a membrane transport mechanism requiring energy whereby chemical entities can be moved against the concentration gradient. requires carrier molecules and is powered by ATP
an organic compound composed of carbon, hydrogen, and oxygen, often in a 1:2:1 ratio. Simple carbs are joined by dehydration synthesis to form long chains called polysaccharides
the cell divisional event wherein the cell membrane invaginates around two newly formed nuclei to form two separate cells. begins during telophase of mitosis or meiosis
a collective term for the fluid and organelles located btwn the cell membrane and nucleus.
the fluid alone inside the cell
the process wherein simple organic compounds are chemically combined to form biological macromolecules. A hydrogen atom (H+) removed from one compound combines with a hydroxyl group (OH-) removed from the 2nd compound to form a molecule of water
progression from less specialized cell types to more specialized ones. Primitive, undifferentiated cells are often termed stem cells and these may give rise to various forms of specialized definitive cells via differentiation
random movement of chemical entities from higher to lower areas of concentration. If membranes are crossed, the term simple diffusion implies that no carrier molecules are involved and facilitated diffusion implies that carriers are required
the full chromosomal complement of regular body cells as opposed to the halved chromosomal number of sex cells. Since human body cells have 46 chromosomes(23 pairs), the diploid (2N) number for human cells is 46 and haploid number (N) is 23
cellular engulfment of particulate matter (phagocytosis) or a liquid droplet (pinocytosis) by surrounding the material with cell membrane. Similar movement of material out of a cell is called exocytosis
(ER) an organelle consisting of double cytoplasmic membranes continuous with the nuclear membrane and golgi apparatus. Those areas on which ribosomes are currently attached (rough endoplasmic reticulum = RER) manufacture proteins for export and those without ribosomes (smooth endoplasmic = SER) synthesize lipids and carry out (perform) detoxification reactions
increase in the size of a structure. Cellular hypertrophy can cause hypertrophy of an organ but the latter can also result from hyperplasia (increase in cell number)
an organic compound composed of carbon, hydrogen, and oxygen the is INSOLUBLE in water. Lipids can be divided into four major categories: Glycerides, steroids, prostaglandins, and phospholipids
the nuclear events associated with gametogenesis (formation of sperm and ova) Meiosis is a "two" divisional process where in the chromosome number is halved in the first division and sister chromatids are separated in the second one
the nuclear part of regular cell division. has four named stages (prophase, metaphase, anaphase, and telophase) based on the dissolution/reformation of the nuclear memberane and on chromosomal events
a biological macromolecule composed of nucleotide subunits. The five carbon sugar component of each nucleotide subunit is either ribose (resulting in RNA) or deoxyribose (resulting in DNA)
a biological macromolecule composed of one hundred or more amino acids linked by peptide bonds. Proteins fulfill many intracellular and extracellular roles in the body including structural components, enzymes, receptors, contractile elements, hormones, and defensive chemicals
a quantitation of the hydrogen ion content of a fluid. 7 is considered neutral, below 7 is acidic, higher is basic
the organelle formed of protein and ribosomal RNA which serves as the site of protein synthesis. Proteins that remain within the cell are synthesized on free ribosomes and those that are exported are manufactured on membrane-bound ribosomes (attached to the endoplasmic reticulum.)
nucleic acid synthesis wherein DNA is used as a pattern to form more DNA. Replication preceded cell division so that each resulting (daughter) cell will have a complete genome
nucleic acid synthesis wherein one strand of a DNA molecule is used as a pattern (via complementary base pairing) for the formation of RNA. Three major kinds of RNA are formed: transfer RNA (tRNA), messenger RNA (mRNA), and ribosomal RNA (rRNA)
protein synthesis = peptide bond formation = using all types of RNA to manufacture protein. Thranslation is a constant occurrence in most body cells
define cell, cytology, and cell theory
Cell: a unit of life, surrounded by semi-permeable membrane, that is capable of reproduction in an environment devoid of other living matter
Cytology: the study of cells
Cell theory: all living things are composed of cells (and cell products) and are derived only from pre-existing cells.
