Cellular Organization & Reproduction

Junhel C. Dalanon, DDM, MAT

Zacharias Janssen – studied the cells using an improvised microscope Robert Hooke

made most important observation on cells (thin slice of cork from oak tree)

“cells” – small rooms he saw on the empty chambersMicrographia (1665) – his findings are published in this book; established the knowledge of cell structure on a firm basis

Anton van Leeuwenhoek – devised a simple microscope (200x magnification)

Johannes Evangelista Purkinje cell is not empty but contains gelatinous fluidnamed the fluid “protoplasm”

Matthias Jakob Schleiden – plants are made up of cells Theodore Schwann – both plants and animals are made of cells Rudolf Ludwig Karl Virchow – all living things are made up of cells

Zaccharias Janssen

Robert Hooke

Anton van Leeuwenhoek

Johannes Evangelista Purkinje

Matthias Jakob Schleiden

Theodore Schwann

Rudolf Ludwig Karl Virchow

Tools for Biological Research

The Microscope

1. Hold it by the arm with one hand2.The other hand should be under the base3.Wipe it clean using a tissue paper or

muslin cloth4.Lens paper may be used for cleaning the

lenses

1. Place the microscope about an inch from the edge of the table.2. Position the lower power objective (LPO) above the center of the

stage.3. Adjust the iris diaphragm by getting the biggest opening.4. If there is a condenser just below the center of the stage, move it

until it is in its uppermost position.5. Adjust the mirror to get the right illumination.6. When starting to focus, see to it that the left eye is before the

ocular lens or eyepiece.7. Adjust the mirror until a bright illumination is seen.8. Place the slide with specimen beneath the LPO to HPO.

The Compound Microscope

MAIN PARTS1. Magnifying Parts – used to enlarge the view of specimens

Ocular Lens Objective Lens

2. Illuminating Parts –used to supply light to the slide on the stage Mirror Condenser Iris Diaphragm

3. Mechanical Parts – used to support and move parts of the microscope Fine Adjustment Knob Coarse Adjustment Knob Others

Specific Parts1. Ocular Lens (Eyepiece) – magnifies the image formed by the

objectives; 5x or 10x magnification2. Objective Lens – most important optical part

Low Power Objective (LPO) o Shortero 10xo Locates and shows structure of specimen

High Power Objective (HPO)o Long & slendero 45x or 60xo Shows detailed structure

Oil Immersion Objectiveo Long or shorto 99x or 100xo Increase the resolution of the microscope

3. Mirror – collects & reflects light to microscope4. Condenser – condenses to direct maximum light to an object5. Iris Diaphragm – controls the entrance of light

6. Stage – holds the slide with the specimen7. Adjustment Knobs – brings object into focus

Coarse Adjustment Knob – focus at 10x (LPO) Fine Adjustment Knob – focus at 40x or 60x (HPO)

8. Draw Tube – houses the ocular lens and connected to the body tube

9. Body Tube – holds the draw tube; connects eyepiece to draw tube

10.Revolving Nosepiece – part where objectives are attached11. Dust Shield – protects objectives from dust12. Base – anchors microscope firmly on table13. Pillar – supports upper parts of microscope14. Inclination Joint – allows upper part of microscope to be bent15. Lever – regulated iris diaphragm

Kinds of Cell

Prokaryote & Eukaryote

bacteria, archaea, or archaeabacteria 1-10 μm (micrometer or microns) have fewer structures no true nucleus no membrane bound organelles no mitochondria no golgi apparatus no endoplasmic reticulum Cell wall contains muramic acid Cell wall of bacteria contains peptidoglycan nucleoid - DNA is single circular double helix located in the region of

cytosol 3 main parts:

1. Appendages / Locomotory Structures (flagella & pili)2. Cell Enevelope (cell wall & membrane)3. Cytoplasm

Prokaryote

Present in higher forms of organismsProtists, plants, fungi, animalsLarger in sizeHave membrane-bound nucleus and organellesMay be single celled, colonial, or multicellularMore chromosomesCell walls have cellulose

Eukaryote

Differences

Unicellular vs. Multicellular Organisms

1. Single celled2. Can function & perform independently3. Can be eukaryote or prokaryote4. Each cells present performs a specific function5. Cells work together for entire organism

1. Consists of numerous cells2. Cells have many membrane system

Cell

Parts & Function

Basic Cell

Cell Wall / Cell Membrane

Cytoplasm

NucleusProtoplasm

Inclusions

1. Cell Wall & Cell Membrane2. Protoplasm

Nucleus Cytoplasm

3. Inclusions

Animal Cell

Plant Cell

Bacteria Cell

1. Cell Wall present in plant cells but not in animal cells Rigid wall Serves as framework Provides protection to cell Made up of non-living substance

