bio final review

1) Living things need to take in energy
2) Living things get rid of "waste"
3) Living things grow and develop
4) Living things respond to their environment
5) Living things reproduce and pass their traits onto their offspring
6) Over time, living things evolve (change slowly) in response to their environment

Not all living organims have ALL thes attributes, moreover, we end up with the same problem as before...

* living thigns with dead material
*viruses

As such, whatever these "life forms" are, our experience has taught us that -in order to exist- they must stay within the bounds of scientific laws that have been established

for the physical and chemical world.....

Scientific Law

a descriptive generalization about how some aspect of the natural world behaves under stated circumstances"

Where, can Life NOT exist……?

Within a state of "chaos" or entropy, or in a vacuum

prerequisite for Life is..

"organization" that is able to harness the laws of the physical world, allowing "life" (whatever it is) to perpetuate, and -at the very least- reproduce itself.

ALL living organisms is that they are all boundered by a well defined, specific and reproducible boundary, or fence.

Minimally, therefore, we can say that "Life is organized".

(a) Living organisms do exist -subject to the laws of chemistry and physics,

(b) One of the central characteristics of living organisms (but clearly not the only one, is the presence and maintenance of some type of reproducible boundary.

(c) the very act of living requires energy. But according to the "laws of physics.....energy can neither be created nor destroyed", so...

(d) to survive -at least in our world- living organisms use organic atoms..."CHONPS " to effectively cycle and recycle the available energy in all its forms... at the expense of the local environment.



(e) Paradoxically, therefore, as a consequence of all these "requirements", I would suggest that a single living organism cannot exist (for any protracted length of time) by itself... ?

life criteria

"Scientific Method", which is the rubric that allows for

objective evaluation of information, that is designed to remove falsehoods, rather than to refine or define any specific "truths

Scientific Hypothesis

"working assumption based upon observations

A Scientific Theory is

"an explanation of some natural phenomenon(a) that can incorporate facts, laws, inferences, and tested hypotheses to provide a conceptual framework that, both explains existing observations, AND predicts new ones -that are also able to be tested"

Scientific Approach

concept of Spontaneous generation was famously refuted by Louis Pasteur in the 19th century, but the initial "broad range" experiment was performed by Francesco Redi some 200 year earlier.

refine, design, collect, analyze, decide
make observations derive a more refined hypothesis

Earth’s geological history is divided into eras and periods. The boundaries between these rather large units of time are based on differences between geological changes..

fossil biotas

mid 19th century, at about the same time that a researcher called Sir Charles Lyell

idea that the age of fossils somehow related to the age of the rocks in which they were found......

Darwin began his

"Voyage of the Beagle" (1831)

Natural selection,

which is the variation of heritable traits that can determine the success of the "reproductive efforts" of animals (life foms) within a given population and can lead to changes in the Genetic makeup or "gene pool" of populations.

evolution impacts

population of individuals
each individual has a slightly different organismal "signature" to donate to the collective "gene pool".

Genetic drift:

a random change in allelic frequency over time and appreciate this as being a key mechanism of evolutionary change.
-fixed
-homogenization
-natural selection

Gene flow

intermingling of separate traits among similar populations. This increase occurs because individuals from other populations will bring in alleles that would otherwise be absent or rare (may be even lost) from the population that is being observed. In other words they would add variety to the gene pool.

bottleneck

severe reduction in population size due to intense selective pressure or a natural calamity or catastrophe, which alters the allele frequency...

*crettacesous period and deccan trap

- founder effect:

whereby a couple or even a single organism becomes "dislodged" from a population, and all genetic variation is limited to the individual or isolated individuals.

Human founder effects ... The Afrikaner population in South Africa and Huntington's disease traced back to 1652

origin of species

1859

kingdoms

5 - plant, animal, fungi, monera, protista

domains

3 - bacteria, eukarya, archaea

"biological" definition of species, or the Biological Species Concept [BSC]

"Species are groups of interbreeding (or potentially interbreeding) natural populations which are reproductively isolated from other such groups."

*BAD: not asexual spexies, nto rpactical to isolate them

The Phenetic (or Morphological) Species Concept -Cronquist (1988)- who proposed an alternative to the BSC that he called a "renewed practical species definition", where he very clearly defines species as

"... the smallest groups that are consistently and persistently distinct and distinguishable by ordinary means."

genetic integration

Genetic integration works on the premise that if individuals within a population mate with one another, but not with individuals of other populations, they are considered to be an "independent evolutionary unit", and can safely be called a Species.

Speciation

"species" splits into two.

