What food substances produce the most energy? Why are dietitians concerned with saturated and unsaturated fatty acids? List the three main structural components of a typical cell? Na

  

Discussion 2

41

UNIT 1: THE BODY AS A WHOLE.

CHAPTER 4: BIOMOLECULES.

CHAPTER 5: CELL STRUCTURE.

CHAPTER 6: CELL FUNCTION.

Compose 400 words or more discussion to respond the following:

What food substances produce the most energy? Why are dietitians concerned with saturated and unsaturated fatty acids? List the three main structural components of a typical cell? Name as many passive processes that transport substances across a cell membrane as you can. How are they alike? How are they different?

Discussion 3

2

UNIT 1: THE BODY AS A WHOLE.

CHAPTER 7: CELL GROWTH AND DEVELOPMENT.

CHAPTER 8: INTRODUCTION TO TISSUES.

CHAPTER 9: TISSUE TYPE

Compose 400 words or more discussion to respond the following:

What are the two major phases of the cell life cycle? During which of these phases does mitosis occur? Which two of the four major tissue types have the greatest capacity to regenerate after an injury? Name the four principal types of body membranes. What makes bone tissue hard? Name the two types of involuntary muscle. Where is each found in the body? I would like to have 2 separate 400-page papers, one about chapters 4,5,6 and one about 7,8,9. 

UNIT 1 CHAPTER 7

CELL GROWTH AND DEVELOPMENT

GROWTH AND REPRODUCTION OF CELLS

Cell growth: Depends on using genetic information in DNA to make the structural and functional proteins needed for cell survival

Cell reproduction: ensures that genetic information is passed from one generation to the next.

GROWTH AND REPRODUCTION OF CELLS (cont.)

Cell growth: a newly formed cell produces a variety of molecules and other structures necessary for growth by using the information contained in the genes of DNA molecules; this stage is known as interphase

Production of cytoplasm: more cell material is made, including growth and/or replication of organelles and plasma membrane; a largely anabolic process

LIFE CYCLE OF THE CELL.

The Cell Cycle: 2 major phases Interphase and Mitosis

Mitosis

Division of somatic cells (non-reproductive cells)

A single cell divides into two identical daughter cells.

Daughter cells have same number of chromosomes as does parent cell.

6

Mitosis

Divided into 4 phases

Prophase

Metaphase

Anaphase

Telophase

Followed with Cytokinesis

Depending on cell- may last a few minutes to several days

Prophase

1st and longest phase

of mitosis

Events

Chromosomes become visible.

Centrioles separate and move to opposite sides of the cell.

Chromosomes become attached to fibers in the spindle at the centromere.

Chromosomes coil more tightly.

Nucleolus disappears .

Nuclear envelope breaks down.

Metaphase

Often lasts only a few minutes

Events

Chromosomes line up across the center of the cell.

Microtubules connect the centromere of each chromosome to the two poles of the spindle.

Anaphase

Centromeres split

Sister chromatids separate and move to opposite poles

Anaphase ends when chromosomes stop moving.

Telophase

Chromosomes begin to disperse into a chromatin.

Nuclear envelope re-forms around each cluster of chromosomes.

Spindle begins to break apart.

Nucleolus becomes visible.

Cytokinesis

Animal cells:

Cell membrane is drawn inward until the cytoplasm is pinched into 2 nearly equal parts

Result? 2 new identical cells

The Process of Cell Division

Two main stages of cell division:

Mitosis: nucleus divides, produces 2 nuclei identical to parent cell and each other

Cytokinesis: cytoplasm divides, produces 2 cells

The CELL CYCLE

3 Parts

Interphase

Mitosis – few minutes to several days

Cytokinesis

Mitosis

4 sub-phases:

1st – Prophase

2nd – Metaphase

3rd – Anaphase

4th – Telophase

followed by

Cytokinesis

From the Virtual Cell Biology Classroom on ScienceProfOnline.com

Image: Mitosis diagram, Marek Kultys

14

I Peed on the MAT.

