BIO 111 Exam #3

UR- Minckley

Fick’s Law

rate of diffusion

=-(membrane permeability)(surface area)(concentration gradient)

• greater concentration gradients = faster

• smaller concentration gradients = slower

basal metabolic rate + flux will limit cell size because of surface-volume ratio

diffusion time + diffusion rate = limit cell size + influence body plan architecture of multicellular organisms (i.e. membrane infoldings to increase surface area in eukaryotic cells)

shape modifications to combat surface area issue

• volvox maximized contact with outer environment (hollow center with all cells on outside)

• sponges- filled with acellular jelly on inside so they don’t need a circulatory system to carry O2 and CO2

• flatworms- flattened to maximize surface area so no circulatory system is needed

costs and benefits of large body size

cost = food

benefits = metabolism per unit of body mass decreases, move faster, access to more food resources because large weight range of food to eat, less prone to predation

germa-soma cell differentiation

somatic cells- eventually die

germline cells- live long with no mitosis (miotic arrest) so low mutation rate and metabolic inactivity reduces DNA damage caused by oxidation

characteristics of the metazoa

• multicellular- different origins

• heterotopic

• collagen

• unique muscle/bone tissue

• diploid dominant life cycle

• gene arrangement

phylogeny classification for animalia

monophyletic

when did all the morphological diversity for animals originate?

in the Cambrian Explosion in aquatic environments

basal metabolic rate

minimum energy production required by a cell/organism to stay alive (measured as oxygen consumption rate b/c of the cellular respiration chemical reaction uses oxygen)

what is the outgroup for animalia

fungi- closest multicellular relative of animalia

• homologous flagella in fungi and in animal gametes

• use glycogen as storage molecule

• genomic synapomorphies

what is the best evidence for animal relationships

gene order- i.e one portion of a gene coding for the head and the next for the body …

difference between classic and modern view of animal relationships

complexity is derived (ordered animalia by primitive —> advanced) but now organized by genomics

choanoflagellates

outgroup (sister group) of metazoa

how many phyla in animalia

36

porifera

sponges

synapomorphy: choancytes- specialized cells with flagella in porifera that facilitate feeding, respiration, excretion, reproduction

• filter food particles from water

• mesohyl- acellular mesoglea with embedded collagen fibers, spicules and various other cells

  • acellular so doesn’t need O2 from blood- no circulatory system

animalia phyla that diverge at radial (multiple planes) symmetry and 2 germ layers

• ctenophora

• placozoa

• cnidaria

ctenophora

comb jellies

• marine predators

• synapomorphy: colloblasts- sticky adhesive structures that are attached to long, retractable tentacles

• 8 comb rows/ciliary bands

tissue

group of specialized cells that work together

missing hox genes

found in cnidaria and bilaterians so what is the first branch after porifera? what is the first animalia? - not a clear story for evolution

cnidaria

coral, jellyfish, hydra

• gastrovascular cavity with 1 digestive system opening

• synapomorphy:

  • nematocysts- stinging cells that help for active feeding

  • opsins- detect light and regulate hunting

animalia phyla that diverged with bilateral symmetry + 3 germ layers

• protostomes- before mouth

• deuterostomes- 2 mouth

cephalization

the centralization of the brain and sense organs to 1 spot in the organism

diploblastic vs. triploblastic tissue

diploblastic: 2 germ layers (endoderm and ectoderm- no mesoderm)

• i.e. cnidarians + ctenophores

triploblastic: 3 germ layers (endoderm, mesoderm, and ectoderm)

• mesoderm allows formation of muscles, circulatory systems, complex organs, body cavities, etc.

