4.1.1  Compare and contrast the methods of light microscopy, transmission electron microscopy, and scanning electron microscopy.

• light microscope produces two dimensional images by passing light through the visible specimen thats stained with colored dyes (colored image)

• The electron microscope uses beams of electrons to illuminate the specimen that stained with heavy metal 

• A transmission electron microscope directs an electron beam through a thin cut section of a specimen (two dimensional image)

• A scanning electron microscope uses an electron beam that is moved across the surface of a specimen and its reflected electrons generate a digital image of the surface topography of the specimen (three dimensional image)

4.1.2  Describe the range in size of human cells.

• Most cells in the human body are between 1 micrometer and 100 nanometers in diameter

• Some can be seen with the naked eye but some need a microscope to see

4.1.3  Describe some of the shapes cells may exhibit.

• Cells throughout the body can have different shapes which also support various functions 

• Irregumar shaped (dendrite): nerve cells

• Biconcave disc (looks like fruitloop shape): red blood cells 

• Cube-shabed (cuboidal): kidney tubule cells 

• Column- shaped (columnar): intestinal lining cells

• Spherical (cube with cells in it): cartilage cells (knee)

• Cylindrical (skeletal): skeletal muscle cells

4.1.4  Describe the three main structural features of a cell.

• Plasma membrane: forms the outer, lining barrier that separated the internal contents of the cell from the interstitial fluid

• Nucleus: largest structure within cell and is enclosed by a nuclear envelope 

• Cytoplasm: all cellular contents located between the plasme membrane and the nucleus

4.1.5  Compare the membrane-bound and non-membrane-bound organelles and distinguish these from cell inclusions.

• Membrane bound organelles: enclosed by a membrane similar to plasma membrane (ex. Endoplasmic reticulum (rough and smooth), golgi apparatus, lysosomes, peroxisomes, and mitochondria) 

• Non membrane bound organelles: NOT enclosed within a membrane

  • These structures are composed of protein and include ribosomes, centrosome, proteasomes, and cytoskeleton

• Cell inclusions are not considered organelles but clusters (aggregates) of a single type of molecule

4.1.6  Explain the general functions that cells must perform.

• Maintain integrity and shape of the cell

• Obtain nutrients and form chemical building blocks 

• Dispose wastes 

4.2.7  List the lipid components of the plasma membrane, and explain the actions of each component.

• Phospholipids are a lipid that forms bilayers of the plasma membrane 

• Cholesterol is a four ring lipid molecule that is scattered within the inner hydrophobic regions of the phospholipid bylarer 

  • It strengthens the membrane and stabilizes it at temperature extremes 

• Glycolipids are lipids with attached carbohydrate groupes 

4.2.8 Differentiate between the two types of membrane proteins based upon their relative position in the plasma membrane.

• Integral proteins are mebrdded within, and extend completely across the phospholipid bylar 

• Peripheral proteins are NOT embedded within the lipid bylarer but instead are loosely attached to either the external or internal surfaces of the membrane and are “anchored: to the exposed parts of an integral protein 

4.2.9 Explain the six major roles played by membrane proteins.

• Transport proteins: regulating movement of substances across the plasma membrane (transport proteins include: channels, carrier proteins, pumps, symporters, and antiporters)

• Cell surface receptors: bind specific molecules called ligands

  • Ligands are molecules that bind to macromolecules

  • Binding initiates muscle contractions 

• Identity markers: communication to cells that they belong in the body 

  • Cells of immune system use identity markers to distinguish normal healthy cells from foreign and damaced cells or infected cells that should be destroyed 

• Enzymes: a protein that catalyzes a chemical reaction by lowering the activation energy 

  • Could be attached to either internal or external surfaces of a cell for catalyzing the reactions

• Anchoring sites: secure sytoskeleton to the plasma membrane 

• Cell-adhesion Proteins: cell to cell attachments 

  • Proteins that form membrane junctions perform functions which include binding cells to one another 

4.3.10  Define the general concept of diffusion.

• Random movement of molecules or particles down a concentration gradient 

4.3.11  Distinguish between the cellular processes of simple diffusion and facilitated diffusion.

• Simple diffusion: 

  • molecules pass between phospholipid molecules, 

  • small and non polar solutes, 

  • not regulated by plasma membrane, 

  • movement is dependent on the concentration gradient, 

  • continues to move as long as their gradient exists 

• Facilitated diffusion:

  • Trans[ort process for small charged or polar solutes 

  • Requires assistance from plasme membrane proteins 

  • Channel mediated diffusion and carrier meditated diffusion

4.3.12  Define osmosis and osmotic pressure.

• Osmosis: passive movement of water through a semipermeable membrane 

  • Movement occurs in response to a difference in relative concentration of water on either side of the membrane 

