Unit 1/Obj 1- Review of Cellular Biology

Metaphase

"Chromosome break in half and identical chromatin material will move to both ends of cell, jostling attachment and movement"Chromosomes cluster at the middle of the cell with their centromeres precisely aligned at the exact center, or equator of the spindle. This arrangement of chromosomes along a plane midway between the poles is metaphase. An enzyme triggers separation for anaphase to begin.

Somatic cells (diploid)

A somatic cell (diploid) is any biological cell forming the body of an organism; that is, in a multicellular organism, any cell other than a germ cell. somatic cells make up all the internal organs, skin, bones, blood, and connective tissue. soma meaning body.

Golgi Apparatus

A stack of smooth membrane sacs and associated vesicles close to the nucleus. Packages, modifies, and segregates proteins for secretion from the cell, inclusion in lysosomes, and incorporation into the plasma membrane.

Composition of matter

All matter is composed of elements that are unique substances that cannot be broken down into simpler substances by ordinary chemical methods, each element is composed of identical particles or building blocks called atoms, every elements atoms differ from those of all other elements and give them unique properties. Atoms themselves are clusters of smaller particles protons, neutrons, and electrons. Combination of two or more atoms held together by chemical bonds is called a molecule. When 2 or more different kind of atoms bind they form a compound.

Cytoskeleton*

As its name implies, the cytoskeleton helps to maintain cell shape. But the primary importance of the cytoskeleton is in cell motility. The internal movement of cell organelles, as well as cell locomotion and muscle fiber contraction could not take place without the cytoskeleton. The cytoskeleton is an organized network of three primary protein filaments: - microtubules - actin filaments (microfilaments) - intermediate fibers

Anaphase

Begins abruptly as the centromeres of the chromosomes split, and each chromatid now becomes a chromosome in its own right. The polar microtubules lengthen and push the two cell poles apart causing the cell to elongate. chromosomes look v shaped. lasts only a few minutes, shortest phase.

Telophase

Begins as soon as the chromosomal movement stops. It is prophase in reverse. Identical sets of chromosomes are at opposite poles of the cell and they uncoil and resume their threadlike chromatin form. A new nuclear envelope reforms around each chromatin mass, nucleoli reappear within the nuclei and the spindle breaks down and disappears. Mitosis is now ended and for a brief period the cell is binucleate.

Amino Acids

Building blocks of proteins of which there are 20 common types. All have 2 important functional groups, a basic group an amine and an organic acid group.

Mitosis or M Phase*

Cell growth and protein production stop at this stage in the cell cycle. All of the cell's energy is focused on the complex and orderly division into two similar daughter cells. Mitosis is much shorter than interphase, lasting perhaps only one to two hours.

Gap 1 (G1)*

Cells increase in size in Gap 1, produce RNA and synthesize protein. An important cell cycle control mechanism activated during this period (G1 Checkpoint) ensures that everything is ready for DNA synthesis.

Interphase*

Cells may appear inactive during this stage, but they are quite the opposite. This is the longest period of the complete cell cycle during which DNA replicates, the centrioles divide, and proteins are actively produced.Generally lasts at least 12 to 24 hours in mammalian tissue. During this period, the cell is constantly synthesizing RNA, producing protein and growing in size. By studying molecular events in cells, scientists have determined that interphase can be divided into 4 steps: Gap 0 (G0), Gap 1 (G1), S (synthesis) phase, Gap 2 (G2).

Differentiate between tissue and organ systems

Cells of similar structure bind together to form tissue and tissues bind together to form organs. An overall integrated organization of tissue and organs is called an organ system, the principal organ systems of the body are nervous, digestive, endocrine, and reproductive.

Globular Proteins

Compact, spherical, water soluble, chemically active molecules and play crucial roles in virtually all biological processes. Aka functional proteins. some (antibodies) help provide immunity, others regulate growth and development, and others (enzymes) are catalysts that oversee every chemical rx in the body. Hemoglobin, transport of O in blood, albumin for ph regulation, salivary amylase which catalyzes breakdown of starch.

Plasma membrane

Fragile barrier, passive envelope, outer boundary of the cell. Defines the extent of a cell separating two of the body's major compartments, intracellular from extracellular fluid. aka cell membrane. Encloses cell contents, mediates exchanges w extracellular environment, plays role in cellular communication. Fluid bilayer of lipids w/in which proteins are inserted. Microvilli are extensions that increase surface area. membrane acts as a semipermeable barrier by passive or active processes, diffusion is movement of molecules down concentration gradient, fat-soluble solutes can diffuse directly through membrane by dissolving in the lipid.

