Natural Selection in Higher Biology

 
Natural Selection in Action
 
Higher Biology
Natural Selection in Action
 
Most mutations produce inferior versions of
original gene
 
Some mutations allow 
adaption to a changing
environment
 
Mutant allele gives mutant form of organism a
selective advantage
 
Change in environment
 
-abiotic factor (e.g. pollution)
 
-biotic factor (e.g. disease)
Sickle cell anaemia
 
Genetically transmitted disease of
the blood
 
Caused by presence of abnormal
haemoglobin S
 
Abnormality occurs as result of
mutation
 
Haemoglobin S
 
H – allele for normal haemoglobin
S – allele for haemoglobin S
 
People homozygous for mutant allele (SS)
 
-sickle-shaped red blood cells
 
-inefficient at carrying oxygen
 
-cells clump together interfering with
circulation
Symptoms of Sickle Cell
Anaemia
 
Fatigue
Breathlessness
rapid heart rate
delayed growth and puberty
susceptibility to infections
ulcers on the lower legs (in adolescents and adults)
jaundice
attacks of abdominal pain
weakness
joint pain
fever
Vomiting
bloody (hematuria) urination
excessive thirst
excessive penis pain
Priapism
chest pain
decreased fertility
Incomplete dominance
 
Allele H 
incompletely dominant
 to allele S
 
Heterozygotes – HS
 
Allele S partially expressed
 
Sickle Cell Trait
 
-a third of the haemoglobin is S
Sickle Cell Anemia in Africa
 
Allele S rare in populations as semi-
lethal
 
Some parts of Africa up to 40% of
population is HS
 
People with Sickle Cell Trait 
resistant
to malaria
 
Distribution of malaria
 
Distribution of sickle
cell trait
Sickle Cell Trait and Malaria
 
In malarial regions
 
-natural selection favours people with
genotype HS
 
People that are HH will die during serious
outbreaks of the disease
 
Hs loses 
selective advantage 
in non-
malarial sites
 
Industrial Melanism in
Peppered Moth
 
Two forms of 
Biston betularia
(peppered moth)
 
(melanic)
Biston betularia
 
Differ by only one allele of the gene
forming dark pigment (melanin)
 
Both forms fly by night
 
Both forms rest on trees during the
day
Prior to Industrial revolution
 
Pre 1800s
 
Light form
common
throughout
Britain
 
Dark arose by
mutation
 
-very rare
Light peppered moths
 
In non-polluted
areas
 
-tree trunks
covered with pale
coloured lichens
 
Moth well
camouflaged
against pale
background
 
Dark form easily
seen and eaten by
predators
Survey in the 1950s
 
Pale form 
most
abundant
 in non-
industrial areas
 
Dark forms 
most
abundant
 in areas
suffering from
heavy air-pollution
Reason for change?
 
In polluted areas
 
-toxic gases kill lichen
 
-soot particles darken
tree trunks
 
Dark coloured well
hidden and favoured
by natural selection
 
Light coloured moth
easily seen
 
Frequencies of two
forms of peppered
moths in the 1950s
 
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Natural selection in action is demonstrated through mutations that impact an organism's adaptation to changing environments. Sickle cell anemia, a genetically transmitted blood disorder, exemplifies the consequences of specific mutations. The condition manifests in various symptoms, affecting individuals differently based on their genetic makeup. Incomplete dominance and the prevalence of sickle cell trait in African populations highlight the complex interplay between genetics, environment, and disease resistance. Ultimately, natural selection favors those with advantageous traits, shaping population genetics over time.

  • Natural Selection
  • Higher Biology
  • Genetic Mutations
  • Sickle Cell Anemia
  • Adaptation

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  1. Natural Selection in Action Higher Biology

  2. Natural Selection in Action Most mutations produce inferior versions of original gene Some mutations allow adaption to a changing environment Mutant allele gives mutant form of organism a selective advantage Change in environment -abiotic factor (e.g. pollution) -biotic factor (e.g. disease)

  3. Sickle cell anaemia Genetically transmitted disease of the blood Caused by presence of abnormal haemoglobin S Abnormality occurs as result of mutation

  4. Haemoglobin S H allele for normal haemoglobin S allele for haemoglobin S People homozygous for mutant allele (SS) -sickle-shaped red blood cells -inefficient at carrying oxygen -cells clump together interfering with circulation

  5. Symptoms of Sickle Cell Anaemia Fatigue Breathlessness rapid heart rate delayed growth and puberty susceptibility to infections ulcers on the lower legs (in adolescents and adults) jaundice attacks of abdominal pain weakness joint pain fever Vomiting bloody (hematuria) urination excessive thirst excessive penis pain Priapism chest pain decreased fertility

  6. Incomplete dominance Allele H incompletely dominant to allele S Heterozygotes HS Allele S partially expressed Sickle Cell Trait -a third of the haemoglobin is S

  7. Sickle Cell Anemia in Africa Allele S rare in populations as semi- lethal Some parts of Africa up to 40% of population is HS People with Sickle Cell Trait resistant to malaria

  8. Distribution of malaria Distribution of sickle cell trait

  9. Sickle Cell Trait and Malaria In malarial regions -natural selection favours people with genotype HS People that are HH will die during serious outbreaks of the disease Hs loses selective advantage in non- malarial sites

  10. Industrial Melanism in Peppered Moth Two forms of Biston betularia (peppered moth) (melanic)

  11. Biston betularia Differ by only one allele of the gene forming dark pigment (melanin) Both forms fly by night Both forms rest on trees during the day

  12. Prior to Industrial revolution Pre 1800s Light form common throughout Britain Dark arose by mutation -very rare

  13. Light peppered moths In non-polluted areas -tree trunks covered with pale coloured lichens Moth well camouflaged against pale background Dark form easily seen and eaten by predators

  14. Survey in the 1950s Pale form most abundant in non- industrial areas Dark forms most abundant in areas suffering from heavy air-pollution

  15. Reason for change? In polluted areas -toxic gases kill lichen -soot particles darken tree trunks Dark coloured well hidden and favoured by natural selection Light coloured moth easily seen

  16. Frequencies of two forms of peppered moths in the 1950s

  17. This powerpoint was kindly donated to www.worldofteaching.com http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.

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