Lab 2

Chemistry Comes Alive

Matter

• The “stuff” of the universe

• Anything that has mass and takes up space

• States of matter– Solid – has definite shape and volume– Liquid – has definite volume, changeable

shape– Gas – has changeable shape and volume

Energy

• The capacity to do work (put matter into motion)

• Types of energy– Kinetic – energy in action– Potential – energy of position; stored

(inactive) energy

Energy ConceptsPLAYPLAY

Major Elements of the Human Body

• Carbon (C)

• Hydrogen (H)

• Oxygen (O)

• Nitrogen (N)

Lesser and Trace Elements of the Human Body

• Lesser elements make up 3.9% of the body and include:– Calcium (Ca), phosphorus (P), potassium (K),

sulfur (S), sodium (Na), chlorine (Cl), magnesium (Mg), iodine (I), and iron (Fe)

• Trace elements make up less than 0.01% of the body– They are required in minute amounts, and

are found as part of enzymes

Atomic Structure

• The nucleus consists of neutrons and protons– Neutrons – have no charge and a mass of one

atomic mass unit (amu)– Protons – have a positive charge and a mass of

1 amu

• Electrons are found orbiting the nucleus– Electrons – have a negative charge and 1/2000

the mass of a proton (0 amu)

Models of the Atom

• Planetary Model – electrons move around the nucleus in fixed, circular orbits

• Orbital Model – regions around the nucleus in which electrons are most likely to be found (like a cloud)

Models of the Atom

Figure 2.1

Molecules and Compounds

• Molecule – two or more atoms held together by chemical bonds

• Compound – two or more different kinds of atoms chemically bonded together

Types of Chemical Bonds

• Ionic

• Covalent

• Hydrogen

Figure 2.8

Comparison of Ionic, Polar Covalent, and Nonpolar Covalent Bonds

Formation of an Ionic Bond

Figure 2.5a

Single Covalent Bonds

Figure 2.6a

Cells: The Living Units

THE CELL

Cell Theory

• The cell is the basic structural and functional unit of life (Schleiden & Schwann)

• Organismal activity depends on individual and collective activity of cells

• Biochemical activities of cells are dictated by subcellular structure

• Continuity of life has a cellular basis

• Virchow expanded on the cell theory and concluded “one living cell could only originate from another living cell”

Human cells are microscopic in size , but they vary considerably in size and differ even more in shape. For example : flat, brick shaped, threadlike, and irregular shapes.

Composition of the CELL

• Plasma membrane

• Cytoplasma• Organelles

• Nucleus

Part of the Cell

• Plasma membrane: surrounds the entire cell, forming its outer boundary

• Cytoplasma: living material inside the cell (except the nucleus)

• Nucleus: this structure contains the genetic code

Plasma membrane

• It is the membrane that encloses the cytoplasm and form the outer boundary of the cell.

• This membrane is compose by two layers of phospolipids, also a fat molecule called cholesterol (help to stabilize) and proteins (as receptor)

Plasma Membrane

Figure 3.3

Functions of Membrane Proteins

• Transport

• Enzymatic activity

• Receptors for signal transduction

Figure 3.4.1

Functions of Membrane Proteins

Figure 3.4.2

• Intercellular adhesion

• Cell-cell recognition

• Attachment to cytoskeleton and extracellular matrix

Passive Membrane Transport: Diffusion

• Simple diffusion – nonpolar and lipid-soluble substances – Diffuse directly through the lipid bilayer

– Diffuse through channel proteins

• Facilitated diffusion – Transport of glucose, amino acids, and ions

– Transported substances bind carrier proteins or pass through protein channels

Carriers

• Are integral transmembrane proteins

• Show specificity for certain polar molecules including sugars and amino acids

Diffusion Through the Plasma Membrane

Figure 3.7

Effect of Membrane Permeability on Diffusion and Osmosis

Figure 3.8a

Effects of Solutions of Varying Tonicity

• Isotonic – solutions with the same solute concentration as that of the cytosol

• Hypertonic – solutions having greater solute concentration than that of the cytosol

• Hypotonic – solutions having lesser solute concentration than that of the cytosol

Active Transport

• Uses ATP to move solutes across a membrane

• Requires carrier proteins

Active TransportPLAYPLAY

Types of Active Transport

Figure 3.11

Cytoplasma

• It is the specialized living material of cells

• It lies between the plasma membrane and the nucleus

• Numerous small structure (organelles) are part of the cytoplasma, along with the fluid that serves as the interior

environment of each cell

Cytoplasmic Organelles

• Specialized cellular compartments

• Membranous

– Mitochondria, lysosomes, endoplasmic reticulum, and Golgi apparatus

• Nonmembranous

– Cytoskeleton, centrioles, and ribosomes

Organelles

• Ribosomes

• Endoplasmic reticulum

• Golgi apparatus

• Mitocondria

• Lysosomes

• Centrioles

CELL PART STRUCTURE FUNCTION(S)