Germ cell (haploid)

Germ cells give rise to spermatozoa and ova which fuse during fertilization to produce a cell called a zygote, which develops into an embryo.

Enzymes

Globular proteins that act as biological catalysts. They regulate and accelerate the rate of biochem rxs. They keep the metabolic pathways flowing. can only increase speed of rx. Most can be recognized by the suffix ase. many cases they are part of cellular membranes in a bucket brigade alignment.

Chromatin

Granular, threadlike material composed of 30% DNA, our genetic material, and 60% histone proteins and 10% RNA chains, and its function is that DNA constitutes the genes. When a cell is prepping to divide the chromatin threads coil and condense enormously to form short barlike bodies called chromosomes. This compactness avoids breakage of the delicate chromatin during movements that occur during division.

Prometaphase and Metaphase*

In this stage the nuclear envelope breaks down so there is no longer a recognizable nucleus. Some mitotic spindle fibers elongate from the centrosomes and attach to kinetochores, protein bundles at the centromere region on the chromosomes where sister chromatids are joined. Other spindle fibers elongate but instead of attaching to chromosomes, overlap each other at the cell center. Tension applied by the spindle fibers aligns all chromosomes in one plane at the center of the cell.

Fibrous Proteins

Insoluble in water and very stable, ideal for mechanical support and tensile strength to body tissues, Collagen is the single most abundant protein in the body, also include keratin, elastin, and certain contractile proteins of muscle. Aka structural proteins

Lipids

Insoluble in water but dissolve readily in other lipids. Like carbs all lipids contain CHO but the O proportion is much lower, in addition some contain phosphorus. Lipids include triglycerides, phospholipids, steroids, and other lipoid substances. Tris are aka fats when solid and oils when liquid, the are composed of two types of building blocks, fatty acids and glycerol. Deposits of tris are found mainly beneath the skin where they insulate the deeper body tissues from heat loss and protect from mechanical trauma. Phospholipids are a chief component of cell membranes.Most important molecule in steroid chemistry is cholesterol that is essential for life, found in cell membranes and is raw material of VitD. Steroids vital for homeostasis, w/o sex hormones reproduction is impossible and lack of corticosteroids produced by adrenals is fatal.

Cytoplasm

Internal to the plasma membrane, "cell forming material". It is the intracellular fluid that is packed with organelles between cell membrane and nucleus. where most cellular activities are accomplished. major functional area, functions mediated by organelles.

Why is carbon so special?

It is precisely electroneutral. Carbon never loses or gains electrons but always shares them.

Nucleus

Largest organelle, surrounded by the nuclear envelope; contains fluid nucleoplasm, nucleoli, and chromatin. Control center of the cell; responsible for transmitting genetic information and providing the instructions for protein synthesis.

RNA

Located chiefly outside the nucleus and can be considered a molecular slave of DNA. It carries out the orders for protein synthesis issued by DNA. Single strands of nucleotides. 3 major varieties, messenger, ribosomal, and transfer distinguished by size and shape and each has a specific role.

Lysosome*

Lysosomes contain hydrolytic enzymes necessary for intracellular digestion.

Lysosomes

Membranous sacs containing acid hydrolases. Sites of intracellular digestion.

Smooth endoplasmic reticulum

Membranous system of sacs and tubules, free of ribosomes, site of lipid and steroid synthesis, lipid metabolism, and drug detoxification.

Mitochondria*

Mitochondria provide the energy a cell needs to move, divide, produce secretory products, contract - in short, they are the power centers of the cell. They are about the size of bacteria but may have different shapes depending on the cell type. Mitochondria are membrane-bound organelles, and like the nucleus have a double membrane. The outer membrane is fairly smooth. But the inner membrane is highly convoluted, forming folds (cristae).The cristae greatly increase the inner membrane's surface area. It is on these cristae that food (sugar) is combined with oxygen to produce ATP - the primary energy source for the cell.

Macromolecule

Most proteins are macromolecules which are large complex molecules containing from 100-over 10,000 amino acids.

