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109 Cards in this Set
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- 3rd side (hint)
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Who were the first observers of cell life?
When did modern cell theory emerge? |
1. Hooke in 1663:
2. Schwann in 1800’s 3. Pasteur’s work with bacteria in 1860. Modern cell theory emerged by 1900 |
One named the cell.
Another disproved idea of spontaneous generation (living things arise from nonliving matter) |
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What are the principles of Modern Cell Theory?
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1. All organisms are composed of cells and cell products.
2. A cell is the simplest structural and functional unit of life. 3. An organism’s structure and all of its functions are ultimately due to the activities of its cells. 4. Cells come only from preexisting cells, not from nonliving matter. 5. Because of this common ancestry, the cells of all species have many fundamental similarities in their chemical composition and metabolic mechanisms. |
Five items
There are no smaller subdivisions of a cell or organism that, in themselves, are alive. |
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Name the differnet types of cell shapes.
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1. Squamous - thin, flat, angular
contours. 2. Spheroid - round to oval. 3. Polygonal - irregular angular shapes, with more than 4 sides. 4. Discoid - disc shaped. 5. Cuboidal -squarish 6. Columnar -taller than wide 7. Fusiform -thick middle with tapered ends 8. Fibrous - long, slender 9. Stellate - star-shaped |
Nine types
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What are the limitations on cell size?
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As the cell enlarges, volume increases faster than surface area so the need for increased nutrients and waste removal exceeds ability of membrane surface to exchange them
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Consisder area to volume ratio
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What is the difference between Resolution and Magnification?
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An object with the same magnification as another will have increased detail if its resolution is higher.
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What are the basic parts of a typical cell?
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1. cell membrane
2. nucleus 3. organelles 4. cytoskeleton 5. cytosol (intracellular fluid or ICF) |
Five major parts
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What is the Plasma Membrane?
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1. Defines cell boundaries
2. Controls interactions with other cells 3. Controls passage of materials in and out of cell |
3 major functions
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What is Cell Adhesion?
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Cells have binders and when two cells make contact they stop dividing.
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Tumor cells do not have this control.
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What is the cell membrane composed of?
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An oily film of phospholipids with diverse proteins embedded in it
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What are the Membrane Protein Functions?
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1. Receptors
2. Second messenger systems 3. Enzymes 4. Channel proteins 5. Carriers 6. Motor molecules 7. Cell-identity markers 8. Cell-adhesion molecules |
Eight functions
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How does the Receptor and Second-messenger System work?
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Cells communicate with chemical signals that cannot enter target cells.
Activation of the receptor may produce a second messenger inside of the cell. |
Membrane receptors bind these messengers (hormones, neurotransmitters).
Each receptor is usually specific for one messenger |
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What do enzymes in the cell do?
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1. May break down chemical messengers to stop their signaling effects
2. Produce final stages of starch and protein digestion in small intestine 3. Involved in producing second messengers inside of the cell |
Three items
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What do Channel Proteins do?
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They are Integral proteins that form pores (channels) for passage of water or solutes.
Some channels are constantly open. Others,Gated-channels, open & close in response to stimuli. |
Important in nerve signal and muscle contraction
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What are Membrane Carriers or Pumps?
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Integral proteins that bind to solutes and transfer them across membrane.
Carriers that consume ATP are called pumps |
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What are Molecular Motors?
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A filamentous protein that arises in the cytoplasm and pulls on membrane proteins causing movement.
Actin and myosin act as molecular motors. |
move materials within a cell (organelles)
move whole cells (WBC’s) change shape of cell during cell division and phagocytosis |
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What are Cell-Identity Markers?
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A surface coating that acts as a cell’s identity tag.
Composed of Glycoproteins. Enables the body to identify “self” from foreign invaders |
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What are Cell-Adhesion Molecules?
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Membrane proteins that adhere cells together and to extracellular material.
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Cells are normally mechanically linked to extracellular material
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What are the functions of the Glycocalyx?
