Prokaryote and Eukaryote Cells IB Topic 2.1-2.3 Prokaryote and Eukaryote Cells

Cell Theory A. There are 3 main points 1. All living organisms are composed of cells. 2. Cells are the smallest unit of life. 3. All cells come from pre-existing cells

Cell theory: history and evidence The discovery of cells is linked to technological advancements (microscopes) B. 1590-Jansen developed the compound microscope (it had two lenses) C. 1665-Robert Hooke discovered the cell 1. Looking at cork D. 1675-Leeuwenhoek discovered unicellular organisms

E. 1838-Mathius Schleiden discovered all plants are made of cells F. 1839-Theodore Schwann discovered all animals are G. 1855-Rudolph Virchow discovers all organisms are made of cells **organism=any living thing

Characteristics of Life: (single cell or multi-cell) 1. Order (organization) – from small to large -Ex: Organelles make up cells. Cell make up tissues. Tissues make up organs. Organs make individuals. 2. Metabolism- organisms take in and release energy 3. Response (to the environment)- response to stimuli 4. Growth and development- heritable programs of DNA direct growth and development (change in one’s shape during life) 5. Homeostasis- organisms have regulatory mechanisms to maintain their internal environments Examples: body temperature, blood sugar, osmoregulation 6. Reproduction- the ability to reproduce ones own kind 7. Evolutionary adaptation- life evolves as a result of interaction between organisms and their environment

Multicellular organisms A. Multicellular organisms show emergent properties B. Emergent properties arise from interaction of the components: - The whole is greater than the parts (Ex: a heart cannot function without the whole body) - A single cell can do nothing on its own, but when you put all of the cells together they can perform many functions

Multicellular organisms and differentiation A. Multicellular organisms differentiate to carry out specialized functions B. All cells originated from the same place and all carry the genetic information to perform any function (your toe cell could have been a brain cell) C. In each cell there is only a small amount of activated genetic material Ex: All cells have the genes for taste. The only cells with activated ‘taste’ genes are on your tongue.

Stem Cells Have ability to reproduce and differentiate Embryo cells all start out as stem cells Valuable for scientific research May be able to differentiate stem cells to desired cell type These may replace damaged cells Sources: Embryonic – cells from human blastocysts Fetal – cells from aborted fetuses Umbilical cord stem cells – cells from the umbilical cord of newborns Placenta derived stem cells – cells from the placenta and amniotic fluid of newborns Adult – cells from adult tissue (bone marrow, fat...)

DO NOT USE WIKIPEDIA AS YOUR RESOURCE!! Homework-Outline one therapeutic use of stem cells for humans or some other animal. DO NOT USE WIKIPEDIA AS YOUR RESOURCE!! You may use any government or university website. Their websites generally end in .edu or .gov.

Viewing Cells 2. Electron microscopes: Light microscopes : See color images have a larger field of view prepare samples easily observe living and non-living material **We cannot see most cell organelles 2. Electron microscopes: - must be dead and no real colors Scanning Electron (SEM): - electron beams that bounce off the specimen Transmission Electron (TEM): - Used electron beams that pass through specimen (more detail because they have a higher resolution)

Transmission Microscope (guess what these structures are...) Scanning Microscope 12

Microscope Vocabulary 1. Resolution- describes clarity of pictures -higher resolution = more detailed pictures 2. Magnification- makes objects larger 3. An increase in magnification may reduce the resolution

Calculating Linear Magnification A. The formula- Magnification = size of image size of specimen B. Example-the object is magnified by two This is the magnified image. This is the original object. Diameter of the image=4cm Diameter of the specimen=2 cm Find the magnification.

Common SI Unit Conversions 1nm (nanometer) = 1 x 10-9 m 1ųm (micrometer) = 1 x 10-6 m 1mm (millimeter) = 1 x 10-3 m 1cm (centimeter) = 1 x 10-2 m 1m (meter) = 1m 1km (kilometer) = 1 x 103 m

Calculating linear magnification Take a measurement of the drawing (width or length) Take this same measurement of the specimen   Remember to convert units if needed to Place your values into the equation Magnification = length of drawing / length of actual specimen You can also calculate the length of the specimen if this is unknown: length of the drawing / magnification. VIDEO: http://www.youtube.com/watch?v=L1d-02yRsRE

Limitations to Cell Size A. Cells cannot grow indefinitely B. They reach a maximum size and divide. C. Bigger cells are less efficient. -They have to transport materials further. -The smaller the surface area to volume ratio the harder it is for the cell.

