THE GENERAL FUNCTIONS OF THE PLASMA MEMBRANE INCLUDE PHYSICAL ISOLATION, REGULATION OF EXHANGE WITH THE ENVIROMENT, SENSITIVITY TO THE ENVIROMENT,AND STRUCTURAL SUPPORT.
Identify the components of the plasma membrane
THE COMPONENTS OF THE PLASMA MEMBRANE THAT ENABLE IT TO PERFORM ITS CHARACTERISTICS FUNCTIONS ARE MEMBRANE LILIPIDS, MEMBRANE PROTEINS, AND MEMBRANE CARBOHYDRATES
Which type of integral protein allows water and small ion to pass through the plasma membrane
Channel proteins and integral proteins that allow water and small ions to pass through the plasma membrane
Differentiate between the cytoplasm and the cytosol
Cytoplasm is the material between the plasma membrane and the nuclear membrane; cytosol is the fluid portion of the cytoplasm.
What are the major differences between cytosol and extracellular fluid?
Cytosol has a higher concentration of potassium ions and suspended proteins, and a lower concentration of sodium ions, than the extracellular fluid. Cytosol also includes small quantities of carbohydrates, and larger reserves of amino acids and lipids
Identify the nonmembranous organelle, and cite a function of each
The nonmembranous organelles ( and their functions) include:
(1) centriole = essential for movement of chromosomes during cell division; organization of microtubules in cytoskeleton
(2) cilia = movement of materials over cell surface
(3) cytoskeleton = strength and support; movement of cellular structures and materials; cell movement
(4) microvelli = increase surface area to facilitate absorption of extracellular materials
(5) proteasomes = breakdown and recycling of intracellular proteins
(6) ribosomes = protein synthesis
Identify the membranous organelles, and cite their functions.
The membranous organelles (and their functions) include: (1) endoplasmic reticulum = synthesis of secretory products; intracellular storage and transport
(2) rough ER = modification and packaging of newly synthesized proteins
(3) smooth ER = lipid and carbohydrate synthesis
(4) Golgi apparatus = storage, alteration, and packaging of secretory products and lysosomal enzymes
(5) lysosomes = intracellular removal of damages organelles or pathogens
(6) mitochondria = productions of 95 percent of the ATP required by the cell
(7) peroxisomes = neutralization of toxic compounds
Describe the contents and structure of the nucleus
The nucleus is a cellular organelle that contains DNA, RNA, and proteins. The nuclear envelope is a double membrane that surrounds the nucleus; the perinuclear space is the region between this double membrane. Nuclear pores allow for chemical communication between the nucleus and cytosol.
What is a gene?
A gene is a portion of a DNA strand that functions as a hereditary unit. Each gene is located at a particular site on a specific chromosome and codes for a specific protein.
Define gene activation.
Gene activation is the process of uncoiling the segment of DNA containing that gene, and temporarily removing histones, so that the gene can be expressed and thus affect cell function
What is a transcription
Transcription is the encoding of genetic instructions on a strand of mRNA
What process would be affected by the lack of the enzyme RNA polymerase?
A cell that lacked the enzyme RNA polymearase would not be able to transcribe RNA from DNA
Name the three major categories of cellular transport processes
The three major categories of cellular transport processes are diffusions, carrier-mediated transport, and vesicular transport
What is meant by "selectively permeable" when referring to a plasma membrane.
A selectively permeable membrane allows the passage of some substances while restricting the passage of others. It falls between two extremes; impermeable, which allows no substance to pass, and freely permeable, which permits the passage of any substance
How would a decrease in the concentration of oxygen in the lings affect the diffusion of oxygen into the blood?
Diffusion is drive by a concentration gradient. The larger the concentration gradient, the faster the rate of diffusion; the smaller the concentration gradient, the slower the rate of diffusion. If the concentration of oxygen in the lungs were to decrease, the concentration gradient between oxygen in the lungs and oxygen in the blood would decrease (as long as the oxygen level of the blood remained constant). Thus, oxygen would diffuse more slowly into the blood
Describe the process of carrier-mediated transport
In carrier-mediated transport, integral proteins bind specific ions or organic substances and carry them across the plasma membrane. All forms of carrier-mediated transport are specific, have saturation limits, and are regulated (as by hormones).
During digestion in the stomach, the concentration of hydrogen ions (H=) within the stomach rises to many time that in cells lining the stomach. which transport process must be operating?
An active transport process must be involved because it takes an energy expenditure to more the hydrogen ions against their concentration gradient - that is, from a region where they are less concentrated (the cells lining the stomach) to a region where they are more concentrated (the interior of the stomach).
