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Chapter 3 Cell Biology
Terms and concepts from Chapter 3
182
Physiology
Undergraduate 1
04/09/2013

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Term
Extracellular Fluid
Definition
Fluid outside the cell (outside the plasma membrane). Includes Interstitial fluid and blood plasma.
Term
Interstitial Fluid
Definition
Fluid found between cells, though not inside blood vessels.
Term
Plasma Membrane
Definition
Membrane that separates stuff inside the cell from stuff outside the cell.
Term
Cytoplasm
Definition
General term for material Plasma membrane and the nucleus of cell.
Term
What are the two major component groups of Cytoplasm?
Definition
Cytosol and Organelles
Term
Cytosol
Definition
Fluid component of Cytoplasm (Intracellular fluid).
Term
Organelles
Definition
"Little Organs" intracellular structures with specific functions.
Term
Describe the two classes of organelles:
Definition
Nonmembranous and membranous.
Term
Name the Nonmebranous Organelles:
Definition
Cytoskeleton, Microvilli, Centrioles, Cilia, Ribosomes.
Term
Name the Membranous Organelles:
Definition
Mitochondria, Nucleous, Endoplasmic Reticulum (ER), Golgi Apparatus, Lysosomes, Peroxisomes.
Term
Peroxisome functions:
Definition
Breakdown organic chemicals, neutralize toxic compounds generated in this process (Reactive Oxygen Species - specifically hydrogen peroxide). May be important in cholesterol creation.
Term
Lysosome functions:
Definition
Breakdown of organic compounds, damaged organelles, and pathogens.
Term
Microvilli functions:
Definition
Increase surface area to facilitate absorption of extracellular materials.
Term
Golgi Apparatus functions:
Definition
Storage, alteration, and packaging of synthesized products.
Term
Nucleus functions:
Definition
Control of metabolism, storage/processing of genetic info., controls protein synthesis.
Term
Endoplasmic reticulum (ER) functions:
Definition
This widely disseminated organelle provides for transport within the cell, as well as the synthesis of secretory products (proteins, lipids and carbohydrates.)
Term
What products come from the smooth ER?
Definition
lipids and carbohydrates.
Term
What products come from the rough ER?
Definition
The ribosomes covering the Rough ER synthesize proteins.
Term
Ribosomes functions:
Definition
Protein synthesis. Target of Ricin poison.
Term
Cytoskeleton functions:
Definition
Strengthen and support the cell. Move cellular structures and materials.
Term
Mitochondria functions:
Definition
Cellular powerhouse where 95% of ATP. Site of Oxidative phosphorylation. Target of cyanide poison.
Term
Glycocalyx location and functions:
Definition
Superficial exterior of plasma membrane. These carbohydrate containing molecules are important in cell recognition, binding to extracellular structures, and lubrication of the cell surface.
Term
Integral Protein location and functions:
Definition
Also known as transmembrane proteins, these span the depth of the cell membrane and create machinery to allow selective movement of molecules into and out of the cell.
Term
Explain the structure and importance of the phospholipid bilayer.
Definition
Composed of two layers of phospholipid molecules with the hydrophilic heads towards the interior and exterior surfaces of the plasma membrane, the hydrophobic layer in the middle provides an effective barrier to separate the interior and exterior of the cell. Sugars and proteins are forced to use transmembrane proteins to enter or leave the cell.
Term
Peripheral proteins: location and function:
Definition
These proteins, locate on the inside or outside of the plasma membrane, are not integral to it, and their removal will not disrupt the integrity of the membrane. They have regulatory and enzymatic functions.
Term
Anchoring Proteins:
Definition
Membrane protein: Stabilizes plasma membrane by attaching (anchoring) it to the cytoskeleton and other internal structures.
Term
Recognition Proteins:
Definition
Membrane protein: Used by immune system to tell self from other cells. May be integral or peripheral.
Term
Recong
Definition
Term
Receptor Proteins:
Definition
Membrane protein: binds to specific extracellular molecules (ligands). Binding can then go on to create a biological response. Ligand examples: epinephrine, Ca++. Also target of many medications.
Term
Carrier Proteins:
Definition
Membrane protein: Binds and transports solutes across cell membrane.
