bio exam 3

key features of animals

• multicellular

• heterotrophs

• active movement through nerve and muscle cells

• reproduction

• embryonic development

• body plan

Cell bonding

• unique to animals

• cells are held together by extracellular matrix (with collagen) and protein junctions

Sexual reproduction

separate sexes or hermaphroditic

• hermaphroditic: both sexes on one organism

Asexual reproduction

• fragmentation

• budding

• parthenogenesis

Animal ploidy

• Adult is diploid

• Egg/sperm is haploid

Animal life cycle

• Egg+Sperm: fertilization

• Zygote

• Cleavage

• Blastula

• Gastrulation

• Gastrula

• Organogenesis

• Larve

• Metamorphosis

• Adult

Larva

different form/habitat from adult; serves as dispersal stage

Do all animals have a larval stage?

No, some go from juvenile to adult gradually

Zygote

• First step of embryonic development

• Fusion of sperm and egg (2n)

Cleavage

• Second step of embryonic development

• zygote divides into little cells without increasing size

Blastula

• Third step of embryonic development

• Hollow ball of cells formed from cleavage

Gastrulation

• fourth step of embryonic development

• Blastula folds inward to create the blastopore, archenteron (primitive gut), and germ layers (ecto, meso, and endoderm)

Gastrula

• final/fifth step of embryonic development

• multi-layered embryo with germ layers and primitive gut

Protostome cleavage

Spiral

Protostome cell type

Determinate

Protostome blastopore becomes

mouth

Deuterostomes cleavage

Radial

Deuterostomes cells

Indeterminate (stem cells)

Deuterostome blastopore becomes

Anus

HOX genes

• conserved genes found in almost all animals

• transcription factors that control embryonic development

• determine body plan, segmentation, number/placement of appendages

• In vertebrates: duplicated into 4 clusters

First animal fossils

• Ediacaran era

• soft bodied like jellyfish or sponges

Closest animal relative

• Choanoflagellates (protists)

• Close to sponges —> probably first animals

Eumetazoa

Animals with true tissues (everything but sponges)

What is an absorptive heterotroph

An organism that breaks down food and then absorbs the nutrients

What are fungi cell walls made of

chitin

Do fungi cell membranes contain ergosterol or cholesterol?

ergosterol

Are fungi mostly multicellular or single

Multicellular (except yeasts)

Are fungi usually terrestrial or aquatic

terrestrial (except chytrids)

Fungi thallus

Whole fungi body

Fungi mycelium

Main body of fungi

• network of thread-like filaments

Fungi hyphae

Individual thread-like filaments that make up mycelium

Septate hyphae

Has walls dividing cells

Coenocytic hyphae

No walls and common cytoplasm

Fungi budding

• asexul reproduction

• New organism grows out of parent from mitosis and pinches off

• (common in yeasts)

Fungi fragmentation

• asexual reproduction

• Piece breaks off without mitosis or special process and grows

Fungi spores

• asexual reproduction

• produced by mitosis to make identical offspring

Fungi sexual reproduction

Plasmogamy → Heterokaryotic stage → karyogamy → zygote

• never multicellular diploid

Plasmogamy

Fusion of cytoplasm from (+) and (-) hyphae

Heterokaryotic stage

Hyphae contain unfused haploid nuclei of n + n

• (not diploid 2n)

Karyogamy

Fusion of +/- nuclei into a diploid zygote

Homothallic

Fungi that are self-fertile

Heterothallic

Fungi that need a compatible mycelia

Mycorrhizae

Mutualistic fungi and plant roots

Ectomycorrhizae

Type of mycorrhizae with fungus outside root cells

Endomycorrhizae

Type of mycorrhizae where fungus penetrates plant cell walls

Lichen

Mutualistic fungi and photosynthetic algae/cyanobacteria

Fungi as plant pathogens

Ex. rusts, smuts, dutch elm, ergot

• (ergot → ergotism: hallucinations, burning skin, etc)

Fungi as human pathogens: Mycosis

Ranges from serious to treatable

Fungi as poisonous organisms

Ex

• Aflatoxin from Aspergillus on corn/peanuts → can kill humans

• Deadly mushrooms: "Death Cap," "Destroying Angel" → never eat wild fungi!

Chytridiomycota

• Only fungi with flagella

• Unicellular

• Aquatic

Zygomycota

• Coenocytic hyphae (no septa)

• Makes zygosporangium

Glomeromycota

Endomycorrhizal with plants

Ascomycota

Sexual spores in sac-like ascus