Biological Diversity

What we mean by the term; diverse organisms solve problems differently;  why solving problems differently is important to you; review some ideas from Chapter 1.

Reading guide pg 332-345

Prokaryotes (Ch. 27)

Shapes; genome organization; reproduction; metabolism; representative groups; importance

Protists (Ch. 28)

Characteristics; endosymbiosis, colonial organisms; sexual reproduction, representative groups

 

Biodiversity is simply a term to describe the incredible variety of forms of life.

Cornell University

One might think that only a few types of beetles would be “enough” to make the world work, but there are actually about a quarter of a million species.

Biological Diversity

What we mean by the term

Diverse organisms solve problems differently

But an extremely important biological truth is that each species of life solves the problems of survival and reproduction differently.

www.entomology.umn.edu

www.lrc.rpi.edu

www.augsburg.edu/home/biology/

Ostracod picture 1

Ostracod picture 2

Biological Diversity

a

lens

retinalight

a

mirror

retina

Biological Diversity

What we mean by the term

Diverse organisms solve problems differently

Why solving problems differently is important

Ideas from Chapter 1

An example of how differences are important: molecules of the antibiotic penicillin prevent the formation of the cell wall* in bacteria, which prevents their growth. Animal cells do not have a cell wall, just a membrane. Thus, we can take penicillin to kill bacteria living inside us, but without killing ourselves. This would not be possible if bacteria and animals didn’t solve the problem of how to contain the cell contents in different ways.

* This is a simplification

1. Fig. 1.2 - properties of life

2. Fig. 1.3 - levels of biological organization

3. A closer look at cells - eukaryotic and prokaryotic (Fig. 1.8). Prokaryotes often also have a cell wall around the membrane.

Some important concepts from Chapter 1 that you should review from your high school biology course

4. Fig. 1.14 - natural groupings of life

Canis familiaris - genus capitalized, species name not, italics. Family (e.g. Canidae) not italicized

Some important concepts from Chapter 1 that you should review from your high school biology course

5. Fig. 1.23 - tree like graphs show relationships

Some important concepts from Chapter 1 that you should review from your high school biology course

Phylogenetic trees are graphs that display genetic relationships of species. They are calculated from molecular data, or from data on visible features

robin dog batdove

Unique feature evolved in only this branch (=clade): feathers

Unique feature evolved in only this branch (clade): hair

Unique (or derived) features are the clues for determining relationships

time

The tree of life (Ch. 26)

The tree of life

(also some Figures discussed with later chapters)

The tree of life (Ch. 26)

Geological time and Fossils

The tree of life

Fig. 26.22. The Tree of Life is really a better description of how life forms are related than a set of names, although we must still use names too. Don’t try to memorize all of this! We will learn important aspects as we discuss the various groups.

Prokaryotes (Ch. 27)

characteristics

genome organization

reproduction

metabolism

representative groups

importance

Prokaryotes (Ch. 27)

characteristics

genome organization

reproduction

metabolism

representative groups

importance

Fig. 27.2 Shape helps in classifying prokaryotesFig. 27.3 The

Gram stain divides bacteria into Gram-positive and Gram-negative bacteria (which often are the more pathogenic ones).

Fig. 27.8. The single chromosome (DNA + proteins) of a prokaryote contains all the directions for making a living cell. The chromosome of a prokaryopte is not organized into a nucleus, although it is generally located in one part of the cell).

Prokaryotes (Ch. 27)

characteristics

genome organization

reproduction

metabolism

representative groups

importance

All the strands are part of the one chromosome, making a loop.

Reproduction in prokaryotes occurs primarily by cell division - each cell divides into two daughter cells.

However, bits of DNA can be exchanged between cells under certain circumstances, resulting in a form of sexual reproduction (making new combinations of genes).

Prokaryotes (Ch. 27)

characteristics

genome organization

reproduction

metabolism

representative groups

importance

Prokaryotes (Ch. 27)

characteristics

genome organization

reproduction

metabolism

representative groups

importance

Metabolism (the chemical reactions of life) is extremely diverse in prokaryotes. Prokaryotes are structurally simple, but far more diverse metabolically than eukaryotes.

