Cellular Reproduction

Cellular ReproductionA Brief History of Genetics Before Mendel

Major Discoveries Circa World War IHistory of Discovery of Cells

Evolution and Diversity of CellsArchitecture of Cells

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History of Genetics Before Mendel

Hippocrates (400 BC): traits are inherited from parents; reproductive products are obtained from all body parts and given to the offspring◦ Example: Macrocephali: species of humans w/ elongated head; Hippocrates believed

they styled their offspring’s head soon after birth Aristotle (350 BC): differed from Hippocrates due to the inheritance

of nails, hair, voice; did not believe it came from reproductive tissue because they were dead cells; based on the fact offspring sometimes resemble grandparents, he believed “reproductive material” was obtained from “nutrient substances” (semen from the father, originates from blood) designed specifically for a part; believed females had something that defined the “form of the embryo” ◦ Both Hippocrates & Aristotle believed trait inheritance was through reproductive

material Al-Jahiz (800s CE): proposed a theory of animal evolution through

natural selection (environmental effects) Abu Alkasem Al Zehrawi (Albucasis) (936 CE): described the genetic disorders in blood, now known as hemophilia • Otto Brunfels (1488-1534): adopted ancient classification of plants,

interested in medical advantages of botany, keep records of his plants, considered “link between ancient and modern botany”

History of Genetics Before Mendel

Hieronymus Brock (1498-1554): studied German plants, recorded them based on relation, resemblance, & medical use

Leonhart Fuchs (1501-1566): wrote book accurately classifying around 500 plants and their medical uses

Andrea Cesalpino (1524-1603): classified plants based on principles (fruits/seeds) not alphabetically or medical usage; established botany; believed plants were not sexual & divided plants by woody/herbaceous

Gaspard Bauhin (1560-1624): botanical classification, 6000 species of plants, classified between genus and species, “introduced binomial nomenclature system”◦ Species of plant receives a name of two terms: 1st is the genus, 2nd is the species

John Ray (1627-1705): classified 18000+ plants in a natural system (reflection of Divine Order); morphology (flowers, seeds…); monocots & dicots (classification of flowers), used term “species”

Joseph Pitton de Tournefort (1656-1708): classification of genera (structure of flower & fruit); didn’t believe in sexual reproduction of plants; used 2 word Latin name for plants; defined genus for future times (own classifications were often wrong)

Carl Linnaeus (1707-1778): defined the princples for natural genera & species of organisms, established a uniform system (binomial nomenclature); presented hierarchical classification (taxonomy)

Augustin Sagaret (1763-1851): crossed plants of a particular trait, usually got that same trait (appearance)

300s BC: Hippocrates-heredity material, throughout body

200s BC: Aristotle- material gained from semen (purified form of blood which mixed w/ the mother's menstrual blood)

800s CE: Al-Jahiz-inheritance of acquired characteristics, environmental factors influence organisms to develop new characteristics to ensure survival, thus transforming into new species."

1700s: increased taxonomy & diversity of plant/animal species, new ideas about heredity

1800s: crossing certain parent plants, particular characteristic, usually led to the appearance of the characteristic in the offspring

1859: Charles Darwin-The Origin of Species, evolution by natural selection; needed genetic inheritance

1866: Gregor Mendel-Experiments in Plant Hybridization, basic theory of genetics

1871: Friedrich Miescher- isolates “nucleic acid” whilst trying to wash the puss off dirty bandages at a local hospital

1879: Walther Flemming- discovers chromosomes using aniline dyes

History of Genetics Before Mendel

Major Discoveries Circa WWI

1900: August Weismann-proposed inheritance takes place through germ cells

1902: Theodor Boveri (sea urchins) and Walter Sutton (grasshoppers) hereditary material is carried in chromosomes: firstly, all the chromosomes had to be present for proper embryonic development to take place; chromosomes occur in matched pairs of maternal and paternal chromosomes which separate during meiosis