Term
Channels:
Definition
Membrane protein, integral: Opens and closes to permit/restrict passage of solutes/ions across membrane.
Term
Microfilaments: Location in cell, size, protein composition.
Definition
Located mostly in periphery of cell. Scarce in center around nucleous. Usually < 6nm in diameter. Made of protein Actin.
Term
Terminal web:
Definition
Found just inside the plasma membrane under microvilli. Microfilaments in the microvilli are anchored to the Terminal Web. The terminal web contains contractile fibers, which allow the cell to spread the microvilli apart, increasing surface area and absorption rate.
Term
Intermediate filaments:
Definition
7-11 nm in diameter...strongest, most durable cytoskeletal elements.
Term
Microtubules:
Definition
Approx. 25nm in diameter, these extend from a region near the nucleus (the centrosome) to the periphery of the cell.
Term
Centrioles:
Definition
Cylindrical structures composed of short microtubules. The ring structure is composed of nine groups of three microtubules.  There are two centrioles in the centrosome.  The centrioles are associated with movement of DNA strands during cell division.  IF A CELL LACKS CENTRIOLES, IT CAN'T DIVIDE (e.g. RBC's and skeletal muscle)
Term
Centrosome:
Definition
Anchor for microtubules. Regulates cell-division cycle.
Term
Cilia:
Definition

Long, slender extensions of the plasma membrane. Found in respiratory and reproductive tract, in particular. Underlying protein structure is similar to cenrioles, except with paired groups of microtubules, rather than triplicate. Additionally, there are to microtubules in the core.

 

 

Term
Basal Body:
Definition
The end of the centriole, and origin of the cilia. The cilia is anchored to the centriole and grows from the basal body.
Term
What is the ribosome comprised of?
Definition
Two sub-units, the small ribosomal subunit and the large ribosomal subunit.
Term
What membranous structure is the ER connected to?
Definition
The nuclear envelope of the nucleus.
Term
What are the chambers in the ER called?
Definition
Cisternae.
Term
Describe the difference between the cisternae in the rough ER vs. the smooth ER:
Definition
The cisternae in the rough ER are flattened, while those in the smooth ER are round/tubular.
Term
Describe the principle functions of the smooth ER in detail:
Definition
- Synthesis of phospholipids for all of the different membranes in the cell, including plasma, nucleus, Golgi, and ER.
- Synthesis of steroid hormones in reproductive cells.
- Synthesis/storage of glycerides in liver and fat cells.
- Synthesis/storage of glycogen in skeletal muscles/liver.
Term
Describe the generalized steps of protein creation and packaging in the rough ER.
Definition
1. Polypeptide synthesis from ribosome. The chain enters the cisterna of the rough ER.
2. Secondary and tertiary folding of polypeptide.
3. Completion of protein/optional addition of carbohydrates to create glycoproteins.
4. Packaging of glycoproteins/protein/enzymes in Transport Vesicles.
5. Delivery of these molecules to the Golgi apparatus via Transport Vesicles.
Term
What is the percentage of smooth ER vs. rough ER in the cells.
Definition
It depends on the cell's need to produce proteins, especially enzymes. Organs, such as the pancreas which create large amounts of digestive enzymes, have large amounts of rough ER and very little smooth ER.
Term
Name the three principle functions of the Golgi:
Definition
1. Renewal/Modification of plasma membrane.
2. Modification and packaging of secretions for release through exocytosis.
3. Packaging special enzymes in vesicles for use in cytosol.
Term
What are the three general areas of the Golgi Ap?
Definition
Forming face, Cisternae, Maturing face.
Term
Explain the path proteins take from the ER through the Golgi App.
Definition
Proteins are packaged into transport vesicles which usually begin interaction with the Golgi app. by fusing with the Forming face. Proteins move from cistern to cistern through small vesicles and may be altered in the process. Eventually, proteins reach the Maturing face (final cistern), where they will leave via vesicles to their ultimate purpose.
Term
What are the three destinations for vesicles leaving the Golgi App.
