AP Biology 2008-2009

Cells

Life’s Lego Blocks

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What’s Biology?

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How do you know

…if something’s alive?

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The Functions of Life Nutrition

Obtain molecules needed for ATP production Glucose, O2, CO2

Excretion Rid of waste

Metabolism ATP production Synthesis of

proteins, carbohydrates, fats, nucleic acids

Response React to stimuli

Homeostasis Maintaining a constant internal environment

Growth Reproduction

Asexual or sexual

ATP

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bacteriacells

bacteriacellsTypes of cells

animal cellsanimal cells plant cellsplant cells

Prokaryote- no organelles

Eukaryotes- organelles

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The Cell Theory 1665 Robert Hooke and his microscope

“I have found that the pith of the Elder or almost any other tree, the inner pith of Cany hollow stems of other vegetables: as Fennel, Carrets Daucus, Bur-docks, Teasles, Fearn, and some kind of Reeds, have much the same structure.”

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Many shapes

Shape Function

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Many sizes

Bacterial cell

Animal cell

micron = micrometer = 1/1,000,000 meter diameter of human hair = ~20 microns

most bacteria 1-10 microns

eukaryotic cells 10-100 microns

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The Cell Theory A cell is the smallest unit of life

Cells come from existing cells

All living organisms are composed of cells

Multicellular Unicellular

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Testing the Cell theory Striated muscle cells

30mm long (average human cell 0.03mm)

Fungi Hyphae and septa

Algae Acetabularia

One nucleus 100mm long

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Multicellular organisms

• Animals• Plants• Some algae• Some fungi

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Unicellular organisms• Bacteria (prokaryotes)• Archaea (prokaryotes)• Protozoa (eukaryotes)• Some algae (eukaryotes)• Some fungi (eukaryotes)• Perform all functions of life!

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Unicellular organisms perform ALL THE FUNCTIONS OF LIFE!

Nutrition Obtain molecules needed for ATP production Glucose, O2, CO2

Excretion Rid of waste

Metabolism ATP production Synthesis of

proteins, carbohydrates, fats, nucleic acids

Response React to stimuli

Homeostasis Maintaining a constant internal environment

Growth Reproduction

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Unicellular organisms Paramecium (heterotroph)

Eats other small protozoa

Chlorella (autotroph) photosynthesis

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Unicellular organisms Paramecium Chlorella

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Unicellular organisms Sometimes live in colonies

Volvox aureus Algae 500+ identical cells inside protein coat

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Multicellular organisms

Cells interact as a cooperative group

Emergent Properties

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Complex Multicellular organisms Cells → Tissues → Organs → Bodies

bodies are made up of cells cells do all the work of life!

Am I Pen or a collection of

cells?

Emergent propertie

s

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Specialization 220 cell types in the human body

Contain all ~25,000 genes Only express the few it needs Differentiation = turning some genes on

some off Alxel and Buck (2004): Differentiation in

olfactory receptors

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Differentiation of Germ Layers

• Triploblast• Diploblast

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Germ Layers

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Stem Cells Pluripotent

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Stem Cells Early stages of embryonic development

Potential to produce copious quantities

Potentially use in Therapeutic (regenerative medicine) Non-therapeutic (meat) Research

Small number remain in adult Bone marrow, skin, liver

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Sources of stem cellsEmbryonic Umbilical cord Adult

Unlimited growth potential

Easily obtained and stored

Difficult to obtain

Unlimited differentiation Fully compatible with other tissues of the body

Less growth potential than embryonic stem cells

Likely genetically different from adult patient

Limited capacity to differentiate

Limited capacity to differentiate

Removal kills embryo Limited number of cells available

Fully compatible with adult tissues

Less chance of accumulation of mutations

No effect on child due to extraction

No effect on adult due to extraction

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Stem Cells 1. Stargardt’s Muscular Distrophy

ABCA4 gene mutation Malfunction in transport membrane in

retina Loss of vision

Therapeutic use of stem cells? How could they help? What are risks?

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Stem Cells Leukemia

Cancer of white blood cells Large production of WBC in marrow

Normal WBCC: 4,000~11,000 per mm3

Leukemia WBCC: >30,000 per mm3

Treatment Destroy cancer-producing cells

Chemotherapy, radiation

Store and reintroduce stem cells into bone marrow

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Ethical Implications

Benefits

Potential for curing diseases Stargart’s Disease Leukemia

Considerations

(esp. Embryonic Stem cells) When does life begin? IVF

Many embryos are not used

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What do you think?Case Study

Jim and the Forgotten Embryos