Starting Small, Getting Bigger, Body Plans, & Natural Histories

What are the main things that categorize something as an organism?

reproduce without host, metabolism, and grow

Lateral/Horizontal Gene Transfer

the transfer of genetic information from one individual to another

Virus

cooperating biological units, cannot grow, no metabolism, cannot reproduce without host, evolves

Are viruses organisms?

mixed opinions

Bacterium

single cells, cooperating biological units, grow, metabolism, reproduce without host, evolve

Is bacterium organisms?

yes

Jellyfish

multicellular, cooperating biological unit, grow, metabolism, reproduce without host, evolve

Are jellyfish organisms?

yes

Siphonophore

colony of individuals, cooperating biological units, grow, metabolism, reproduce without host, evolve

Are siphonophores organisms?

yes if whole colony

Eukaryota

eukaryotic; variable size range; some single cells, some colonies, some multicellular

Archaea

prokaryotic; small (a few μm); single cells, some colonies

Bacteria

prokaryotic; small (a few μm); single cells, some colonies

What are the 3 Domains?

Eukaryota, Archaea, Bacteria

What is the environment dominated by?

viscous-based forces

Viscous

resistant to flow

Diffusion

passive; moves materials within cell and in/out cells

What is moved in/out of cells with diffusion?

supply for metabolic demands, metabolic wastes, chemical signals

What does diffusion depend on?

distance; surface area; difference in concentration; “Diffusion Coefficient”

The larger the distance between two points, the _____ diffusion will take

longer

What is the time required for a particle to move via diffusion?

x²; x = distance

More Surface Area, _____ rate of diffusion

faster

Bigger difference in concentration, ______ rate of diffusion

faster

What can organisms not modify in Fick’s Law?

diffusion coefficient

Fick’s Law

What are the benefits to increasing size?

more room for larger genome; more room for internal processes; bigger cells can engulf smaller cells

Moore room for larger genome allows for

more complex gene networks

More room for internal processes leads to

greater specialization and stability

Predation

bigger cells digest smaller cells when they engulf them

Endosymbiosis

bigger cells do not digest smaller cells when they engulf them

How did eukaryotes arise?

from endosymbiotic event between archaea and bacteria

What is a reason why endosymbiosis occurred?

mitochondria bc they have their own genome

Reynolds Numbers

dimensionless number that describes how an object or organism moves through a fluid (water or air)

Low Rynolds Numbers

Re < 10

What does a Reynold Number <10 mean?

small objects/organisms and/or slow movement; forces dominated by viscosity & flow is orderly and reversible

High Reynolds Numbers

Re > 100

What does Reynolds number > 100 mean?

larger objects/organisms and/or fast movement; forces dominated by velocity & flow is disordered

Volume

Demand; energy/resources needed

Surface Area

supply; area where diffusion can occur

Which grows much faster: supply/demand?

demand

How to overcome problem of size?

modify supply and demand

Increase supply by

changing overall shape to increase surface area : volume ratio; spheres have lowest SA:V

Decrease Demand

slow down metabolic processes, etc.; but leads to slower growth and reproduction

Multicellularity allows for ____ & __ that would be faced by single large cells, or by groups of un-connected cells

larger size & relief from some of the constraints of diffusion

True or False: Multiple Cells is not the same as Multicellular.

True

How can multicellularity happen?

aggregation & clonal development

Aggregation

cells come together (adhere); less common (slime molds, etc.)

Clonal Development

serial division without separation of cells; more common

Body Plan

the general structure of an organism; cooperating entities at different levels are arranged in

Cooperating biological Units

proteins, nucleic acids, some organelles

Life History

the lifetime pattern of growth, reproduction, and survivial for an average individual

Photosynthetic organisms

obtain energy from sunlight; need chloroplasts

Heterotrophic

obtain energy and nutrients from pre-formed, external source

Multicellularity Hierarchy Order

cells → tissues → organs → systems → individuals

convergent evolution

have similar morphological features but evolved independently; probably from similar external pressures

Somatic cells

body cells; all genetically identical

Housekeeping genes

essential genes no matter the cell specialization; all cells express

Tissues

made up of cells; common developmental line, morphology, and function; cell-cell connections

Organs

groups of tissues that work together for a common goal/function

Organ systems

groups of tissues and organs that work together for a common goal/function

Hypertrophy

an increase in cell size

Hyperplasia

increase in cell number by mitosis

Meristem cells

undifferentiated cells; with hyperplasia can contribute to normal growth in plants and algae

Stem Cells

undifferentiated cells; with hyperplasia can contribute to normal growth in animals

How do plant cells connect?

hemicellulose fibers (structure & flexibility) and pectin (glue) in apoplast

How do plants communicate?

via the plasmodesmata

Adherens junctions & Desmosomes

connect cells to each other or the extracellular matrix

Tight Junctions

close adherence between two cells, prevents most movement from one side of cell sheet to another

Gap junctions

channels allow communication between cells

Which is a tight junction?

1

Which is a adherens junction?

2

Which is a desmosome?

3

Which is a Gap junction?

4

Dermal Tissue

surface of body, protection, regulates exchange with enviornment

Ground Tissue

bulk of body, photosynthesis, storage

Vascular Tissue

plants only; bulk flow

Hyphae

branching tubular strands of fungal cells

mycelium

hyphae joined together; body of multicellular fungus

Epithelial tissue

surface of body, protection, regulate exchange with environment

Contractile tissue

muscles, cells get shorter

nervous tissue

neurons and glial cells, electrical signaling

connective tissue

support tissues, fibrous tissues, blood and adipose tissue, characterized by extensive extracellular matrix