4.3.13  Describe the relationship of osmosis and tonicity.

• When water crosses the plasma membrane of a cell by osmosis the cell with either gain or lose water with an accompanying change in the cells volume this is called tonicity

4.3.14  Compare and contrast primary and secondary active transport.

• Active trasport: movemembt of a solute against its concentration gradient (movement from a low to high concentration gradient) across the cellular membrane 

• Primary active transport: uses energy derived directly from the breakdown of ATP

  • Uses ATP to provide the energy to moce a substance up its concentration gradient 

• Secondary active transport: involves the movement of a substance (ex. Na+) down its concentration gradient to provide the energy to move a different substance up its concentration gradient

4.3.15  Compare and contrast the types of vesicular transport (i.e., exocytosis and the different types of endocytosis).

• Vascular transport: membrane bound sac filled with materials 

  • Allows movement of large substances across the plasma membrane 

• Exocytosis: either large substances or large amounts of substances are secreted from the cell 

  • The cell secretes bulk volumes of materials within cellular vesicles into the interstitial fluid as a vessicle fuses with the plasma membrane 

  • Fusion of the vessicle to the plasma membrane is the energy requiring step 

  • The membran of the vessicle becomes incorporated into the plasma membrane and only the contents within the vessicle is released

• Endocytosis: the cellular uptake of either large substances or large amounts of substances from the external environment into the cell 

  • Process where a vessicle is formed as the cell acquires materials from the interstitial fluid

  • Phagocytosis (cellular eating): occurs when a cell engulfs or captures a large particle external to the cell by forming membrane extensions (pseudopodia) to surround the particle 

  • Pinocytosis (to drink): aka cellular drinking, process occurs when multiple small regions of the plasma membrane invagine and multiple small vesicles are formed as the cell internalized interstitial fluid that contains dissolved sollutes 

  • Receptor- mediated endocytosis: uses receptors on the plasma membrane to bind specific molecules within the interstitial fluid and bring molecules into the cell

    • This enables the cell to obtain bulk quantities of certain substances even though those substances may not be very concentrated in the interstitial fluid 

4.4.16  Define a resting membrane potential (RMP).

• The membrane potential when a cell is at rest 

4.4.17  Describe the cellular conditions that are significant for establishing and maintaining a resting membrane potential.

• A cell has unequal distribution of ions and charges molecules across the plasma membrane 

• Relative amounts of positive and negative charges are not equally distributed at the plasma membrane

4.4.18  Explain the role of both K+ and Na+ in establishing and maintaining an RMP.

• Role of K+: potassium ions exit the cell through K+ leak channels moving down their relaticelt steep chemical concentration gradient from the cytosol into the interstitial fluid 

  • This creates a negative charge inside of the membrane 

• Role of Na+: sodium ions enter the cell through Na+ leak channels moving down ther chemical concentration gradient from the interstitial fluid to the cytosol

  • At rest the membrane is impermeable to Na+ as all of its channels are closed

4.5.19  Explain how cells communicate through direct contact.

• Body cells communicate to our immune cells that they both belong to the body and are healthy through direct contact that involves the glycolayx

• Sperm and oocyte: during fertilization

  • Sperm recognizes and binds to oocyte by its unique glycocoalyx

• If you cut the skin of your finger the cells upper layer of the skin (epidermis) begins to divide

  • Cell decision continues to fill in the gap created by the injury 

  • When the damaged tissue has been replaces overgrowth fo tskin tissue is prevented by inhibition caused by direct cellular contact 

4.5.20  Describe the three general mechanisms of response to the binding of a ligand with a receptor.

• Channel linked receptors: permit ion passage either into or out of a cell in response to ligand bonding 

  • Channel linked receptors are required to initiate electrical changes to the resting membrane potential in skeletal, muscle, and cardiac cells

• Enzymatic receptors: sunction as protein kinase enzymes and are activated to directlyass a phosphate to other enzymes within the cell

• G protein- couples receptors: involve protein kinase activation; these protein kinase enzymes are activated indirectly thought the G protein that serves as an intermediate molecule 

4.6.21  Describe the structure and main function(s) of the membrane-bound organelles of a typical human cell.

• Membrane bound organelles: surrounded by a membrane that separates the organelles contents from the cytosol

  • Endoplasmic reticulum: extensive, interconnected membrane network that can carry in shake 

    • Extends from the nuclear encelope to the plasma membrane and composes about one half of the membrane within a cell

    • Serves as a point of attachment for both ribosomes and various types of enzymes 