One way to divide types of prokaryotic metabolisms is into autotrophic (can make the complex chemicals of life starting only with carbon dioxide and an energy source) and heterotrophic (requires chemicals more complicated than CO2)

Another way to divide is into phototrophic (energy derived from light) and chemotrophic (energy derived from inorganic molecules like amonia)

All four combinations occur in prokaryotes.Fig. 27.10 - photosynthetic bacteria

Different forms of life solve the problem of obtaining energy in very different ways.

Prokaryotes (Ch. 27)

characteristics

genome organization

reproduction

metabolism

representative groups

importance

Fig. 26.22

Prokaryotes (Ch. 27)

characteristics

genome organization

reproduction

metabolism

representative groups

importance

Fig. 27.13

Learn about:

Chlamydias

Spirochetes

Cyanobacteria

Read about and know characteristics

Prokaryotes (Ch. 27)

characteristics

genome organization

reproduction

metabolism

representative groups

importance

Fig. 27.16 Lyme disease.

Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

Fig. 27.1 Protists in pond water, light microscope

It is difficult to describe the exact characteristics of protists because we don’t know how to organize them into natural groupings yet. Look at the enormous diversity of protists at the left.

They do have some common features

eukaryotic

single-celled, or, if multicellular, only a few differentiated cell types.

sexual reproduction

Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

The protist cell ( and in fact all eukaryotic cells) has some unusual features that are best explained as the results of endosymbionts. (symbiosis means living with another organisms, endosymbiosis means living inside another organism) evolving into a part of the host cell. If two organisms benefit each other, they are said to be engaging in mutualism. (Fig. 26.13). The first evidence of eukaryotes appears in the fossil record about 2 billion years ago.

Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

Multicellular eukaryotes first appear in the fossil record some 1.5 billion years ago. It is likely that a first step towards multicellular organisms was the appearance of colonial organisms - groups of cells functioning as a unit, like this flat algal species (Fig. 26.16). If some cells develop different features, they are said to be differentiated or show differentiation.

Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

Sexual reproduction to a biologist means making new combinations of genes.

Protists (and all eukaryotes) have, at least at some point in their life cycle, two sets of the genes needed for life. A complete set of necessary genes is called a genome.

Two genome states -

Haploid - one genome - 1N

Diploid - two genomes - 2N

2N 2N

1N

1N

meiosis Syngamy

Meiosis and syngamy have opposite effects on the number of genomes

Both haploid and diploid cells can undergo cell division - asexual reproduction.

Fig. 28.31 In the single-celled Chlamydomonas, the gametes (sex cells, having the function of eggs and sperm) are unlike sperm and eggs in that they look the same. This is called isogamy. When cells join, it is called syngamy. A diploid cell formed by syngamy is called a zygote.

Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

Fig. 26.22Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

Diatoms

Single-celled protists that make unique cell walls of, essentially, glass.

These have an extensive fossil record.

Fig. 28.15 - diatom

Fig. 28.16

Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

Brown algae

Many brown algae are quite complex and large, and many are harvested to be used in food (nori in sushi, also in making various gels that are used to thicken food).

Fig. 28.20 - edible seaweed

Fig. 28.18

Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

Cellular slime “molds”

The life cycle includes a single-celled amobae, and a multicellular “slug”. What is an organism?

Fig. 28.7

Protists (Ch. 28)

characteristics

endosymbiosis

colonialism

sexual reproduction

representative groups

Some thoughts on how bacteria and protists solve the same problem in different ways:

Problem: osmoregulation (water regulation). When cells are placed in a hypotonic solution (one with less solute than in a cell), water tends to rush into the cell (osmosis). If you put human blood cells in distilled water, they swell up and burst (lyse).

Both fresh-water bacteria and protists live in a hypotonic solution.

Bacterial solution to problem (in part): Rigid cell wall prevents lysis.

Protist solution to problem (for some protists): Contractile vacuole - pumps out water