Evolution Flashcards
What is evolution?
The process by which species change over time through genetic variation and natural selection, leading to the development of new species and adaptations.
What is represented in phylogenic trees?
The evolutionary relationships between organisms as determined by phenotype and/or genotype. The show divergence of organisms away from a common ancestor over time.
How many years ago did the first cell exist?
3.5 billion years ago.
What are considered the first cells?
Anaerobic prokaryotes.
Where did life begin?
In the ocean.
How many years ago did the first eukaryotic cell appear?
1.5 billion years ago.
What is symbiosis?
Where two organisms help each other and both benefit.
What is endosymbiosis?
One cell living in another and both benefit.
Why is it likely that the first cells used RNA rather than DNA?
It is a simpler molecule than DNA and therefore most likely to have evolved first.
What is a ribozyme?
An RNA molecule with catalytic properties, capable of speeding up biochemical reactions.
What evidence supports that prokaryotes appeared before eukaryotes?
Microfossils dating back 3.5 billion years and simpler cell structure suggest prokaryotes existed first.
What is comparative genomics?
The study of similarities and differences in DNA sequences across different species.
What is DNA-DNA hybridization?
A technique used to assess genetic similarity between species by comparing their DNA sequences.
What are cytochromes and why are they used in evolutionary studies?
Cytochromes are proteins involved in cellular respiration. Their amino acid sequences vary between species, allowing scientists to compare evolutionary relationships.
What is the molecular clock concept?
It’s the idea that mutations accumulate at a constant rate, allowing scientists to estimate the time since two species diverged based on genetic differences.
How can the sequencing of common proteins, like cytochromes, support evolutionary relationships?
Similarities in protein sequences indicate shared ancestry, while greater differences reflect longer evolutionary divergence.
What is the first step in DNA-DNA hybridization?
Isolate DNA from the two species being compared.
What happens to the DNA after it’s isolated in DNA-DNA hybridization?
The DNA is heated to denature it, separating it into single strands.
What is the purpose of denaturing the DNA in DNA-DNA hybridization?
Denaturing creates single-stranded DNA, which can then bind with complementary DNA from another species.
What happens after DNA is denatured in DNA-DNA hybridization?
Single-stranded DNA from each species is mixed and allowed to cool to form hybridized DNA strands.
What is measured after the DNA strands hybridize?
The melting temperature (Tm) of the hybrid DNA is measured to assess how strongly the strands are bonded.
Why is melting temperature important in DNA-DNA hybridization?
A higher melting temperature indicates more similar DNA sequences, as more hydrogen bonds are formed between closely related sequences.
What is DNA sequencing?
Different species’ nucleotide sequences are read then compared for homology.
What is a community?
All of the populations of different species in an area at a particular time.
What is a population?
A group of organisms of the same species occupying a particular area at a particular time. Individuals share a common gene pool.
What is a species?
A group of organisms that are more or less alike and can reproduce fertile offspring in their natural environment.
What is parthenogenesis?
Where sexual reproduction isn’t required to produce fertile offspring.
What is morphological similarity?
Generally have common characteristics that make them recognisably similar to one another.
What is a gene pool?
The complete set of genetic information, including all the different genes and their variants (alleles), present in a population of a particular species. The gene pool represents the diversity of traits available in that population, which can influence evolution and adaptation.
What can reproductive isolation be achieved by?
Pre-zygotic and post-zygotic factors.
What are pre-zygotic factors?
Factors that prevent meeting and/or fertalisation.
Temporal isolation
Behavioral isolation
Mechanical isolation
Gamete isolation.
What is mechanical isolation?
Anatomical differences between the genitals of animals and the floral structure of plants so the transfer of gametes cannot take place.
What is temporal isolation?
Species may produce gametes in different seasons or times.
What is behavioral isolation?
Mating behavior is not interesting to a different species.
What is gamete isolation?
Prevents fertalisation. Even if gametes are transferred, male gametes might die due to inappropriate conditions or male and female gametes might fail to recognise each other.
What are post-zygotic factors?
Barriers that opperate after fertalisation and prevent the development of fertile hybrids.
What is hybrid inviability?
The zygote or embryo may not develop normally as the genes from the parents are too different.