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1. It enables the immune system to recognize normal cells from transplanted tissue, diseased cells and invading organisms.
2. It cushions and protects the cell membrane. 3. It assists in cell adhesion, fertilization and embryonic development. |
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What is the function of Microvilli?
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They increase the surface area for absorption from 15-40 times.
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What are the function of Cilia?
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Sensory: in inner ear, retina and nasal cavity
Motile: cilia beat in waves, sequential power strokes followed by recovery strokes |
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What is a flagella?
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A long whiplike structure that has an axoneme identical to that of a cilium.
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What can be said about the permiability of the plasma membrane?
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The Plasma membrane is selectively permeable.
It controls which things enter or leave the cell. |
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What is Passive transport?
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It requires no ATP
Movement of particles is down their concentration gradient. Filtration and simple diffusion are examples of passive transport. |
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What is Active transport?
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It transports particles against their concentration gradient.
Carrier mediated (facilitated diffusion and active transport) and vesicular transport are examples of active transport. |
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What is Filtration?
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Movement of particles through a selectively permeable membrane by hydrostatic pressure.
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filtration of wastes from the blood occurs in the kidneys
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What is Hydrostatic pressure?
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The force exerted on the membrane by water.
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What is Simple Diffusion?
What is Net diffusion? |
Simple diffusion is the movement of particles as a result of their constant, random motion.
Net diffusion is the movement of particles from an area of high concentration to an area of low concentration (down or with the concentration gradient) |
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What are the factors that affect the rate of diffusion through a membrane?
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1. temperature - increased temp = increased motion of particles
2. molecular weight - larger molecules move slower 3. steepness of concentration gradient - an increase in difference = increased rate 4. membrane surface area - increased area = increased rate 5. membrane permeability - increased permeability = increased rate |
Five factors
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What is Osmosis?
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Diffusion of water through a selectively permeable membrane.
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What is Osmotic Pressure?
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The amount of hydrostatic pressure required to stop osmosis is the osmotic pressure.
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What is Tonicity?
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The ability of a solution to affect fluid volume and pressure within a cell.
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What is a Hypotonic solution?
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It has low a concentration of nonpermeating solutes (high water concentration).
Cells in this solution would absorb water, swell and may burst (lyse) |
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What is a Hypertonic solution?
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It has a high concentration of nonpermeating solutes (low water concentration).
Cells in this solution would lose water +shrivel (crenate). |
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What is Carrier Mediated Transport?
What types are there? |
Proteins carry solutes across the cell membrane.
Facilitated diffusion and active transport. |
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What is Facilitated Diffusion?
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Carrier-mediated, passive transport of solute across membrane DOWN its concentration gradient.
No energy is needed. |
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What is Active Transport?
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Carrier-mediated, active transport of solute across membrane AGAINST its concentration gradient.
Energy required. ATP is used. |
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What is Vesicular Transport?
What are two types? |
Transport of large particles or fluid droplets through membrane in bubblelike vesicles of plasma membrane, uses ATP.
Exocytosis – vesicular transport out of cell Endocytosis – vesicular transport into cell |
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What are phagocytosis and pinocytosis?
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Phagocytosis – engulfing large particles by pseudopods
Pinocytosis – taking in fluid droplets |
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What are two types of Organelles?
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1. surrounded by membrane
2. not surrounded by membrane |
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Give examples of organelles
surrounded by membranes. |
nucleus, mitochondria, lysosome, perioxisome, endoplasmic reticulum, and golgi
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Seven items
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Give examples of organelles not surrounded by a membrane.
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ribosome, centrosome, centriole, basal bodies
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What is the Cytoskeleton?
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A collection of microfilaments and microtubules in the Cytoplasm.
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Describe the Nucleus.
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It is the largest organelle (5 m in diameter)
The Nuclear envelope has two unit membranes held together at nuclear pores |
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What is contained in the Nucleoplasm?
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1. Chromatin - is thread-like matter containing DNA and protein
2. Nucleoli - is dark masse where ribosomes are produced |
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Describe the Endoplasmic Reticulum.