MPCT

Multipotential connective tissue cells- these cells divide irregularly and are more differentiated than VIM and DIM, intermediate to radiation sensitivity. Examples include endothelial cells lining blood vessels and fibroblasts composing connective tissue

Ribosomes*

Ribosomes are packets of RNA and protein that play a crucial role in both prokaryotic and eukaryotic cells. They are the site of protein synthesis. Each ribosome comprises two parts, a large subunit and a small subunit. Messenger RNA from the cell nucleus is moved systematically along the ribosome where transfer RNA adds individual amino acid molecules to the lengthening protein chain.

Nucleus*

The nucleus is the most obvious organelle in any eukaryotic cell. It is enclosed in a double membrane and communicates with the surrounding cytosol via numerous nuclear pores. Within the nucleus is the DNA responsible for providing the cell with its unique characteristics. The DNA is similar in every cell of the body, but depending on the specific cell type, some genes may be turned on or off - that's why a liver cell is different from a muscle cell, and a muscle cell is different from a fat cell. When a cell is dividing, the nuclear chromatin (DNA and surrounding protein) condenses into chromosomes that are easily seen by microscopy.

Nucleolus*

The prominent structure in the nucleus is the nucleolus. The nucleolus produces ribosomes, which move out of the nucleus and take positions on the rough endoplasmic reticulum where they are critical in protein synthesis.

anabolism

The synthesis of complex molecules in living organisms from simpler ones together with the storage of energy; constructive metabolism

Golgi*

The Golgi apparatus is a membrane-bound structure with a single membrane. It is actually a stack of membrane-bound vesicles that are important in packaging macromolecules for transport elsewhere in the cell. The stack of larger vesicles is surrounded by numerous smaller vesicles containing those packaged macromolecules. The enzymatic or hormonal contents of lysosomes, peroxisomes and secretory vesicles are packaged in membrane-bound vesicles at the periphery of the Golgi apparatus.

catabolism

The breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy; destructive metabolism

Gap 0 (G0)*

There are times when a cell will leave the cycle and quit dividing. This may be a temporary resting period or more permanent. An example of the latter is a cell that has reached an end stage of development and will no longer divide (e.g. neuron)

Cytoplasm*

This is a collective term for the cytosol plus the organelles suspended within the cytosol.

Centrosome*

The centrosome, or MICROTUBULE ORGANIZING CENTER (MTOC), is an area in the cell where microtubules are produced. During animal cell division, the centrioles replicate (make new copies) and the centrosome divides. The result is two centrosomes, each with its own pair of centrioles. The two centrosomes move to opposite ends of the nucleus, and from each centrosome, microtubules grow into a "spindle" which is responsible for separating replicated chromosomes into the two daughter cells.

Cytosol*

The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs. Though mostly water, the cytosol is full of proteins that control cell metabolism including signal transduction pathways, glycolysis, intracellular receptors, and transcription factors.

Telophase and Cytokinesis*

The daughter chromosomes arrive at the poles and the spindle fibers that have pulled them apart disappear. The spindle fibers not attached to chromosomes begin breaking down until only that portion of overlap is left. It is in this region that a contractile ring cleaves the cell into two daughter cells (cytokinesis). Microtubules then reorganize into a new cytoskeleton for the return to interphase.

Proteins

Compose 10-30% cell mass and is the basic structural material of the body, they play many vital roles in cell fx. Have the most varied fx of any molecules in the body, all contain CHON and many contain S and Ph as well. Long chains of amino acids, joined together by dehydration synthesis, with the amine end of one amino acid linked to the acid end of the next, the resulting bond produces a characteristic arrangement of linked atoms called a peptide bond. We can think of each type of amino acid as a letter of a 20 letter alphabet and each letter is used for a different combination yielding proteins w diff structures and fxs. The structure of a protein determines its fx, usually globular or fibrous.

Nucleic acids

Composed of CHON and phosphorus are the largest molecules in the body. Their structural units are called nucleotides and they are complex. Include 2 major classes of molecules DNA and RNA, deoxyribonuleic acid and ribonucleic acid.

Nucleoli

Dense spherical non membrane bounded bodies, composed of ribosomal RNA and proteins, they are the site of ribosome subunit manufacture.

Meiosis

Different process of nuclear division that produces sex cells with only half the # of genes found in other body cells.

DIM

Differentiated intermitotic cells, produced by division of VIM cells and although are actively mitotic are more differentiated than VIM cells, therefore are more resistant to radiation than VIM. examples include intermediate and type B spermatagonia.