Definition
Secretory vesicles fuse with the Plasma Membrane and dump their contents into the extracellular fluid. Lysosomes package enzymes for use within the cell. Membrane renewal vesicles fuse with the Plasma membrane, where the surface of the vesicle increases the surface area of the Plasma membrane. Conversely, parts of the plasma membrane can move inward, pinching off and later fusing with the Golgi App. in order to decrease plasma membrane surface area.
Term
What are three basic functions of lysosomes?
Definition
1. Fuse with the membrane of another organelle. This will cause the release of degradative enzymes which dissolve the organelle.
2. Fuse with a vesicle containing fluid or solid from outside the cell. One example of this is phagocytosis.
3. Autolysis or Autophagy: the release of large amounts of degradative enzymes into the cytosol following irreversible cell injury. Leads to necrosis.
Term
How does Apoptosis differ from autolysis?
Definition
Apoptosis is Programed Cell Death, and is both a physiological and pathophysiological phenomenon. Unlike autolysis, Apoptosis progresses in an orderly fashion to break down the cell. Some characteristics of Apoptosis are: blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation.
Term
What are the physiologic and pathologic conditions under which Apoptosis can occur?
Definition
During development, it is necessary to remove cells that were originally placed. For example Apoptosis is used to remove the cells between the fingers, allowing for the differentiation of them.
Pathological causes of Apoptosis usually involve conditions which fatally injure the cell's DNA: radiation damage, cancer, and viral infection. Additionally, conditions which result in atrophy in an organ can trigger Apoptosis signals.
Term
"With the exception of ___________, all organelles are either interconnected or in communication through the movement of vesicles."
Definition
mitochondria.
Term
Membrane flow:
Definition
The continuous movement and exchange of chemicals via vesicles. IN A ACTIVELY SECRETING CELL, AN AREA EQUAL TO THE ENTIRE MEMBRANE SURFACE MAY BE REPLACED EACH HOUR.
Term
Describe the structure of the mitochondrial membrane.
Definition
There is an inner and outer membrane. The outer membrane is smooth, while the inner membrane has numerous infolds, called Cristae.
Term
Explain the purpose of the Cristae's geometry.
Definition
The folds greatly increase surface area, allowing more sites for the metabolic enzymes.
Term
Explain the roll of energy production within the cytosol:
Definition
Glycolysis, which cleaves glucose into two parts produces a net of 2 ATP.
This process costs 2 ATP to happen, and produces 4 ATP and 2 NADH. The latter are only useful if oxidative phosphorylation is available.
Term
Besides high-energy molecules, what is the end product of glycolysis?
Definition
2 Pyruvate
Term
Explain the function of the Citric Acid Cycle:
Definition
To break down Pyruvate into carbon dioxide and hydrogen atoms.
Term
What are the hydrogen atoms used for?
Definition
They are delivered to enzymes on the surface of the Cristae, where they catalyze ATP synthesis.
Term
What percentage of ATP production is produced using aerobic metabolism?
Definition
95%
Term
How many proteins can the nucleus code for?
Definition
> 100,000.
Term
Describe the structure of the nuclear envelope:
Definition
The nuclear envelope is composed of a double membrane. Nuclear pores punctuate the surface (about 10% of the surface).
Term
What is the perinuclear space?
Definition
The space in between the two membranes of the nuclear envelope.
Term
What is the function of the nuclear envelope?
Definition
This membrane separates the nuclear material (DNA, RNA, nucleoplasm) from the cytosol.
Term
What is the function of the Nuclear Pores?
Definition
Permit chemical communication between cytosol and nucleus.
Term
What is nucleoplasm?
Definition
The fluid component of the nucleus contents.
Term
What is the nuclear matrix?
Definition
A network of fine filaments within the nucleoplasm provides structural support and may be involved in the regulation of genetic activity.
Term
What other components are found in the nucleoplasm?
Definition
Ions, enzymes, RNA and DNA nucleotides and small amounts of RNA and DNA.
Term
What are nucleoli?
Definition
These are temporary organelles that synthesize Ribosomal RNA.
Term
What are nucleoli composed of?
Definition
RNA, enzymes, and histone proteins.
Term
What cells are nucleoli most prominent in?
Definition
Those which make a lot of proteins: liver, nerve, muscles.
Term
What is the purpose of Histone?
