BSC 314 Lecture Notes - Lecture 40: Glycoprotein, Lignin, Molly Mcguire
27 Jun 2018
School
Department
Course
Professor
Classifying Groups of Organisms
Biologists use the following features of organisms to identify the major groupings of
current classifications. (This book does not discuss animals and animal like protists ‐
beyond placing them in general perspective.)
Presence or absence of a defined nucleus
Unicellular or multicellular with specialized organelles
Mode of nutrition
Presence or absence of a cell wall
Composition of the cell wall
Motility
Mode of reproduction
Kind of life cycle
Nucleus
The most basic division of organisms separates the living world into two groups on the
basis of those possessing and those lacking a defined nucleus(plural: nuclei). The
nucleus is an organelle, which contains the major portion of the genetic material (DNA)
of the cell and is surrounded by a nuclear membrane. The genetic material of
Prokaryotes is not contained within a membrane bounded nucleus. Eukaryotes all have ‐
nuclei.
Cellularity
The form (morphology) of an organism can be unicellular (one celled) ‐
or multicellular (many celled). Some unicellular organisms form filaments (strings of ‐
cells), others form sheets of cells held together by pectins, and still others form colonies
that give a superficial resemblance to multicellularity. Unicellular organisms do not
form tissues (similar cells organized into a functional unit) nor organs (groups of
tissues organized for a particular function). Some organisms alternate a unicellular
stage with a multicellular stage in their life cycles. Eukaryotic organisms
have organelles, membrane bounded structures within their cells specialized to ‐
perform certain functions.
Nutrition
All organisms need a source of energy to fuel their metabolism, the chemical
processes that maintain life. Organisms obtain their nutrients for metabolism in one of
two basic ways: 1.) Autotrophs are able to make the organic compounds they use for
metabolism directly from inorganic materials; and 2.) Heterotrophs are unable to do
this and obtain their nutrients from the organic materials manufactured by autotrophs.
Some autotrophs are photoautotrophs. They use radiant energy from the sun in the
process of photosynthesis to manufacture organic
compounds. Chemoautotrophs use chemical energy in chemosynthesis, oxidizing
inorganic compounds to manufacture organic nutrients. Chloroplasts are present in the
photoautotrophs, absent in the chemoautotrophs. Animals are heterotrophs;
they ingest (swallow) their food and then digest it internally. Fungi are heterotrophs,
which release digestive enzymes into their surroundings and then absorb the nutrients
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Biologists use the following features of organisms to identify the major groupings of current classifications. (this book does not discuss animals and animal like protists beyond placing them in general perspective. ) Presence or absence of a defined nucleus. Presence or absence of a cell wall. The most basic division of organisms separates the living world into two groups on the basis of those possessing and those lacking a defined nucleus(plural: nuclei). The nucleus is an organelle, which contains the major portion of the genetic material (dna) of the cell and is surrounded by a nuclear membrane. Prokaryotes is not contained within a membrane bounded nucleus. The form (morphology) of an organism can be unicellular (one celled) or multicellular (many celled). Some unicellular organisms form filaments (strings of cells), others form sheets of cells held together by pectins, and still others form colonies that give a superficial resemblance to multicellularity.