Cytokinesis

Division of cytoplasm begins during late anaphase and is completed after mitosis ends. The plasma membrane is drawn inward to form a cleavage furrow, it deepens until the cytoplasmic mass is pinched into 2 parts so that at the end of cytokinesis there are 2 daughter cells. Each is smaller and has less cytoplasm that the mother cell but it is genetically identical to it, the daughter cells then enter the interphase portion of the life cycle until it is their turn to divide.

Nuclear envelope

Double membrane structure, pierced by pores; outer membrane continuous endoplasmic reticulum. selectively permeable.

Gap 2 (G2)*

During the gap between DNA synthesis and mitosis, the cell will continue to grow and produce new proteins. At the end of this gap is another control checkpoint (G2 Checkpoint) to determine if the cell can now proceed to enter M (mitosis) and divide.

Prophase*

During this first mitotic stage, the nucleolus fades and chromatin (replicated DNA and associated proteins) condenses into chromosomes. Each replicated chromosome comprises two chromatids, both with the same genetic information. Microtubules of the cytoskeleton, responsible for cell shape, motility and attachment to other cells during interphase, disassemble. And the building blocks of these microtubules are used to grow the mitotic spindle from the region of the centrosomes.

Centriole*

Each centriole is a ring of nine groups of fused microtubules. There are three microtubules in each group. Microtubules (and centrioles) are part of the cytoskeleton. In the complete animal cell centrosome, the two centrioles are arranged such that one is perpendicular to the other.

Cell Membrane*

Every cell is enclosed in a membrane, a double layer of phospholipids (lipid bilayer). The exposed heads of the bilayer are "hydrophilic" (water loving), meaning that they are compatible with water both within the cytosol and outside of the cell. However, the hidden tails of the phosopholipids are "hydrophobic" (water fearing), so the cell membrane acts as a protective barrier to the uncontrolled flow of water. The membrane is made more complex by the presence of numerous proteins that are crucial to cell activity. These proteins include receptors for odors, tastes and hormones, as well as pores responsible for the controlled entry and exit of ions like sodium (Na+) potassium (K+), calcium (Ca++) and chloride (Cl-).

FPM

Fixed Postmitotic cells- do not divide, highly differentiated both morphologically and functionally therefore this group is the most resistant to radiation, some cells in this category have long lives, others short. when the short lived cells die they are replaced by DIM cells and when the others die they may not be replaced. examples include some nerve cells, muscle, erythrocytes, and spermatazoa.

Smooth Endoplasmic Reticulum*

Throughout the eukaryotic cell, especially those responsible for the production of hormones and other secretory products, is a vast network of membrane-bound vesicles and tubules called the endoplasmic reticulum, or ER for short. The ER is a continuation of the outer nuclear membrane and its varied functions suggest the complexity of the eukaryotic cell. The smooth endoplasmic reticulum is so named because it appears smooth by electron microscopy. Smooth ER plays different functions depending on the specific cell type including lipid and steroid hormone synthesis, breakdown of lipid-soluble toxins in liver cells, and control of calcium release in muscle cell contraction.

S Phase*

To produce two similar daughter cells, the complete DNA instructions in the cell must be duplicated. DNA replication occurs during this S (synthesis) phase ensuring that the two future cells being created will receive identical copies of the genetic material. 4 chromatids attached to central centromere (in interphase not mitosis)

DNA

Typically found in the nucleus of the cell where it constitutes the genetic material, also called genes. It has 2 fundamental roles, 1. It replicates itself before a cell divides ensuring that the genetic info in the descendant cells is identical 2. It provides the basic instructions for building every protein in the body. By providing the info for protein synthesis, DNA determines what kind of organism you will be (frog, human, etc) and directs your growth and development. Long double stranded polymer- double chain of nucleotides. Molecular structure is called a double helix. Serves as the master blueprint for protein synthesis.

VIM

Vegitative intermitotic cells- rapidly dividing undifferentiated cells that have a short life span, comprise the most radiation sensitive group of cells in the body, examples include basal cells of the epidermis, crypt cells of the intestines, spermatagonia of the testis, and erythroblasts

Differentiate between stroma and parenchyma

When various kinds of tissue are combined to form an organ they are identified according to two parts of the organ. The parenchymal part contains tissues that represent that particular organ, whereas the stromal part is composed of connective tissue and vasculature that provide the supporting structure to the organ.