Definition
It winds the DNA when it is not dividing so that it is not so long.
Term
What are the coiled complexes of DNA called?
Definition
Nucleocomes.
Term
What is the loosely coiled tangle of DNA found under normal circumstances called?
Definition
Chromatin.
Term
What happens to the coils of DNA at the start of cell division?
Definition
The coils become tighter and more complex until chromosomes are formed.
Term
What is the centromere?
Definition
The connecting point connecting the duplicates in the chromosomes.
Term
How many pairs of chromosomes are there in somatic cells?
Definition
23.
Term
What is the triplet code?
Definition
The genetic code is organized in groups of three, with each iteration of three nitrogenous bases coding for a different amino acid.
Term
What are the four nitrogenous bases in DNA?
Definition
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Term
What is a gene?
Definition
the functional unit of heredity...A section of DNA containing all the nucleotides needed to code for a specific protein. A gene's size depends on the size of the protein it codes for.
Term
What must happen before a section of DNA can be used to make protein?
Definition
It must be uncoiled and have its histones removed.
Term
What is Gene Activation.
Definition
The process that controls DNA preparation for protein synthesis.
Term
What happens after DNA has been unwound?
Definition
Messenger RNA (mRNA) is assembled by enzymes. The mRNA contains the complimentary base pairs to the DNA.
Term
What are the complimentary base pairs for DNA?
Definition
T-A
C-G
Term
What are the complimentary RNA-DNA base pairs?
Definition
U-A
C-G
Term
What are the triplets coded on the mRNA called?
Definition
codons
Term
Where happens to the completed mRNA?
Definition
It passes through a nuclear pore to the cytoplasm.
Term
What is an anticodon?
Definition
A complimentary triplicate to a codon on the mRNA. Each anticodon is part of a specific tRNA, which carries a specific amino acid.
Term
What is the function of the Ribosomal RNA (rRNA)?
Definition
String together amino acids in the order they are presented by the tRNA.
Term
What is Transcription?
Definition
The production of RNA from DNA.
Term
Explain the steps of Gene Activation:
Definition
1. Disruption of hydrogen bonds
2. Removal of histone guarding Control Segment (first segment of Gene)
Term
What is mRNA polymerase?
Definition
The enzyme that helps form hydrogen bonds between the DNA bases and their complimentary RNA bases.
Term
How are mRNA bases attached to each other?
Definition
By covalent bonds.
Term
What happens when mRNA polymerase reaches the "stop" signal in the DNA strand?
Definition
The enzyme detaches, transcription ends, and the complimentary DNA strands come back together.
Term
What is immature or pre-RNA?
Definition
mRNA before the removal of non-functional triplets.
Term
What are introns and exons?
Definition
Introns are the non-functional or nonsense regions of the mRNA that have to be removed before meeting up with tRNA.
Exons are the functional parts of the mRNA that are the spliced together.
Term
Does each gene code for only one protein?
Definition
No. By controlling which introns are removed, the gene can code for different proteins.
Term
What is Translation?
Definition
The formation of linear chains of amino acid based on the mRNA sequence. The nucleotide sequence is "translated" into an amino acid sequence.
Term
Describe the steps of Translation, including the functioning of the ribosome:
Definition
1. mRNA binds to small ribosomal subunit.
2. First tRNA binds to start codon of mRNA.
3. Large ribosomal subunit interlocks around mRNA.
4. 2nd tRNA with anticodon moves into 2nd space in ribosome.
5. Ribosome connects the two amino acids.
6. The first tRNA (without its amino acid) leaves the ribosome. The second moves over to where the first was as the ribosome moves down 1 codon.
7. A third tRNA moves into the spot that was formally occupied by the second.
8. The amino acids on the second tRNA are attached by the ribosome to the new tRNA's amino acid. The second tRNA leaves.
9. This continues until the stop signal.
10. The ribosomal units detach, leaving the intact mRNA strand and a polypeptide.
Term
How long does the translation process take?
Definition
About 20 seconds for a typical protein.
Term
Does the mRNA code for only a single protein?
Definition
A single mRNA strand can be used to produce many copies of the same protein over minutes to hours before being broken down.
Term
Can multiple ribosomes be used to make the same protein?