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1. ROUGH ER - is covered with ribosomes, continuous with nuclear envelope -function in protein synthesis and production of cell membranes
2.SMOOTH ER - lacks ribosomes, continuous with rough ER function in lipid synthesis, detoxification, calcium storage |
Two types
The'Factory' |
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Describe the Golgi Complex.
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Function: is to refine, package, and deliver proteins which were made on the ribosomes
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Packaging unit
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What do Golgi vesicles do?
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They are irregular sacs near golgi complex that bud off cisternae.
Some become lysosomes, some fuse with plasma membrane and some become secretory vesicles |
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What are Lysosomes?
What are their functions? |
A package of enzymes in a single unit membrane, variable in shape.
1. Intracellular digestion - hydrolyze proteins, nucleic acids, complex carbohydrates, phospholipids and other substrates. 2. Autophagy - the digestion of worn out organelles and mitochondrion. 3. Autolysis - programmed cell death. 4. Glucose mobilization - lysosomes in liver cells break down glycogen. |
Four functions
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What are Peroxisomes?
What are their functions? |
Rhey appear similar to lysosomes but not produced by golgi complex.
In all cells but abundant in liver and kidney. 1. neutralize free radicals. 2. produce H2O2 in process of alcohol detoxification and killing bacteria. 3. break down excess H2O2 with the enzyme catalase. 4. break down fatty acids(lipids). |
Four functions
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Describe a Mitochondrion.
What is its main function? |
It is Double unit membrane
The Inner membrane contains folds called cristae Space between cristae called the matrix - contains ribosomes and small, circular DNA (mitochondrial DNA) Reproduce independently of cell and live for 10 days. ATP is synthesized by enzymes on cristae from energy extracted from organic compounds. |
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Describe Centrioles.
What is their main function? |
Short cylindrical assembly of microtubules, arranged in nine groups of three microtubules each
Two centrioles, perpendicular to each other, lie near the nucleus in an area called the centrosome these play a role in cell division these play a role in cell division also form basal bodies of cilia or flagella |
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What is the Cytoskeleton composed of?
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It is a collection of filaments and tubules that provide internal support and movement of cell
Composed of microfilaments, intermediate filaments and microtubules |
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What is a Microtubule?
What is its function? |
Acylinder of 13 parallel strands called protofilaments
Hold organelles in place and maintain cell shape Form tracks to guide organelles and molecules to specific destinations in a cell |
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Describe microfilaments and intermediate filaments.
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MICROFILAMENTS - form network on cytoplasmic side of plasma membrane called the membrane skeleton
produce cell movement, and with myosin causes muscle contraction INTERMEDIATE fibers - in junctions that hold epithelial cells together and resist stresses on a cell |
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Who first named DNA?
What did he believe it was? |
named by biochemist Johann Friedrich Miescher (1844-1895) and his student
believed it was heriditary matter of cell, but no real evidence |
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What is the structure of DNA?
When was it discovered? Who discovered it? |
The double helix
1953 Nobel Prize awarded in 1962 to 3 men: Watson, Crick and Wilkins but not to Rosalind Franklin who died of cancer at 37 from the x-ray data that provided the answers. |
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What are the DNA side rails composed of?
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A sugar phosphate backbone
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What are the horizontal rails called?
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Base pairs
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What are the horizontal rails composed of?
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PURINES - a double
carbon-nitrogen ring Can be guanine adenine PYRIMIDINES -a single carbon-nitrogen ring uracil - RNA only thymine - DNA only cytosine - both |
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What is Complementary Base Pairing?
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The Nitrogenous bases form hydrogen bonds
The following Base pairs are formed A-T and C-G Law of complementary base pairing one strand determines base sequence of another |
Law of complementary base pairing
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What are the functions of DNA?
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1. Serves as code for protein (polypeptide) synthesis
2.Gene - sequence of DNA nucleotides that codes for one polypeptide |
Two items
DNA makes up a Gene. Genes make up a Chromosome. |
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What is the Human Genome?