Describe the different types of tissue comp in body

in order of abundance (muscle, fat, organs, skeleton, blood, subcutaneous tissue, bone marrow, skin) -Epithelium is the covering tissue, lines all exposed surfaces of the body, both exterior and interior. Covers skin, blood vessels, abdom and chest cavities, and GI tract -Connective and supporting tissue- high in protein and are composed usually of highly elastic fibers, connective tissue binds tissues and organs together, bone ligaments and cartilage are examples -Muscle special type of tissue that can contract. High protein, found throughout the body -Nervous tissue consists of specialized cells called neurons, avenue by which electrical impulses are transmitted for control and response

Polysaccharides

long chains of simple sugars linked together by dehydration synthesis. These are called polymers because they are chainlike molecules made of many similar units. Because they are large and fairly insoluble they are ideal storage products. Only two are of importance in the body, starch and glycogen. because of their size they lack the sweetness of monos and disaccs. Starch is a storage carb formed by plants. Glycogen is stored in liver cells and skeletal muscle and when blood sugar levels drop liver cells break down glycogen and release its many glucose units to the blood.

2 events of cell division

mitosis- division of the nucleus cytokinesis- division of the cytoplasm

Organic compounds

molecules unique to living systems- proteins, carbohydrates, lipids (fats), and nucleic acids- all contain carbon and hence are organic compounds.

Mitochondria

rod-like double membrane structures, inner membrane folded into projections called cristae. Sites of ATP formation, powerhouse of the cell. Their internal enzymes carry out the oxidative rxs of cellular respiration

Monosaccharides

simple sugar, single chain structures containing from 3-7 carbon atoms. They are usually named according to how many carbon atoms they contain. Most important in the body are the pentose (5C) and hexose (6C), for ex pentose deoxyribose is part of DNA and hexose glucose is blood sugar.

diploid cells

somatic cells are diploid cells containing 2n number of chromosomes.

Cells are...

the smallest living units, basic structural and functional unit of living organisms. All cells are composed of CHON and trace amounts of other elements. All have the same basic parts and some common functions. Human cells have 3 main parts; the plasma membrane, the cytoplasm, and the nucleus. Miniature protein factories that synthesize the huge variety of proteins that determine the chemical and physical nature of cells, and therefore the whole body.

Prophase

"Paired centrioles outside of nucleus double, form two pairs and divide, and then migrate to opposite ends of cell, nucleus swells, and starting of the appearance of the DNA, nuclear envelope disappears and contents dumped into cytoplasm, spindles appears between centrioles, chromosomes start to align along center of cell attach to spindle fibers". Earliest and longest phase of mitosis, each chromosome is made up of 2 chromatin threads now called chromatids, they are held together by a small body called a centromere, as the chromosomes appear the nucleoli disappear, the centriole pairs separate and act as focal points for growth of a new assembly of microtubules called the mitotic spindle, as they lengthen they push centrioles farther apart toward opposite poles of cell, the nuclear envelope fragments and is dispersed into ER allowing spindle to occupy middle of cell, and chromosomes are drawn to middle of cell

Organelles

"small organs" Small structures that perform specific cell functions.

Differentiate between stem cells, transit cells, and static cells

-A Stem cell population is one in whose sole purpose it to divide, they are undifferentiated. (basal cells in epidermis, bone marrow cells, spermatagonia) they divide to self renew and produce cells for another cell population. -Transit cells are on their way from one place (stem cell compartment) to another place (end cell compartment). they may or may not divide. example of diving transit cell is the nucleated red cell, reticulocyte in bone marrow is one that does not divide -Static cells lose cells throughout the life of an organism, they are fully differentiated and exhibit no or very little mitotic activity. examples are adult nervous tissue and muscle

The human body structural organization heirarchy

-At the chemical level atoms (building blocks of matter) form molecules, which associate in certain ways to form organelles (the basic components of cells), which form cells (the smallest living units), and similar groups of cells that have common function form tissues, and an organ is a structure composed of at least 2 tissue types that perform a specific function for the body.

Forms of energy

-Chemical energy, form stored in bonds of chemical substances when chemical reactions occur that rearrange the atoms the potential energy is released and becomes kinetic -Electrical energy, results from movement of charged particles, flow of electrons along wires -Mechanical energy, directly involved in moving matter -Radiant or electromagnetic energy, energy that travels in waves, which vary in length, and are collectively called the electromagnetic spectrum and include radiowaves, microwaves, visible light, infrared waves, ultraviolet waves, xrays, and gamma rays.

