Genetics, Variation And Relationships Between Organisms Flashcards
What is a gene?
It is a section of DNA that codes for a particular polypeptide or protein.
What is the position of a gene called?
A locus
What is the triplet code that always starts a sequence?
Methionine
How many stop codons are there and what do they do?
There are 3 stop codons. They don’t code for amino acids and mark the end of the chain.
What does it mean when we say genetic code is universal?
It means that the same sequence of 3 bases will always code for the same amino acid.
What does it mean when we say genetic code is non-overlapping?
Each DNA base is only read once in the sequence.
What does it mean when we say genetic code is degenerate?
Most amino acids have more than one triplet code.
What are mini satellites?
They are large amounts of DNA that do not code for any proteins or polypeptides, found between genes.
What are introns?
They are areas of non-coding DNA within a gene.
What is the coding DNA in a gene called?
Exons
Which type of organisms can have mini satellites and introns?
Eukaryotic organisms
What is a genome?
All the genes required to build a functional organism.
What is an allele?
It is the different form of a gene.
What is the structure of an RNA molecule?
Ribose sugar attached to a phosphate and an organic base (AUCG)
and a phosphate.
Made in a condensation reactions
What is the order of taxon?
Domain (dont)
Kingdom (kill)
Phylum (Phil)
Class (cause)
Order (our)
Family (friends)
Genus (get)
Species (sad)
Define species.
A group of similar organisms able to reproduce and produce fertile offspring.
How do we name organisms?
(in italics) Genus name + species name
Define hierarchal system.
Smaller groups contained within larger groups with no overlap.
What is phylogenetics?
The study of patterns of evolutionary history.
All organisms evolved from…
… shared common ancestors.
Define natural selection.
The process by which organisms that are better adapted to their environment survive and reproduce in greater numbers, resulting in the increase of the frequency of advantageous alleles within the population.
How does natural selection occur?
- Selection pressures within the environment change.
- Variation caused by mutation leads to new alleles of certain genes.
- Better adapted individuals are more likely to survive and reproduce.
- Adaptations can be anatomical (related to anatomy), physiological (related to normal function of body systems) or behavioural (the organisms behaviour in the environment)
- These organisms are more likely to pass on their advantageous allele.
- The allele is inherited by the next generation.
- Over many generations, the advantageous allele frequency increases
- Selection pressure determines the spread of an allele within a gene pool.
What are the different types of adaptation?
- Anatomical (related to anatomy)
- Physiological (related to normal function of body systems)
- Behavioural (the organisms behaviour in the environment)
What is stabilising selection?
It occurs in all populations where the environment is stable. There is selective pressure at both ends of the distribution so favours the average.
This type tends to eliminate extremes, reduces variability (the size of the range within the population) and reduces the opportunity for evolutionary change.