    • Endoplasmic reticulum with ribosomes attaches is referred to as rough ER 

    • Endoplasmic reticulum without ribosomes attaches is referred to as smoother ER

  • Golgi apparatus: composed of several elongated, flattened, membranous sacs 

    • Exhibits distinct polarity 

    • Poles are called cisface (closer to the ER) and the diameter of its flattened sac is larger compared to transface

  • Lysosomes: small membrane enclosed spherical sacs 

    • Contains digestive enzymes that are immersed in acidic fluid 

      • These enzymes are contributes to lysosomes as portions of the golgi apparatus containing digestive enzymes pinch off to form cessicles and these vessels then fuse with the lysosome 

4.6.22 Describe the structure and main function(s) of the non-membrane-bound organelles of a typical human cell.

• Non membrane bound organelles are composed of either protein alone or protein and ribonucleic acid

• Ribosomes: non membrane organelles containing protein and RNA that are arranges into both a large subunit and small subunit

  • Bound ribosomes: attached to the external surface of the ER membrane to form rough ER

    • Bound ribosoles synthesize proteins destined to be incorporated into the plasma membrane, exported from the cell, or housed with lysosomes

  • Free ribosomes are suspended within the cytosol 

    • Free ribosomes synthesize proteins for use within the cell

• Centrosome: a structure typically in close proximity to the nucleus 

  • Contains a pair of perpendicularly oriented, cylindrical centrioles surrounded a protein that doesnt have a distinctive shape (amorphous)

    • Functions: organize microtubules (proteins of cytoskeleton) and support their growth in nondividing cells

      • Cell division, a direct formation of spindle fibers in dividing cells

• Proteasomes: large barrel shaped protein complezed; major protein digesting organelles located within bith the cytosol and nucleus of the cells 

  • Functions: protein digestion; degrade proteins that are damaged, incorrectly folded, or no longer needed

    • Quality assurance; control the quality of exported cell proteins

• Cytoskeleton: framework of diverse proteins that extends bith beneath the plasma membrane and through the interior cell

  • Functions: structural support and organization of cell; maintains its shape and organize organelles (all cytockeleton proteins) 

    • Provide internal support to plasma membrane and mictovilli (microfillaments)

    • Stabilize desmosome cell junctions (intermediate fillaments)

  • Cell division; separate chromosomes during cell division (microtubules) 

    • Split cell into two daughter cells by cytokenesis (microfillaments)

  • Movement; facilitate cytoplasmic streaming (microfillaments)

    • Serve as a track for movement of organelles and vesicles (microtubules)

    • Participate in muscle contraction (microfilaments)

    • Contractile proteins of cullia and flagella (microtubules)

4.6.23  Compare and contrast the structure and function of cilia, flagella, and microvilli.

• Cillia ( 5 nanometers - 10 nanometers in length) are small, hairlike projections extending from the exposed surfaces of some cells 

  • Found in large numbers 

  • Contain supportive microtubule proteins and enclosed by a plasma membrane

• Flagella: similar to cilia but longer and wider (50 nanometers in length and 0.5 nanometer in width)

  • Function is to help propel an entire cell 

  • (example: sperm) 

  • Only one present 

• Microvilli: thin microscopic membrane extensions of the plasma membrane 

  • More shorter and narrow than cilia 

  • More densely packed together 

  • Lack powered movement 

4.6.24  Compare and contrast the structure and function of the three major types of membrane junctions.

• Tight junction: composed of plasma membrane proteins that form strants or rows of proteins 

  • Positioned like spot welds at the apical surfaces around the circumference of each of the adjacent cells 

  • Function: seal off the intercellular space and prevent subsances from passing unregulated between the epithelial cells

  • Prevent the mixing of membrane proteins and lipids on either side of the junctions, therefor maintaining the polarity of the epithelium 

• Desmosomes: composed of several different proteins that bind neighboring cells 

• Gap junction: composed for six integral plasma membrane proteins called connexons 

  • Provide direct passageway for substances to move between neighboring cells 

    • Provide small pore for movement of small molecules between adjoining cells 

4.7.25  Describe the structure and function of the nuclear envelope and the nucleolus.

• Nuclear envelope: a nucleus that is enclosed withina  double membrane

  • Function: separated the cytoplasm from the nucleoplasm (the fluid within the nucleus) 

    • This boundary controls movement of materials between the nucleus and the surrounding cytoplasm 

4.7.26  Describe the relationship of DNA, chromatin, and genes.

• DNA is organized functionally into discrete unites called genes 

• Genes are segments of nucleotides within DNA that provide the instructions for the synthesis of specific proteins 

• Tightly coiled mass called chromosomes is needed only to prevent the DNA from becomung tangled during cell division

4.8.27  List the required structures for transcription.

• DNA: major structure required

  • A specific segment of DNA serves as the template to form an RNA molecule

  • Bases of the segment of DNA will be read

• Ribonucleotides: monomers that are used to synthezise the newly formed RNA polymer

