Patho Ch. 4 and 5
Smallest functional unit that has the characteristics necessary for life.
made of cells based on their embryonic origin
Characteristics of all cells
Cells are able to exchange materials with their environment.
Obtain energy from nutrients
make complex molecules
Some replicate themselves
made up of internal membrane bound compartments called organelles e.g. the nucleus
have at least one nucleus
such as bacteria do not contain membrane bound organelles, lack a nucleus and nuclear membrane
3 major components of eukaryotic cell
intracellular fluid, composed of water, proteins, lipids, carbohydrates, and electrolytes.
control center b/c it contains the instructions to makes proteins, and proteins can then make other molecules needed for cellular function and survival.
Contains DNA which contains genes
Site for the synthesis of the three main types of RNA
mRNA, made from genetic information transcribed from DNA in a process called transcription.
travels to ribosomes in the cytoplasm so these instructions can be used to make proteins.
rRNA is the RNA component of ribosomes, the site of proteins production
tRNA transports amino acids to ribosomes so that mRNA can be turned into a sequence of amino acids.
This process known as translation, uses the mRNA template to link amino acids to synthesize proteins.
surrounds the nucleus separating the nucleoplasm inside the nucleus from the cytoplasm outside of the nucleus.
Contains many nuclear pores, fluids, electrolytes, RNA, some proteins, and some hormones move in both directions through the nuclear pores.
includes fluids and organelles outside the nucleus but within the cell membrane.
A solution that contains water, electrolytes, proteins, fats, and carbohydrates.
Pigments can accumulate in the cytoplasm such as melanin (normal) or bilirubin (jaundice)
the sites of protein synthesis in the cell.
two subunits made up of rRNA and proteins. During protein synthesis, the two ribosomal subunits are held together by a strand of mRNA.
an extensive system of paired membranes and flat vesicles that connect various parts of the inner cell.
two forms exist-smooth and rough.
has ribosomes attached, and the ribosomes appear under a microscope as "rough" structures.
Proteins made by the rough ER usually become parts of organelles or cell membranes, or are secreted from cells as protein.
e.g. digestive enzymes found in lysosomes and proteins that are secreted such as the protein hormone insulin
Free of ribosomes and has a smooth structure when viewed under a microscope.
Involved in the synthesis of lipids including steroid hormones.
The sarcoplasm reticulum of muscle cells is a form of smooth ER
a form of smooth ER, calcium ions are stored in and released from the SR to stimulate muscle contraction.
Smooth ER of the liver
involved in storage or extra glucose as glycogen as well as metabolism of some hormone drugs.
when proteins build up in the ER faster than they can be removed.
The cell responds by slowing down protein synthesis and restoring homeostasis.
Abnormal responses can cause inflammation and have been linked to IBS, a genetic form of diabetes, and a disorder of skeletal muscle known as myositis.
aka golgi apparatus, consists of four or more stacks of thin, flattened vesicles or sacs.
Substances produced in the ER are carried to the golgi complex in small , membrane-covered transfer vesicles and are modified and packaged into secretory granules or vesicles.
e.g. insulin is synthesized as a large, inactive proinsulin protein that is cut apart to make smaller, active insulin proteins within the golgi complex of the beta cells in the pancreas.
thought to make large carbohydrate molecules that combine with proteins produced in the rough ER to form glycoproteins.
Shiga and cholera toxins and plant toxins such as ricin that have cytoplasmic targets have exploited which pathway?
a retrograde transport mechanism used by the golgi apparatus
digestive system or the stomach of the cell
contain powerful enzymes that can break down excess and worn-out cell parts as well as foreign substances that are taken into the cell (e.g. bacteria taken in by phagocytosis).
maintain a pH of approx 5
membrane-bound intracellular organelles that contain a variety of enzymes that have not yet entered the digestive process.
They receive their enzymes as well as their membranes from the golgi apparatus.
they become secondary lysosomes after they fuse with membrane-bound vacuoles that contain material to be digested.
refers to digestion of a substance phagocytosed from the cell's external environment.
An infolding of the cell membrane takes external materials into the cell to form a surrounding phagocytic vesicle, or phagosome.
most common in phagocytic white blood cells such as neutrophils and macrophages
involves the digestion of damaged cellular organelles, such as mitochondria or ER, which the lysosomes must remove if the cell's normal function is to continue.
