Cells units of life
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CELLS: UNITS OF LIFE. Chapter 4 Hyperlink is the 3 rd one that says component of cells – same as above, but narrated!. The Discovery of Cells. All organisms consist of cells. The Discovery of Cells. Cells – the place where biochemical activity occurs. The Discovery of Cells.

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Cells units of life

CELLS: UNITS OF LIFE

Chapter 4

Hyperlink is the 3rd one that says component of cells – same as above, but narrated!


The discovery of cells

The Discovery of Cells

  • All organisms consist of cells


The discovery of cells1

The Discovery of Cells

  • Cells – the place where biochemical activity occurs


The discovery of cells2

The Discovery of Cells

  • Cells – have ALL characteristics of life

    • All made of cells – and have levels of organization

    • All grow, develop, and reproduce

    • All use energy

    • All adapt

    • All respond to stimuli

    • Maintain internal constancy


The discovery of cells3

The Discovery of Cells

  • Cells – cell membrane – separates living matter from the environment and limits size of organism


The discovery of cells4

The Discovery of Cells

  • Organelles – structures where life processes occur to keep cell alive


The discovery of cells5

The Discovery of Cells

  • Cellular Cytoplasm- remainder of interior of cell besides organelles


The discovery of cells6

The Discovery of Cells

  • Cells can specialize (examples : muscle cells, leaf cells, root cells)


The discovery of cells7

The Discovery of Cells

  • Stem cells – from which all cells differentiate in many celled organism


Lenses reveal the world of the cell

Lenses Reveal the World of the Cell

  • 13th Century – world recognized glass magnifies


Lenses reveal the world of the cell1

Lenses Reveal the World of the Cell

  • 16th Century – began using paired lenses (Jansen and church spire)


Lenses reveal the world of the cell2

Lenses Reveal the World of the Cell

  • Robert Hooke (1660)

    • 1st person to see the outlines of cells

    • Spun glass and looked at bee stingers, fish scales, fly legs, insects and CORK

  • Antonie van Leeuwenhoek (1673)

    • developed over 500 high magnification lenses

    • 1st record of microorganisms- he called “animalcules” found in tooth tartar


The cell theory emerges not till 19 th century

The Cell Theory Emerges – not till 19th Century

  • Robert Brown – discovered cellular nucleus

    • Houses DNA

  • Schleiden

    • Cells were basic unit of plants

  • Schwann

    • Cells were basic unit of animals

  • Together

    • Cells were elementary particles of all organisms, the unit of structure and function


Cells units of life

The Cell Theory Emerges – not till 19th Century

  • Virchow

    • All cells come from pre-existing cells

    • Believed abnormal cells cause diseases


Cells units of life

Cell Theory

1. All living things are composed of cells. [Schleiden & Schwann]

2. All cells come from preexisting cells. [Virchow]

Cell Theory still evolving: Organelles have precise locations in cells


Cells units of life

Variations on the Cellular Theme

C. Types of Cells

3 basic types:

  • Bacterial

  • Archaean

Prokaryotic

  • Eukaryotic


Cells units of life

Variations on the Cellular Theme

Review surface area to volume relationship – Large volume justifies the need to have organelles


Cells units of life

Variations on the Cellular Theme

Folding membranes also increase surface area for reactions


Cells units of life

1. Bacterial cells

  • 1-10 m in diameter

  • NO membrane-bound organelles

  • Some photosynthetic – use pigment only

  • Some cause illness some don’t

  • Vital to life on earth

  • 1 circular DNA molecule located in nucleoid region

    • MAKE PROTEINS RAPIDLY DUE TO CLOSE LOCATION OF ORGANELLS

  • plasma membrane, cytoplasm & ribosomes

  • most have a cell wall (peptidoglycan)

    • Many antibiotics interfere with cell wall construction

  • may have a polysaccharide capsule to protect or attach

    • Film on teethn morning

      Ex. bacteria & cyanobacteria


Bacterial shapes

Bacterial Shapes

  • Cocci

  • Bacilli

  • Spirilla

  • Fibrios

  • fusiform


Cells units of life

Gram-staining

Distinguishes 2 types of bacteria

  • Gram – negative – thin cell wall

  • Gram positive – thick cell wall

Structure of a Gram-Negative Cell Wall

Gram positive cell wall


Cells units of life

Archaean cells represent a distant ancestor???