– A single germ cell divides into four unique daughter cells.

Daughter cells have half the # of chromosomes as parent cell, so they are considered haploid.

Image: Overview of Meiosis, National Institutes of Health

What is cell division of gametes called?

Meiosis

From the Virtual Cell Biology Classroom on ScienceProfOnline.com

15

Diploid organisms receive one of each type of chromosome from female parent (maternal chromosomes) and one of each type of chromosome from male parent (paternal chromosomes)

Refers to the number of sets of chromosomes in cells.

● Haploid – one copy of each chromosome

– designated as “n”, the number of chromosomes in one “set”

– gametes

● Diploid – two sets of chromosomes (two of each chromosome)

– designated as “2n”

– somatic cells

Genetics Terminology: Ploidy

From the Virtual Cell Biology Classroom on ScienceProfOnline.com

16

Meiosis – Sex Cell (Gamete) Formation

In meiosis, there

are 2 divisions

of the nucleus:

meiosis I

&

meiosis II

Image: Overview of Meiosis, National Institutes of Health

From the Virtual Cell Biology Classroom on ScienceProfOnline.com

17

18

______________________________________________________________________________________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________________________________________________________________________________

______________________________________________________________________________________________________________________________________________________________________________________________________

,

Unit 1
Chapter 6 Physiology of Cells

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES:
PASSIVE TRANSPORT

  • Passive transport processes do not require any energy expenditure of the cell membrane (Table 4-1)
  • Diffusion: a passive process (Figure 4-1)
  • Molecules spread through the membranes.
  • Molecules move from an area of high concentration to an area of low concentration down a concentration gradient(Figure 4-2)

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: PASSIVE TRANSPORT (cont.)

  • Simple diffusion (Figure 4-3)
  • Molecules cross the phospholipid bilayer.
  • Solutes permeate the membrane; therefore the membrane is called permeable.

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: PASSIVE TRANSPORT (cont.)

  • Osmosis (Figure 4-4)
  • Diffusion of water through a selectively permeable membrane.

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: PASSIVE TRANSPORT (cont.)

  • Osmosis (cont.)
  • Isotonic: when two fluids have the same potential osmotic pressure (Figure 4-5)
  • Hypertonic (higher pressure): cells placed in solutions that are hypertonic to intracellular fluid always shrivel as water flows out of them; if medical treatment causes the extracellular fluid to become hypertonic to the cells of the body, serious damage may occur.
  • Hypotonic (lower pressure): cells placed in a hypotonic solution may swell as water flows into them.

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: PASSIVE TRANSPORT (cont.)

  • Facilitated diffusion (mediated passive transport)
  • A special kind of diffusion in which movement of molecules is made more efficient by the action of transporters embedded in a cell membrane.
  • Transports substances down a concentration gradient.

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: PASSIVE TRANSPORT (cont.)

  • Channel-mediated passive transport (Figure 4-6)
  • Channels are specific; allow only one type of solute to pass through.
  • Gated channels may be open or closed (or inactive); may be triggered by any of a variety of stimuli.
  • Channels allow membranes to be selectively permeable.
  • Carrier-mediated passive transport (Figure 4-7)
  • Carriers attract and bind to the solute, change shape, and release the solute on the other side of the carrier.
  • Carriers are usually reversible depending on the direction of the concentration gradient.

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: PASSIVE TRANSPORT (cont.)

  • Role of passive transport processes.
  • Move substances down a concentration gradient, thus maintaining equilibrium and homeostatic balance.
  • Types of passive transport: simple and facilitated diffusion (channels and carriers); osmosis is a special example of channel-mediated passive transport of water.

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: ACTIVE TRANSPORT

  • Active transport processes require the expenditure of metabolic energy by the cell (Table 4-2)
  • Transport by pumps
  • Pumps are membrane transporters that move a substance against their concentration gradient; opposite of diffusion.
  • Examples: calcium pumps (Figure 4-8) and sodium-potassium pumps (Figure 4-9)

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: ACTIVE TRANSPORT (cont.)

