General BiologyIAnswers to FAQ

• Professor Garcia or Roman.• Exam material is based on powerpoint presentation. • There will be 50 multiple choice exam questions.• Each lecture will be weighed equally on exam.• Makeup exams will be far more difficult.• If you cannot make it to my office hours make appointment

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Classroom Text book = Biology by Raven 8th edition.

Laboratory Information

Labs are held this week

You need:

A lab book (Biology Vodopich)

Safety glasses

Lab coat

The Tree of LifeChapter 26

5

Origins of LifeThe Earth formed as a hot mass of molten

rock about 4.5 billion years ago (BYA)

-As it cooled, chemically-rich oceans were formed from water condensation

Life arose spontaneously from these early waters (@ about 49-88 Celsius)

Or life may have infected Earth from some other planet (via meteors or cosmic dust)

-This hypothesis is termed Panspermia

6

Fundamental Properties of Life

Cellular organization

Sensitivity

Growth

Development

Reproduction

Regulation

Homeostasis

Heredity

Paramecia (protists) “eating” yeast

7

Environmental Conditions on Early

EarthEarth’s Early atmosphere had

CO2, N2, H2O and H2

Carbon-Rich Reducing atmosphere...energetically easier

to form carbon-rich molecules

8

First Organisms

May have been born in Earth’s crust, in clay, or at deep-sea vents

3.5BYA We have Oldest fossils of prokaryotes.

2.5-2BYA Cyanobacteria...Appearance of oxygen in atmosphere

1.5BYA Oldest definite fossils of eukaryotes

9

Miller-Urey Experiment (1953)

Reproduced Earth’s early atmosphere

Prebiotic

Chemistry

10

Evolution of Cells*Self replicating RNA may have been first genetic

material

*Amino acids polymerized into proteins

*Metabolic pathways emerged

*Lipid bubbles became living cells with cell membranes-CONCENTRATED MOLECULES

*Several innovations contributed to diversity of life

-Eukaryotic cells

-Sexual reproduction

-Multicellularity

11

Classification of OrganismsMore than 2000 years ago, Aristotle divided living

things into animals and plants

Greeks and Romans later grouped plants and animals to basic units called genera

Felis (cats) and Equus (horses)

In the 1750s, Carolus Linnaeus instituted the use of two-part names, or binomials

-Homo sapiens (Genus and Species name)

12

Classification of Organisms

Taxonomy is the science of classifying living things

*A classification or organization is called a taxon

*Scientific names avoid confusion

caused by common names

13

The Linnaean Hierarchy

Taxa are based on shared characteristics

-Domain (most inclusive)

-Kingdom

-Phylum

-Class

-Order

-Family

-Genus

-Species (least inclusive)

14

Eukaryotic Cells

Heterotrophs w/ no cell wall

Mammary Glands

Gnawing teeth

4 front toes 5 back toes

Morphological Differences

Arboreal

Vertebrates

Hierarchical System

Notocord

Chapter 23Linnaean Hierarchy may represent Convergent Evolution

and NOT COMMON ANCESTRY...(this is relative to ahypothesized recent ancestor)

Everybody in the shown animal group has an ancestral trait from this animal here

Some in the shown animal group have a

derived trait from this animal here

We would have a polyphyletic group if we said all the animals in this group Descended from here

18

Limitations of the HierarchyHierarchies are being re-examined based on

molecular analysis

Do not accurately correspond to evolutionary relationships amongst animals

Hiearchies may suggest 2 animals came from the same predecessor (monophyletic) but in fact don’t (polyphyletic).

Linnaean ranks (listed in the hierarchy) do not give strict inheritance information of the members in a rank

19

Grouping Organisms

Biologists are increasingly adopting a three-domain phylogeny based on rRNA studies

-Domain Archaea

-Domain Bacteria

-Domain Eukarya

Each of these domains forms a clade

Archaea and Eukarya are more closely related to each other than to bacteria

21

Grouping Organisms

Carl Woese proposed a six-kingdom system

Prokaryotes Eukaryotes

22

Grouping Organisms via Molecular Analysis

• Since all life has genetic material in common we can group each life form according to differences and similarities in genetic material.

• The sequenced genetic material is usually rRNA.

• Two organisms that inherit similar rRNA sequence are closer related than two organisms with a dissimilar sequence--NO MATTER HOW THEY LOOK LIKE.

23

Phylogeny prepared from rRNA analyses. During evolution, microbes swapped genetic

information via horizontal gene transfer (HGT)

24

Bacteria*Most abundant organisms on Earth...more in

your mouth than mammals on Earth*Extract nitrogen from the air, and recycle

carbon and sulfur *Perform much of the world’s photosynthesis*Responsible for many diseases*Make up our natural intestinal flora*Most taxonomists recognize 12-15 different

groups

25

ArchaeaProkaryotes that are more closely related to

eukaryotesCharacteristics

-Cell walls lack peptidoglycan-Membrane lipids are branched-Distinct rRNA sequences

Divided into three main groups

26

Methanogens

-Use H2 to reduce CO2 to CH4

-Strict anaerobes that live in swamps

Extremophiles

-Thermophiles – High temperatures

-Halophiles – High salt

-Acidophiles – Low pH

Nonextreme archaea

-Grow in same environments as bacteria

-Nanoarchaeum equitans – Smallest cellular genome

27

28

EukaryaProkaryotes ruled the earth for at least one

billion years

Eukaryotes appeared about 2.5 BYA

Their structure and function allowed multicellular life to evolve

Eukaryotes have a complex cell organization

-Extensive endomembrane system divides the cell into functional compartments

29

Mitochondria and chloroplasts most likely gained entry by endosymbiosis

-Mitochondria were derived from purple nonsulfur bacteria

-Chloroplasts from cyanobacteria

30

The Four Eukaryotic Kingdoms

Protista

-Unicellular with few multicellular organisms

-Not monophyletic

Fungi

Plantae

Animalia

-Largely multicellular organisms

-Each is a distinct evolutionary line derived from a unicellular protist

31

Symbiotic Events

32

Key Eukaryotic Characteristics

Compartmentalization

-Allows for increased subcellular specialization

Multicellularity

-Allows for differentiation of cells into tissues

Sexual reproduction

-Allows for greater genetic diversity

33

34

35

Making Sense of the Protists

Protists are a paraphyletic group

-Catchall for eukaryotes that are not plant, fungus or animal

Divided into six groups

-However, at least 60 protists do not fit into any of these groups

36A new kingdom, Viridiplantae, has been suggested

-Plants + green algae(Chlorophyta)

Notice that Protists (olive green color) are not monophyletic

37

Origin of Plants

38Land plants arose from an ancestral green alga,

and only once during evolution

Streptophyta has 7 clades, including land plants

Sister clades

Green alga consist of 2 monophyletic groupsChlorophyta and Streptophyta

39

Some land plants show evidence of horizontal gene transfer

The flowering plant Amborella acquired three moss genes

Close contact increases the probability of HGT

40

Modeling evolutionary relationships provides...

An orderly and logical way to name organisms

Insights in understanding the history of major features and functions--Gather clues about the genes involved in speciation and trait formation

41

Segmentation is regulated by the Hox gene family

Segmentation has been used in the past to group

arthropods and annelids close together

rRNA sequences now suggest they’re distantly related