zoology exam 3

Taxonomy

• naming species and classifying them into groups (taxa)

• Doesn’t show relationship within a taxon

what are the 8 taxonomic levels

• Domain, kingdom, phylum, class, order, family, genus, and species

• Did Katy Perry come over for grape soda?

Taxon

any taxonomic group

Taxonomy grammar

• first word is the genus is capitalized second is lower case

• scientific name must be in italics or underlined

what do biologist use to identify species

1. common descent- members of species must trace their ancestry to a common ancestral population

2. smallest distinct grouping - sharing patterns of ancestry and descent

3. reproductive community- speaks must form a reproductive community that excludes members of other species

geographic range

• species with very large geographic ranges or worldwide distributions.

• endemic- species with very restricted geographic distributions

evolutionary duration

distribution through time

Taxonomic characters

• are any feature used to study variation within/between species

• these characters can be used to reconstruct the phylogeny of a group taxa

Taxonomic characters and phylogenetic reconstruction

1. comparative morphology- examines shapes, sizes, and development of organisms. living specimens and fossils are used

2. comparative biochemistry- analyzes sequences of amino acids in proteins. analyzes nucleotides sequences in DNA and RNA. recent studies show this can be applied to fossils

3. comparative cytology- examines variation in number shape and size of chromosomes. used almost exclusively on living specimens

clade

• a group with evolutionary common descent

• a clade or monophyletic group consists of an ancestor and all its descendants

ancestral character

• the character state present in the common ancestor

• pre-existing trait within a clade

derived character

• all other variant forms of the character the character that arose later within the groups

• an evolutionary novelty

synapomorphy

• derived character shared by members of a clade

• used as evidence of homology

• infers that a group of organisms forms a clade

• ex: true tissue, bilateral symmetry

How to find out if its ancestral

does the group share the trait with its sister and its most recent common ancestor with that sister if

Protist

eukaryotes that aren’t plants, animals, or fungi

protozoan characteristics

• lack a cell wall

• have one motile stage in life

• most ingest their food

• single cell

• can survive only within narrow environmental ranges

• domain: eukarya

• heterotphos

Commponents of protozoan cells

• nucleus

• ER

• golgi

• Mitochondria

• Ribosomes

• Cytoplasm & cytoskeleton

• cell membrane

What is the difference between cilia and flagella

• cilia usually shorter and numerous

• flagella usually longer and fewer

how are cilia and flagella formed?

• contain 9 pairs of microtubules arranged around a central pair

• 9 + 2 arrangement

• arrangement called an axoneme covered by the plasma membrane

• all motile flagella and cilia in animal kingdom

microtubule review

• microtubules are polymers of alpha and Beta-tubulin dimers

• tubular dimers polymerize (form polymers) and arrange in helix

• capable of growing and shrinking in order to generate force

• motor proteins that allow organelles and other cellular factors to move along microtubules of the cytoskeleton

How do microtubules work?

• microtubule doublets are linked to each other by dyne cross bridges

• dynein- is an ATP-dependent molecular motor

Sliding microtuble hypothesis

• movement occurs due to a conformational change of the dynein, causing sliding of one tubule past another, then release then reattach.

• each cilium/flagella is anchored to the cytoskeleton this leads to bending

Pseudopodia

• primary means of locomotion in ameobozoans and ameboid cells of many higher animals

• extensions of cell cytoplasm

Actin Filaments

• long chains of actin proteins

• form cell cortex underneath plasma membrane

• affect cell movement, cell shape

what are in the cytoskeleton

• microtubels- in cilia and flagella

• and actin filaments

Pseudopod formation

• Actin subunits make actin filaments that pushes against plasma membrane

• actin-binding proteins (ABP) cross link actin filaments to stabilize

• narrow pseudopod straight actin filaments

• wide pseudopod branching filaments branches connected with different ABP

What are the extensions of cell cytoplasm in pseudopodia?

1. endoplasm: contains nucleus and cytoplasmic organelles. Fluid (sol state). Unpolymerized actin.

2. Ectoplasm: more transparent (hyaline). often more rigid (gel state). Polymerized actin

How do pseudopod forms?

• forms by extending ectoplasm; this forms the hyaline cap

• endoplasm flows into hyaline cap

How do pseudopodia work?

1. flowing endoplasm contains actin subunits with proteins (ABP) that prevent actin form polymerizing

2. lipids in the cell membrane release the ABP from actin

3. Actin filaments can now cross-link via another actin-binding protein to form semisolid gel in ectoplasm

4. at the edge of the gel Ca2+ activates actin-serving protein

5. filaments are released from gel

6. myosin associates and pulls the filaments

7. contraction at trailing edge fluid endoplasm towards the hyaline cap