-black-bellied seed cracking finsihes

Species richness

the larger the number of species, the greater will be the number of opportunities for new species to form, even though there may be few actual differences among the different species

speciation rate is impacted by

-bheavior
-population bottlnecks
-enviornemntal chane

traits

homologous - shared
derived - different from ancestral
homplastic - traits similar other than inheritance

Making such distinctions is quite difficult,

divergent evolution may make homologous traits appear dissimilar, and convergent evolution can often make homoplastic traits appear quite similar.

operational taxonomic units or "OTU's"

homoplastic traits

Batesian mimicry

non-aggressive species mimics the look of a more aggressive and dangerous one, or a more palatable species mimics an unpalatable or noxious one.

predator-prey relationships

also evolve over time

Four events need to occur before any given cell can undertake cell division.

A signal to "reproduce" must be received.

Replication of DNA and dupication (multiplication) of vital cell components must occur.

DNA must be distributed in to the new cells.

The cell membrane begins to separate and ultimately divide (along with a new cell wall in some organisms) into two new daughter cells.

gram positive

- purple
-thick peptidogylocan layer
-no outer lipid membrane

gram negative bacteria

-pale reddish color
-thin peptidoglycan layer
-outer lipid membrane present

Yes, bacteria do have life cycles,, and, therefore, do need to coordinate expression of their genes accordingly. They can transfer DNA from one bacterium to the next..

conjugation, transformation and transduction (phage).

-bacteria can also be mutlicellular

• During Prophase I, homologous chomosomes of the diploid cell undergo pairing or synapsis.

This is where the two homologues appear to be joined together by what is termed a series of synaptonemal complexes of chromatin, which ulttimately allows the DNA / protein complexes complexes (chromatin) to be exchanged between the two sets of chromosomes.
-tetrad/bivalent

early mid-prophase 1

At a later point, the chromosomes appear to repel each other except at the centromere and at points of attachments, called chiasmata, which give the appearence of multiply associated chromosomes.

Nondisjunction

either homologous chromosomes fail to separate during anaphase I, or sister chromatids fail to separate during anaphase II......resulting in a condition known as aneuploidy.

mendel scientific method

-sufficeint qunatities
-self-pollinate
-well-defined, alternative traits, true-breeding

Gregor Mendel's hypotheses:

1. Hereditary determinants are of a particulate nature. Each genetic trait is governed by unit factors , which "hang around" in pairs (or gene pairs) within individual organisms.
2. When two different unit factors governing the same phenotypical trait occur in the same organism, one of the factors is dominant over the other one, which is called the recessive trait.

3. During the formation of gametes the "paired" unit factors separate or segregate randomly so that each gamete receives either one or the other of the two traits, but only one .

4. The union of one gamete from each parent to form a resultant zygote is random with respect to that particular characteristic.

5. During production of gametes, only one of the "pair members" for a given character passes to the gamete.

6. When fertilization occurs, the zygote gets one from each parent, thus restoring the pair.

Mendel's First Law

Two members of a gene pair segregate from each other into the gametes, whereby one half of the gametes carries one of the traits, the other half carries the other.

Mendel's Second Law

During gamete formation the segregation of one gene pair is independent of all other gene pairs

Alleles can be randomly mutatagenized to become a different allele, depending on DNA sequence changes and maintained or lost -again in a random manner- unless

acted upon by a selective pressure

"Wild Type

*most common allele in a population
* does not mean that it is dominant or superior allele

hybrid vigor or heterosis

whereby crossbred strains show superior qualities, and it is a result of the fact that continued genetic "in-breeding" often leads to deleterious traits becoming "fixed" in the gene pool (an aspect we wil address later). The mixing of two strains, therefore, reintroduces a number of selectible traits which can enhance the gene pool of the newly defined strains...

An hypothesis called overdominance

heterozygous condition -in certain important genes- is often considered to be selectively "superior" or have a higher fitness than the presence of either homozygote.

extensions or modifactions of mendelian genetics - same scheme but diff phenotypic expression

*incomplete dominance (blending) (1:2:1)
*codiminance (blood) (1:2:1)
* allelic interactions - multiple alleles, episasis, pleitropic genes/pleitropy = lethal alleles (2:1)
*duplicate genes (15:1)
*complementary gene activity (9:7)
*polygenes = mediate quantitative inheritance, several genes that intensify or diminsih the phenotype

Mendel's 2nd Law DOES NOT ALWAYS APPLY

Remember, that ......to equate Mendel with meiosis we had to invoke the role of "chiasmata" an their occurance between two gene loci on adjacent chromatids in paired, "bivalent" chromosomes during prophase I of meiosis.

CANNOT occur for X and Y chromosome.

Bateson and Punnett, who observed some curious "asssociations"

To appreciate the importance of the HW equilibrium, Five essential assumptions about the population must be made.

Mating is random.
Population size is very large.
There is no migration between populations.
Mutation can be ignored.
Natural selection does not affect the alleles under consideration.