1902: Archibald Garrod-recessive inheritance in humans

1910: Thomas Hunt Morgan- chromosome theory of heredity using the fruit fly; genes are linked in a series on chromosomes, responsible for hereditary traits

1919: Phoebus Levene-identified units of DNA which he calls "nucleotides". (base, a pentose sugar, & a phosphate group); hypothesis DNA structure: chains short & bases repeated

1928: Frederick Griffith- discovers harmless strain of bacteria could be dangerous after being exposed to heat; some kind of substance ("transforming principle") from the heat-killed strain was taken up & incorporated in the harmless strain, making them virulent

1937: William Astbury-X-ray diffraction patterns revealing DNA has a regular structure

Major Discoveries Circa WWI

ZymotechnologyStudy of fermentation (breakdown of

carbohydrates)Initially focused on beer…WWI, focused on

industrial problems◦ Due to industrial support of war -> massive production

Later called, biotechnology (1919)- “convert raw materials into a useful product”◦ Possible solutions for food and resource shortages

http://www.lifesciencesfoundation.org/events-item-111.html http://www.spartacus.schoolnet.co.uk/FWWinventors.htm

Major Discoveries Circa WWI

Eugenics: Refer to the “science of heredity”Eugenic groups appeared after WWI due to fear of

immigration (foreigners)◦ Race Betterment Foundation◦ American Eugenic Society (1923)

Promoted fine breedingDiscouraged maintaining people w/ undesirable traits with

others ◦ Banned reproducing (if allowed)

Attained some goals- Immigration Act (1924) passed by Congress, limited immigration through quotas, signed by President Coolidge

Behaviorism (1913) & Thomas Hunt Morgan’s genetic work helped reduced focus on eugenics◦ WWII-German actions on Jew completely disbanded the

movement

Major Discoveries Circa WWI

Rise in industrialism & mass production◦ Warfare technology

Wireless telegraphy, radio, telephone (often broken); used runners, mirrors, flashing lights, dogs, aircraft , microphones

Naval Warfare◦ Germany & Britain

Britain built HMS Dreadnaught, revolutionized ship building◦ Submarine: caused the US to enter the war (Germany attacked 1917)

Armaments, Supplies◦ Hand grenades & explosives: trench warfare◦ Barbed Wire: invented in 1874 to control cattle, was used to fence trenches,

troops would get tangled which permitted machine gun usage ◦ Machine guns (replaced Gatling guns), allowed quick, rapid shooting l flame

throwers (used by Germany)◦ Airplanes: invented 11 yrs prior to the war; two alliances would deny the

other air advantage – coined Flying Circus Red Baron: Manfred von Richthofen: pilot, shot down 80 planes Germany: Zeppelins (bombing raids) Observation Balloons: crew of 2, observed trenches

◦ Tanks: Allies (1915-16, 1917-used), not as decisive, helped win the Allied summer offensive of 1918

◦ Poison gas: used by Germany to stop “stalemate of trench warfare,” effects were fatal, wasn’t as utilized after 1916

◦ Railroads aided in the transport of artillery & troops

Vocabulary

Cell: structural, functional, and biological unit of all organisms

Organisms: all living thingsUnicellular: has one cellCytology: study of cellsOrganelles: small structure inside a cellProkaryotic Cells: simplest type of cell, unicellular,

most have a cell wall, asexual (reproduce through binary fission)

Eukaryotic Cells: complex type of cell, more organelles than prokaryotes, most are multicellular, undergo a process called differentiation

Important Figures

Democritus (460 BC)• All things are composed of “minute, invisible particles of

pure matter”Hans & Zacharias Jansen (1590)• Created the early version of the compound microscope

Robert Hooke (1665)• Described the composition of cork through a compound

microscope: “tiny, hollow, room-like structures,” called them cells (were in actuality cell walls)

