•Some properties of lifeeldora.as.arizona.edu/~yshirley/Arizona/AST202/Properties_of_Life.pdfCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Life’s

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

The Nature of Life•Some properties of life


Life Displays Order


Life Uses Energy


•Energy flows through an ecosystem

• Usually entering as sunlight and exiting as heat

Producers(plants and other

photosyntheticorganisms)

Consumers(including animals)

Sunlight

Chemical energy

Heat

Heat

Ecosystem

Figure 1.4


A Closer Look at Cells

•The cell

• Is the lowest level of organization that can perform all activities required for life

• all enclosed by a membrane• all use DNA as genetic information

25 µmFigure 1.5


CELL

Nucleus

Cytoplasm

Outer membrane and cell surface

Figure 1.10


•Essential elements

• Include carbon, hydrogen, oxygen, and nitrogen

• Make up 96% of living matter

•A few other elements

•Make up the remaining 4% of living matter

Carbon-based Life


•The backbone of biological molecules

•All living organisms are made up of chemicals based mostly on this one element --> organic chemistry

•The bonding versatility of carbon allows it to form many diverse molecules, varying in length and shape

Carbon is Special


Molecular Components of Cells

•Carbohydrates

• food energy, sugars and starches

• structure (cellulose)

•Lipids/fats

• Can store energy

• Major ingredient in cell membranes

•Proteins

• Work-horses of cells


Proteins

Proteins have many roles inside the cell

•Some serve as structural elements

•Enzymes serve as catalysts to biochemical reactions in cell

•Built from amino acids

•organic molecules possessing both amino group [N bonded to 2 H and 1 C] and carboxyl group [COOH]

•Differ in their properties due to differing side chains, called R groups


Enzymes

• Are a type of protein that acts as a catalyst, speeding up chemical reactions

Substrate(sucrose)

Enzyme (sucrase)

Glucose

OH

H O

H2O

Fructose

3 Substrate is convertedto products.

1 Active site is available for a molecule of substrate, the

reactant on which the enzyme acts.

Substrate binds toenzyme.

22

4 Products are released.

Figure 5.16


Proteins

Proteins have many roles inside the cell

•Some serve as structural elements

•Enzymes serve as catalysts to biochemical reactions in cell

•Built from amino acids

•organic molecules possessing both amino group [N bonded to 2 H and 1 C] and carboxyl group [COOH]

•Differ in their properties due to differing side chains, called R groups


• 20 different amino acids make up proteins

O

O–

H

H3N+ C C

O

O–

H

CH3

H3N+ C

H

C

O

O–

CH3 CH3

CH3

C C

O

O–

H

H3N+

CH

CH3

CH2

C

H

H3N+

CH3CH3

CH2

CH

C

H

H3N+ C

CH3

CH2

CH2

CH3N+

H

C

O

O–

CH2

CH3N+

H

C

O

O–

CH2

NH

H

C

O

O–

H3N+ C

CH2

H2C

H2N C

CH2

H

C

Nonpolar

Glycine (Gly) Alanine (Ala) Valine (Val) Leucine (Leu) Isoleucine (Ile)

Methionine (Met) Phenylalanine (Phe)

C

O

O–

Tryptophan (Trp) Proline (Pro)

H3C

Figure 5.17

S

O

O–

Amino Acid Monomers


O–

OH

CH2

C C

H

H3N+

O

O–

H3N+

OH CH3

CH

C C

HO–

O

SH

CH2

C

H

H3N+ C

O

O–

H3N+ C C

CH2

OH

H H H

H3N+

NH2

CH2

OC

C C

O

O–

NH2 O

C

CH2

CH2

C CH3N+

O

O–

O

Polar

Electricallycharged

–O O

C

CH2

C CH3N+

H

O

O–

O– O

C

CH2

C CH3N+

H

O

O–

CH2

CH2

CH2

CH2

NH3+

CH2

C CH3N+

H

O

O–

NH2

C NH2+

CH2

CH2

CH2

C CH3N+

H

O

O–

CH2

NH+

NHCH2

C CH3N+

H

O

O–

Serine (Ser) Threonine (Thr)Cysteine

(Cys)Tyrosine

(Tyr)Asparagine

(Asn)Glutamine

(Gln)

Acidic Basic

Aspartic acid (Asp)

Glutamic acid (Glu)

Lysine (Lys) Arginine (Arg) Histidine (His)


• Nucleic acids store and transmit hereditary information

• Genes

• Are the units of inheritance

• Program amino acid sequences

• Are made of nucleic acids

Nucleic Acids

•There are two types of nucleic acids

•Deoxyribonucleic acid (DNA)

•Ribonucleic acid (RNA)


• Set of operating instructions for cell - directs RNA synthesis and protein synthesis through RNA

• Way of passing down information through generations

1

2

3

Synthesis of mRNA in the nucleus

Movement of mRNA into cytoplasm

via nuclear pore

Synthesisof protein

NUCLEUSCYTOPLASM

DNA

mRNA

Ribosome

AminoacidsPolypeptide

mRNA

Figure 5.25

DNA Stores Information


• Cellular DNA molecules

• Have two 'zipper edges' that spiral around an imaginary axis

• Form a double helix backbone

The DNA Double Helix

•The base sequence of 'zipper teeth'