Most common in cells undergoing atrophy
undigested materials that stay in the cytoplasm
Lysosomal storage disorders
a specific lysosomal enzyme is absent or inactive, and the digestion of certain cellular substances does not occur.
there are approx 50 lysosomal storage disorders, each disorder is rare.
an autosomal recessive disorder, cells do not make hexosaminidase A, a lysosomal enzyme needed for degrading the GM2 ganglioside found in nerve cell membranes.
smaller than lysosomes, round membrane-bound organelles contain a special enzyme that degrades peroxides (e.g. hydrogen peroxide) in the control of free radicals.
also contain the enzymes needed for breaking down fatty acids with very long chains.
In liver cells, peroxidases help make bile acids.
breakdown of proteins
involved in apoptic cell death
small organelles made up of protein complexes in the cytoplasm and nucleus.
these organelles recognize misformed and misfolded proteins that have been targeted for degradation.
the power plants of the cell because they contain enzymes that can change carbon-containing nutrients into energy that is easily used by cells. this process is referred to as cellular respiration b/c it requires oxygen.
Contain their own DNA and ribosomes and are self-replicating.
shelflike projections that form the inner membrane of the mitochondria
the narrow space between the outer and inner membranes
large space inside the inner membrane
contains the respiratory chain enzymes and transport proteins needed to make ATP.
mtDNA is found in the mitochondrial matrix and is different from the chromosomal DNA found in the nucleus.
AKA the "other human genome" mtDNA is a double-stranded, circular molecule that contains the instructions to make 13 fo the proteins needed for mitrochondrial function.
inherited from the mother
Mitochondria also function as key regulators of
apoptosis or programmed cell death.
too little apoptosis is implicated in
too much apoptosis is implicated in
a network of microtubules, microfilaments, intermediate filaments, and thick filaments.
controls cell shape and movement
formed from protein subunits called tubulin
long, stiff, hollow structures shaped like cylinders.
can rapidly disassemble in one location and reassemble in another location
function in the development and maintenance of cell formation.
participate in transport mechanisms inside cells, including transport of materials in the long axons of neurons and the melanin in skin cells
participate in mitosis
Cilia and flagella
microtubule-filled cellular extensions surrounded by a membrane that is continous with the cell membrane.
in humans sperm cells are the only type of flagella
cilia are found on many epithelial linings including the nasal sinuses and bronchi in the upper respiratory system.
polycystic kidney disease
linked to a genetic defect in the cilia of the renal tubular cells
primary ciliary dyskinesia (PCD)
also called immotile cilia syndrome, causes problems in the cilia of the respiratory tract so that inhaled bacteria cannot be removed, leading to a chronic lung disease called bronchiectasis.
thin, threadlike cytoplasmic structures. There are three classes.
present in the microvilli of the intestine
similar to thin actin filaments in muscle
a group of filaments with diameter sizes between those of the thick and thin filaments
help support and maintain the shape of cells e.g. keratinocytes of the skin and glial filaments found in glial cells of the nervous system.
thick myosin filaments
in the muscle cells but may also exist temporarily in other cells
muscle contraction depends of the interaction between which two microfilaments
thin actin filaments and thick myosin filaments
found in the brain in Alzheimer disease are formed by aggregated microtubule-associated proteins and result in abnormal cytoskeletons in neurons.
a thin membrane that separates the intracellular contents form the extracellular environment.
acts as a semi permeable structure that helps determine what can and cannot enter and exit cells
contains receptors for hormones, neurotransmitters, and otehr chemical signals, as well as transporters that allow ions to cross the membrane during electrical signaling in cells
helps regulate cell growth and division
can function on both sides of the membrane or transport molecules across it. many form ion channels and are selective for which substances move through them.
mutations in channel proteins can cause genetic disorders
e.g. cystic fibrosis involves an abnormal chloride channel, which causes the epithelial cell membrane to be impermeable to the chloride ion. The defective chloride secretion with excessive sodium and water causes abnormally thick and viscid respiratory secretions, blocking the airways.
water channels or pores are also transmembrane proteins in the cell membrane.
changes in water transport through the aquaporin can cause diseases, including diabetes insipidus.
another type of transmembrane protein that allows substances to cross membranes.
e.g Glucose transporters (GLUT) are examples of carriers, and changes in movement of glucose through these carriers are involved in diabetes mellitus.
temporarily bound to one side or the other of the membrane and do not pass into the lipid bilayer, and they have functions involving the inner or outer side of the membrane where they are found.
occurs when a cell releases a chemical into the extracellular fluid that affects its own activity
acts mainly on nearby cells
relies on hormones carried in the bloodstream to cells throughout the body.