• all bilaterians are triploblastic

blastula

hollow ball of cells in early development (undifferentiated cells)

gastrulation

movement of cells to form interior cavity

gastrula

early embryo stage with 2 tissue layers (endoderm + ectoderm)

what is the connection between the developmental body plan and germ layers?

the embryonic tissue layers give rise to all tissue and organs

• cnidaria + ctenophora- no mesoderm- no organs

• porifera- no germ layers so not tissues

fate of the blastophore

protosome- mouth

deuterosome- anus

protostomes

spiral cleavage

8 cell stage- spiral and cell fate determined (pluripotent)

mouth develops from blastophore

deuterostomes

radial cleavage

8 cell stage- radial and indeterminate (totipotent)

anus develops from blastophore

lophotrochozoansec

lophotrochozoans- larvae (mollusk)

• synapomorphy: mantle, muscular foot

advantage of segmentation

easier to grow into larger animals because repeat the same tissues/structures (i.e. worms)

worms- phylum annelida

ecdysozoa

shed exoskeleton

platyhelminthes phylum

flatworms

neoblasts and stem cells: totipotent (become blood, nerves, skin) nervous system regenerates

explain indefinite vs. definite hosts using Platyhelminthes as an example

schistosomiasis (in the phylum of Platyhelminthes) is a parasitic worm that uses snails as an indefinite host and humans as a definite host

• indefinite host: harbor the larval, asexual stages of worm

• definite host: harbors the adult, sexually reproducing worms

skeleton functions and types

functions: support, protection, movement

types: exoskeleton, endoskeleton, hyrostatic

nematoda

round worms

thin exoskeleton, moves by hydrostatic pressure

Caenorhabditis elegans

causes trichinosis infection

Arthropoda

spiders

• thick exoskeleton, movement by attachment of muscles to skeleton

• drive ecosystems

• no marine Arthropoda (water spider only walks on top of water) because crustacea dominate marine environments

• fused body segments- tagmosis

• open circulatory system

• stepwise growth through molting

what are the big four Arthropoda?

• Chelicerata (spiders)

• acari (mites)

• crustacea (crab, barnacles, crayfish)

• insecta

what is the outgroup/sister group of insects?

crestaceans

insect evolution timeline

origin of hexapods (first insect) —> origin of wings (evolved independently) —> origin of wing folding —> origin of metamorphosis

why are insects successful?

• coevolutionary relationship with flowering plants- origin of flowering plants led to a major radiation among insects because major food source on land- created big diverse groups

describe deuterostomes

blastophore: anus

bilateral symmetry (as larvae), secondarily radial symmetry (as adult)

Echinodermata

phylum including starfish and sea urchins

• endoskeleton and epidermis

• synapomorphy: water vascular system and tube feet

Chordata

phylum including Urochordata, cephalochordate, and craniata

• synapomorphy:

  • notochord- structure located between the gut and nerve cord in the embryo and functions as a support and locomotion in free living forms

  • dorsal hollow nerve cord eventually evolved into the spinal cord

  • pharyngeal slits for filter feeding

urochordata

tunicates

• only animals able to synthesize cellulose

• potentially useful chemical compounds include didemnins and aplidine- anti cancer drug properties

what does the amphioxus genome tell us?

• divergence occurred 520 mya

• gene loss has not occurred in amphioxus but gene loss is common in craniata and Urochordata

Craniata

deuterostomes with heads where all the sense organs are in the head protected by cartilage/bone

vertebrata

rigid internal skeleton with vertebral column enclosing the spinal cord

internal organs are suspended in a coelom

well-developed circulatory system

what is the problem with life on land

• the exchange of O2 and CO2 in breathing- hug water loss

• need to support weight to stand and move to get food

internalization of breathing structure

preadaptation to life on land to prevent water loss during respiration

• gills on the inside (sharks) not on external like axolotl

• e.g. ray finned fishes have internal gills with a large lung surface area to obey Fick’s law

original function of the lung

buoyancy in water

• swim bladder in ray-finned fishes

physotomous vs. physoclistous

physotomous: the swim bladder has a direct connection to gut (inflates + deflates)

physoclistous: veins and arteries control the swim bladder by diffusion

importance of lungfish

can breathe both air and water

• vascularized swim bladder that is homologous to the tetrapod lung

• largest vertebrate genome

• paedomorphic

paedomorphic

retention of juvenile traits as adults

ossification

synthesis of bone from cartilage

• calcium- needed for the synapses in the nervous system

• bones- need rigidity to support weight on land and to store calcium to be used for nervous system responses

