Assignments

Sunday, February 13, 2011

Chapter 11 & 12

a) Gene locus & disulfide bridge
The disulfide bond is a strong covalent bond that is important in linking polypeptide chains in proteins that form during the tertiary structure of protein synthesis. A gene locus is the DNA site of a gene, and a certain part of it could be called an allele which codes for certain traits. The disulfide bond holds together the chromosome that is composed of DNA.
b) Nondisjunction & 9-triplet pattern
The nondisjunction is a failure of sister chromatids to move apart in meiosis or mitosis, therefore resulting in daughter cells getting too little or too many chromosomes. The nine triplet pattern is the organization and structure of microtubules in cells, therefore when the sister chromatids fail to separate in this process, it is called a nondisjunction.
c) Autosome & Steroid
Autosome is of a sexually reproducing species, any chromosome of a type that is the same in both males and females. A steroid is a class of organic compounds that can have functions ranging from fat cholesterol in order to be like hormones. The two are similar for they function similarly.
d) Polygenic & Glycocalyx
Polygenic is the term that means of or relating to an inheritable character that is controlled by several genes at once. Glycocalyx is a general term referring to extracellular polymeric material that is produced by some bacteria. Therefore, polygenic can contribute to traits such as glycocalyx because an example of glycocalyx is the slime on fish, which is the outer cells of fish.

a.
- Mendal’s law of segregation:
In Mendal’s law of segregation mendal explains how traits are passed from parents to offspring through gene transmission. He said that genes that consists of DNA are located on the chromosomes. The DNA is passed from parents to their offspring by reproduced. His four main concept was that organisms could inherit two alleles for each trait, a gene can have more than one form, when meiosis occurs and gametes are produced, allele pairs separate which leaves each cell with a single trait, and when two alleles of a pair are different, one becomes dominant and the other recessive.
-Mendal’s law of independent assortment:
Mendal’s law of independent assortment says that allel pairs separate by themselves s (independently) while they are forming gametes. Therefore, the traits are transferred to the offspring independently of one another. 

Thursday, February 3, 2011

Chapter 10

Connection:
a. carrying capacity and biotic potential: The biotic potential is the maximum rate that a population can grow under ideal conditions. The carrying capacity is the maximum number of individuals an environment can contain. These work together because the biotic potential may have to yield to the carrying capacity and therefore the environment must be able to sustain the whole population or many will die.
b. biological magnification and trophic level: The trophic level is all organisms having the same number of transfer steps away from the energy input into an ecosystem while the biological magnification is the increasing concentration of a slowly degradable or non degradable substance in body tissues as it is passing along in the food chains. Both processes deal with energy being inputted into a larger system. In addition each species is put on a trophic level as a smaller organism is eaten by a bigger one and the process continues, this can lead to a biological magnification.
c. Detrivores and autotrophs: Detrivores are animals that feed on decomposing matter or organisms and an autotroph is an organism that synthesizes its own food from simple inorganic compounds in its environment with energy from the sun. These two are similar for instead of feeding off of living organisms, they find their food through what the ecosystem provides for them, autotrophs being the sun and detrivores feeding off organism that are already decomposed.


A)
45.4: limits on the Growth of Populations

1) Density-Dependent Limiting Factors
a) Many times the environmental factors keep a certain population of species from growing to its biotic potential
b) When resources of a specie or organism is lower in numbers, this supply is called the limiting factor
          - This can be extrensively detrimental to a population and one factor can affect the whole population

2) Carrying Capacity and Logistic Growth
     a) In the end, it is the sustainable supply of resources that will determine population   size
     b) the carrying capacity is the maximum number of individuals of a population given   the sustainable supply
     c) The pattern of logistic growth is used to show how the carrying capacity can affect           a population size
     d) When exponential or logistic growth are overcrowded, factors function as density-  dependent controls putting an individual’s survival over the population.
3) Density-Independent Limiting Factors
     a) Density-independent factos cause more deaths and fewer birth rates

B)
Survivorship curve: a graph line that emerges when ecologists plot a cohort’s age-specific survival habit.

Type I: Type I These curves are used to indicate population and it curves when there is a drop of survival during their lifetime.
Ex. The population of people in America who have easy access to health insurance as opposed to some of the starving children in Africa then the curve would drop because of the population, if the whole world is taken into consideration, will drop.
Type II: This curve reflects the death rate of all ages this includes all organisms.
Ex. The death of snowy egrets is very constant.
Type III: This curve is used to describe organisms with high death rate at an early stage in life.
Ex. Sea star larvae die at a very early age.

C)
a. Negative Growth: A negative growth population has a small amount of individuals in its pre-productive time with a higher amount when it is productive and after the productive stage is when the largest number of individuals can exist.
b. No Growth: A population with no growth steadily declines but as it gets older, it would have a smaller population.
c. Rapid Growth: A population with rapid growth has a dramatic increase in its population as the years go on.
d. Slow Growth: A population with slow growth is when the growth of a population decreases at a consistent rate.

D) The nitrogen cycle is when gaseous nitrogen is changed into ammonia (N2 à NH3). This occurs when the ammonia created by nitrogen-fixing bacteria in the soil and nitrogen fixation happen. Then the organisms use the two forms, nitrate and ammonium to live. Then as organisms pass on, they decompose and nitrogen enters back into the soil. And in the soil, the nitrogen is absorbed and nitrate is converted to gaseous nitrogen again.