occurs in the nervous system, where neurotransmitters are released from neurons to act only on neighboring cells at synapses.
chemical messengers bind to protein receptors on the cell surface or inside of cells
cell surface receptors
receptors found in the cell membrane
receptors found within the cells
activate receptors as extracellular chemical signals including neurotransmitters, hormones, and growth factors and other chemical messengers.
chemicals that bind to receptors
additional intracellular molecules that are involved in changing the signal into a response
enzymes that catalyze the addition of a phosphate to proteins and change their structure and function.
when the number of active receptors decreases due to excess chemical signals
when the number of active receptors increases due to decreased chemical signals
G-protein linked receptors
the largest family of cell surface receptors. These receptors rely on the activity of membrane-bound, intracellular regulatory proteins to convert external signals (first messengers) into internal signals (second messengers).
Bind to guanine diphosphate (GDP) and guanine triphosphate (GTP)
transmembrane proteins with ligand-binding site on the outer surface of the cell membrane. instead of having an intracellular part that associates with a G-protein, their intracellular part either has enzyme activity or binds directly with an enzyme.
stimulate cellular responses such as calcium entry into cells, increased sodium-potassium exchange across the cell membrane, and stimulation of glucose and amino acid entry into cells.
Ion channel-linked receptors
involved in the rapid signaling between electrically excitable cells such as neurons and muscle cells.
many neurotransmitters stimulate this type of signaling by opening or closing ion channels in the cell membrane.
when the cell may leave the cell cycle and either remain in a state of inactivity or reenter the cell cycle at another.
when the cell begins to prepare for mitosis by increasing proteins, organelles, and cytoskeletal elements.
the synthesis phase, when DNA synthesis or replication occurs and the centrioles begin to replicate.
the premiotic phase and similar is similar to G1 in terms of RNA activity and protein synthesis.
when cell mitosis occurs.
what cells are not capable of mitotic division in postnatal life?
nondividing cells, such as neurons, skeletal and cardiac muscle cells, they have left the cell cycle.
cell division, the process during which a parent cell divides and each daughter cell receives chromosomes identical to the parent cell.
the process that changes the calorie-containing nutrients (carbohydrates, proteins, and fats) into ATP; which provides for the energy needs of the cell.
Three major pathways in which ATP is formed?
citric acid cycle
the electron transport chain
the process by which energy is released from glucose.
an important energy provider for cells that lack a mitochondria
also provides energy in situations when delivery of oxygen to the cell is delayed or impaired (e.g. in skeletal muscle during the first few minutes of exercise).
anaerobic conditions that result in pyruvate being converted to lactic acid?
cardiac arrest and circulatory shock
a process in which the liver and a few other tissues remove lactic acid from the bloodstream and convert it to glucose
influenced by chemical or electrical gradients and does not require an input of energy.
A difference in the number of particles on either side of the membrane creates a chemical gradient, and a difference in charged particles or ions creates an electrical gradient.
when electrical and chemical gradients are linked
e.g. positively charged sodium is higher outside the cell compared to inside and this creates both a chemical gradient (higher concentration) and electrical gradient (higher charge).
the process by which substances become widely dispersed and reach a uniform concentration b/c of the energy from their spontaneous kinetic movements.
substances move from an area of higher concentration to an area of lower concentration.
e.g. liophilic substances such as oxygen, carbon dioxide, alcohol, and steroid hormones can diffuse through the lipid layer of the cell membrane.
when a substance needs help to the cross the membrane, e.g. glucose cannot pass through the cell membrane b/c they are not lipophilic or are too large and require insulin.
regulated by the concentration of substances on either side of a membrane that cannot diffuse across the membrane e.g. if there are no open sodium channels, sodium cannot diffuse across the membrane, so that water will travel through aquaporins to dilute the area of high sodium concentration.
when cells use an input of energy to move substances against an electrical or chemical gradient
voltage gated channels
open or close with changes in the membrane potential.
chemically gated channels, which open or close when chemicals bind to the channels; these channels are also receptors, and the chemicals that bind to receptors are called ligands (e.g. the neurotransmitter acetylcholine)
open or close in response to such mechanical stimulations such as vibrations, tissue stretching, temperature, or pressure.
the concentrations of ions are often different on the two sides of the cell membrane, and this leads to differences in charge on the two sides of a cell membrane. These differences create electrical potentials across the cell membranes of most cells in the body.