chapter 9 - architectural patterns of animals

homeobox

DNA sequences within developmental genes (like hox genes) that encode the homeodomain, a DNA-binding region of transcription factors

function of homeodomain transcirption factor proteins

regulate gene expression

How do Wnt, FGF, and Sonic Hedgehog signaling lead to organogenesis?

Wnt/FGF/Shh activate transcription factors → induce homeobox (HOX) genes → specify cell fate → organogenesis

what tissue gives rise to the neural plate

dorsal ectoderm

what induces neural plate formation

signals from underlying mesoderm (including the notochord)

what forms from the neural tube

brain and spinal cord

what do neural crest cells do

migrate and form diverse tissues (facial structures, pigment cells)

what happens if homeobox genes are mutated

developmental abnormalities, like the transformation of body parts

how many phyla are recognized in kingdom animalia

32, which appeared during cambrian explosion, and the different phyla represent distinct body plans

age of fossil from cambrian period

500 million years old

5 grades of hierarchical organization of animal complexity

protoplasm, cells, tissues, organs, organ systems

ex of protoplasm complexity

unicellular organisms

ex of cell complexity

sponges

ex of tissue complexity

jellyfishes

ex of organ complexity

flatworms

ex of organ systems complexity

most animal phyla

three main types of animal symmetry

no symmetry, radial symmetry, and bilateral symmetry

ex of no symmetry

poriferia (a sponge)

ex of radial symmetry

cnidaria/jellyfish

ex of bilateral symmetry

most animal phyla

what is cephalization and which type of symmetry is it associated with

cephalization = differentiation of a head with a concentration of sensory organs and feeding apparatus - associated w/ bilateral symmetry

planes of symmetry

sagittal plane - Divides the body into left and right

SAG = Side (left vs right)

frontoal (coronal) plane - Divides the body into front (anterior) and back (posterior)

FRONT-al = Front

transverse plane - Divides the body into upper (superior) and lower (inferior)

TRANS = Across (across the body)

parenchyma

Spongy, space-filling tissue

PARENCHYMA = PADDING
→ fills space like a sponge

acoelomate

lacks a body cavity

A = Absent coelom
→ all solid, no space

pseudocoelom

is a “fake” coelom not completely lined w/ mesoderm

PSEUDO = Pretend
→ looks like a cavity but isn’t proper

pseudocoelomate

Body cavity from blastocoel

Partly mesoderm-lined

-ate = has it

coelom

true body cavity lined with mesoderm

COELOM = Complete lining

eucoelomate

Animal with a true coelom

“Eu-” = true

diploblasts

animals w/ 2 germ layers (ectoderm and endoderm)

ex) cnidaria (jelly fish, sea anemone)

triploblasts

animals w/ 3 germ layers (ectoderm, mesoderm, endoderm)

ex) most animals

segmentation

segmentation - metamerism

repetition of similar body segments along the body axis

each segment = metamere