Reminders: A chromosome as a thread-like structure of
DNA, carrying genetic information in the form of genes.
A gene is a length of DNA that codes for a protein. An
allele as a version of a gene.
A genetic change is a mutation and how new alleles are formed.
Reminder that in the biological
science of genetics, inheritance is the transmission of genetic
information from one generation to the next generation by chromosomes of
DNA, BUT, things are not that simple!.
Different species of plants or animals
have different genes.
Individual species look different from each other
because they have different combinations of genes.
The gene differences within a species are very similar,
BUT, not absolutely identical, just look around and see the variation in
the human species!
You see differences in height, eye colour, hair colour,
height, skin colour, all of which are characteristic features
within the same species.
Characteristic features can be inherited from your
parents via the gene combination when an egg is fertilised (genetic
factors), though some characteristic features can develop due to
your surroundings and lifestyle (environmental factors).
This page will help you understand that ...
Genetic variants are caused by
alterations in the common nucleotide sequences in the DNA of genes -
specifically the change in base sequence from a mutation.
The term variant can be used to describe
the result of a genetic alteration that may be benign
(harmless), pathogenic (harmful), or of unknown significance.
Variation is the differences between individuals of the same species.
Variants are key to successful evolution because genotype changes (usually of
the smaller type) can lead to changes in phenotype.
Human genetic
variation is
the genetic differences
both within and among populations.
There may be multiple variants of
any given gene in
the human population, that is
two different alleles.
The different
alleles, different versions of a same gene, can lead to difference in
phenotypes - the characteristics an organism displays.
A
mutation
may defined as
any change in a DNA compared to normal that results in a rare and abnormal variant.
See the
evolution page for lots more notes on
variation - genetic and environmental
INDEX
of biology notes on genetic variation, causes, formation and consequences of
mutations
INDEX of all my BIOLOGY NOTES
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