4 basic tissue types in human body

-Epithelium, covers the body surface and lines its cavities -Muscle, provides movement -Connective, supports and protects body organs -Nervous, Provides a means of rapid internal communication by transmitting electrical impulses

Disaccharides

A "double sugar" is formed when two monos are joined by dehydration synthesis, in this rx a water molecule is lost as the bond is made. Example is sucrose (glucose+fructose) which is table sugar and lactose (glucose+galactose) found in milk and maltose (glucose+glucose) aka malt sugar. Disaccharides are too big to pass through cell membranes so they must be digested to their simpler sugar units to be absorbed into blood. This happens by hydrolysis, the adding of a water molecule to break the bond formed by dehydration synthesis.

The cell life cycle 2 phases

A cell encompasses two major periods from the time it is formed until it reproduces, interphase in which the cell grows and carries on its usual activities and cell division or the mitotic phase, during which it divides into 2 cells.

What are Carbohydrates?

A group of molecules that includes sugars and starches and represent 1-2% of cell mass. They contain carbon, hydrogen, and oxygen (reflected in the name meaning hydrated carbon), A carbohydrate can be classified according to size and solubility as a monosaccharide (one sugar), disaccharide (two sugars), or polysaccharide (many sugars). monos are the structural units or building blocks of other carbs. The larger the molecule the less soluble it is generally.

Energy

No mass and does not take up space, it can only be measured by its effects on matter. Energy is defined as the capacity to do work. There is kinetic (energy in action) and potential (stored energy). All living things are composed of matter and they all require energy to grow and function.

Carbohydrate Function

Provide a ready, easily used source of cellular fuel in the body. Most cells can only use a few simple sugars and glucose is at the top of the "cell menu". Glucose is broken down and oxidized within cells and during these rx's e- are transferred, this relocation of e- releases bond energy stored in glucose, and this energy is used to synthesize ATP. When ATP supplies are sufficient, dietary carbs are converted to glycogen or fat and stored.

RPM

Reverting postmitotic cells- cells in this category normally do not undergo mitosis but retain the capability under specific circumstance, long lived and more differentiated still than VIM, DIM, and MPCT.This category of cells is relatively radioresistant but the exception is the mature lymphocyte which is in this category because it does not usually undergo mitosis but in comparison to other RPM cells like liver cells it is very radiosensitive

Rough endoplasmic reticulum

Ribosome-studded membrane system that encloses a cavity, the cisterne,and coiling through the cytoplasm. It's cisterne act as sites for protein modification. It's external face acts in phospholipid synthesis. Vesicles pinched off from the ER bind and transport the proteins to the Golgi apparatus and other sites.

Rough Endoplasmic Reticulum*

Rough endoplasmic reticulum appears "pebbled" by electron microscopy due to the presence of numerous ribosomes on its surface. Proteins synthesized on these ribosomes collect in the endoplasmic reticulum for transport throughout the cell.

Salts role...

Salts are ionic compounds that dissolve in water and act as electrolytes. Calcium and phosphorus salts contribute to the hardness of bones and teeth. Ions of salts are involved in many physiological processes. Major positive ion found in extracellular fluids important for water balance, conduction of nerve impulses, and muscle contraction.

Water's role...

Single most abundant compound in the body. It absorbs and releases heat slowly, acts as a universal solvent, participates i n chemical rxs, and cushions body organs.

Anaphase*

Spindle fibers shorten, the kinetochores separate, and the chromatids (daughter chromosomes) are pulled apart and begin moving to the cell poles.

Nucleotide

Structural unit of nucleic acids, each consists of 3 components. 5 bases can contribute to the structure, adenine A, guanine G, cytosine C, thymine T, and uracil C. A and G str large 2 ring bases called purines whereas C, T, and U are single ring bases called pyrimidines. These bases are letters of the genetic dictionary and the information of DNA is found in the sequence of these bases. Each sequence of 3 bases makes a "word" that specifies a particular amino acid.

Matter

anything that occupies space and has mass, for practical purposes it can be seen, smelled, and felt.

G1 phase

cell is metabolically active, synthesizing proteins rapidly, and growing vigorously. The most variable phase in length of time. minutes to hours in rapidly dividing cells and days to years in slow cells. Cells that cease to be dividing are said to be in the G0 phase. If cell functions it functions here. Nerve cells live in G1 because they will never go past. Very small G1 is skin cells.

Polymer

chainlike molecules made of many similar units

Ribosomes

composed of 2 subunits containing ribosomal RNA and proteins, are the sites of protein synthesis, they may be free or attached to rough ER.

haploid cells

haploid cells (example: sperm and ova) containin only one set (or n) number of chromosomes