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Genome - all the genes of one person
humans have estimated 35,000 genes base sequence of all human genes (6 billion base pairs). |
human genome project completed in 2000 mapped it
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What is the function of RNA?
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The essential function is to interpret the DNA code and direct protein synthesis in the cytoplasm
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What is the structure of RNA?
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RNA is much smaller than DNA (fewer bases)
transfer RNA (tRNA) has 70 - 90 bases messenger RNA (mRNA) has over 10,000 bases Where DNA has over 6 billion base pairs RNA has only one nucleotide chain (not a helix) ribose replaces deoxyribose as the sugar uracil replaces thymine as a nitrogenous base |
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Give the sequence of protein synthesis.
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1. Transcription - messenger RNA (mRNA) is formed next to an activated gene
2. mRNA migrates to cytoplasm 3. transfer RNA delivers the amino acids to the ribosome 4. Translation - mRNA code is “read” by ribosomal RNA as amino acids are assembled into a protein molecule |
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How is DNA Replication accomplished?
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The Law of complimentary base pairing allows building of one DNA strand based on the bases in 2nd strand
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What are the steps in DNA Replication?
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1. DNA helicase opens short segment of helix
point of separation called replication fork 2. DNA polymerase strands replicated in opposite directions |
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What are DNA mutations?
What is the DNA error rate? |
Changes in DNA structure due to replication errors or environmental factors
Some cause no effect, some kill cell, turn it cancerous or cause genetic defects in future generations 1 error per 1,000,000,000 bases copied |
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List the pases of the Cell Cycle.
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1. G1 phase, the first gap
phase normal cellular functions begins to replicate centrioles 2. S phase, synthesis phase DNA replication 3. G2 phase, second gap phase preparation for mitosis replicates centrioles, synthesizes enzymes for cell division 4. M phase, mitotic phase nuclear and cytoplasmic division NB: G0 phase, cells that have left the cycle |
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What is Mitosis?
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The process by which one cell divides into 2 daughter cells with identical copies of DNA
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What are the functions of Mitosis?
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1. embryonic development
2. tissue growth 3. replacement of old and dead cells 4. repair of injured tissues |
nuclear division
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What are the phases of mitosis?
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1. prophase
2. metaphase 3. anaphase 4. telophase |
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What happens during Prophase?
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Chromatin supercoils into chromosomes
each chromosome = 2 genetically identical sister chromatids joined at the centromere each chromosome contains a DNA molecule Nuclear envelope(membrane) disintegrates Centrioles sprout microtubules pushing them apart towards each pole of the cell |
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What happens during Metaphase?
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Chromosomes line up on equator
Spindle fibers (microtubules) from centrioles attach to centromere Asters (microtubules) anchor centrioles to plasma membrane |
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What happens during Anaphase?
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Centromeres split in 2 and chromatids separate
Daughter chromosomes move towards opposite poles of cells Centromeres move down spindle fibers by kinetochore protein (dynein |
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What happens during Telophase?
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Chromosomes uncoil forming chromatin
Nuclear envelopes form Mitotic spindle breaks down |
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What is Cytokinesis?
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The division of the cell cytoplasm
It overlaps telophase |
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How is is Cytokinesis accomplished?
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Myosin pulls on microfilaments of actin in the membrane skeleton
Causes crease around cell equator called cleavage furrow Cell pinches in two |
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What cell phase begins after Cytokinesis?
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Interphase has begun
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What influences the timing of cell division?
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Cells divide when:
they have enough cytoplasm for 2 daughter cells DNA is replicated there is an adequate supply of nutrients there is Growth factor stimulation there is an open space in tissue due to neighboring cell death |
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When do cells stop dividing?
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When there is:
Loss of growth factors or nutrients Contact inhibition |
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What is Heredity?
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Heredity = transmission of genetic characteristics from parent to offspring
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What is a Karyotype?
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Karyotype = chart of chromosomes at metaphase
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What are Somatic cells??
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Somatic Cells are all cells other than sperm or eggs.
