animals Flashcards
how does the volution of animals occur?
- first chordate: spinophores
- evolution of land plants
- evolution of tetrapods: fish and frogs
- first amniotes: reptiles, birds mammals
- MAJOR EXTINCTION
- era of the dinosaurs: first mammals appeared
- first group of birds
- MAJOR EXTINCTION
- current day !
all animals are?
multicellular eukaryotes
do animal cells have a cell wall?
no !
how are our bodies held together?
structural protein called collagen that allows for cell connection
what tissues allow animals to move?
nervous and muscle tissue
what are tissues?
groups of cells that have a common structure, function or both
how can you be certain that something is a true tissue?
a true tissue will separate from other tissue by a membranous layer
what are some characteristics of animals?
- chemoheterotrophic: we cannot make our own food
- sexual reproduction: motile haploid sperm fertilizes larger non-motile haploid egg to make zygote
how do animals reproduce?
- all have a haploid gamete, with a small motile sperm cell and a large egg cell
- cleavage: diploid zygote undergoes several miotic cell divisions
- cleavage leads to the formation of the hollow, multicellular blastula
- the blastula undergoes gastrulation to form a gastrula with different layers of embryonic tissue (ectoderm, endoderm and blastopore)
- germ layers give rise to the tissue and organs of the animal embryo
- protostomia: first invagination of the gastrula (blastopore) forms into the mouth
- deuterostomia: second invagination becomes the mouth, and the first opening becomes the anus or closes
what process happens with protostomes?
the new row of cells becomes slightly off center
what kind of cleavage do protostomes undergo?
spiral cleavage
what does it mean when protostomes are determinate?
a new cell is destined to form some part of the later embryo, and the removal of some of these cells results in the embryo missing organs
what process happens with deuterostomes?
each cell division stacks the new cells directly above the previous one
what kind of cleavage do deuterostomes experience?
radial cleavage
what does it mean when deuterostomes are indeterminate?
early embryotic cells are not differentiated, which means that the young embryo could split and develop into two complete embryos (how identical twins are formed)
what is a homeobox?
a highly conserved nucleotide sequence, meaning it has been unchanged over millions of years of evolution
what type of genes are homeobox genes?
regulatory!
what is the function of a homeobox regulatory gene?
it can turn genes on and off
what does the homeobox control?
anterior to posterior developmental sequence of the embryo, which can cause a pattern formation during development
what are homeobox containing genes called?
hox genes
what are the properties of hox genes?
the order of genes along chromosomes are similar among different animals groups, but the number of repetitions can differ
does the number of hox genes vary among different animal phyla?
yes, absent in sponges by many in vertebrates
what are the two types of potential body plans an organism can posses?
radial symmetry or bilateral symmetry
what is radial symmetry?
no front and back, or left or right
radial animals often possess what characteristics?
planktonic or sessile (weakly swimming)
what is bilateral symmetry?
two sided symmetry with a left and right side, dorsal (top) and ventral (bottom) side, and an anterior (head) and posterior (tail)
(think of drawing a line right down the middle of your body)
bilateral animals posses what characteristics?
often move more actively and have a central nervous system
what is the process of cephalization?
the development of the head (cns)
in cephalization, what is concentrated in the head?
sensory organs, including sensory structure and receptors
cephalization centers what in the brain?
internal concentration of the neural system, which forms the cns
what was cephalization developed? what does this allow for? (3)
allowed for forward and directional movement, which allows for quicker responses to stimuli, better ability to search for food, and better defenses and capabilities
the class of animals called eumetazoa are all animals that posses?
true tissues
what are tissues?
an integrated group of cells with a common structure and function
all true tissues have a?
membranous layer
what does the membranous layer do?
isolate tissues from other tissues
what is the parazoan design?
collection of cells, specialized cells perform specific functions
what is the eumetazoan design?
specialized cells are collected into a distinct tissue, which causes more advanced designs and tissue combining to form organs
what are the three germ layers involved in tissue formation?
endoderm, ectoderm and mesoderm
what does the endoderm form?
the digestive tract (gut)
what does the ectoderm form?
outer covering (skin and nerves)
what does the mesoderm form?
muscle and other organs (think middle)
the class ‘radiata’ refers to animals that have?
two embryonic cell layers
what do diploblastic animals have?
an endoderm and ectoderm
the class “bilateria’ refers to animals that have?
three embryonic cell layers
what do triploblastic animals have?
endoderm, ectoderm and mesoderm
what do most triploblastic animals possess?
a fluid-filled body cavity
what is a true body cavity called? where is it derived from?
coelom, which is derived from the mesoderm
animals that have a true coelom are called?
coelomates
what are the qualities a coelomate has? (4)
- a digestive tract from the endoderm
- bodily covering from the ectoderm
- tissue layer lining the coelom and suspending internal organs from the mesoderm
- body cavity!
some triploblastic animals do not have a coelom, but rather a?
hemocoel
what is the function of the hemocoel?
to provide circulation, nutrient transport, waste removal and a hydrostatic skeleton (in some animals)
what is a hemolymph?
the fluid-filled cavity for a hemocoel
what are the qualities an animal with a hemocoel has? (4)
- a digestive tract from the endoderm
- body covering from ectoderm
- muscle layer from the mesoderm
- body cavity
triploblastic animals that lack a body cavity are called?
acoelomates
what are qualities that an acoelomate has? (4)
- body covering from ectoderm
- tissue-filled region from the mesoderm
- wall of the digestive cavity from the endoderm
- no body cavity
what is the function of the coelom?
to cushion internal organs from blows to the outside of the body
what does having a coelom allow internal organs to do?
internal organs can grow and shift without deforming the outside of the body, like the heart beating
what can the fluid-filled cavity of the coelom be used as?
a hydrostatic skeleton by tensing the muscles around an incompressible fluid (earthworms)
animals common ancestor resembled that of a?
choanoflagellate
what are choanoflagellates?
heterotrophic protists
what does the choanoflagellate have (structurally)?
a single flagellum that is surrounded by a collar of microvilli
what are microvilli?
finger-like projections of the cell membrane
choanoflagellates have a cell morphology that is similar to that of?
sponges
what is the colonial hypothesis?
a ball-shaped colony of choanoflagellates may have evolved inti a simple animal with endodermal and ectodermal layers
what are the steps of the colonial hypothesis?
- collagen and oxygen allow for cell adhesion, creating a colonial protist (an aggregate of identical cells)
- aggregation of similar cells form into a hollow sphere of unspecialized cells
- cell specialization begins; may specialize in reproduction, growth, etc through natural selection
- an infolding is formed
- gastrula-like ‘protoanimal’ with germ layers and a digestive cavity is formed
what is the dna evidence that the colonial hypothesis took place?
genes for cell signaling and adhesion proteins found in both choanoflagellates and animal cells
what are the advantages of being multicellular?
- they get bigger and more complex
- easier to gather and eat food
- less likely to get eaten - defense
- specialization of tasks - sensory, digestion
what are some costs to multicellularity?
- most cells do not reproduce
- requires cooperation
what is diffusion?
random motion of molecules from a high to low concentration
what are some limitations of diffusion?
only effective over small distances and limits size
how was diffusion overcome?
bulk flow
what is bulk flow?
active flow of oxygen, nutrients and other molecules in large quantities from point a to point b
specialized cells and tissues ________ _________ oxygen and nutrients throughout the body?
actively transport
what are the four major eras?
edicarian, aleozoic, mesozoic, cenozoic