Microscopes and the Cell Thursday, October 17th

What is “cell theory”?

Who helped developed the cell theory? 1665 Robert Hooke Observed cork under a primitive microscope Coined the term “cell” Looked like monks cells

Who helped developed the cell theory? 1674 Antonie van Leeuwenhoek Observed and described the first microscopic organisms Father of microbiology Improved the light microscope Made more than 25 different types

Who helped developed the cell theory? 1830’s Schleiden (PLANTS) & Schwann (ANIMALS) Worked independently but upon meeting, made important connections in regards to the cell nucleus Summarized many observations into what is now know as the cell theory 1840’s Virchow Studied bacteria and disease Claimed that bacteria was also made of cells

What is “cell theory”? Cell Theory (3 parts) All living things are made of cells. (Hooke) Cells are the basic unit of structure and function in organisms. (Schleiden & Schwann) All cells come from other cells. (Virchow)

UNAIDED EYES LIGHT MICROSCOPE ELECTRON MICROSCOPES

What are the different types of microscopes? Light (or Optical)Microscope Light passes through one or more lenses to enlarge Magnification = the ability to make things larger Resolution = the measure of clarity of an image Can magnify images: 40x - 100x - 400x

Light Microscope

What are the different types of microscopes? Electron Microscopes (EMs) Allows scientists to view a universe too small to be seen with a light microscope Forms an image using a beam of electrons Focus a beam of electrons through a specimen (TEM) or onto its surface (SEM)

What are the different types of microscopes? Scanning Electron Microscope (SEM) Provides for detailed study of the surface of a specimen Creates a 3D image Cannot view living specimens

Surface of Tongue

Head louse clinging to a human hair

Eyelash hairs growing from the surface of human skin

The surface of a strawberry

Cut human hairs and shaving foam between two razor blades

Household dust – pollen, human hair, pet dander, leaf litter

Toothbrush bristle

Snowflake

What are the different types of microscopes? Transmission electron microscope (TEM) Provides for detailed study of the internal structure of cells Electrons are passed through thin specimens 2 dimensional

TEM vs. SEM Viruses leaving a cell

Cell Structure and Function

What are the common features of ALL cells? Cell Membrane: AKA plasma membrane Encloses the cell Separates the inside from the outside Regulates what goes in & out of cell DNA Genetic code Cytoplasm: the “fluid” inside of the cell Provide support of internal structures Site of cellular reactions

What are prokaryotes? Single celled organism that lack nuclei More primitive; appeared first in the geologic record Many have flagella, that help them move Bacteria

What are eukaryotes? Have a nucleus Compartment that houses the DNA Controls all functions of the cell Have organelles structures that carries out specific jobs in the cell

What’s found in the nucleus? Nuclear envelope A double membrane which encloses the nucleus Has pores that regulate molecular traffic in and out of the nucleus Chromosomes Condensed and coiled DNA Each species has characteristic chromosome number

What is the cytoskeleton? Skeletal system of the cell membrane Gives the cell its shape & structure Involved with transport AND cell division Microtubules Long hollow cylinders Movement of chromosomes during cell division

Cytoskeleton Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Michondrion Go to Section:

What organelles are found within eukaryotes? Endoplasmic Reticulum (ER) Moves proteins/other substances through the cell Makes proteins from the ribosomes Rough ER is covered with ribosomes Connected to the nucleus Smooth ER makes lipids (fats) Ribosomes: structures that make proteins

What organelles are found within eukaryotes? Golgi Apparatus/ Golgi Body Packaging and distribution center Modifies lipids and proteins from the ER Ships out the new products to their final destinations Vacuoles: Storage containers that can also provide structure

What organelles are found within eukaryotes? Mitochondria Organelle that takes energy from sugar and turns it into ATP (energy) that the cell can use Has its own DNA

What are the organelles found only in plant cells? Cell wall Made of proteins & carbohydrates Helps keep the cell’s shape Provides rigid support Protects from cell damage Connects the cell with adjacent cells Chloroplasts Organelle that uses light energy to make carbohydrates through photosynthesis

What are the organelles found only in plant cells? Central Vacuole Large membrane covered space that stores water and other substances

Plant Cell

ENDOPLASMIC RETICULUM (ER) An Animal Cell ENDOPLASMIC RETICULUM (ER) Nucleolus DNA Nuclear envelope NUCLEUS Rough ER Smooth ER Flagella Plasma membrane Centrioles CYTOSKELETON Microfilaments Microtubules Ribosomes Golgi apparatus In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm) Lysosome Mitochondrion

A Plant Cell Rough endoplasmic reticulum Smooth endoplasmic reticulum Nuclear envelope Nucleolus NUCLEUS DNA Ribosomes (small brown dots) Central vacuole Golgi Micro- filaments CYTO- SKELETON Micro- tubules Mitochondrion Plasma membrane Chloroplast In plant cells but not animal cells: Chloroplasts Central vacuole Cell wall Cell wall

