Wk 1 Chpt 7: Basic Cell Properties and Processes

What is histology, and what is another term for it?

study of microscopic structure and function of cells and associated tissue; Another term for histology is microanatomy because dimensions of anatomic structures studied are on microscopic scale

What are artifacts?

artificial patterns that appear in the specimen with microscopic magnification

What is the smallest living unit of organization in the body, and why?

cell; Because each cell is capable of performing any necessary functions without the aid of other cells

What does each cell have?

a cell membrane, intracellular fluid, organelles, and inclusions

What is tissue?

a collection of similarly specialized cells, which are most often surrounded by extracellular matrix

What is an organ, and what can organs function together globally as?

Various tissue types bonded together to form somewhat independent body part that performs a specific function or functions: organ; Organs can function together globally: system

Why do cells in tissue undergo cell division?

to reproduce themselves and replace dead tissue cell

What is mitosis?

As result of division process: 2 daughter cells identical to each other and to original parent cell formed

What are exocytosis and endocytosis?

Exocytosis: active transport of material from vesicle within cell out into extracellular matrix; Endocytosis: uptake of materials from extracellular matrix into the cell

How does exocytosis occur?

fusion of a vesicle membrane with the cell membrane and subsequent expulsion of the contained material

What is phagocytosis?

engulfing and then digesting of solid waste and foreign material by cell through enzymatic breakdown of material

What is the cell membrane or plasma membrane, and what is it composed of?

surrounds cell; The usual cell membrane is an intricate bilayer, consisting mostly of phospholipids and proteins

What are the functions of the phospholipids and proteins of the cell membrane?

The phospholipids serve largely as a diffusion regulator. The proteins of the cell membrane serve as structural reinforcements, as well as receptors for specific hormones, neurotransmitters, and immunoglobulins (or antibodies).

What is intracellular fluid (ICF) or cytoplasm?

semifluid part contained within cell membrane boundary

What is the ICF made up of?

a jelly-like fluid called the cytosol and other structures that surround the nucleus

What cavities does the ICF contain?

vacuoles

What are organelles, and what are the major organelles?

metabolically active specialized structures within the cell; nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi complex, lysosomes, cytoskeleton

What do organelles allow each cell to do?

Organelles allow each cell to function according to its genetic code. Organelles also subdivide the cell into compartments.

When do changes in organelles of periodontal tissue happen?

during periodontal inflammation

What is the nucleus?

largest, densest, most conspicuous organelle in the cell with microscopic magnification; "command center" of the cell, controlling the other organelles in the cell

Where is the nucleus found, and what are examples of multinucleated cells?

Nucleus found in all cells of the body except mature red blood cells; Most cells have single nucleus; However some cells are multinucleated such as osteoclasts or skeletal muscles

Why are striated muscle cells multinucleated?

to enhance oxygen uptake and tissue repair

What is deoxyribonucleic acid (DNA) in the nucleoplasm?

main nucleic acid in nucleoplasm: chromatin

How does chromatin look when the cell is viewed with lower-power microscopic magnification?

diffuse stippling

What is a gene?

the basic physical and functional unit of heredity. Genes, made up of DNA, act as instructions to make proteins.

How many genes has the Human Genome Project estimated humans have?

between 20,000 and 25,000 genes

How many copies of each gene does every person have?

two copies of each gene, one inherited from each parent

What are alleles?

forms of the same gene with small differences in their sequence of DNA bases. These small differences contribute to each person’s unique physical features.

Why is the nucleus the cell’s "data bank"?

because it stores genetic code

What give directions for everything the cell is and will become?

DNA and ribonucleic acid (RNA)

Where can a small amount of DNA also be found?

in the mitochondria as mitochondrial DNA (mtDNA)

What happens to chromatin in an actively dividing cell?

chromatin condenses into notable and discrete rodlike: chromosomes

What is a centromere, and what do chromosomes become during cell division?

centromere: clear constricted area near middle; Chromosomes become 2 filamentous or threadlike chromatids as daughter chromosomes joined by centromere during cell division

What must occur with DNA before cell division?

new DNA must be synthesized with every single gene being replicated

What three important types of RNA are produced in the nucleus?

messenger RNA (mRNA) molecules, which are complementary copies of distinct segments of DNA; transfer RNA (tRNA) molecules, which are capable of specifically binding to and transporting amino acid units for protein synthesis; and ribosomal RNA (rRNA) molecules

What is nucleoplasm?

Fluid part within nucleus; Contains important molecules used in construction of: ribosomes, nucleic acids, other nuclear materials

What is the nuclear envelope?

