A3: Diversity of Organisms Flashcards
Variation
Variation refers to differences between members of a group. Variation can be discrete or continuous.
Discrete Variation
Traits that can be put into distinct qualitative categories.
e.g. blood type
Continuous Variation
Traits that vary along a quantitative continuum. Most types of biological variation are continuous.
e.g. Height
Intraspecies variation
Variation within a species - is inheritable
Interspecies variation
Variation between species
Biological Species Concept
A species is a group of actually or potentially interbreeding populations which are reproductively isolated from other such groups.
Looks at a combination of Morphology, habitat, and allele.
Championed by ornithologist Ernst Mayr (1942)
Binomial Nomenclature Benefits
- Reflects evolutionary relationship between organisms
- Enables scientists to talk to each other in the same language
Speciation
the formation of new and distinct species in the course of evolution.
Diploid Cells
Cells that have an even number of chromosomes (one of each parent)
Haploid gametes
cells for sexual reproduction have half the chromosome or one set of chromosomes.
Karyogram
Diagram or photograph of the chromosomes present in a nucleus arranged i homologous pairs of decreasing length.
Telomere DNA
DNA at the end of chromosomes that does not code for proteins.
Genome Wide Association Studies (GWAS)
a research approach used to identify genomic variants that are statistically associated with a risk for a disease or a particular trait.
Single Nucleotide Polumorphism
Asexual reproduction
Asexual reproduction occurs when a single parent passes on its full set of genes to offspring, resulting in genetically identical offspring.
Asexually reproducing organisms are classified into species based on appearance or biochemical similarities.
Horizontal Gene Transfer
The movement of DNA between individuals through mechanisms that are not the normal movement of DNA from parent to offspring.
E.g. bacteriophage
Horizontal gene transfer is frequent among bacteria. Horizontal gene transfer can occur in eukaryotes, however it appears to be less frequent.
Apomixis
Scientific name for cloning.
A huge number of genetically unique clones can be formed via apomixis, resulting in populations of related, but genetically isolated clones. Since there is no interbreeding between populations, each population is considered a separate species according to the Biological Species Concept
Chromosome number as a species trait
Species tend to be able to mate if they have the same number of chromosomes.
E.g. Horses have 64 chromosomes while donkeys have 62 - Mules have 63 and can not reproduces as they can not be a homologous pair.
Dichotomous Key
Tool used to identify a species based on observable traits.
If statement A is true go to step 3 e.g.
Taxonomy
The branch of biology called taxonomy focuses on the classification of living things
Benefits of Taxonomy
- Communication of biological information between scientists
- Predictions of characteristicsts
- Species in the same group probably share a common ancestor, indicating information about how species evolved.
Characteristics that determine cladograms
- Morphological homologies
- Developmental patterns
- Fossil records
- Genetically determined behavioral traits
- Molecular homologies
Homologous
shared characteristics due to common ancestry (divergent evolution)
Analogous
shared characteristics not due to common ancestry (convergent evolution)
