bio

collagen

protein that provides external, structural support to the cell membrane of animal cells

cleavage

mitotic cell divisions without cell growth between divisions

zygote —> 8 cell stage

the zygote to 8 cell stage is done is 3 rounds of cleavage

blastula

hollow ball of cells that surrounds the blastocoel

gastrulation

one end of the embryo folds inwards, expands, and fills the blastocoel to produce layers of embryonic tissue like the ectoderm and endoderm

blastocoel

hollow cavity in the bastula

larva

sexually immature form of animal that is morphologically different from the adult

typically:

eats different food

exist in different habitat than adult

metamorphosis

developmental transformation that turns the animals into a juvenile that resembles an adult but is not yet sexually mature

body plan

set of morphological and developmental traits that are integrated into a functional whole (the living animal)

symmetry

the pattern of how body structures are balanced and positioned in relation to each other.

radial symmetry

Body parts are arranged around a central point and allow them to meet the environment equally from all sides

either sessile or planktonic

example: jellyfishes

bilateral symmetry

The body can be divided into two equal halves

sensory equipment concentrated at head end of body (CNS) which allows for coordination of complex movement

example: humans

absence of symmetry

The body is irregular and uneven

example: sponges

sessile animals

living attached to a substrate

sessile animals are radial animals

example: sea anemones

planktonic

animals that drift or weakly swim

planktonic animals are radial

example: jellyfish

tissue

collections of specialized cells that act as a functional unit

tissue development

occurs during the process of gastrulation

germ layers

concentric layers of embryonic tissue that form various tissues and organs.

ectoderm

covers the surface of the embryo and gives rise to the outer covering of the animal and the CNS

endoderm

innermost germ layer that lines the developing digestive tube (archenteron) + gives rise to the lining of the digestive tract and the organs derived from it, such as the liver and lungs of vertebrates

diploblastic

animals that only have the ectoderm and endoderm germ layers

mesoderm

fills the space between the ecto and Endo derm

triploblastic

having 3 germ layers

all bilateral animals have the mesoderm (triploblastic)

body cavity

fluid or air filled space located between the digestive tract (endoderm) and the outer body wall (ectoderm)

provide structural support and facilitates internal transport of nutrients, gases, and wastes

coelom

a body cavity formed from tissue that is derived from the mesoderm

cushions and suspends organs to prevent internal injury

hemocoel

body cavity that forms between the mesoderm and endoderm

A body space where blood (hemolymph) flows freely around organs— Part of an open circulatory system

hemolymph

fluid in the hemocoel that functions in the internal transport of nutrients and waste

differences in protostome development and deuterostome development

clevage

coelom formation

fate of the blastopore

spiral clevage

planes of cell division are diagonal to the vertical axisis of the embryo

determinate clevage

animals with protosome development casts the developmental fate of embryonic cells early

radial cleavage

in deuterosome development, the cleavage planes are either parallel or perpendicular to the vertical axis of the embryo

indeterminate cleavage

deteursome development

each cell produced by early cleavage divisions retain the capacity to develop into a complete embryo

archenteron

during gasturalation, embryos digestive tube is this blind pouch

will later become the gut

protosomal development of the blastospore

the mouth develops from the first opening of the blastospore

deutrosomal development of the blastopsore

mouth is derived from secondary opening and the blastopore forms the anus

eumetazoa

all animals except for sponges and a few others belong to the eumetazoans clade

have muscle and nervous tissue

basal eumetazoans are diploblastic and have radial symmetry

3 major clades of bilaterian animals

deuterostomia

lophotrochozoa and ecdysozoa (sister taxa)

diversification of animals

all animals share a common ancestor
sponges are the sister group to all other animals
eumetazoa is a clade of animals with tissues
most animal phyla belong to the clade bilateria
3 major clades of bilaterian animals

3 characteristics of animals

nutritional mode
cell structure and specialization
reproduction and development

Animals are Heterotrophs

this is because they have enzymes within their body to digest food

Animals cells lack cell walls

strucutral proteins stabilize cells

Animal cell reproduction

zygote —> cleavage —> blastula —> gasturulation

Invertebrates

polyphyletic

have no backbone

95% of species

Porifera

sponges= the simplest animals

multicellular but no tissue system

Sessile filter feeders

Cnidaria

They are the simplest animals with true tissues

part of the Eumetazoa clade

examples: sea anemones and jellyfish

Eumetazoa

all animals with true tissues (everything except sponges)

Porifera → Cnidaria

• ❌ No tissues → ✅ True tissues

• ❌ No coordination → ✅ Basic nervous system

• ❌ Asymmetry → ✅ Radial symmetry

Cnidarians True Tissues

epidermis = outer layer

Gastrodermis = inner layer

Mesoglea= jelly like layer in-between the epidermis and gastrodermis

cnidarians = diploblastic

Hox Gene

Hox genes = master control genes for body layout

tells an embryo what body part goes where along the head → tail axis

Lophotrochozoa

a major group of bilaterally symmetrical animals

Bilateral symmetry (left/right sides)

True tissues + organs

Incredible diversity of body plan

Lophotrochozoa vs. Cnidarians

❌ Radial symmetry → ✅ Bilateral symmetry

❌ Simple nerve net → ✅ centralized nervous system

❌ One opening → ✅ more complex digestive systems (often two openings)

Platyhelminthes (flatworms)

First appearance of cephalization (simple head region)

few organs

Annelida (Segmented worms)

Segmented body (repeating units)

Allows for more efficient movement

Different segments can specialize

Mollusca (snails, clams, octopus, etc.)