Anton van Leeuwenhoek (1670)• Improved lenses (allowed magnification), observed blood, rain,

teeth scraping, called some cells “animalcules” (bacteria)Matthias Schleiden (1838)• Observed plant parts, discovered they were made of cells

Theodor Schwann (1839)• Observed animal parts, made of cells

Rudolph Virchow (1855)• All living cells come from other living cells

CELL THEO

RY

Important Figures

Caspar Wolff (1759)• All organs in animal embryos are made of “globules”

Felice Fontana (1781)• Described nucleolus, found in eel’s skin’s slime

Jean Baptiste de Lamarck (1809)• Declared that cellular tissue is the “general matrix of all organization”

Henri Dutrochet (1824)• All organic tissue is globular cells

Pierre Turpin (1826)• Observations on cell division

Franz Meyen (1830)• Cells form independent whole, which then builds itself up

Robert Brown (1831)• Discoveries of occurrence of nuclei

Hugo von Mohl (1839)• Described mitosis in plants

Anton Schneider (1873)• Observations of chromosomes during cell division

Gregor Mendel• Plant hybrids, genetics

Cell Theory

Discoveries of Hooke, Schleiden, and Virchow helped the formation of the theory

Improvement in microscopy permitted these discoveries

Consists of three parts1. Anything living is made up of cells2. Chemical reactions inside an organism occur in cells3. All cells come from preexisting cells

http://youtu.be/4OpBylwH9DUhttp://youtu.be/h85_U9OJFQ0

Modern Cell Theory

1. All known living things are made up of cells.2. The cell is structural & functional unit of all

living things.3. All cells come from pre-existing cells by

division. (Spontaneous Generation does not occur)

4. Cells contains hereditary information which is passed from cell to cell during cell division.

5. All cells are basically the same in chemical composition.

6. All energy flow (metabolism & biochemistry) of life occurs within cells.

Cell Evolution: Cell Wall

Diversity in molecular compositions Secondary cells walls, reinforced with lignin-provides

durability Some have pollen tubes that enable their tip growth Lupin seed cell walls are thicker due to galactan, a

storage polysaccharide Dependent on developmental stage, cell type, and

season. Plants & algae: phylogenetic history, endosymbiotic

events; “organisms that have the shared features of photosynthesis and possession of a cell wall do not form a monophyletic group”◦ Phylogenetic: study of evolutionary development of

organism, higher taxonomic groups Taxonomy: Classification of organisms based on shared feature

◦ Monophyletic: Descended from a single taxon

Cell Evolution: Endosymbiotic Theory

Endosymbiotic Theory: accepted assumption explaining how eukaryotes evolved from prokaryotes

Introduced by Lynn Margulis in the late 1960sStated that the main organelles of eukaryotes were

initially prokaryotes ◦ Endosymbiosis: organism lives inside another, mutually

beneficialOrganelles proposed to have been their own cell

include the mitochondria and chloroplast◦ Both organelles have their own DNA & ribosomes that do

“not match” the rest of the cell◦ Because of this, they can survive & reproduce

independently◦ Chloroplast DNA is alike to cyanobacteria ◦ Mitochondria DNA is alike to typhus bacteria

Prokaryotes vs. Eukaryotes

Prokaryotes Eukaryotes

Bacteria

Animal Plant

Prokaryotes vs. Eukaryotes

Cell Structures in Prokaryotes

Prokaryote: single celled organism w/ no nucleus, lack internal membranes◦ Plasma Membrane: around cytoplasm, regulates flow of substances in & out

of cell◦ Cytoplasm: Gel-like substance that is made of mostly water & enzymes, salts,

cell components, & organic molecules◦ Nucleoid Region: area of cytoplasm that contains the single bacterial DNA

molecule◦ Ribosomes: responsible for protein production◦ Plasmids: Gene carrying, circular DNA structures (not involved in reproduction)◦ Cell Wall: outer covering, protects, & gives cells their shape◦ Suface Appendages:◦ Pili: hair-like structures that attach to other bacterial cells