  • 1-10 m in diameter

  • Use carbon dioxide and hydrogen to make methane (methanogens)

  • Have co-enzymes that make methane

  • NO membrane-bound organelles

  • cell walls lack peptidoglycan

  • have characteristics of both bacteria & eukaryotic cells

  • Half of genes are same as bacteria, other half totally different

  • mRNA and tRNA are different than in other domains

Methanogen


Archaean extremophiles con t

Archaean Extremophiles, con’t

Ex. Extremophiles: extreme environments: temp, pressure, pH, salinity

methanogens, extreme halophiles & extreme thermophiles

  • Live in Swamps, rice paddies and oceans

Extreme halophile


Cells units of life

3. Eukaryotic cells

  • 10-100 m in diameter

  • Includes plants, animals, fungi and protists

  • nucleus & other membrane-bound organelles

  • Nucleus

    • Protects and organizes the cell’s linear DNA

    • DNA combined with protein forming chromosomes

  • plasma membrane, cytoplasm & ribosomes

  • some have a cell wall (cellulose or chitin)

  • Animal cells: half the volume of a cell is organelles

  • Plant cells: 90% may be water (found in vacuole)

  • Cytoskeleton – rods and tubules within cells to give cell shape or appendages to move


Introduction to organelles

Introduction to Organelles

  • Organelles –

    • improve efficiency,

    • protect contents,

    • secrete substances,

    • derive energy

    • Degrade debris

    • reproduce


Introduction to organelles1

Introduction to Organelles

  • Organelles Synthesize and Process Proteins

    • Enzymes – key to determining function of cell

    • Endomembrane system

      • Rough endoplasmic reticulum

        • Compartments use enzymes that assist with protein production and transportation

      • Smooth endoplasmic reticulum

        • Lipids synthesized, modified and toxins neurtalized


Cells units of life

Generalized Generalized

Animal Cell Plant Cell


Introduction to organelles s cont

Introduction to Organelles’s cont

  • Golgi apparatus

    • Sorts proteins for exports out of cell or into lysosomes

    • links simple carbohydrates together to form starch

    • links simple carbohydrates to proteins (glycoprotein) or lipids (glycolipid)

    • completes folding of proteins

    • temporarily stores secretions (milk)


Cells units of life

Organelle interaction in a mammary gland cell.


Introduction to organelles s cont1

Introduction to Organelles’s cont

  • Lysosomes (suicide sacs)

    • Contain digestive enzymes – 40 types

    • Function to recycle damaged organelles, break down cellular by products & destroy invading microbes


The nucleus

The Nucleus

  • Exports RNA instructions

    • Genes: instructions on DNA are copied onto mRNA

    • mRNA exits nucleus through nuclear pores (found in nuclear envelope

      • Not just holes

      • Channels with 100 types of proteins (importins and exportins)


The cytoplasm

The Cytoplasm

  • Site of Protein synthesis and other reactions

    • mRNA binds to ribosomes

      • A complex of MANY proteins surrounding an rRNA

        • rRNA + proteins are assembled in the nucleolus then exit the nucleus through pores