Definition
No, but multiple ribosomes can be attached to the same mRNA to simultaneously make multiple protein copies.
Term
What is the property of the plasma membrane that determines what substances can cross it?
Definition
Permeability.
Term
What differences in materials can be selectively allowed or blocked by selectively permeable membranes?
Definition
Size, electrical charge, molecular shape, lipid solubility, or other factors.
Term
Do all cells share the same membrane permeability?
Definition
No, differences in lipids and proteins in the plasma membrane cause different cells to have different membrane permeabilities.
Term
What is the difference between passive and active transport.
Definition
Active transport requires ATP.
Term
Explain diffusion.
Definition
The movement of molecules down a concentration gradient.
Term
What is carrier-mediated transport, and is it passive or active?
Definition
It is transport via carrier proteins. It can be passive or active.
Term
What is vesicular transport and is it passive or active?
Definition
The transport of molecules by being enveloped by a vesicle and take into the cell. This is active.
Term
What is diffusion driven by?
Definition
The innate motion of molecules, and the tendency of this movement to spread out a collection of molecules over time.
Term
What happens to the motion of molecules after they have spread out evenly?
Definition
The motion of the molecules continues, but there is no further NET movement of molecules from one place to another.
Term
What factors influence diffusion rates?
Definition
Distance - the shorter the faster.
Size - the smaller the faster.
Temperature - the hotter the faster.
Gradient - the steeper the faster (the greater the difference in concentration of solute from one area to another).
Electrical forces - Opposites attract, alike repel. This can work for or against diffusion speed.
Term
What is Osmosis?
Definition
The diffusion of water through solutes.
Term
Explain the concept of Osmosis, esp. across semi-permeable membranes.
Definition
Water is a molecule, too, and if there is a semi-permeable membrane that restricts the movement of solutes, and a concentration difference between the two areas separated by this membrane, the water will diffuse across the membrane towards the side with a higher solute concentration. In effect, the water is moving DOWN its concentration gradient.
Term
What is osmotic flow?
Definition
The movement of water driven by osmosis.
Term
What is osmotic pressure?
Definition
The force of the water moving into the solution of higher solute concentration.
Term
What is hydrostatic pressure?
Definition
Pressure exerted by a fluid.
Term
What is osmolarity?
Definition
How much solute there is in a solution (osmotic concentration).
Term
What is tonicity?
Definition
Osmolarity in regards to cells.
Term
Explain isotonic:
Definition
The concentration of solutes does not cause a net flow of water in or out of a cell through osmosis (same effective concentration of solutes outside and inside of cell).
Term
Explain hypotonic:
Definition
A solution that cause a flow into the cell (lower effective concentration of solutes outside the cell as in.) This can cause the cell to SWELL and pop like a balloon (Hemolysis).
Term
Explain hypertonic:
Definition
Concentration of solutes that causes water to flow out of cell (Higher effective concentration of solutes outside the cell as in). Leads to shrinkage and Crenation of cell.
Term
What is normal saline?
Definition
An isotonic solution comprised of 0.9% Sodium Chloride.
Term
What kinds of molecules do carrier proteins move?
Definition
Lipid insoluble and ones that are too large to fit through a membrane channel.
Term
What is cotransport?
Definition
Moving more than one substance in the same direction siumultaneously.
Term
What is countertransport?
Definition
Moving two substances in opposite directions.
Term
What are carrier proteins that perform countertransport called?
Definition
Exchange pumps.
Term
Explain how Facilitated Transport works:
Definition
A molecule moves down its concentration gradient by way of a carrier protein. It binds to a receptor site on one side of the membrane. The protein changes shape, moving the molecule into a position where it can disengage and have access to the cytosol.
Term
Does a higher concentration gradient speed up movement with Facilitated Transport.
Definition
To a point...once all carrier proteins are saturated, further increases in concentration gradient don't increase movement speed across membrane.
Term
What is a key advantage of active transport?
Definition
It can move molecules AGAINST the concentration gradient.
Term
Explain how the Na/K ATPase pump works:
Definition
By using 1 ATP, this pump moves 3 Na out of the cell at the same time it moves 2 K into the cell.