  • storage hypothesis that bones developed from tissues that evolved to store minerals- greater structural integrity of bone = byproduct of storage

articulation of appendages

mobility for tetrapod

• coelacanth- articulated fin

lobe fin vs. ray fin

ray finned fish: shoulder girdle fused to cranium- stiff

lobe-finned fish: shoulder girdle fused to cranium, narrow base of pectoral fin allows for rotation along its long axis= increases swimming efficency

• girdle eventually detached from cranium, pelvis enlarged and attached to spine with ligaments and muscles to form 4 appendages connected to 1 spine (e.g. tiktaark- foot like structure and protoneck and semi-aquatic)

preadaptations to life on land

• internalization of breathing structures (gills)- protection of delicate organ

• ossification of skeleton- jaw rigidity

• jointed appendages- mobility

amphibians

aquatic larval stage

• earliest vertebrates released eggs into the water, so they don’t dry out

advantages of an egg

• protects embryo

• provides all the nutrients

• homeostasis

terrestrial eggs

• inner aquatic environment

• need O2 and CO2 through diffusion

• need to preserve water but wax and oils on top of the skin

amniotes

mammals, turtles, sphenodon, lizards, crocodilians, and birds

• young in amniotic egg that contains everything they need to mature but O2

structure of amniotic egg

amniotic membrane to protect the embryo

allantois- allows for transfer of waste product out and other nutrition into the egg

chorion- outer membrane underneath the shell

how does a chicken egg develop?

initial weight: 60 grams

final weight: 51 grams (water loss)

air sac inside egg begins small but enlarges as embryo grows larger- space from the water loss allows more oxygen to enter egg corresponding to the higher oxygen needs of the growing embryo- more gas exchange

amniote reproductive strategies

• oviparity- lay eggs (i.e. fish, some sharks, amphibians, reptiles, bird, monotremes)

• oviviviparity- hold eggs in body but give live birth- embryo develops from YOLK

• viviparity- live birth- embryo develops and is nourished in the mother from PLACENTA

divergence in animalia after tetropods

amniote egg, glandular skin, water-conserving kidney

aglandular skin

skin of terrestrial animals = aglandular

fish epidermis is exterior layer

mammal epidermis is covered by waxy/oily layer

mammals

• monotremes (i.e. echidnas, platypus)

• marsupials (i.e. kangaroo, Tasmanian devil)

• eutherians (i.e.beluga whale, naked mole rat)- placental animals

placenta

union of embryonic and maternal tissue

only organ that develops as an adult and has an end time

viviparous sharks (sharks can also be oviparous or ovoviviparous too)

histotroph- uterine milk

offspring nourishment from placenta

transition from histotroph to placenta

uterus function changes to nutrient-producing/transporting organ:

• enhanced secretory functions

• protection-enlarged to protect the embryo

• physiological homeostasis for embryo (respiration, waste disposal, osmoregulation)

strepsirrhines vs haplorrhines

strepsirrhines: wet nose

haplorrhines: dry nose

what is Hominidae

superfamily for apes and humans

how do we determine relatability in Hominidae?

• diet

  • i.e. strepsirrhines = omnivores, tarsiers = insectivorous

• Locomotion

  • i.e. strepsirrhines = arboreal (live in trees)

• When diverged?

• biogeography?

