Module 4: Biodiversity

Ch 26 1-3 Prokaryotes | Ch 27 1-3 Evolution of Eukaryotes; Protists | Ch 28 1-3 Land Plants | Ch 29 1-3 Fungi | Ch 30 1-3 Animals | Ch 31 1 and Ch 32 1, 3-6 |

Are viruses alive?

No, cannot reproduce independently (require a host cell)

What are the 3-domain phylogeny of life?

Bacteria, Archaea, Eukaryotes

What is the structure of a virus?

DNA & RNA, Protein coat (capsid), sometimes lipid envelope

What is the evolutionary timeline of prokaryotes?

~3.7 Bya

What is the evolutionary timeline of eukaryotes?

~1.8 Bya

What is the difference between prokaryote and eukaryote cell structures?

Eukaryotes have a nucleus, internal membrane, mitochondria, (sometimes chloroplasts), bigger and multicellular

What are the three ways scientists determine prokaryotes?

1. gene transfer

2. morphology

3. metabolism

What is the process of Transformation?

bacteria or archaea that take in DNA from the environment that was released by cell lysis

What is the process of Transduction?

when viruses pick up DNA from one prokaryote and transfer it to another

What is the process of Conjugation?

when genetic info is transferred cell to cell directly

What are the 4 steps for a prokaryotic cell to be a eukaryotic cell?

1. develop a nucleus

2. develop inner membrane system (Er and GA)

3. acquire mitochondria

4. acquire chloroplasts (only in some lineages)

What happens to the cell from prokaryotic to eukaryotic?

• grows bigger

• loses cell wall

• becomes multicellular

How does the nuclear envelope and endoplasmic reticulum improve the eukaryotic cells?

It improves gene expression

How does mitochondria improve the eukaryotic cells?

More efficient respiration (energy usage)

How do chloroplasts improve the eukaryotic cells?

Autotrophism (produces own food)

How does multicellularity (in some) improve the eukaryotic cells?

Greater specialization (more specific roles)

How does the haploid/diploid life cycle (meiosis) improve the eukaryotic cells?

Improves genetic variation and response to changing environments (adaptability)

What was the origin of the nuclear envelope? (draw out)

1. infoldings of plasma membrane surrounded chromosome

2. Eukaryotic cell arises with infoldings → production of nuclear envelope and ER

What is the origin of mitochondria?

The endosymbiosis theory

What is the endosymbiosis theory?

1. Host cell surrounds & engulfs bacterium

2. Bacterium lives in host cell

3. Endosymbiosis

What is endosymbiosis?

When an organism lives inside the body or cells of another ~ mutualistic relationship

What are pieces of evidence for the endosymbiotic theory of mitochondrian?

1. mitochondria similar size as bacterium

2. double membranes ~ consistent with engulfing mech.

3. replicates fission ~ like bacteria

4. have own ribosomes to manufacture proteins

5. have genomes w/ genes to encode enzymes that replicate and transcribe

6. genes are phylogenetically closer to eubacterial genes than eukaryotic genes

What is the origin of chloroplast?

1. photosynthetic protist is engulfed

2. nucleus from photosynthetic protist is lost

3. organelle has four membranes

What evidence is there for the endosymbiotic theory for origin of chloroplast?

1. mutualistic relationship

2. same as mitochondria (same bacterial structure & chromosomes, DNA sequence similarities, photosynthetic machinery - chlorophylls -)

(more complicated due to multiple independent origins)

Are protists a monophyletic group or a paraphyletic group?

paraphyletic (represent some but not all descendants of common ancestor)

Approximately how many species of protists are there? Diversity?

~100,000, relatively low diversity but high abundance

What was the time of origin for protists?

About 2 billion years

What are major lineages of protists?

Crown groups (plants, animals, fungi)

What was the evolution of haploid-diploid life cycle for protists?

Prokaryotes originally reproduced asexually (haploid)
Eukaryotes began reproducing sexually (meiosis)

• fusion of gametes → diploid

• meiosis → haploid

Draw the life cycle dominated by haploid cells

Draw the life cycle dominated by diploid cells

How are protists ecologically important?

• primary producers

• nutrient cycling & decomposers

• responsible for crop killing infections (medical research)

How are photosynthetic protists ecologically important?

• primary producers

• take in CO₂ and replenish with high # ATP (chemical energy) that plants use to grow and reproduce

What are land plants’ species diversity?

~300,000 species (up to 1 mil.)

What are land plants’ time of origin?

500 million years from algal ancestors

What are the major lineages of land plants?

• Bryophytes: mosses, liverworts (non vascular, spore reproducing)

• Fern & relatives: vascular, spore reproducing

• Gymnosperms: “naked seed” (coniferous seed reproducing)

• Angiosperms: “vesseled seed” (flowering plants w/ fruits reproducing)

Why are land plants ecologically important?

• enhance life-supporting attributes (atmosphere, soil, surface water, etc)

• produces oxygen

• fallen leaves & decaying roots → food for works, fungi, bacteria, archaea, etc.

• hold water and moderate climate

• primary producers, provide chemical energy used other organisms

• food, fuel, fiber, building materials, medicines