Name four most common elements in body
oxygen, hydrogen, nitrogen, and carbon
Most common chemical compound in body and %of body weight
Water, 2/3 of body mass
Seven elements that form most the rest of the body besides O, H, C, N
Calcium, potassium, sodium, phosphorus, magnesium, chlorine, and sulfur
"California Pot Smokers Forget My Clean Soul"
more than 20 different amino acids, bonded together by peptide bonds to form proteins
chains of amino acids too long to easily count
polypeptides of one hundred or more amino acids
five or six carbon sugars, simple sugars
monosaccharides combined by dehydration synthesis, containing two monosaccharides
containing many monosaccharides
compounds composed of glycerol (3 carbon alcohol) and a long chain fatty acids
a group of lipids, are long-chain, cyclical fatty acids, serve in several hormone-like capacities in the body
a group of lipids that have a basic structural backbone of three, six carbon rings and a five carbon ring
lipids that contain phosphorus
consists of a purine or pyrimidine nitrogenous base combined with 5-carbon sugur and with phosphoric acid. Nucleic acids are polymers of nucleotides
RNA vs. DNA
DNA: double-stranded polymer of nucleic acid; uses deoxyribose as sugar component; nitrogenous bases are Adenine, Guanine, Cytosine, and Thymine; forms genetic material within each cell.
RNA: single-stranded polymer; has ribose as sugar component; and has uracil in place of thymine; made by DNA and has 3 types: rRNA, tRNA, and mRNA
functions of cell membrane
serves as limiting membrane which contains all other cellular structures, controls what enters and exits, and contains certain receptors and identifiers that have hormonal and antigenic significance
the passive movement of a substance from an area of higher concentration of that substance to an area of lower concentration
a passive movement similar to simple diffusion except that a specific molecule is required (a carrier)
the passive movement of a solvent through a semi-permeable membrane from an area of higher concentration of solvent to an area o lower concentration. Similar to simple diffusion except that a semi-permeable membrane is required and the substance diffusing is a solvent.. (biological systems this solvent is always water)
the engulfment of LIQUID droplets into the cell by invagination of the cell membrane and pinching off of vacuoles
the engulfment of SOLID particles by cell membrane manipulation similar to those of pinocytosis. requires energy but no carrier
serve as site of protein synthesis
endoplasmic reticulum (ER)
complex systems of double membranes, extends through cytoplasm from nuclear membrane to cell membrane. 2 types... smooth and rough
currently studded w/ ribosomes, produce proteins primarily for secretion
lackes attached ribosomes, functions primarily in production of lipid materials and certain types of detoxfication reaction
consists of series of membranous sac and vesicles near nucleus, are interconnected to ER. manufactures carbs and glycoproteins, modifies and packages material for secretion
double-membrane-bound organelles, serve as site of oxidative phosphorlation and electron transport reactions. these reactions produce high energy ATP that is used in energy consuming (anabolic) reactions. Because of this, mitochondria is often called POWERHOUSE
a non-dividing period, during which cellular growth and synthesis of compounds and organelles occur. divided into 3 stages: G1, S, and G2
First growth in interphase, normal cell functions, plus cell growth, duplication of organelles, protein synthesis
interphase stage of protein synthesis, DNA replicates
second growth stage of interphase, used for synthesis of the enzymes and other compounds needed cell division
occurs after G2, divided into prophase, metaphase, anaphase, and telophase
the chromatin condenses to form visible chromosomes, nuclear membrane begins to disappear
the chromosomes line up at cells equator
the period where the sister chromatids separate at centromere
two nuclear membrans reform and cytokinesis occurs
decrease in cell size
increase in cell size resulting in enlargement of parent organ
increased number of cells
refers to a change in cell type
metaplasia which is accompanied by a change from more primitive cells to more specialized cell types
Since (essentially) all cells in a human body have the same genome (identical DNA) explain how different types of cells can exist
Not all of the DNA is used (transcribed) in a given type of cell. In face, large amounts of it are not used.
For illustration purposes, assume that a library contained all human knowledge. Those individuals desiring to be physicians would need (use) primarily the information in the medial science area (only)
Since red blood corpuscles (RBC's) lack nuclei, how are they produced?