Nucleus is surrounded by membrane similar to cell membrane: nuclear envelope; Except that its double-layered

What are nuclear pores?

avenues of communication between inner nucleoplasm and outer ICF

What affects the number and distribution of nuclear pores?

the cell type, with the level of cell activity, and with states of differentiation level of the same cell type

What is the nucleolus, and what does it produce?

pronounced rounded nuclear organelle centrally placed within nucleoplasm when the cell undergoes microscopic magnification contained in nucleus; The nucleolus mostly produces rRNA and the nucleotides of the two other types of RNA.

What would occur without a nucleolus?

no protein synthetic activity would occur within the cell

What are mitochondria, and what are they associated with?

most numerous organelles in the cell; Associated with energy conversion

What is the relationship between mitochondrial levels and cellular activity?

Cells with high levels of mitochondria also have high levels of cellular activity: such as with young fibroblasts within healthy oral mucosa

Why are mitochondria called the "power stations" for the cell?

They are the main source of adenosine triphosphate (ATP) and are the site of many metabolic reactions.

Why do mitochondria have inner folds?

to increase the surface area for more dense packing of the particular proteins and enzyme molecules involved in aerobic cellular respiration

What is present internal to the mitochondrial folds?

mitochondrial DNA, calcium and magnesium granules, enzymes, electrolytes, and water are present in a matrix

What two pathways of aerobic cellular respiration produce most of a cell’s energy?

the Krebs cycle (or citric acid cycle) with its multienzyme system as well as the hydrogen pathway, which uses the electron transport chain of enzymes

What happens to mitochondrial levels with lowering of healthy cellular activity during periodontal inflammation?

aging fibroblasts having lower levels of mitochondria

What possible interrelationship may mitochondrial changes help explain?

between 2 common inflammatory pathologies: periodontal disease and cardiovascular disease (CVD) as well as with other chronic inflammatory conditions

What are ribosomes, and where are they produced?

small spherical organelles in the cell produced in nucleolus from rRNA and protein molecules and assembled in ICF

Where can ribosomes be located?

Within mitochondria, free in ICF, or bound to membranes, either to outer nuclear membrane or onto surface of the rough ER

What is the function of ribosomes?

They function as mobile "protein factories" for the cell

What do free-floating ribosomes in the ICF synthesize?

proteins that remain in the ICF, such as keratin or enzymes that mediate apoptosis

How can ribosomes occur within the cell, and how many may attach to a single molecule of mRNA?

singly or in clusters; As many as 30 separate ribosomes may be attached sequentially to a single molecule of mRNA

What is the endoplasmic reticulum (ER)?

parallel membrane-bound channels; All membranes of ER interconnect forming system of channels and folds, continuous with the nuclear envelope providing a "highway" system for the cell.

Where is ER more concentrated?

in the cell’s inner or endoplasmic region as compared to peripheral or ectoplasmic region

How is ER classified, and what determines the classification?

smooth or rough; Determined by absence or presence of ribosomes

What is the difference between smooth ER (SER) and rough ER (RER)?

Smooth ER (SER), which is free of ribosomes, appears with lower-power microscopic magnification to have smoother in surface texture; rough ER (RER) dotted with ribosomes on its outer surface, which makes appear to have rougher surface texture

What are the primary functions of ER?

modification, storage, segregation, and finally transport of proteins that the cell manufactures on the ribosomes for use in other sections of the cell or even outside the cell

What happens to a new protein after the ER has modified it?

transferred to Golgi complex or Golgi apparatus for subsequent segregation, packaging, transport of protein compounds

What is the Golgi complex composed of?

stacks of 3 to 20 flattened smooth-membrane vesicular sacs arranged parallel to one another

What does the Golgi complex do with protein molecules from the RER?

further modified, concentrated, and packaged by the Golgi complex

How does the Golgi complex release molecules from the cell?

wraps many of these molecules into a single membranous vesicle and then sends it on its way to the cell’s surface to be released by the process of exocytosis

What protein molecules and examples of substances can be released after Golgi complex processing?

hormones, enzymes, and other secretory products; mucus secretory product for the salivary glands or insulin for the pancreas

How are lysosomes produced?

produced on the RER, then packaged by Golgi complex, developing as a bud that pinches off the end of one of the Golgi complex’s flattened sacs

What is the function of lysosomes?

Function in both intracellular and extracellular digestion by the cell by lysing or digest various waste and foreign materials within or around the cell during phagocytosis, serving as a "sewer system" for the cell

How do lysosomes break down molecules?

using the powerful hydrolytic and digestive enzymes contained within them, even bone tissue

What is the main hydrolytic enzyme in lysosomes?

hyaluronidase

What happens to usable and indigestible material after lysosomal digestion?

usable material diffuses out of the lysosome into the cell’s ICF to be incorporated into new molecules being synthesized; Indigestible material remains in the lysosome and becomes a residual body.