  • phylogeny- not clear where they first evolved

Gondwana breakup

broke up supercontinent into Africa, S. America, Antarctica, Australia, Madagascar and India

when did homo sapiens diverge

500 mya from chimpanzees

bipedalism

required morphological change from 4 legs (tetrapod) to 2 legs to use for walking

• frees up upper body for more mobility

complicated aspects of biogeographic history of primates

• oldest primates seem to be from Asia

• migration from Asia to Africa and N. America

• N. America had primates until 40 mya

• S. American primates rafted from Africa 40 mya

skeletal modifications for bipedalism

• skull size

• phalanges (foot structure)

  • humans: straight toe structure, parallel non-grasping toes

  • apes: curved toe structure, divergent grasping toes

• pelvis

  • humans: ball joint of hip directly above the outside of the knee to provide a great angle between femur and the top of the knee for running/walking on 2 legs

  • apes: ball joint directly above the inside of the knee

Australopithecus afarensis

Lucy- bipedal with small brain

• identified bipedalism by shape of pelvis

• lived 4-2.7 mya

• inhabited northern rift valley of east Africa

species in Hominidae that originated in Africa

• gorillas + chimps (current distribution)

• Australopithecus (fossils)

• homo habilis (fossils)

• homo erectus (fossils)

• homo sapiens (fossils)

what is the geographical boundary between chimps/gorillas and humans in Africa when they divereged?

East African Rift Valley

• west of rift valley = rainforest with chimps/gorillas

• east of rift valley = savanna with humans

Australopithecus anamensis

• bipedal (determined by looking at pelvis structure)

• small brain

• about 4.2 mya

Homo habilis

• earliest known member of genus Homo

• differentiated based on larger brain size and reduced molars and premolars

  • brain = 30% larger than A. africanus

• 2.2-1.6 mya

• evidence of tool use

Homo ergaster

• close relative of modern humans

• 1.8-1.2 mya

• higher vaulting of skull than previous species

• lacks sagittal crest and flaring zygomatic arch of more robust forms

Homo erectus

• 1.8-400,000 years ago

• larger brain (larger than 900 cc)

• evolved in east Africa 1.8 mya

  • moved out of Africa into Asia/Europe

• flaked tools included spears

• fire and cooking

Homo neaderthalensis

• 150,000-30,000 years ago

• Europe and ASia

• short, robust stature

Denisovans

• interbred with neanderthals in Asia where their geography overlapped

• Central and SE Asia

Homo sapiens

• evolved in Africa

• oldens H. sapiens fossil is 195,000 years old

• cranial capacity of homo sapiens < neanderthals generally

what is a method used to track geneology

mitochondrial DNA sequences- passes maternally through the egg

what is the difference between a chimpanzee and a human?

the timing of gene expression (heterochrony)

human development- greater resemblance to juvenile than adult chimpanzees

humans and chimps have incredibly similar DNA but when, where, and how long their genes are expressed results in the differences of the two species

• i.e. humans extend the period of brain growth longer than chimps, but chimps mature faster

• continual learning

why are plants essential for all life on Earth?

• source of all fixed carbon

• source of oxygen- supports aerobic life

• source of ozone layer- allowed for evolution of terrestrial life by reflecting harmful, mutative radiation away from Earth’s surface

plant characteristics

• autotrophs- primary producers

• stationary

• chloroplasts- photosynthesis

  • hold pigment (chlorophyll)

• synapomorphy: alteration of generations

how do plant groups differ?

combinations of pigments

all photoautotrophs have chlorophylls (a,b,c,d, or f, or combination)

• i.e. land plants and green algae have chlorophyll a and b

what is PAR?

photosynthetically active radiation- small portion of all radiation is visible to humans

cyanobacteria

stromatolites

chlorophyll f or d

dinoflagellates

• shape reinforced by internal cellulose plates

• 2 flagella

• mass bloom cause red tide in ocean

brown algae

chlorophyll c (and carotenoids)

• kelp- group of crown algae with the same pigments

diatoms

chlorophyll c (and carotenoids)

• unicellular algae

• 2 part glass like wall made of hydrated silica

• major component of phytoplankton (primary producer in aqautic ecosystems)

• highly diverse in shape