Plasma Membrane

Phospholipid bilayer studded with proteins

Serves as the boundary of the cell. P and C (outer surface) perform various functions (Ex. markers and receptor)

Ribosomes Tiny particles each made up of rRNA subunits

Synthesize proteins; a cell’s “protein factories”

Endoplasmic

Reticulum

(ER)

Membranous network of interconnected canals and sacs, some with ribosome (rough ER) and some without (smooth ER)

Rough ER receives and transports synthesized proteins

Smooth ER synthesizes lipids and carbohydrates

CELL PART STRUCTURE FUNCTION(S)

Golgi apparatus

Stack of flattened, membranous sacs

Chemically processes, then packages substances from ER

Mitochondria Membranous capsule containing a large, folded membrane encrusted with enzyme

ATP synthesis; a cell’s “powerhouse”

Lysosomes “Bubble” of enzymes encased by membrane

A cell’s “digestive system”

CELL PART STRUCTURE FUNCTION(S)

Nucleus Double-membraned, spherical envelope containing DNA strands

Dictates protein synthesis, thereby playing and essential role in other cell activities, namely active transport, metabolism, growth and heredity

Nucleolus Dense region of the nucleus

Plays an essential role in the formation of ribosomes

Mitochondria

Figure 3.17

Endoplasmic Reticulum (ER)

Figure 3.18a and c

Golgi Apparatus

Figure 3.20a

Nucleus

• Contains nuclear envelope, nucleoli, chromatin, and distinct compartments rich in specific protein sets

• Gene-containing control center of the cell

• Contains the genetic library with blueprints for nearly all cellular proteins

• Dictates the kinds and amounts of proteins to be synthesized

Nucleoli

• Dark-staining spherical bodies within the nucleus

• Site of ribosome production

Nucleus

Figure 3.28a

Cell Cycle

• Interphase– Growth (G1),

synthesis (S), growth (G2)

• Mitotic phase– Mitosis and

cytokinesis

Figure 3.30

Mitosis

Cell Division

• Essential for body growth and tissue repair

• Mitosis – nuclear division

• Cytokinesis – division of the cytoplasm

Mitosis

• The phases of mitosis are:– Prophase– Metaphase– Anaphase– Telophase

Cytokinesis

• Cleavage furrow formed in late anaphase by contractile ring

• Cytoplasm is pinched into two parts after mitosis ends

Early and Late Prophase

• Asters are seen as chromatin condenses into chromosomes

• Nucleoli disappear

• Centriole pairs separate and the mitotic spindle is formed

Early prophase

Early mitotic spindle

Pair of centrioles

Centromere

Aster

Chromosome, consisting of two sister chromatids

Late prophase

Fragments of nuclear envelope

Polar microtubules

Kinetochore

Kinetochore microtubule

Spindle pole

Metaphase• Chromosomes cluster

at the middle of the cell with their centromeres aligned at the exact center, or equator, of the cell

• This arrangement of chromosomes along a plane midway between the poles is called the metaphase plate

Metaphase

Metaphase plate

Spindle

Anaphase

• Centromeres of the chromosomes split

• Motor proteins in kinetochores pull chromosomes toward poles

Daughter chromosomes

Anaphase

Telophase and Cytokinesis• New sets of

chromosomes extend into chromatin

• New nuclear membrane is formed from the rough ER

• Nucleoli reappear

• Generally cytokinesis completes cell division

Telophase and cytokinesis

Nucleolus forming

Contractile ring at cleavage furrow

Nuclear envelope forming

THE MICROSCOPE

PROCEDURES

• 1- Turn on the illuminator using the on/off switch• 2- Turn the nosepiece to bring the 4X objective (scanner) into

position• 3- Raise the stage into its highest position• 4- Place a slide of the letter “e” in the slide clamp on the stage• 5- Turn the coarse adjustment knob to bring the “e” into focus• 6- Measure the field (the brightly lighted circle that you see

when you look through the ocular lens)• 7- Center the ”e” in your field of view and then rotate the

nosepiece to 10X• 8- Use the fine adjustment knob to focus until the image is

sharp. Draw the image. Do not use the coarse adjustment• 10- Rotate the nosepiece until the 40X. Draw the image

CARES OF THE MICROSCOPE

• When moving the microscope, carry it with 2 hands (one hand to grip the arm and the other under the base

• Lenses have to be clean with lens paper (to keep them free of oil and dust).

• Do not use the coarse adjustment when focusing with the higher power objectives

THE END