Endocytosis is the movement of relatively large volumes of extracellular material into the cytoplasm via the formation of a membranous vesicle at the cell surface; it includes pinocytosis ( the introduction of fluids into the cytoplasm by enclosing them in membranous vesicles at the cell surface) and phagocytosis ( the movement of extracellular materials into the cytoplasm by enclosure in membranous vesicle).
Exocytosis is the ejection of cytoplasmic materials by the fusion of a membranous vesicle with the plasma membrane.
What is the transmembrane potential, and in what units is it expressed?
The transmembrane potential is the difference in electrical potential that results from the uneven distribution of positive and negative ions across the plasma membrane. It is expressed in millivolts.
If the plasma membrane were freely permeable to sodium ions (Na+), how would the transmembrane potential be affected?
If the plasma membrane were freely permeable to sodium ions, more of these positively charged ions would move into the cell, and the transmembrane potential would move closer to zero
Give biological terms for (a) cellular reproduction and (b) cellular death.
The biological term for cellular reproduction is cell division, and the term for cell death is apoptosis
Describe interphase, and identify its stages
Interphase is the portion of a cell's life cycle during which the chromosomes are uncoiled and all normal cellular functions except mitosis are under way. The stages of interphase include G1, S, G2, and G0. A cell in G0 is not preparing for cell division
Define mitosis, and list its four stages.
Mitosis is the essential step in cell division in which a single cell nucleus divides to produce two identical daughter cell nuclei. the four stages of mitosis are prophase, metaphase, anaphase, and telophase.
What effect do telemores have on cell division?
Telomeres are segments of DNA found on the ends of chromosomes that limit the number of divisions by a cell and its descendants.
An illness characterized by mutation that disrupt normal control mechanisms and produce potentially malignant cells is termed ___________________.
An illness characterized by mutations that disrupt normal control mechanisms and produce potentially malignant cells is termed cancer.
Metastasis is spread by cancer cells from one organ to another, leading to the establishment of secondary tumors.
The process that transports solid objects such as bacteria into the cell is called
Plasma membranes are said to be
________________ ion concentrations are high in the extracellular fluids, and _________________ ion concentrations are high in the cytoplasm.
In a resting transmembrane potential, the inside of the cell is _______________, and the cell exterior is ___________________.
The organelle responsible for a variety of functions centering around the synthesis of lipids and carbohydrates is
a the Golgi apparatus
b. the rough endoplasmic reticulum
c. the smooth endoplasmic reticulum
The construction of a functional polypeptide by using the information in an mRNA strand is
Our somatic cell nuclei contain ___________ pairs of chromosomes.
The movement of water across a membrane from an area of low solute concentration to an area of higher solute concentration to an area of higher solute concentrations is known as
The interphase of the cell life cycle is divided into
List four basic concepts that make up modern-day cell theory.
(1) CELLS ARE THE BULIDING BLOCKS OF ALL PLANTS AND ANIMALS
(2) CELLS ARE PRODUCED BY THE DIVISION OF PREEXISTING CELLS
(3) CELLS ARE THE SMALLES UINTS THAT PERFORM ALL VITAL PHYSIOLOGICAL FUNCTIONS
(4) EACH CELL MAINTAINS HOMEOSTASIS AT THE CELLULAR LEVEL.
What are four general functions of the plasma membrane?
FOUR GENERAL FUNCTIONS PF THE PLASMA MEMBRANE ARE
(1) PHYSICAL ISOLATION
(2) REGULATION OF EXCHANGE WITH THE ENVIROMENT
(4) STRUCTURAL SUPPORT
What are the primary functions of membrane proteins?
MEMBRANE PROTEINS FUNCTIONS AS RECPTORS, CHANNELS, CARRIERS, ENZYMES, ANCHORS, AND IDENTIFIERS
By what three major transport mechanisms do substances get into and out of cells?
THE MAJOR TRANSPORT MECHANISMS ARE
(2) CARRIER-MEDIATED TRANSPORT
(3) VESICULAR TRANSPORT
List four import factors that influence diffusion rates
FACTORS THAT AFFECT DIFFUSION RATE ARE
(2) SIZE OF THE GRADIENT
(3) MOLECULE SIZE
What are four major functions of the endoplasmic reticulum?
MAJOR FUNCTIONS OF THE "ER" ARE
(1) SYNTHESIS OR PROTEINS, CARBOHYDRATES, AND LIPDS
(2) STORAGE OF ABSORBED OR SYNTHESIZED MOLECULES
(3) TRANSPORT OF MATERIALS
(4) DETOXIFICATION OF DRUGS OR TOXINS
Diffusion is important in body fluids, because it tends to