In-Semester Exam L6 Evolution

How was the diversity of animals classified before modern molecular biology?

Linnaeus developed a classification scheme called taxonomy.

Linnaeus assigned binomial nomenclature of genus and species, for example, Homo sapien and Felis catus.

List the ranking of groups into taxa

Kingdom

Phylum

Class

Order

Family

Genus

Species

What is the definition of species?

A group of organisms capable of interbreeding and producing fertile offspring

What suffix does the family name always end in?

-idae

Or for a super family -oidae

Outline the taxonomy of a domestic cat

Domain - Eukarya

Kingdom - Animalia

Phylum - Chordata

Class - Mammalia

Order - Carnivora

Family - Felidae

Genus - Felis

Species - Felis catus

Describe scientific names of animals

Scientific names of animals are descriptors of that species in Latin

Briefly describe dichotomous key

Dichotomous key is a tool used to identify different organisms based on the organisms observable traits. Dichotomous keys consist of a series of statements with two choices in each step that leads users to identification. Dichotomous keys ignore the true relationship of organisms.

Define homologous structures.

Homologous structures are similar physical features in organisms that share a common ancestor, but the features serve completely different functions. An example of homologous structures are the limbs of humans, cats, whales and bats.

Define analogous structures

Analogous structures are features of different species that are similar in function, but not necessarily in structure. They do not derive from a common ancestor and evolved in response to similar environmental challenges. The wings of birds and butterflies are examples of analogous structures.

Define morphology

Morphology is the study of the size, shape and structure of animals, plants, and microorganisms and of the relationship of their constituent parts.

Describe phylogeny

It is the study of the evolutionary history of species

It infers the relationships of organisms

It uses more homologous characteristics as these are the most informative in inferring evolution

It traces changes in species over time

What are some of the ways we can identify species?

Morphology, ecology, geographic distribution, biochemistry and physiology, nucleic acid sequence

Describe the chromosomes of prokaryotes

Prokaryotes usually have one circular chromosome and no nucleus

Describe the chromosomes of eukaryotic cells

Eukaryotic cells have chromosomes located in the nucleus. Most eukaryotic cells have multiple chromosomes, which are linear in shape. The DNA is wrapped tightly within chromosomes.

There is also DNA in mitochondria for animals and the mitochondria and chloroplasts for plants.

What is an orthologous gene

It is a gene found in different species that evolved from a common ancestor by speciation

What do genes code for?

Each gene has the instructions for making a specific protein, and each protein does a specific job in the cell. Some proteins are used to replicate or reproduce, some produce energy, some form structure and perform specific functions.

Briefly describe genetic similarity

There are similarities in every organism with respect to their DNA, replication and protein synthesis

There are orthologous genes across all lifeforms in both prokaryotes and eukaryotes

Define phenotype

Observable characteristics of an individual based on the expression of the gene, such as size and colour.

Genetic diversity occurs due to mutations within the genome. Describe the two types of mutations.

Defective chromosomes (usually occurs during division) through rearrangement, recombination, insertions or deletions.

Point mutation occurs in the genome when a single base pair is added, deleted or changed.

What are endogenous mutations?

Endogenous mutations are produced by the body. They are spontaneous and due to normal cellular division or cell metabolism by-products. Spontaneous mutation rates are low.

What are exogenous mutations?

Exogenous mutations come from environmental agents such as chemicals, radiation, transposable elements and viruses.

When are genetic mutations heritable?

Genetic mutations are only heritable if they occur in germ cells (tissues) they’re not heritable if they occur in somatic cells (tissues).

When there is a mutation in the DNA or RNA code, the genetic information is changed, which leads to the translation of the mutated protein. What three things could this result in?

No change in protein function, called a synonymous mutation

Change in protein function, leading to a new phenotype

Loss of protein function, leading to a new phenotype or disease.

One of the driving forces of evolution is natural selection. Describe this process.

Organisms that are more adapted to their environment are more likely to survive and pass on their genes.

This process causes species to change and diverge over time. Individuals that have a trait that is better adapted to the environment survive and produce more offspring.

An example of this is the peppered moth. In the United Kingdom in the 1800s trees were becoming covered in soot. The numbers of dark coloured moths increased as they were camouflage better while the lighter moths were predated upon. Later, when the pollution was reduced the light coloured moths once again became more dominant.

What are four factors that affect the genetic diversity of the population and species evolution.

Mutations, natural selection, migration and random genetic drift.

A bottleneck can cause genetic drift. Describe a bottleneck.

A bottleneck occurs when there is a large amount of predation, or a catastrophic event which significantly reduces the numbers of a population. When the population subsequently increases the animals have much less genetic variation than expected for a population of that size.

Phylogenetics on a genetic level uses gene sequences and looks at the differences in gene sequences. Animals with the least differences in their gene sequences would be closer on the phylogenetic tree. True or false.

True