Zoology Lecture Midterm Review (Shsu Fall 2014)

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Prokaryotes

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No membrane-bound nucleus or organelles

Small size

Circular DNA molecule

Cell division by binary fission or budding

First known cells

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Eukaryotes

Back 2

Membrane-bound nucleus, organelles

Large

Homologous chromosomes

Mitosis

Evolved from prokaryotes

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Endosymbiotic Theory

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"endo" = inside

"symbiotic" = life together

explains origin of cellular organelles

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Endosymbiotic Theory Evidence

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1) double membranes on chloroplasts & mitochondria

2) organelles with own DNA - circular molecules

3) size of organelles similar to prokaryotes

4) endosymbiotic relationships occur in many Protists today

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Levels of Organization

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1) Protoplasmic: unicellular level; organelles carry out functions (Protozoans)

2) Cellular: aggregation of cells; division of labor (Sponges)

3) Tissue: group of similar cells organized to carry out particular function (Jellyfish)

4) Organ: Composed of tissues and have more specialized function (flatworms)

5) Organ system: organs work together to carry out a specific function

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Four main tissue types

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1) Epithelial: protective covering of body; linings of organs, ducts, passages (epidermis)

2) Connective: cells (fewer) & fibers embedded in matrix (blood, fat, bone)

3) Muscular: most abundant in animals; muscle fiber; from embryonic mesoderm (skeletal, cardiac, smooth)

4) Nervous: reception of stimuli & conduction of impulse (neurons)

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Diploblastic

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2 embryonic tissue layers

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Triploblastic

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3 embryonic tissue layers

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Body Symmetry

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Asymmetry: no planes of regular symmetry (sponges)

Radial symmetry: lines of symmetry exist, but only in vertical planes (cnidaria)

Bilateral symmetry: only one plane of symmetry; divides animal into symmetrical halves; axis passes from front to back; found in animals with controlled mobility; front end confronts the environment first

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Cephalization

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Presence of a head

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Body Cavity

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Body cavity = coelom; fluid-filled space between body wall and digestive tube

Acoelomate: solid body; only cavity is digestive tube; mesoderm (Flatworms)

Pseudocoelomate: "false" body cavity' not fully lined with tissue derived from mesoderm (roundworms)

Coelomate: true body cavity; fully lined with tissue derived from mesoderm; muscle, mesentery (insects)

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Zygote

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Fertilized egg

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Blastula

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Ball of cells arranged around fluid filled cavity (blastocoel)

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Gastrula

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Gastrulation: cells of blastula rearrange to form 3 layers (ectoderm, mesoderm, endoderm)

Primitive gut forms (archenteron)

Opening to outside (blastopore)

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Protostome vs Deuterostome

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Protostome:

1) Spiral cleavage

2) Mosaic embryo

3) Blastopore becomes mouth, anus forms secondarily

4) Coelom forms by splitting (schizocoelous)

Deuterostome:

1) Radial cleavage

2) Regulative embryo

3) Blastopore becomes anus, mouth forms secondarily

4) Coelom forms by outpocketing (enterocoelous)

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Metamerism

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- serial repetition of similar body segments along longitudinal axis of the body

- "metameres" (segments)

- greater mobility, complexity, specialization

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Kinds of Protistans

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Protozoans: Heterotrophic/ingestion

Algae: autotrophic/photosynthesis

Slime molds: heterotrophic

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Phylum Retortamonada

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Giardia:

parasite of the small intestine

backpacker's diarrhea

cysts ingested in contaminated water

2 haploid nuclei

no mitochondria

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Phylum Euglenozoa

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Trypanosoma:

free-living and parasitic forms

some autotrophic with chloroplasts

two flagella

stiffened cell membrane

brucei - African sleeping sickness - tsetse fly

cruzi - Chagas' Disease - assassin bug

leishmania - Leshmaniasis - sand fly

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Phylum Apicomplexa

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All endoparasites

Cilia and flagella largely absent

Apical complex at anterior end

Toxoplasma - toxoplasmosis

Plasmodium - malaria

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Phylum Ciliophora

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Cilia - movement

Macronucleus - polypoid

Micronuclei - diploid

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Phylum Dinoflagellata

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2 flagella

Planktonic - primary producers

Photosynthetic - fucoxanthin (yellow/brown pigment)

Some parasitic

Some form mutualisms

Pfiesteria - causes lesion, stun and kill fish

Red tide - harmful algal blooms that produce toxin that affect nervous system of vertebrates

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Phylum Amoebozoa

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Pseudopodia - false feet; engulf food - phagocytosis

Soil and water

Some parasitic

Amebic dysentery - entamoeba histolytica

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Kingdom Animalia - General Characteristics

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Multicellular eukaryotes

Specialized cells - tissues in most

Heterotrophic - Internal digestion

Locomotion

Reproduction usually sexual

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Vertebrates vs Invertebrates

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33-35 phyla

1 contains animals with a backbone

<5% of all animals

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Porifera

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All aquatic mostly marine

Cells not organized into tissues

Many brightly colored

Mostly asymmetrical

No nervous system

Sexual and asexual reproduction

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Porifera body plan

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Ostia: incurrent pores

Osculum: excurrent opening

Choanocytes: flagellate collar cells

Mesenchyme cells: amoeboid cells in matrix multiple functions

Mesphyl: gelatinous matrix

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Types of structures

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Asconoid: simplest; choanocytes line spongocoel

Syconoid: folded body wall forms incurrent & radial canals

Leuconoid: most complex; greater size; most sponges

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Sexual Reproduction in Sponges

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Hermaphroditic

Gamete development

Fertilization in mesohyl

Larval development internal in most

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Coral Reef Structure

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Barrier Reef - parallel to shore; deep lagoon

Fringing Reef - close to shore; no lagoon or narrow lagoon

Atoll - reefs encircle lagoon; sunken volcanic island (Darwin's Theory)

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Coral Bleaching

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Loss of symbiotic dinoflagellates that occurs with increased ocean temperatures

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Symbiotic Relationships

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Hydrozoans living on the shell of a hermit crab:

mutualistic; protection; food and movement

Hermatypic (Reef-building) Coral:

mutualism with dinoflagellates; conduct photosynthesis; waste products of coral

Commensalism: (one helps another without harming the other)

mutualistic; damsel fish protection from anenome; ventilate anemone, free of sediment

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Phylum Platyhelminthes

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Bilateral symmetry: cephalization

Some free-living; most parasitic (>80%)

Triploblastic (ectoblastic, endoderm, mesoderm)

Acoelomate: solid body

Dorso-ventrally flattened

Branched intestines: extra cellular and intracellular digestion

Excretory structures: osmoregulation

Nervous system & cephalization

Sexual and asexual reproduction

no respiratory system: diffusion

no circulatory system: diffusion