What can happen to a residual body?

It either migrates to the cell surface to be released by exocytosis or remains as a remnant in the lysosome and becomes an inclusion.

Where is phagocytosis very active?

in the tissue associated with the gingival sulcus around the teeth

What is a centrosome, and what does it contain?

dense and somewhat oval-shaped organelle; Contains pair of cylindrical structures: centrioles

What is the role of the centrosome during cell division?

plays a significant role in forming the mitotic spindle apparatus during cell division

How are the centrioles within the centrosome structured?

There are two centrioles within the centrosome, and each is composed of triplets of microtubules arranged in a cartwheel pattern.

What happens without the self-replicating centriole-centrosome unit?

a cell from the body cannot reproduce

What is the cytoskeleton (CSK), and what structures make it up?

3D system of support using cellular scaffolding having length, width, depth: cytoskeleton (CSK); microfilaments, intermediate filaments, and microtubules

What are the functions of the cytoskeleton?

This design lends basic stability to the cell functioning like reinforcing girders. It also acts to compartmentalize the ICF creating preferred "carpool freeways" for the movement of needed molecules formed by cellular processes.

What are microfilaments and microtubules?

Microfilaments: delicate threadlike structures noted with microscopic magnification; Microtubules: slender hollow tubular structures that may appear individually, doubly, as triplets

What structures have an internal framework formed by microtubules?

cilia and flagella, centrioles, mitotic spindle for cell division

What functions do microtubules have?

assist microfilaments in maintenance of overall cell shape and in transport of intracellular materials

What are cilia and flagella?

Projections on cell shorter and more numerous: cilia; Projections fewer and longer: flagella

Where are cilia noted, and what do they do?

in the respiratory mucosa lining the nasal cavity and paranasal sinuses as they move the mucous coating of these tissue types along the surface

How are sperm propelled?

by their own flagella

What are intermediate filaments and tonofilaments?

Intermediate filaments: various types of thicker threadlike within cell with microscopic magnification; Tonofilaments: type of intermediate filaments have main role in intercellular junctions

Where is keratin found in certain types of epithelium in the oral cavity?

attached gingiva as well as dorsal surface of the tongue

What are inclusions?

metabolically inert substances that are transient; Include: masses of organic chemicals, often recognizable with microscopic magnification

What are examples and functions of inclusions?

Lipids and glycogen can be used for energy from inclusions in the cell. Melanin is stored as inclusions in certain cells of the skin and oral mucosa being responsible for the pigmentation of these tissue types including physiologic pigmentation. Inclusions also include residual bodies, which are spent lysosomes and their digested material.

How long do epithelial cells within the oral cavity lining and gingival sulcus live before tissue turnover?

days

Why must epithelial cells in the oral cavity lining and gingival sulcus neutralize acids and enzymes in their lysosomes before dying?

so as to not damage surrounding healthy tissue

When is this protection from lysosomal acids and enzymes not available?

when pathology is present such as with periodontal disease

Where is physiologic pigmentation described on the tongue and attached gingiva?

Tongue with physiologic pigmentation with its darker pink to brown coloration present at tops of fungiform lingual papillae especially noted with darker skin tones; Physiologic pigmentation of attached gingiva associated with permanent dentition mainly at base of interdental gingiva due to denser deposits of melanin with darker skin tones

What is mitosis or cell division?

complex process involving many organelles of the cell, functions during tissue growth or regeneration, and is dependent on length of individual cell’s lifespan

What does the surveillance system monitor as cells cycle through interphase and mitosis?

DNA damage and failure to perform critical processes

What happens if the surveillance system senses a problem?

a network of signaling molecules instructs the cell to stop dividing

What do cell cycle "checkpoints" do?

let the cell know whether to repair the damage or initiate programmed cell death, apoptosis. This ensures that the damaged cell is not further propagated.

What is the role of p53 in DNA damage?

p53, accepts signals provoked by DNA damage. It responds by stopping the DNA replication process.

What can happen without proper p53 function?

DNA damage can accumulate unchecked. A direct consequence is that the damaged gene progresses into a cancerous state.

What cancers are defects in p53 associated with according to the material?

a variety of cancers, including some breast and colon cancers

What occurs during interphase?

DNA replicated as part of cell cycle; The cell’s “living” time; Cells between divisions engage in growth, metabolism, organelle replacement, substance production including chromatin and centrosome replication

What are the 3 phases of interphase and what occurs during each?

Gap 1 or G1 phase (with initial resting phase that has cell growth and functioning); Synthesis or S phase (with cell DNA synthesis by duplication); Gap 2 or G2 phase (with 2nd resting phase that resumes cell growth and functioning)