Fimbriae: shorter pili, help bacteria attach to surface◦ Flagella: long, whip-like protrusion that aids in cellular locomotion

Cellular Locomotion: http://www.youtube.com/watch?v=Jt1oMaxrp3U◦ Capsule: outer covering protecting the cells when it is swallowed by other

organisms, retains moisture, and helps cell hold on to surfaces & nutrients ◦ http://www.vetmed.vt.edu/education/curriculum/vm8054/Labs/Lab3/Lab3.htm

Cell Structures in Eukaryotes

Plasma Membrane: thin, semi-permeable membrane that surrounds cytoplasm of a cell, enclosing its contents◦ http://www.youtube.com/watch?feature=player_embedded&v=Mv247P8ufCA

Cytoplasm: gel-like substance within the cell containing water, enzymes, salts, organelles

Cell Wall: outer covering of the cell that protects the plant cell and gives it shape Nucleus: membrane bound structure that contains the cell’s hereditary

information◦ Nucleolus: structure w/in the nucleus, helps in synthesis of ribosomes, RNA◦ Nucleopore: tiny hole within nuclear membrane that allows nucleic acids and protein to

move into & out of the nucleus Extracellular Matrix: support, adhesion, movement, and cell regulation Chromatin: chromosomes DNA and protein Nuclear Envelope: ER, golgi apparaturs, vacuoles, plasma membrane Ribosome: consist of RNA & protein, responsible for protein assembly Rough Endoplasmic Reticulum: synthesis & packing of proteins Smooth Endoplasmic Reticulum: storage of steroids and ions Golgi Apparatus: responsible for manufacturing, storing, & shipping certain

cellular products Lysosomes: sacs of hydrolytic enzymes that digest cellular macromolecules such

as nucleic acids Vesicles: small, contains proteins, enclosed by phospholipids layers Centrioles: organize the assembly of microtubules during cell division

Cell Structures in Eukaryotes

Mitochondria: power producers and the sites of cellular respiration Microtubules: hollow rods that function to help support & shape cells Chloroplasts: sites of photosynthesis in a plant cell, contain chlorophyll

(green pigment that absorbs energy from the sunlight) Central Vacuoles: structure in a plant cell that provides support and

participates in a variety of cellular functions including storage, detoxification, protection, and growth

Peroxisomes: tiny structures bound by a single membrane that contain oxidative enzymes that produce hydrogen peroxide as a byproduct, help in photorespiration

Centrosomes: contains microtubules, as centrioles, regulator of “cell-cycle” Cilia & Flagella: protrusions that aid in cellular locomotion Cytoskeletal Elements: network of fibers in the cytoplasm that helps the

cell maintain its shape◦ Microtubules: hollow rods, help support and shape cell, “routes” along which organelles can

move, responsible for chromosome movement in cell division, movement of organelles◦ Microfilaments/Actin Filaments: solid rods, help in muscle contraction, cell division,

maintenance of cell shape◦ Intermediate Filaments: provide support for microfilaments and microtubules by holding

them in position, anchor nucleus, forms nuclear lamina Endomembrane System: contains different membranes in the cytoplasm,

divide the cell into organelles

Subcellular Organelles Involved in Cell Reproduction

Nucleus: control center & location for genetic information replication (contains DNA), DNA binds to proteins (histones) & form nucleosomes; RNA is obtained from DNA & interpreted

Centrosomes: microtubules are produced, contains centrioles; cell division-centrosome divides & centrioles replicate resulting in 2 centrosomes w/ centrioles, they move to opposite side of nucleus where microtubules become a spindle ◦ Spindle: separates replicated chromosomes into the

daughter cells Microtubules: form spindle fibers, manipulate &

separate chromosomes during mitosis Cell Membrane: closes and splits the cell into two

daughter cells (telophase during mitosis) Cell Wall: splits in half when the daughter cells divide