•Adenine (A), guanine (G), thymine (T), cytosine (C)

•unique for each gene

•The bases in DNA form bonds in a complementary fashion (A with T only, C with G only)


• The DNA double helix

• Consists of two anti-parallel nucleotide strands3’ end

Sugar-phosphatebackbone

Base pair (joined byhydrogen bonding)

Old strands

Nucleotideabout to be added to a new strand

A

3’ end

3’ end

5’ end

Newstrands

3’ end

5’ end

5’ end

Figure 5.27


DNA

Cell

Nucleotide

A

C

T

A

T

A

C

C

G

G

T

A

T

A

(b) Single strand of DNA. These geometric shapes and letters are simple symbols for the nucleotides in a small section of one chain of a DNA molecule. Genetic information is encoded in specific sequences of the four types of nucleotides (their names are abbreviated here as A, T, C, and G).

(a) DNA double helix. This model shows each atom in a segment of DNA.Made up of two long chains of building blocks called nucleotides, a DNA molecule takes the three-dimensional form of a double helix.Figure 1.7

Nucleus


• DNA replication – 'unzipping' of two strands to make new, complementary strand


The “Book” of DNA

Base pair 10 1 LetterCodon 100 6 WordGene 10,000 1000 SentenceBacterium 10,000,000 1,000,000 Short bookHuman 3,000,000,000 6,000,000,000 Encyclopedia

Level Atoms Bits Language analog


•The Genetic Code

•Uses a four “letter” alphabet with specific pairing rules

•Contains redundancy because 4 x 4 x 4 codons could specify 64 amino acids

•Does not require perfect fidelity in copying because of cross-checking elsewhere

•Extends to the huge information content of 3 billion base pairs and 25,000 genes (in humans)


The Genetic Code


•The Modern Tree of Life

•Maps evolution via the gradual deviation of the base pair sequences in DNA or RNA

•Shows relationships between species

•Does not depend on identifying or recognizing distinct species

•True diversity of life found almost entirely within microscopic realm

•WORK IN PROGRESS!

Now...


The Modern Tree of Life


The Three Domains of Life

•At the highest level, life is classified into three domains

• Bacteria

• Archaea

• Eukarya

•The “species” concept is tricky. Its normally defined by the ability to reproduce (and by a similar appearance) but many organisms can clone or reproduce asexually, and microbes don’t look very different from each other.


• Life’s three domains

Figure 1.15

100 µm

0.5 µm

4 µmBacteria are the most diverse and widespread prokaryotes and are now divided among multiple kingdoms. Each of the rod-shapedstructures in this photo is a bacterial cell.

Protists (multiple kingdoms)are unicellular eukaryotes and their relatively simple multicellular relatives.Pictured here is an assortment of protists inhabiting pond water. Scientists are currently debating how to split the protistsinto several kingdoms that better represent evolution and diversity.

Kingdom Plantae consists of multicellula eukaryotes that carry out photosynthesis, the conversion of light energy to food.

Many of the prokaryotes known as archaea live in Earth‘s extreme environments, such as salty lakes and boiling hot springs. Domain Archaea includes multiple kingdoms. The photoshows a colony composed of many cells.

Kindom Fungi is defined in part by thenutritional mode of its members, suchas this mushroom, which absorb nutrientsafter decomposing organic material.

Kindom Animalia consists of multicellular eukaryotes thatingest other organisms.

DOMAIN ARCHAEA


•Domain Bacteria and domain Archaea

• Consist of prokaryotes, cells without nuclei

•Domain Eukarya, the eukaryotes

• Includes the various protist kingdoms and the kingdoms Plantae, Fungi, and Animalia

•Simple, single-celled organisms or microbes dominate life on Earth: 5000x more mass in ocean microbes than all humans combined


Cells and Energy

• We know cells are the ingredients of life...

• And that they carry the instructions for life...

• But how do they MAKE

LIFE?

• Cells need:

• Materials

• Energy

Light energy

ECOSYSTEM

CO2 + H2O

Photosynthesisin chloroplasts

Cellular respirationin mitochondria

Organicmolecules

+ O2

ATP

powers most cellular work

HeatenergyFigure 9.2


•Cells can build incredible variety of molecules from limited set of starting materials --> due to enzyme variety and...

•ATP!

•Used to store and release energy for nearly all chemical manufacturing

•Once produced, can be used to provide energy for any cellular reaction

ATP


Completely recyclable!

ATP


Categorizing Life by Carbon and Energy

•Metabolism comes down to needing primary raw material of life – carbon – and energy

• Carbon sources

• Eating = heterotroph• Environment = autotroph

• Energy sources

• Sunlight = photo(synthesis)• Organic compounds (food) = chemo-• Neither = inorganic chemicals w/o C from

environment


Categorizing Life by Carbon and Energy

•Liquid water is the final ingredient in metabolism

• Allows organics to float within cell --> readily available for chemical reactions

• Medium of transport for chemicals to and within cells, way to transport waste away

• Ingredient in many metabolic reactions within cells

Documents

•Some properties of lifeeldora.as.arizona.edu/~yshirley/Arizona/AST202/Properties_of_Life.pdfCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Life’s