  • Transport by vesicles allows substances to enter or leave the interior of a cell without moving through its plasma membrane.
  • Endocytosis: the plasma membrane “traps” some extracellular material and brings it into the cell in a vesicle.
  • Two basic types of endocytosis (Figure 4-10)

Phagocytosis (“condition of cell eating”): large particles are engulfed by the plasma membrane and enter the cell in vesicles; the vesicles fuse with lysosomes, which digest the particles..

Pinocytosis (“condition of cell drinking”): fluid and the substances dissolved in it enter the cell.

  • Receptor-mediated endocytosis: membrane receptor molecules recognize substances to be brought into the cell (Figure 4-11)

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: ACTIVE TRANSPORT (cont.)

  • Exocytosis
  • Process by which large molecules, notably proteins, can leave the cell even though they are too large to move out through the plasma membrane.
  • Large molecules are enclosed in membranous vesicles and then pulled to the plasma membrane by the cytoskeleton, where the contents are released.

MOVEMENT OF SUBSTANCES THROUGH CELL MEMBRANES: ACTIVE TRANSPORT (cont.)

  • Role of active transport processes
  • Active transport requires energy use by the membrane.
  • Pumps concentrated substances on one side of membrane, such as when storing an ion inside an organelle.
  • Vesicle-mediated (endocytosis, exocytosis): move large volumes of substances at once, such as in secretion of hormones and neurotransmitters.

,

UNIT 1 .CHAPTER 4.

BIOMOLECULES

BIOMOLECULES : Substances that are produced by cells and living organisms.

There are four major types of biomolecules:

Carbohydrates.

Lipids.

Proteins.

Nucleid acids.

2

ORGANIC AND INORGANIC COMPOUNDS

Inorganic compounds: few have carbon atoms and none have C–C or C–H bonds

Organic molecules

Have at least one carbon atom and at least one C–C or C–H bond in each molecule

Often have functional groups attached to the carbon-containing core of the molecule (Figure 2-13)

INORGANIC MOLECULES

WATER.

OXYGEN.

CARBON DIOXIDE.

ELECTROLYTES.

ACIDS.

BASES.

SALTS.

4

The Principal Functional Chemical Groups

INORGANIC MOLECULES

Water

The body’s most abundant and important compound.

Properties of water (Table 2-2)

Polarity: allows water to act as an effective solvent; ionizes substances in solution (Figure 2-10)

The solvent allows transportation of essential materials throughout the body (; enables the body to maintain a relatively const Figure 2-14)

High specific heat: water can lose and gain large amounts of heat with little change in its own temperature.

High heat of vaporization: water requires the absorption of significant amounts of heat to change it from a liquid to a gas; allows the body to dissipate excess heat.

INORGANIC MOLECULES (cont.)

Oxygen and carbon dioxide: closely related to cellular respiration

Oxygen: required to complete decomposition reactions necessary for the release of energy in the body,

Carbon dioxide: produced as a waste product and helps maintain the appropriate acid-base balance in the body.

INORGANIC MOLECULES: ELECTROLYTES

Electrolytes

Large group of inorganic compounds that includes acids, bases, and salts.

Substances that dissociate in solution to form ions (resulting ions are sometimes called electrolytes)

Positively charged ions are cations; negatively charged ions are anions.

INORGANIC MOLECULES: ELECTROLYTES (cont.)

Acids and bases: common and important chemical substances that are chemical opposites

Acids

Any substance that releases a hydrogen ion (H+) when in solution; “proton donor”

Level of acidity depends on the number of H+ a particular acid will release

Bases

Electrolytes that dissociate to yield hydroxide ions (OH) or other electrolytes that combine with H+

Described as “proton acceptors”

pH scale: assigns a value to measures of acidity and alkalinity (Figure 2-15)

pH indicates the degree of acidity or alkalinity of a solution

pH of 7 indicates neutrality (equal amounts of H+ and OH); a pH less than 7 indicates acidity; a pH higher than 7 indicates alkalinity

The PH Scale.