  • Four different kinds if ribonucleotides which contail one of four nitrogenous bases; (A) adenine, (C ) cytosine, (G) guanine, and (U) uracil

• RNA polymerase: enzyme that facilitates the placement of ribonuclleotides with the bass of the DNA template as an RNA molecule is synthesized 

4.8.28  Explain the three steps of transcription.

• Initiation: Dna is unwound by enzymes to expose a segment of a gene; RNA polymerase attaches to promoter region of the gene

• Elongation: RNA polymerase assists with complementary base pairing of free ribonucleiotides with exposed bases of the template strand of DNA. hydrogen bonds form between bases of DNA and the newly forming RNA molecule; this process continues as RNA polymerase moves along the DNA strand

• Termination: RNA polymerase reaches the terminal region of the gene; newly formed RNA strands are released from the DNA strand; transcription is complete and DNA finishing rewinding into a double helix

4.8.29  List the required structures for translation.

• Ribosomes:

• mRNA: uses information in mRNA to direct protein synthesis

• Transfer RNA:

• Large numbers of free amino acids

4.8.30  Name the three functional forms of RNA, explain what is meant by codon, and identify three types of codon sequences.

• Ribosomal RNA

• Messenger RNA

• Transfer RNA

• Codon: each three base unit

  • Start codon: always contains three bases: AUG which codes for the amino acid methionine; a start codon is the signal that indicates where protein synthesis belongs along the mRNA strand

  • Stop codon: follows the codons used to assemble the new protein and it is always one of these three sequences of bases 

    • UAA

    • UAG

    • UGA

  • These three codons do not code for an amino acid; collectively they serve as the point where the reading od mRNA ends

4.8.31  Describe the three steps of translation.

• Initiation: Small subunit, large subunit, and charged tRNA with UAC anticodon and attached mehtionine (Met) come together to form a complex (tRNA is in the P site)

• Elongation: anticodon of a charged tRNA complementary base-pairs with codon on mRNA in the A site 

  • Peptide bnd is formed between teo amino acids

  • Ribosome shifts down one codon; additional amino acids delivered by tRNA base-pair with mRNA until a stop codon is reached

• Termination: release factor binds with stop codon of mRNA; newly formed protein strand is released

4.8.32  Explain why DNA is considered the cell’s control center.

• DNA is responsible for directing the synthesis of the proteins that carry out body functions

• DNA is indirectly responsible for other metabolic changes that occur withing a cell 

  • Including the synthesis of steroids and other lipids and enzymatic pathway of glucose oxidation

• DNA controls synthesis of enzymes that are responsible for catalyzing both the decomposition and the synthesis of chemical structures 

4.9.33  Describe the structural difference between chromatin and chromosomes, and note when each is present in a cell.

• The centrosome organizes the microtubules that facilitate movement of chromosomes during cell division

• DNA molecules within the nucleus if human somatic cells are organized as either loosely coiled chromatic or tightly coiled chromosomes

4.9.34  Summarize the phases of the cell cycle and the activities that occur in each phase.

• Interphase: cell is preparing for cellular division

  • Three phases in interphase: G1: cells grow and produce new organelles and other structures that needed for DNA replication, S: double helix strands of DNA are replicated , unwinding the DNA molecule, breaking the parent strands appart, assembly of new DNA strands, restoration of DNA double helix, G2: centriole replication is completed and enzymes and other structures needed for the mitotic phase of cell division are synthesized, 

4.9.35  Describe the main events of the mitotic phase, including the four stages of mitosis and cytokinesis.

• Prophase (first): chromosomes appear due to coiling chromatin 

  • Nucleus breaks down

  • Spindle fibers form centrioles and they move toward the opposing cell poles 

  • Nuclear envelope breaks down at the end of this stage

• Metaphase (second): spindle fibers attach to the centromeres of the chromosomes extending from the centrioles

  • Chromosomes are aligned at the equatorial plate of the cell by spindle fibers

• Anaphase (third): sister chromatids are separated by spindle fibers and moved toward opposite ends of the cell

  • Cytokinesis begins

• Telophase (last): chromosomes uncoil to form a chromatic 

  • A nucleus re forms within each nucleus 

  • Spindle fibers break up and disappear

  • New nuclear envelope forms around each set of the chromosomes and cytokinesis continues as clevage durrow deppens

4.10.36  Define apoptosis and describe the actions that occur in a cell during apoptosis.

• Apoptosis: induced to commit suicide, a process of programmed cell death

• Destruction of DNA polymerase to prevent the synthesis of new DNA

• Digestion of the DNA into small fragments 

• etc.