2. Mitochondria (Chondriosomes) Rod-shaped or spherical For cellular respiration For ATP (adenosine triposphate) production

3. Endoplasmic Reticulum Series of tubules For transport of substances Site for lipid and protein synthesis Types:

a) Smooth ER – no ribosomes attachedb) Rough ER – with ribosomes attached

4. Microbodies Peroxisomes – oxidative enzymes that catalyze the removal of

amino acids Glyoxysomes – oxidative enzymes that catalyze the removal of

amino acids Lysosomes – made up of digestive enzymes

5. Golgi Apparatus Consists of membrane-delimited vesicles arranged parallel

6. Centrioles Small, dark bodies in animal cells Play important role in mitosis

7. Vacuole Membrane enclosed, fluid filled space Consists of crystals, inorganic salts, sugars

8. Nucleus Control center of the cell Easily stained Consists of chromosomes (for cell reproduction & heredity

transmission)

4. Nucleolus Round structure in nucleus with minute fibers & granules For ribosomal formation

5. Nuclear Sap Liquid matrix in nucleus Makes possible for chemical reaction to take place

6. Cytoplasm Gel-like or viscous solution Where organelles are suspended

7. Plastids Large membrane bound organelles Found in cytoplasm of plant cells Types:

o Chromoplast – consists of chloroplast, chlorophyll a, chlorophyll b, carotenes, and xantophyll

o Leucoplast – colorless plastid; center of starch grain formation

8. Ribosomes Actual sites of protein synthesis Attached to ER or suspended in cytoplasm

1. Cytoskeleton Responsible for cell movement Provides shape and structural support to cell Gives cell proper spatial relationship Made up of:

- microfilaments- microtubules- intermediate filaments

2. Glycocalyx Made up of: Attaches one cell to another Attaches one cell to external structures

3. Plasmodesmata Made up of strands of protoplasm Connects two adjacent plant cells

4. Desmosomes Button-like structures between two plasma membranes

1. Nutrition Means by which organisms obtain food

2. Digestion Breaking down complex substances into smaller & soluble

form3. Absorption

All needed materials are carried into or absorbed by the cells

4. Respiration Gas exchange between cells & environment Aerobic or Anaerobic

5. Excretion Discharging waste materials from cell to environment

6. Reproduction Cell division resulting to increase number of cells or

organisms

7. Secretion Cell produces vitamins & hormones Discharges synthesized molecules Complex molecules of Carbohydrates, Fats, and

Proteins are synthesized8. Egestion

Elimination of food eaten or digested9. Movement

Flow of cell content Locomotion Cellular Contraction

10. Irritability Reaction to stimuli

1. Diffusion Substance is spread throughout space from area of greater

concentration to lesser From greater diffusion pressure to lesser pressure

2. Osmosis A form of diffusion involving water

3. Turgidity All needed materials are carried into or absorbed by the cells

4. Plasmolysis Shrinkage of cells caused by diffusion of water into environment

due to exposure to solution with high osmotic pressure5. Filtration

Separating materials from liquid mixture through a membrane filter

6. Passive Transport Does not use chemical energy in transporting materials

Diffusion

Osmosis

Turgidity

Plasmolysis

Filtration

Passive Transport

Passive Transport

• Transport by simple diffusion • Facilitated diffusion: carrier proteins and ion channels • Osmosis and hydrostatic pressure

Active Transport• Active Transport• Exocytosis• Endocytosis• Phagocytosis• Pinocytosis

Cell Reproduction

Cell Cycle

The Cell Cycle

• The sequence of growth and division of a cell.

• 95% of cell cycle in interphase• 5% of cell cycle in mitosis

Interphase

• Growth Stage 1 (G1) – metabolic activity of the cell

• Synthesis Stage (S) – metabolic activity of the cell, replication of DNA

• Growth Stage 2 (G2) – metabolic activity of the cell, prepare for division

• M-Phase – Mitosis and Meiosis

Cell Reproduction

Mitosis & Meiosis

Where is all the genetic information found in a cell?

• On the genes on the Chromosomes• Chromosomes are actually DNA and proteins• If cells were the size of a basketball, your DNA would stretch 64km (40

miles)

A Tale of Tall DNA

If you unraveled all your chromosomes from all of your cells and laid out the DNA end to end, the strands would stretch from the Earth to the Moon about 6,000 times.

ProkaryotesThey have to be different!!!

• Usually, only have 1 chromosome in a circular pattern called a Plasmid

• Chromosomes• Before coiling, DNA & proteins w/in nucleus are called

Chromatin• DNA coils around a protein histone (spool)• Coiling continues w/ supercoiling• Structure shortens up Chromosome• DNA copies itself & are called chromatids & are held

together by a centromere

Chromosome Structure

Chromatid

Double ChromosomeDouble Chromosome

How many chromosomes do we have?

