fertilisation happens the
gametes fuse together to make a
single cell called a ZYGOTE.
•The zygote (like every other
human cell) has 46
chromosomes
Genotype
•Each gene does a different job
•Every person has 2 copies of the
same gene (1 from mum, 1
from dad)
•Different form of the same
gene- ALLELE
•Alleles may be the same or
different- VARIATION
Is variation only in humans?
•Variation in animals and in
plants too
•Variation between different
species is usually greater
than the variation within a
species.
Variation in Humans
•Eye colour
•Height
•Hair colour
•Tongue roller
•Ear lobes
Variation in Plants
•Colour of petals
•Length of stem
•Shape of leaves
Inherited Variation: Copy
• Genes are found on DNA on the chromosomes in the
nucleus
• We get a full set of genes from our mum and a full set of
genes from our dad
• The two copies of the gene are called ALLELES- they may be
the same or different
• Variation is caused by the different alleles
• Examples in humans- eye colour, hair colour
• Examples in plants- petal colour, leaf shape
Match the parents to the child and explain why
Match the parents to the child and explain why
Match the parents to the child and explain why
Match the parents to the child and explain why
Match the parents to the child and explain why
Match the parents to the child and explain why