        • Remainder of section completes milk production example


Lysosomes and peroxisomes cellular digestion centers and more

Lysosomes and Peroxisomes: Cellular Digestion Centers – and more

  • Lysosomes are cellular recycling centers

    • Lyse – cut apart

    • Enzymes within organelle – lyse targets

      • Dismantle bacteria

      • Dismantle worn out organelles and debris

      • Break down large nutrients into useable monomers

      • Fuse with vesicles carrying debris

      • Made in rough ER

      • Function in very acidic environment


Lysosome s con t

Lysosome’s con’t

  • Numbers very based on cell function

    • White blood cells have many

    • Liver have MANY – process cholesterol

  • Human cells have more than 40 enzyme types

  • Balance of enzyme related to health

    • Too many, causes storeage problems in cell – crowds other organelles

    • Tay Sachs – missing an enzyme in a lysosome


Tay sachs events

Tay Sachs events


Peroxisomes facilitate oxidative reactions

PeroxisomesFacilitate oxidative Reactions

  • Contain enzymes that oxidize other molecules

  • Enzymes made in the cytoplasm – then transported to vesicles

  • Environmental toxins: cause explosion of peroxisome production

    • Toxins are oxidized and removed

  • Synthesize bile acids


Peroxisomes con t

Leopard spot retinal pigmentation

Peroxisomes, con’t

  • Break down lipids

  • Degrade rare biochemicals

  • Metabolize free radicals

  • Some produce hydrogen peroxide

    • Produces free radicals

    • So contain catalase – removes oxygen from hydrogen peroxide to make water

  • Found in leaves

  • Adrenoleukodystrophy (Lorenzo’s disease) – two proteins missing in peroxisomes outer membrane pg 59


Mitochondria organelle of energy

Mitochondria – organelle of energy

  • Mitochondria Extract Energy from nutrients

    • Numbers vary from few to 1000’s

    • Cristae – inner folds contain enzymes

    • Site of cellular respiration (ATP)

      • Converts glucose into ATP energy

    • Has own genetic material (DNA)

      • Inherited only from female


Chloroplast organelle of energy

Chloroplast – organelle of energy

  • Chloroplasts provide plant cells with nutrients (THEREFORE ENERGY)

  • Chloroplast

    • carry out photosynthesis

    • Form glucose or other carbohydrates

    • Have stroma – space inside chloroplast for reactions

    • Thylakoids – membrane system of stacked sacks called grana where reactions take place

    • Has own DNA

    • See Table pg 60


Origin of complex cells

Origin of Complex Cells

  • Endosymbiont theory – large celled critters engulfed smaller simpler cells. Simple cells became organelles in the larger critter

    • Structure and DNA sequences provide evidence

      • Evidence in FAVOR of EST

        • Resemblance between mitochondria and chloroplasts to certain kinds of bacteria

          • Size

          • Shape

          • Membrane structure

          • Presence of pigments

          • Reproduction method

          • Relative relationship of DNA, RNA and ribosomes


Origins of complex cells con t

Origins of Complex Cells, con’t

  • Technology Evidence

  • DNA evidence – bacteria and archaea contributed

    • Theory: archaean cells enveloped bacterial cells that became mitochondria and chloroplasts

    • Theory: bacteria share genes with bacteria and vice versa

      • Ricettsia


Endosymbiant theory

Endosymbiant Theory


Origins of complex cells cont

Origins of Complex Cells, cont

  • How Endosymbiosis May have worked, pg 61


Cells units of life

2. Endoplasmic reticulum (ER)

interconnected network of membranes extending from nucleus to plasma membrane


Cells units of life

3. Golgi apparatus

  • stacks of membrane-enclosed sacs


Cells units of life

4. Lysosomes (suicide sacs)

  • vesicles containing > 40 types of digestive enzymes

  • function to recycle damaged organelles, break down cellular byproducts & destroy invading microbes


Cells units of life

5.Perixisomes

  • vesicles containing several types of enzymes (produced in cytoplasm)

  • found in all eukaryotic cells

  • function to help cell use oxygen & metabolize potentially toxic compounds

    • hydrogen peroxide is produced as a by-product of peroxisome activity

    • the enzyme catalase converts hydrogen peroxide to water


Cells units of life

6. Mitochondria

  • double-membrane

    • outer is smooth

    • inner is highly folded (cristae)

  • #/cell varies

  • contain DNA

  • inherited from female parent

  • site of cellular respiration (production of ATP)


Cells units of life

7. Chloroplasts

  • possess 3 membranes

    • outer/inner membranes surround stroma

    • 3rd membrane system folded into flattened sacs (thylakoids)

  • #/cell varies

  • contain DNA

  • found in plants & protists

  • function in photosynthesis


Cells units of life

E. The Endosymbiont Theory

Proposes that chloroplasts and mitochondria evolved from once free-living bacteria engulfed by larger archaea.

Based on fact that mitochondria & chloroplasts resemble certain bacteria (size, shape, membrane structure & method of making proteins).


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