• Chromosome number: (# of Chromosomes in a body cell) – Diploid (2N) number

• Specific for each species of organisms Human – 46 Fruit fly - 8 Chimpanzee – 48 Mosquito - 6 Gorilla – 48 King Crab - 208 Horse – 64 Potato - 48 Donkey - 62 Bat - 44

Types of Chromosomes

• Autosomes body chromosomes – 22 pairs in us

• Sex chromosomes X or Y chromosomes – We should have 2

Chromosome Number

• Diploid (2N) number – 2 of every chromosome – found in body cells

1 set came from each of your parents – 23 pairs for the 2 sets

2 identical chromosomes are called homologous chromosomes

• Haploid (1N) number – 1 set of chromosomes per sex cell

Karyotypes • Shows individual’s chromosomes during cell division Males have 44 autosomes and 1 unmatched set of

sex chromosomes – XY Females have all 23 pairs matching – XX sex chromosomes

Why do cells make copies of themselves, instead of just getting larger?

• Need cell differentiation to be more efficient• Information crisis – DNA can not get message to entire

cell.• Transport in, out and throughout cell is difficult – Surface

area: Volume ratio is too small.

Prokaryotic organisms and unicellular organisms

• Reproduce asexually by binary fission • DNA makes a copy (attach to plasma membrane)• Cell makes a new nucleus• Cell divides up contents of cell• 2 identical cells result when wall forms between the 2 cells Binary fission

Cell Division in Eukaryotic cells

• Mitosis – production of 2 identical 2N nuclei.Involved with body cells

• Meiosis – production of 1N sex cells

http://biotech-adventure.okstate.edu/low/basics/mitosis/mitosis-diagram/diagram.gif

Cell Cycle

Mitosis• One type of cell division

Cell process in which the nucleus divides to form two nuclei identical to

each other, and identical to the original nucleus, in a series of steps

(prophase, metaphase, anaphase, and telophase)

Mitosis allows for growth and replaces worn out or

damaged cells.

Interphase

• Period of growth & development• Hereditary information (DNA)

copied (replicated / duplicated)• Cells that do not divide (nerves)

are always in interphase

Prophase

•DNA begins to shorten & thicken –Now called chromatids / chromosomes

•Centromeres form•Nuclear membrane breaks apart•Spindle fibers form

Metaphase

•Chromatids / chromosomes line up•Centromere attaches to spindle fibers

Anaphase

•Centromeres divide•Spindle fibers shorten•Chromatid pairs separate – move to ends of cell•Chromatids are now called

–Each ½ of the pair is now called a chromosome

Telophase

•Spindle fibers disappear •Chromosomes uncoil•Nuclear membrane forms•Cell divides (cytokinesis)

Interphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

Results of Mitosis

• Division of nucleus–Nuclei are identical to each other

• Same number & type of chromosomes

Asexual Reproduction

A type of reproduction - fission, budding, and regeneration - in

which a new organism is produced from one parent and has DNA

identical to the parent organism.

Asexual Reproduction

• Offspring produced from one organism

• Hereditary information is identical

• Mitosis is one form of asexual reproduction

Sexual Reproduction

Meiosis

Sexual Reproduction

A type of reproduction in which two sex cells, usually an egg and a sperm, join to form a zygote, which will develop into a new

organism with a unique identity.

Sexual reproduction results in a great

variety, or diversity, of offspring.

Meiosis

• The nucleus divides twice– Meiosis I– Meiosis II

Interphase• DNA is duplicated

Prophase I

• DNA shorten & thicken– Forms chromatids / chromosomes

Metaphase I

• Copied chromatids / chromosomes line up in middle of cell

• Centromeres attach to spindle fibers

Anaphase I

• Chromatid pairs are pulled apart–They DO NOT separate

• Move to ends of cell

Telophase I

• Cell divides • No further replication of

hereditary material

There are now two cells. Both cells have

full sets of genetic material

(chromosomes)

Prophase II

• Similar to mitosis–Starts with TWO cells instead of one• Spindle fibers appear

Metaphase II

• Duplicated chromatid / chromosomes line up in middle of cell

• Spindle fibers attach to centromeres

Anaphase II

• Centromere divides –Chromatids separate & move to ends of cell• Chromatids are now individual chromosomes

Telophase II

• Spindle fibers disappear• Nuclear membranes form at

each end of cell• Cells divide

–Results in 4 cells • Each with ½ the original number of chromosomes

In summary:Meiosis

• Two cells form during meiosis I• In meiosis II, both of these cells form

two cells• The two divisions of the nucleus

result in four sex cells (gametes)• Each has one-half the number of

chromosomes in its nucleus that was in the original nucleus