introduction to molecular biology Flashcards
What is evolution?
Evolution is the slow and continual change in organisms over a long period of time. This causes changes in the heritable characteristics of organisms over generations.
Name the 3 different types of evolution
1.Anagenesis 2.Speciation 2.Extinction
Explain the Anagenesis?
Gradual changes within a species which do not create a new phylogenic branch.
e.g. change in colour of the ‘peppered moth‘
Explain the Speciation?
Creation of a new species as a result of evolution.
e.g. Darwin’s Galapagos finch
Explain the Extinction?
Extinction Death of a species or no longer able to survive.
e.g. West African Black Rhinoceros
Name 3 different proving the evidence for evolution?
- Fossils
2.DNA evidence - Molecular evidence
Explain Fossiles?
Rock-preserved remains of organisms
Fossil records can demonstrate how much organisms have changed over time
E.g. horse
Not all organisms fossilize well
Gaps are present in some fossil records
Explain DNA evidence ?
All organisms evolved from a common ancestor
Based on the gradual changes observed in base sequences
Closely related species evolved more recently, therefore have more similar base sequences
Explain Molecular evidence?
Sequence analysis of other molecules
Amino acids, proteins, antibodies
Based on similarities between molecules, especially those common to organisms e.g. Cytochrome C.
Molecular clocks
used to illustrate the time between evolution based on molecular evidence
What were the four key observations that Charles Darwin reported after studying fossils and during his time aboard HMS Beagle?
1.All organisms produce more offspring than their environment can support to survive, often leading to competition between offspring.
2.Variation occurs between offspring, even within the same species
3.Observable characteristics are often passed on from the previous generation
4.Not all offspring will survive due to the environment, but those that do often produce their own offspring
Molecular evidence used to demonstrate that genes are responsible for ………., held in different ……… .
Variation in phenotype are the result of this genetic variation
1.phenotype
2.alleles
When successful organisms survive and reproduce, alleles coding for successful characteristics are passed on, relative to the environment.
e.g. peppered moths
Name the 3 different forms of variation?
1.Interspecific variation
2.Intraspecific variation
Explain Interspecific variation?
Variation occurs between different species.
Explain Intraspecific variation?
Variation occurs between individuals of the same species e.g dogs.
name 2 different types of variations and explain
Continuous variation: Variation which occurs where this is no distinct categories
e.g. Height
Age
Discontinuous variation: Variation where there are 2 or more distinct categories / possibilities
e.g. Blood groups
Eye colour
Plumage colour
Explain genotype and Phenotype?
Genotype: Genetic information as coded for by specific alleles
Phenotype: Physical expression, often observable
Why does variation occur?
1.Genetic variation As a result of genetic factors passed on from parent organisms, or different alleles for specific genes
2.Sexual reproduction leads to intraspecific variation due to independent assortment of chromosomes during meiosis.
Characteristics determined by one gene are monogenic.
Characteristics that show continuous variation are polygenic.
3.Environmental factors: Variation caused as a result of environmental factors which can have an impact on survival or life. e.g. temperature, light, nutrition
illustrating variance(continuous variance)
Drawn as a bar chart with a curved line.
No distinct categories – demonstrated by x axis
To be as accurate as possible, large population numbers are included in relatively small categories.
Often displays normal distribution
illustrating variance(Discontinuous variance)
Drawn as a bar chart without a curved line.
Distinct categories with no intermediates– demonstrated by x axis
To be as accurate as possible, large population numbers are included.
name and explain different types of adoptation?
1.Behavioural: Change to the way an organism acts of behaves(Polar bears have learnt, over generations, that grouping together preserves body heat )
2. Physiological: A change to bodily processes which improve chances of survival(Llama have additional haemoglobin molecules to increase uptake and storage of oxygen)
3. Anatomical: Changes to structural features of the body(Grizzly bears have binocular vision allowing them to judge distance well)