INORGANIC MOLECULES: ELECTROLYTES (cont.)

Buffers

Maintain the constancy of pH

Minimize changes in the concentrations of H+ and OH

Act as a “reservoir” for hydrogen ions

Salts (Table 2-3)

Compound that results from chemical interaction of an acid and a base

Reaction between an acid and a base to form a salt and water is called a neutralization reaction.

ORGANIC MOLECULES

Organic” describes compounds that contain C–C or C–H bonds

CARBOHYDRATES FUNCTIONS.

The four primary functions of carbohydrates in the body are:

Provide energy.

Store energy.

Build macromolecules such as  fat for other uses.

Glucose energy is stored as glycogen, with the majority of it in the muscle and liver.

ORGANIC MOLECULES: CARBOHYDRATES

Carbohydrates: organic compounds containing carbon, hydrogen, and oxygen; commonly called sugars and starches

Monosaccharides: simple sugars with short carbon chains; those with six carbons are hexoses (e.g., glucose); those with five are pentoses (e.g., ribose, deoxyribose) (Figure 2-17)

Disaccharides and polysaccharides: two (di-) or more (poly-) simple sugars bonded together through a synthesis reaction (Figure 2-18)

14

Glucose Structure.Example of Monosaccharide.Simple Sugar.

ORGANIC MOLECULES: LIPIDS

Lipids (Table 2-5)

Water-insoluble organic molecules that are critically important biological compounds

Major roles:

Energy source.

Structural role.

Integral parts of cell membranes.

ORGANIC MOLECULES: LIPIDS (cont.)

Phospholipids (Figure 2-21)

Fat compounds similar to triglyceride.

One end of the phospholipid is water soluble (hydrophilic); the other end is fat soluble (hydrophobic).

Phospholipids can join two different chemical environments.

Phospholipids may form double layers called bilayers that make up cell membranes.(Figure 2-22)

PHOSPHOLIPID MOLECULE

PHOSPHOLIPID BILAYER MOLECULE

19

ORGANIC MOLECULES: LIPIDS (cont.)

Steroids (Figure 2-23)

Main component is steroid nucleus .

Involved in many structural and functional roles.

Prostaglandins (Figure 2-24)

Commonly called tissue hormones; produced by cell membranes throughout the body.

Effects are many and varied; however, they are released in response to a specific stimulus and are then inactivated.

20

ORGANIC MOLECULES: PROTEINS

Proteins (Table 2-6)

Most abundant organic compounds

Chainlike polymers

Amino acids: building blocks of proteins (Figures 2-25 to 2-27)

Essential amino acids: eight amino acids that cannot be produced by the human body

Nonessential amino acids: 12 amino acids that can be produced from molecules available in the human body

Amino acids consist of a carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a side chain

Proteins Functions

Two special and common types of proteins are enzymes and hormones. 

Table 1. Protein Types and Functions
Type Examples Functions
Digestive Enzymes Amylase, lipase, pepsin, trypsin Help in digestion of food by catabolizing nutrients into monomeric units
Transport Hemoglobin, albumin Carry substances in the blood or lymph throughout the body
Structural Actin, tubulin, keratin Construct different structures, like the cytoskeleton
Hormones Insulin, thyroxine Coordinate the activity of different body systems
Defense Immunoglobulins Protect the body from foreign pathogens
Contractile Actin, myosin Effect muscle contraction
Storage Legume storage proteins, egg white (albumin) Provide nourishment in early development of the embryo and the seedling

22

ORGANIC MOLECULES: PROTEINS (cont.)

