L1 - Introduction to Animals Flashcards
What are animals?
Multicellular heterotrophic eukaryotes that ingest and digest their food, their cells lack cell walls, most have nerves, muscles, capacity to move at some point in the life cycle, ability to reproduce sexually, specialised sensory structures and nervous system, cells exist in extensive extracellular matrix, unique cell junctions, possess Hox genes
What is the two kingdom system?
All living things were classified as either plants or animals.
What are plants?
Autotrophic (produce organic food molecules through photosynthesis) and are sessile (don’t move)
What are animals?
Heterotrophic (obtain organic food molecules by eating other organisms or their products) and are mobile
What are some problems with the 2 kingdom system?
For example : Euglena ; mobile and autotrophic ; is this a plant or animal. Moulds and mushrooms : sessile and heterotrophic ; are these plants or animals
What is the new kingdom system?
5 Kingdom system
What does the 5 kingdom system divide organisms based on?
Cell structure, cell number, mode of nutrition
What are the 5 kingdoms in the 5 kingdom system?
Monera (Prokaryotes), Protista (protozoa) , Plantae (autotrophic), Fungi (absorptive), Animalia (Ingest/Digest). (rest are eukaryotes) (rest are Metazoa) (rest are heterotrophic)
How are prokaryotes and eukaryotes divided?
Based on the structure of cells, presence or absence of a membrane-bound nucleus and organelles
What are the differences in structure of cells in Prokaryotes and Eukaryotes?
Prokaryotes - loose DNA, no nucleus or organelles. Eukaryotes - membrane bound nucleus and organelles
What is an example of division of life based on the number of cells?
Protozoa - unicellular
Metazoa - multicellular
What is an example of division based on mode of nutrition?
Autotrophs, Heterotrophs : carnivore, herbivore
How can Heterotrophs differ?
Absorptive and ingestive/digestive. Fungi digest their food externally and absorb the digested food. With some exceptions, animals must ingest and digest their food internally.
When did the 6 kingdom system come into prevalence?
Mid-1970s onwards. Increasing emphasis on molecular-level comparisons of genes (initially ribosomal RNA genes) as the primary factor in classification. Genetic similarity was stressed over outward appearances and behaviour. Prokaryotes (previously classified as Monera) split into two groups : Eubacteria and Archaebacteria. There is as much genetic difference between these two groups as between either of them and all eukaryotes
What are plants cell walls comprised of?
Cellulose
What are fungis cell walls comprised of?
Chitin
What are animals cell walls comprised of?
They don’t have cell walls
What are Hox genes and what possess them?
All animals have regulatory genes called homeobox genes. Hox genes have been identified in all major animal groups, they play a key role in the developments of the animal body plan. Hox genes are a group of related genes that determine the basic structure and orientation of an organism, play a role in permitting evolution of complex organ systems
What are Hox genes?
A DNA seq found within genes that are involved in the regulation of anatomical development (morphogenesis) in animals, fungi and plants. ‘Lower’ animals (e.g. jellyfish) have one or two hox genes in a complex. ‘Higher’ animals have several complexes of hox genes. Hox genes switch on cascades of other genes which determine the identity of embryonic regions along the anterioposterior axis
Why is there complexity in Hox genes in vertebrates?
Evolution of the head, the neural crest, new cell types (e.g. osteoblasts). Regionalisation and development of brain. Specification of somatic segments associated with skeleton and complex (pentadactyl) limbs.
What controls segment specialisation in the vertebrates?
Shifting of Hox gene expression
What does evidence show about animal kingdom?
It is monophyletic (single ancestral type). About 35-37 recognised animal phyla ; this includes everything from sponges to humans (invertebrates and vertebrates
What did Linnaeus do?
Classified and named over 10,000 organisms
What two parts the linnaean system consist of?
Binomial e.g. Genus and species. Hierarchial - kingdoms, phyla, orders etc
What is the order of classification?
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Of 35 to 37 recognised animal phyla, how many subphylum do the vertebrates make up?
1 subphylum of the phylum chordata. Phylum Chordata - subphylum vertebrata (all fish, amphibians, reptiles, mammals and birds), subphylum Tunicata (salps, sea squirts), subphylum Cephalochordata (lancelets)