Complex nervous systems
Muscular foot (movement)

Visceral mass (organs)

Mantle (can secrete shell)

Ecdysozoa

animals that molt (shed their outer covering)

grow by expanding before new cover hardens

ecdysis

molting because cover rigid but animal needs to grow

Lophotrochozoa vs. Ecdysozoa

• ❌ Soft bodies → ✅ protective outer covering

• ❌ Continuous growth → ✅ growth in stages (molting)

Nematoda ( round worms)

parasitic but abundant Ecdysozoa

Anthropods

the most diverse and abundant animals on Earth

“jointed feet” animals

Advantages of Anthropods

hard exoskeleton (chitin)

segmentation

lrgs are joined allowing for efficient movement

open circulatory system

Central nervous system

Insects

co-evolved with angiosperms
Metamorphosis
live in all environments

Stages of Metamorphosis

Larva (caterpillar)

Pupa (chrysalis)

Adult

Deuterostome

group of bilaterally symmetrical animals

anus —> mouth

Echinoderms

spiny skin with internal skeleton made of calcium plates

Adults = radial symmetry

Larvae = bilateral symmetry

sesile movement

water vascular system

4 key traits of chordates

Notochord
Dorsal, hollow nerve cord
Pharyngeal slits (or clefts)
Muscular, post-anal tail

Notochord

A flexible, rod-like structure running along the body that provides support for muslces

Present in embryos but replaced by the spine

Dorsal, hollow nerve cord

A tube of nervous tissue running along the back (dorsal side) —> later becomes the CNS

Allows for fast communication and complex behavior

Arthropod vs Chordate nerve cords

Arthropods → ventral nerve cord

Chordates → dorsal nerve cord

Pharyngeal slits (or clefts)

openings in the throat region

fish —> gills

humans —> ears, jaws, neck

Muscular, post-anal tail

A tail that extends past the anus

Used for balance and movement

Vertebrates

Chordates with backbones

Notochord → replaced by backbone

Simple nerve cord → brain + spinal cord

Basic movement → complex locomotion

Tetrapods

vertebrates with four limbs

represents life moving from water to land

limbs with fingers/toes + stronger skeleton

Amphibians

live partly on water and partly on land

metamorphosis

eggs live in aquatic environments

ectothermic (cold blooded)

dual life = dual sensitivity ( Skin absorbs chemicals easily so eggs fragile bc depend on both water AND land)

Amniotes

animals that fully conquered land

tetrapods with an amniotic egg

Amniotic egg

An egg with a specialized membranes that support the embryo

this allows for reproduction away from water

Amnion fluid

Surrounds embryo with fluid

Reptiles

Amniotes adapted to dry land

Scaly skin (keratin) —> prevents water loss

Internal fertilization

Amniotic egg

Mammals

Amniotes with hair and milk production

mammary glands produce milk for young

keratin hair insulates

endothermic

diaphragm help ventilation

differentiated teeth for digestion and diet

Monotremes

egg laying mammals

ex: platypus

Marsupials

young born and develop in pouches

ex: kangaroos

Eutherians

embryos develop in uterus and then nourished by placenta

Primates

mammals adapted for life in trees

opposable thumbs

developed brains

sociaility

Form predicts function

An organism’s structure (form) tells you what it does (function)

Local Exchange

Diffusion at cell membrane between cells and interstitial fluid

Bulk Transport

long distance movement of materials across the body using organ systems

Interstitial fluid

fluid between cells that acts as a middle layer and bridges the inside of cells to transport systems

Body Organization

organisms —> organ systems —> organs —> tissues —> cells

4 types of tissue

epithelial
connective
muscle
nervous

Epithelial Tissue

covers surfaces, lines cavities, and forms glands

Apical Surfaces

a side of the cell that faces the lumen

basal surface

attached to basal lamina and anchors the tissue

Function of Epithelial Tissue

Protection
Secretion
Absorption

Epithelial Cells Polarity

Epithilial cells are polar —>

apical = top (environment)
basal = bottom ( anchors)

Connective Tissue

Connect tissues together

ECM + Protein Fibers

Extracellular Matrix

Ground Substance + Fibers

Ground Substances

Gel-like material

Protein Fibers

Provide structure + function

Types of Protein Fibers

collagen —> strength
reticulater —> network
elastic —> stretch

Types of Connective Tissues

L = Loose Connective Tissue (anchors)
D = Dense Connective Tissue (Dense bundles)
C = Cartilage (cushioning)
B = Bone
A = Adipose Tissue
B = Blood (transport)

Tendons

attach muscles to bones