Download 1. Yr10 GENETICS MA

Every living organism inherits a blueprint for life from its parent(s).
Genetic information is carried inside each and every cell of all living things.
INTRODUCTION TO GENETICS AND THE
DNA MOLECULE
Every living organism inherits a blueprint for life from its parent(s).
Genetic information is carried inside each and every cell of all living things.
INTRODUCTION TO GENETICS AND THE
DNA MOLECULE
INHERITANCE OF CHARACTERISTICS
Experiments in the 19th century showed that
there were heritable factors being passed on to
offspring such as eye colour.
 How were offspring aquiring features from their
parents?
 In the 20th century biologists confirmed that
DNA found inside the cells of living things were
responsible for these heritable features.
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INSIDE THE CELL OF PROKARYOTES AND
EUKARYOTES
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DNA is found in the nucleus of the Eukaryotic cell
DNA is found in the cytoplasm of the prokaryote as they do
not have a nucleus.
INSIDE THE NUCLEUS OF A HUMAN CELL
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There are 46
chromosomes
23 from each parent
Each chromosome pair
contains the genetic
codes for thousands of
features.
Each genetic code is
called a gene. For
example, there is a
gene which codes for
hair colour.
A GENE IS A LENGTH OF DNA THAT IS THE UNIT
OF HEREDITY AND CODES FOR A SPECIFIC
PROTEIN
AN ALLELE
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An allele is one of a number of alternative forms
of the same gene
For example, the human genome has 23 pairs
of chromosomes
Lets look at one pair of those chromosomes
Along the length of each chromosome are the
same genetic codes for example: hair colour,
eye colour
HOWEVER, the fathers gene for eye colour may
indeed be different to the mothers gene for eye
colour
One parent may be contributing blue eyes,
whilst the other is contributing the gene for
brown eyes
These genes for eye colour are called ALLELES
THE ALLELE

This pair of chromosomes are
homologous, they carry the
same sequence of genes

if both chromosomes carry the
same allele this is called
‘homozygous’

If each chromosome is
carrying a different trait of the
same gene it is called
heterozygous
THE HUMAN GENOME
CHROMOSOME NUMBER 23
INHERITANCE OF SEX
THE COMPLEXITY OF THE GENOME FOUND IN
EVERY LIVING THING
A CLOSER LOOK AT THE DNA WHICH MAKES UP
EACH LINEAR STRAND OF EACH AND EVERY
CHROMOSOME
A NUCLEOTIDE UNIT OF DNA CONTAINS A
SUGAR, PHOSPHATE AND A BASE

Nucleotides are the
same in every living
thing from bacterial
cells and plants to
cockroaches and
elephants!

Every living thing on
earth contains
these genetic
components
EVERY GENOME OF EVERY LIVING THING
CONTAINS ONLY 4 BASES
Adenine pairs
with Thymine
 Guanine pairs
with cytosine
 The sequence of
these bases
codes for each
and every gene
for every living
thing.
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DEOXYRIBONUCLEIC ACID (DNA)
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The ‘double helix’ is held together by hydrogen bonds.