What are the 2 different cell types? Prokaryotic vs Eukaryotic YOU are eukaryotic Larger cells Found in all other kingdoms Often multicellular Nucleus Contains membrane bound organelles Linear DNA Asexual OR sexual reproduction Small cells Bacteria types ALWAYS unicellular No nucleus No membrane bound organelles Circular DNA Asexual reproduction Eukaryotic Prokaryotic

The Cell Membrane

What is the cell membrane made of? Provides protection and support for cells Separates the cell from the outside environment Phospholipid Molecule that allows the CM to be selectively permeable Certain substances can pass in and out of the cell Lipid Bilayer (2 layers) Phospholipids - phosphate and 2 fatty acids

Cell Membrane

What is the cell membrane made of? They are SELECTIVELY impermeable Some substances (not all) can pass across the membrane Hydrophobic tails… Water HATING Fats & oils Hydrophilic heads... Water LOVING

What is the cell membrane made of? Protein channels Allow nutrients (sugars or amino acids) to enter the cell Allow products of metabolism to leave (waste products) These channels are quite specific Recognize only a limited group of chemical substances to pass through the membrane

What is the function of the cell membrane? Gives the cell a flexible structure Forms a barrier between the cell and its environment Anchors the cytoskeleton to provide shape to the cell Attaches to the extracellular matrix to help group cells together (tissues)

What is the Structure of the Cell Membrane? Outside of cell Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains Inside of cell (cytoplasm)

What is the Structure of the Cell Membrane? Carbohydrates Act like chemical ID cards Allows individual cells to identify one another Membrane allows the following materials in and out of the cell: Water, Glucose (sugars), Oxygen, chemical compounds & wastes

How do things pass in and out of the cell? Concentration # of molecules present Diffusion Spreading of molecules OUT into available space From MORE concentrated to LESS concentrated

How do things pass in and out of the cell? DRAW THIS! Concentration # of molecules present DIFFUSION Spreading out of molecules into available space From MORE concentrated to LESS concentrated

How do things pass in and out of the cell? DRAW THIS! Notice it’s not the MOLECULES THAT MOVE IT’S THE WATER/LIQUID SOLUTION Passive transport clip

How do things pass in and out of the cell? Diffusion depends on random particle movements Doesn’t require cellular ENERGY Called PASSIVE TRANSPORT Equilibrium

How do things pass in and out of the cell? Osmosis The diffusion of WATER through a cell membrane

How do things pass in and out of the cell? Isotonic = Same strength Concentrations are the same on either side of the membrane Hypertonic = Above strength More concentrated solution OUTSIDE of cell membrane Hypotonic = Below strength Less concentrated solution OUTSIDE of cell membrane

DRAW THIS DIAGRAM

Osmosis Video Higher Concentration of Water Water molecules Cell membrane Sugar molecules Lower Concentration of Water

Needs water for movement Osmosis vs Diffusion Diffusion Osmosis Water? Doesn’t need Needs water for movement What it is Spontaneous movement of molecules from high to low concentration Spontaneous movement of WATER across a semipermeable mebrane, from high to low conc. Process Mainly occurs in gases and liquids Occurs when the medium (liquid) around a cell has a higher WATER concentration than the cell

What is another example of passive transport? Facilitated Diffusion Passage of molecules with transport proteins across a membrane Uses channels Does NOT require ENERGY

What is Active Transport? Movement of a substance against its concentration gradient with the use of ENERGY Moving in the OPPOSITE direction From LOW to HIGH concentration Active transport uses MOST of the energy a cell has for daily activities Active transport clip

What is Active Transport? Cells try to accumulate high concentrations of molecules they need: Ions Glucose (sugar) Amino acids (proteins) Carried out by protein channels

What are the types of Active Transport? Exocytosis Molecules EXIT through the cell membrane Endocytosis Molecules ENTERING the cell through the membrane VIDEO

How is Passive different from Active Transport? Does not use any type of energy Uses energy (Active) Examples: Diffusion Exocytosis Osmosis Endocytosis

Specialization vs Differentiation SPECIALIZATION - Multicellular organisms have cells that perform SPECIFIC jobs Ex – blood cells carry nutrients, skin cells protect the interior of the body Cells work together to perform a specific function for TISSUES Similar tissue types make up ORGANS Organs function together make up ORGAN SYSTEMS Cells  Tissues  Organs  Organ Systems  Organisms

Specialization vs Differentiation Normal process where less specialized cells develop to perform a function A fertilized egg (zygote) will develop into an adult human being Stem cells will develop into neurons, somatic cells and germ cells