Levels of protein structure (Figure 2-28)

Protein molecules are highly organized and show a definite relation between structure and function

Protein organization is defined by four levels:

Primary structure: the number, kind, and sequence of amino acids that make up the polypeptide chain

Secondary structure: polypeptide is coiled or bent into pleated sheets stabilized by hydrogen bonds

Tertiary structure: a secondary structure can be further twisted and converted to a globular shape; the coils touch in many places and are “welded” by covalent and hydrogen bonds

Quaternary structure: highest level of organization; occurs when protein contains more than one polypeptide chain

PROTEIN SHAPES

ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES

Nucleic acids and related molecules

DNA (deoxyribonucleic acid)

Composed of deoxyribonucleotides: structural units consist of the pentose sugar (deoxyribose), phosphate group, and nitrogenous base (cytosine, thymine, guanine, or adenine)

DNA molecule consists of two long chains of deoxyribonucleotides coiled into a double-helix shape (Figure 2-31)

Specific sequence of more than 100 million base pairs constitutes one human DNA molecule; all DNA molecules in one individual are identical and different from those of all other individuals

DNA functions as the molecule of heredity

25

THE DNA MOLECULE

26

ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES (cont.)

RNA (ribonucleic acid) (Figure 2-32; Table 2-7)

Composed of the pentose sugar (ribose), phosphate group, and a nitrogenous base

Nitrogenous bases for RNA are adenine, uracil, guanine, or cytosine (uracil replaces thymine)

Some RNA molecules are temporary copies of segments (genes) of the DNA code and are involved in synthesizing proteins

Some RNA molecules are regulatory and act as enzymes (ribozymes) or silence gene expression (RNA interference)

TRANSFER RNA

ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES (cont.)

Nucleotides

Nucleotides have other important roles in the body

Adenosine triphosphate (ATP) (Figure 2-33)

Composed of:

Adenosine

Ribose, a pentose sugar

Adenine, a nitrogen-containing molecule

Three phosphate subunits

High-energy bonds present between phosphate group

29

ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES (cont.)

Adenosine triphosphate (ATP) (cont.)

Energy stored in ATP is used to do the body’s work

ATP often called the energy currency of cells

ATP is split into adenosine diphosphate (ADP) and an inorganic phosphate group by a special enzyme

,

Unit 1
Chapter 8: Introduction to Tissues.
Chapter 9: Tissue Types

INTRODUCTION

  • Tissue: Group of similar cells that perform a common function.
  • Matrix: Nonliving intercellular material.

PRINCIPAL TYPES OF TISSUE

  • Epithelial tissue
  • Connective tissue
  • Muscle tissue
  • Nervous tissue

EXTRACELLULAR MATRIX

  • Extracellular matrix (ECM) is a complex, nonliving material between cells in a tissue
  • Some tissues have a large amount of ECM; other tissues have hardly any.
  • Different kinds of components give ECM in different tissues a variety of characteristics.

EXTRACELLULAR MATRIX (cont.)

  • Components
  • Water
  • Proteins
  • Structural proteins
  • Collagen: strong, flexible protein fiber.
  • Elastin: elastic fibers.
  • Includes glycoproteins: proteins with a few carbohydrate attachments.
  • Fibronectin and laminin help connect the ECM components to cells by binding with integrins in plasma membranes
  • Glycoprotein attachments also allow local communication within a tissue

EXTRACELLULAR MATRIX (cont.)

  • Proteoglycans
  • Hybrid molecules that are mostly carbohydrates attached to a protein backbone.
  • Examples: chondroitin sulfate, heparin, and hyaluronate.
  • Different proteoglycans give different characteristics to ECM, such as thickness and shock absorption .

EXTRACELLULAR MATRIX (cont.)

  • Functions
  • Helps bind tissues together structurally
  • ECM components bind to each other and to integrins in plasma membranes of cells
  • Some tissues are held together primarily by intercellular junctions
  • Allows local communication among ECM and various cells through connection with integrins in plasma membranes

EPITHELIAL TISSUE

  • Types and locations
  • Epithelium is divided into two types:
  • Membranous (covering or lining) epithelium
  • Glandular epithelium
  • Locations
  • Membranous epithelium: covers the body and some of its parts and lines the serous cavities; blood and lymphatic vessels; and respiratory, digestive, and genitourinary tracts
  • Glandular epithelium: secretory units of endocrine and exocrine glands.