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How many pairs of chromosomes do humans have in Somatic cells?
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Humans have 23 pairs homologous chromosomes in SOMATIC cells (diploid number)
1 chromosome inherited from each parent 22 pairs called autosomes one pair of sex chromosomes (X and Y) normal female has 2 X chromosomes normal male has one X and one Y chromosome |
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How many pairs of chromosomes do humans have in Genetic cells?
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Sperm and egg cells contain 23 haploid chromosomes
paternal chromosomes combine with maternal chromosomes |
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What are Gene loci?
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The location of a gene on the chromosome
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What are Alleles?
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different forms of gene at same locus on 2 homologous chromosomes
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What is a Dominant allele?
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It produces protein responsible for visible trait
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What is a Recessive allele?
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expressed only when both alleles are recessive
usually produces abnormal protein variant |
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Define the Gene pool?
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The collective genetic makeup of a whole population
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What are Multiple alleles?
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more than 2 alleles for a trait
such as IA, IB, i alleles for blood type |
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What are Codominant alleles?
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Both alleles are expressed,
IAIB = type AB blood |
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What is Incomplete dominance?
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The phenotype is intermediate between traits for each allele
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What is Polygenic Inheritance?
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2 or more genes combine their effects to produce a single phenotypic trait
such as skin and eye color, alcoholism and heart disease |
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What is Pleiotropy?
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A single gene causes multiple phenotypic traits (ex. sickle-cell disease)
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What is a tumor?
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Tumors (neoplasms)
are abnormal growth, when cells multiply faster than they die oncology is the study of tumors |
oncology is the study of tumors
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What are the characteristics of benign tumors?
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connective tissue capsule, grow slowly, stays local
potentially lethal by compression of vital tissues usually have a round capsule |
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What are the characteristics of malignant tumors?
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unencapsulated, fast growing, metastatic (causes 90% of cancer deaths)
have finger-like outgrowths |
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What are the causes of Cancer?
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Carcinogens - estimates of 60 - 70% of cancers caused by environmental agents
Chemical - cigarette tar, food preservatives Radiation - UV radiation, alpha particles, gamma rays, Beta particles Viruses type 2 herpes simplex - uterus, hepatitis C - liver |
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What are is a Mutagen?
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a chemical or physical agent that induces or increases genetic mutations by causing changes in DNA.
It triggers gene mutations the cell may die, be destroyed by immune system or produce a tumor |
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What are the body's defenses against mutagens?
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1. Scavenger cells - remove them before they cause genetic damage
2. Peroxisomes - neutralize nitrites, free radicals and oxidizing agents 3. Nuclear enzymes - repair DNA 4. Tumor necrosis factor (TNF) from macrophages and certain WBCs destroys tumors |
Four ways
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What is an Oncogene?
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A gene capable under certain conditions of causing the initial and continuing conversion of normal cells into cancer cells.
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What are Sis and Ris Oncogenes?
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Sis oncogene causes excessive production of growth factors - stimulate neovascularization of tumor
Ras oncogene codes for abnormal growth factor receptors - sends constant divide signal to cell |
They usually occur together
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What are Tumor suppressor genes?
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They inhibit development of cancer
damage to one or both removes control of cell division |
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What are the effects of Malignancies?
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Displaces normal tissue, organ function deteriorates
Block vital passageways block air flow and compress or rupture blood vessels Diverts nutrients from healthy tissues - tumors have high metabolic rates They cause weakness, fatigue, emaciation, susceptibility to infection |
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What is Cachexia?
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cachexia is extreme wasting away of muscle and adipose tissue
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What is the end product of Mitosis?
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Mitosis produces 2 genetically identical daughter cells (occurs in tissue repair & embryonic growth)
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What is the end product of Meiosis?
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Meiosis produces gametes - haploid cells required for sexual reproduction
2 cell divisions (after only one replication of DNA) meiosis I separates homologous chromosome pairs producing 2 haploid cells meiosis II separates duplicated sister chromatids producing 4 haploid cells |
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