Term
Explain Secondary Active Transport, and give an example:
Definition
The carrier protein doesn't require energy, but energy will need to be expended, nonetheless, in order to maintain homeostasis because of the way the pump works.

An example is a carrier protein that passively moves 1 Na into the cell along with 1 glucose. If this transport continues functioning, Na levels in the cell will increase to unacceptable levels. A Na pump will have to be employed to move Na back out of the cell, and this will cost ATP.
Term
What are the two main categories of vesicular transport?
Definition
Endocytosis and exocytosis.
Term
What is endocytosis?
Definition
The formation of vesicles at the cell surface.
Term
What is an Endosome?
Definition
This is the name for the vesicle formed during endocytosis.
Term
What is receptor-mediated endocytosis?
Definition
Endocytosis that is set in motion by the interaction of a carrier protein with specific recognition substances like Fe++ or cholesterol on its surface. These interact with receptors and set in motion endocytosis.
Term
Explain the steps of receptor-mediated endocytosis:
Definition
1. Materials bind to receptors on membrane surface. Most receptors are ligand-specific.
2. An area of receptors is covered in ligands. Once enough receptors are covered, this area begins to move inward forming a groove, then a pocket.
3. The sides of the cell membrane surrounding the pocket move towards each other until they meet and pinch off. This pocket is now a sealed vesicle.
4. This vesicle is called a Coated Vesicle because the inside is coated with a protein-fiber network.
5. The coated vesicle fuses with lysosomes.
6. The lysosome enzymes free the ligands from their receptors and the ligands enter the cytosol by diffusion or active transport.
7. The vesicle membrane detaches from the lysosome.
8. The vesicle membrane fuses again with the surface membrane and is ready to bind with ligands again.
Term
Explain pinocytosis:
Definition
"Cell Drinking" - the formation of endosomes filled with extracellular fluid.
Term
Compare pinocytosis to receptor-mediated endocytosis.
Definition
Though vesicle creation is similar, pinocytosis is less selective in the material enclosed because of the lack of receptor-ligand binding.
Term
Explain phagocytosis:
Definition
"Cell Eating" - this is the envelopment and digestion of large, solid objects, such as bacteria.
Term
What kind of cells can perform phagocytosis?
Definition
Only phagocytes or macrophages.
Term
What is produced when a bacteria is enveloped by a phagocyte?
Definition
A Phagosome, analogous to a vesicle, but much larger, and irregularly shaped, is formed within the cytosol.
Term
Explain the steps of Phagocytosis:
Definition
Cytoplasmic extensions (pseudopodia) surround the object, then fuse their tips together, engulfing the object. The container (phagosome) fuses with a lysosome, which deliver digestive enzymes into the phagosome to break down the object. Nutrients are released into the cytosol, while the rest is ejected from the cell by exocytosis.
Term
What is exocytosis?
Definition
The release of material to the extracellular environment by the fusing of the vesicle to the plasma membrane.
Term
How many cells are there in the human body at maturity?
Definition
~ 75 trillion.
Term
What is apoptosis?
Definition
Genetically controlled death of a cell - it is orderly and efficient, as compared with cell necrosis.
Term
What is mitosis?
Definition
The production of two daughter cells, each with a complete set of 46 chromosomes (normal cell division).
Term
What is meiosis?
Definition
The production of sex cells, which only have 23 chromosomes.
Term
What is interphase?
Definition
The period of the cell life cycle when the cell is NOT actively dividing.
Term
When are the chromosomes duplicated?
Definition
During interphase.
Term
What is cytokinesis?
Definition
The division of the cytoplasm, which ends the period of mitosis and results in two daughter cells.
Term
What are daughter cells?
Definition
The two cells resulting from mitosis. They both have the complete set of 46 chromosomes, but are have the size of the original cell.
Term
What are the phases of Interphase, in order?
Definition
Go G1 S G2
Term
What is the Go phase?
Definition
This is the part of interphase where no preparation for cell division is occurring. Normal cell functions occur.
Term
What cells remain in Go indefinitely?
Definition
Skeletal muscles and neurons.
Term
What cells never enter Go?
Definition
Stem cells.
Term
What happens during the G1 phase?