How Big Is A Cell? OBJECT SIZE Eukaryotic 10-100 μm Prokaryotic 1-5 μm Nucleus 10-20 μm Chloroplast 2-10 μm Mitochondrion 0.5-5 μm Large virus (HIV) 100 nm Ribosome 25 nm Cell membrane 7.5 nm DNA dbl. helix 2 nm H atom 0.1 nm

Diagram of a typical prokaryote

Prokaryote organelles 1. Cell wall- gives the cell structure and strength (covered by sticky capsule) 2. Plasma membrane- separates the internal features from the outside environment 3. Cytoplasm- holds cell’s organelles and enzymes 4. Pili- help the cell hold on to other structures and aid in movement 5. Flagella- aid in organism movement 6. Ribosomes- make protein from mRNA 7. Nucleoid- area containing naked DNA (ring) 8. Slime capsule- a protective barrier around the cell (may help shield it from antibiotics)

An electron micrographs of E. coli ** For IB you must be able to identify the structures on a micrograph. http://www.cellsalive.com/index.htm

(b) A thin section through the bacterium Bacillus coagulans (TEM) Pili: attachment structures on the surface of some prokaryotes Nucleoid: region where the cell’s DNA is located (not enclosed by a membrane) Ribosomes: organelles that synthesize proteins Plasma membrane: membrane enclosing the cytoplasm Cell wall: rigid structure outside the plasma membrane Capsule: jelly-like outer coating of many prokaryotes Flagella: locomotion organelles of some bacteria (a) A typical rod-shaped bacterium 0.5 µm Bacterial chromosome

Prokaryote reproduction 1. Most prokaryotes divide by binary fission

Eukaryote Cells

Eukaryote Information 1. All eukaryotes have enclosed nuclei and other membrane bound organelles 2. Eukaryotes are true cells (‘eu’ = true) 3. Eukaryotic cells are present in protists, plants, fungi and animal 4. Animal cells have a secretory vesicle -It secretes glycoproteins that makeup the extracellular matrix -The extracellular matrix functions in support, adhesion and movement

Animal Cell Organelles: Nucleus: contains genetic material, controls the cell Ribosome: synthesizes proteins from mRNA. Free floating, rough ER, chloroplast and mitochondria. Rough ER: synthesizes proteins to be excreted by the cell Smooth ER: synthesizes lipids and carbs Golgi Apparatus: modifies, packs and ships via vesicles Lysosome: digestion (enzymes) Peroxisome: produces and breaks down hydrogen peroxide Mitochondrion: aerobic respiration, converts chemical energy into ATP using oxygen

Intermediate filaments ENDOPLASMIC RETICULUM (ER) A animal cell Rough ER Smooth ER Centrosome CYTOSKELETON Microfilaments Microtubules Microvilli Peroxisome Lysosome Golgi apparatus Ribosomes In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm) Nucleolus Chromatin NUCLEUS Flagelium Intermediate filaments ENDOPLASMIC RETICULUM (ER) Mitochondrion Nuclear envelope Plasma membrane Figure 6.9

Plant Cells Organelles found in plants only: - cell wall: -provides rigid support for the cells -made mostly of cellulose -plays important role in turgor (hardening of cells by the intake of water) -prevents cells from taking in too much water - chloroplasts- organelle required for photosynthesis - vacuole- membrane bound sac used for storage of organic compounds

Ribosomes (small brwon dots) A plant cell Ribosomes (small brwon dots) Central vacuole Microfilaments Intermediate filaments Microtubules Rough endoplasmic reticulum Smooth Chromatin NUCLEUS Nuclear envelope Nucleolus Chloroplast Plasmodesmata Wall of adjacent cell Cell wall Golgi apparatus Peroxisome Tonoplast Centrosome Plasma membrane Mitochondrion CYTOSKELETON In plant cells but not animal cells: Chloroplasts Central vacuole and tonoplast Cell wall Plasmodesmata Figure 6.9

Summary of differences between eukaryotes and prokaryotes! Prokaryotic Cells Eukaryotic cells small cells (< 5 mm) larger cells (> 10 mm) always unicellular often multicellular no nucleus or any membrane-bound organelles always have nucleus and other membrane-bound organelles DNA is circular, without proteins (naked) DNA is linear and associated with proteins to form chromatin (not naked) ribosomes are small (70S) ribosomes are large (80S) no cytoskeleton always has a cytoskeleton cell division is by binary fission cell division is by mitosis or meiosis reproduction is always asexual reproduction is asexual or sexual