EPITHELIAL TISSUE (cont.)

  • Functions
  • Protection
  • Sensory functions
  • Secretion
  • Absorption
  • Excretion

EPITHELIAL TISSUE (cont.)

  • Generalizations about epithelial tissue
  • Limited amount of matrix material.
  • Membranous type attached to a basement membrane.
  • Avascular.
  • Cells are in close proximity, with many desmosomes and tight junctions.
  • Capable of reproduction.

EPITHELIAL TISSUE: MEMBRANOUS

  • Classification of epithelial tissue
  • Membranous (covering or lining) epithelium .
  • Classification based on cell shape
  • Squamous
  • Cuboidal
  • Columnar
  • Pseudostratified columnar

EPITHELIAL TISSUE:
MEMBRANOUS (cont.)

  • Classifications based on layers of cells
  • Simple epithelium

Simple squamous epithelium

One-cell layer of flat cells

Permeable to many substances.

Examples: endothelium, which lines blood vessels; mesothelium, which lines pleura

Simple cuboidal epithelium

One-cell layer of cuboidal cells

Found in many glands and ducts

EPITHELIAL TISSUE (cont.)

Classifications based on layers of cells (cont.)

Simple columnar epithelium.

Single layer of tall, column-shaped cells

Cells often modified for certain functions such as goblet cells (secretion), cilia (movement), microvilli (absorption)

Often lines hollow visceral structures

Pseudostratified columnar epithelium

Columnar cells of differing heights

All cells rest on basement membrane but may not reach the free surface above

Cell nuclei at odd and irregular levels

Found lining air passages and segments of male reproductive system

Motile cilia and mucus are important modifications

EPITHELIAL TISSUE (cont.)

  • Classifications based on layers of cells (cont.)
  • Stratified epithelium

Keratinized stratified squamous epithelium

Multiple layers of flat, squamous cells

Cells filled with keratin

Covering outer skin on body surface

Nonkeratinized stratified squamous epithelium

Lining vagina, mouth, and esophagus

Free surface is moist

Primary function is protection

Stratified cuboidal epithelium

Two or more rows of cells are typical

Basement membrane is indistinct

Located in sweat gland ducts and pharynx

EPITHELIAL TISSUE (cont.)

  • Classifications based on layers of cells (cont.)

Stratified columnar epithelium

Multiple layers of columnar cells

Only most superficial cells are typical in shape

Rare

Located in segments of male urethra and near anus

Transitional epithelium

Located in lining of hollow viscera subjected to stress (e.g., urinary bladder)

Often 10 or more layers thick

Protects organ walls from tearing

EPITHELIAL TISSUE: GLANDULAR EPITHELIUM

  • Glandular epithelium
  • Specialized for secretory activity
  • Exocrine glands: discharge secretions into ducts.
  • Endocrine glands: “ductless” glands; discharge secretions directly into blood or interstitial fluid.

CONNECTIVE TISSUE

  • Functions, characteristics, and types
  • General function: connects, supports, transports, and protects.
  • General characteristics
  • ECM predominates in most connective tissues and determines its physical characteristics.
  • Consists of fluid, gel, or solid matrix, with or without extracellular fibers (collagenous, reticular, and elastic) and proteoglycans or other compounds that thicken and hold together the tissue .

CONNECTIVE TISSUE (cont.)

  • Four main types (Table 5-6)
  • Fibrous
  • Loose (areolar)
  • Adipose
  • Reticular
  • Dense
  • Irregular
  • Regular (collagenous and elastic)
  • Bone
  • Compact bone
  • Cancellous bone
  • Cartilage
  • Hyaline
  • Fibrocartila

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