Definition
The creation of two sets of the necessary organelles: mitochondria, Golgi App, ER, cytoskeletal elements, ribosomes, cytosol. Centriole replication begins and usually continues through G2.
Term
How long can G1 phase? last?
Definition
As short as 8-12 hours.
Term
What happens during S phase?
Definition
Duplication of chromosomes, histones, and nucleic proteins.
Term
How long does S phase last?
Definition
6-8 hours.
Term
What happens during the G2 phase?
Definition
This is a period after DNA replication when additional proteins are synthesized and centriole replication completed.
Term
How long does G2 phase last?
Definition
2-5 hours.
Term
What are the phases of Mitosis, in order?
Definition
Prophase Metaphase Anaphase Telophase
Term
How long does Mitosis take?
Definition
1-3 hours.
Term
Summarize the times needed for all phases of cell life:
Definition
Go: very short to indefinite G1: 8 or more hours S: 6-8 hours G2: 2-5 hours Mitosis: 1-3 hours.
Term
Describe the steps of DNA replication:
Definition
1. Enzymes unwind strands and disrupt hydrogen bonds between bases.
2. DNA polymerase molecules bind to these exposed bases. This enzyme encourages binding between the strand and free floating complimentary bases in the necleoplasm and links the arriving complimentary bases together with covalent bonds.
3.The unzipping of the strand and work of DNA polymerase molecules continues until there are two complete sets of DNA.
Term
How does the work of DNA polymerase differ between the two unwinding strands?
Definition
DNA polymerase can only work towards the "zipper" on one strand and away from the "zipper" on the other. The former simply attaches at the end, and works continuously towards the zipper as the two strands separate. The latter must use multiple DNA polymerase molecules which "hop on" to the strand near the zipper point and work away from it. As they reach a section of DNA that has already been duplicated by another DNA polymerase molecule, the ends of the complimentary bases are spliced together.
Term
What is the name of the enzyme that splices together the complimentary base sections added during DNA replication?
Definition
Ligase.
Term
Compare mitosis vs. cytokinesis:
Definition
Mitosis is the division and duplication of the cell's nucleus.
Cytokinesis is the division of the cytoplasm into two distinct cells.
Term
Describe Prophase:
Definition
- The chromosomes coil tightly enough to be visible under light microscope.
- The pairs of centrioles move to opposite sides of the nucleus.
- Microtubules are visible in two types: Astral rays, looking like a corona around the centrioles extend into the cytoplasm. Spindle fibers connect to the Kinetochores on the Chromatids.
- The nuclear membrane disintegrates.
Term
Describe Metaphase:
Definition
The Chromatids move towards the a narrow central zone called the Metaphase plate. When they are lined up, Anaphase begins.
Term
Describe Anaphase:
Definition
The Chromatid centromere splits, and the chromosomes are separated and pulled along the spindle fibers.
Term
Describe Telephase:
Definition
- Creation of new nuclear envelopes.
- Enlargement of nuclei.
- Uncoiling of DNA.
- Thus ends Mitosis
Term
Describe Cytokinesis and the phases it occurs during:
Definition
Separation of the cells begins as the plane of the metaphase plate begins to cleave inward. This process begins during anaphase and competes during telophase.
Term
What is the cause of cancer?
Definition
Permanent alterations to the DNA (mutations) which disrupt normal control mechanisms of cell division.
Term
Which tissues are the most common to have cancer in?
Definition
Because during mitosis, there is a chance of an error occurring during DNA replication, cells that divide rapidly and continuously are more likely to get cancer. E.g. epithelial cells in intestines or skin.
Term
What is a tumor or neoplasm?
Definition
A mass or swelling caused by abnormal cell growth and division.
Term
Explain benign tumor:
Definition
A tumor that remains within its original tissue.
Term
Explain malignant tumor:
Definition
A tumor that has some of these properties:
- Divides very rapidly, releasing chemicals to stimulate blood vessel growth to support it.
- Metastasis: cells that break off from the original tumor to create other tumors elsewhere.
Term
How does the cancer kill the patient?
Definition
Destruction of vital processes by replacing useful cells with useless cells. Compression of vital organs.
Increased or decreased creation of key hormones or enzymes.
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