They (themselves) cannot reproduce because of the lack of a nucleus. RBC's are derived from bone marrow cells called hemocytoblasts that do have nuclei and can reproduce
Since the process for endocytosis reduces the total amount of cell membrane, how is it replenished?
endocytosis depletes the cell membrane but exocytosis replenishes it
Biological osmosis can be defined as 1) the simple diffusion of water through a semipermeable membrane OR 2) the diffusion of water through a semipermeable membrane from an area of higher water concentration to an area of lower water concentration.
Which is the better definition?
These definitions say the same thing and are equally accurate
Why are some cancers fatal while others are not life threatening?
Uncontrolled cell division (cancer) is not inherently life threatening. Only when the increased cell populations interfere with vital processes does a cancer threaten life. Some cancers (benign) grow so slowly that life is never threatened
What is the purpose of meiosis?
Meiosis reduces the regular cellular chromosome # (diploid, 2N=46) to the haploid (N=23) #. Consists of two divisions. In first division, chromosome # is halved (46 - 23). In second division, sister chromatids are separated at connecting centromeres.
Thus, at end of 1st ÷, daughter cell has only 23 chromosomes-but each have 2 copies of portion of DNA. After 2nd ÷, each daughter cell has 23 chrom, each single copy of part of DNA.
Thus, when a sperm (23 chromosomes) fertilizes an ovum (23 chromosomes) the diploid (2N) # is restored.
This explains why some traits are inherited from the father and some from the mother
Why is thymine involved in replication and transcription but not in translation?
Thymine is found in DNA but not in RNA.
Replication and transcription both involve DNA.
Translation involves RNA ONLY, and RNA contains no thymine
Of the four major groups of biological macromolecules in the body, which ones are typically formed from monomers by dehydration synthesis?
All of them except some subtypes of lipids
What can cells do that viruses cannot?
A cell can multiply (by dividing) in an environment that contains no other cells.
Viruses are obligate intracellular parasites
What is the difference btwn polypeptides and proteins?
Size. By definition, a protein is a polypeptide of 100 or more amino acids
Which cell membrane modification aids...
Movement of other substances along a cell's membrane?
In most body cells, chromosomes cannot be observed (microscopically) most of the time. Why?
Chromosomes become visible just before cells divide. Most body cells are not dividing most of the time
Which chemical transport mechanism can occur without the presence of a membrane?
What do free ribosomes do?
Membrane bound ribosomes?
Free ribosomes serve as the site of synthesis for polypeptides and proteins that remain in the cell.
Membrane-bound ribosomes are the site of synthesis for polypeptides and proteins that are exported from the cells as part of the secretory product.
What do plant cells typically have that animal cells do not?
cell walls formed of polysaccharides and chloroplasts.
The plant cell membrane is within this cell wall
Some cells like skeletal muscle cells and osteoclasts are multinucleated. In theory, how can this occur?
Multinucleated cells can occur by fusion of single cells which pool their nuclei into a common cell membrane or by nuclear division without concurrent cytoplasmic division
Why does cellular hyperplasia typically result in hypertrophy of the parent organ?
Can hyperplasia occur without hypertrophy?
An increase in cell # in most cases necessitates an increase in organ size.
Hyperplasia can occur, however, without an increase in overall size if the dividing cells get smaller. This happens during the first several cell divisions of the fertilized ovum. The cell number increases but the total mass of the conceptus remains unchanged.
Why cannot some body cells (like neurons in an adult) divide?
They have become so differentiated (specialized) that they have lost the microtubules, etc. involved with mitosis.
RBC's cannot divide because they do not have a nucleus
Which atom type (element) is present in the greatest number in the human body?
Hydrogen. Although hydrogen is only about 10% of the total body mass (vs. 65% for oxygen and 18% for carbon), hydrogen atoms are only 1/16 as heavy as oxygen atoms and only 1/12 as heavy as carbon atoms. Hydrogen's smaller % of total body mass is more than offset by the small size of the hydrogen atoms