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169 Cards in this Set
- Front
- Back
Cells
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Smallest units that perform all vital physiological functions
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Atoms
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Building blocks of molecules
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Cytology
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Study of the structure and function of cells
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Somatic cells
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Include the other cells in the human body
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The human body contains _______ classes of cells. (#)
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2
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What are the two classes of cells in the human body?
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Somatic and sex cells
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What is another name for somatic cells?
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Germ cells
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There are more than _________ cells in the human body. (#)
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100 trillion
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Plasma membrane
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Barrier between cell and external environment
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Intracellular fluid (ICF)
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Fluid inside cell
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Extracellular fluid (ECF)
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Fluid outside cell
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Plasmalemma
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Plasma membrane; forms the outer boundary of the cell
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Cell membrane
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Physical barrier that separates the inside of the cell from the surrounding extracellular fluid
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Differences in and outside of the cell must be maintained to preserve _______.
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Homeostasis
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The cell membrane controls the entry of _______ and _______.
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Ions and nutrients
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What three structures does the cell membrane contain?
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Lipids, proteins, and carbohydrates
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What forms most of the cell membrane surface?
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Lipids
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Why is the cell membrane called a phospholipid bilayer?
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The phospholipids form two distinct layers
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________ and ___________ cannot enter the interior of a micelle.
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Ions and water-soluble compounds
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What is the importance of cytoplasm being isolated from the surrounding fluid environment?
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Cytoplasm composition is different than extracellular fluid and the cell can't survive if differences are eliminated
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Phospholipids
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Basic structure of membrane
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Cholesterol
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Adds fluidity to membrane and decreases permeability
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Are there more integral proteins or peripheral proteins?
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Integral proteins
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Peripheral proteins
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Bound to the inner and outer surfaces of membrane
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What are the ways membrane proteins may function? (6)
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Anchoring proteins, identifiers, enzymes, receptors, carriers, or channels
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Anchoring proteins
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Membrane proteins that may attach the cell membrane to other structures to stabilize its position
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Recognition proteins
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Identifier proteins that recognize other cells as normal or abnormal on the basis of the presence or absence of characteristic recognition proteins
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Many important recognition proteins are __________.
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Glycoproteins
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Enzymes may be _______ or ________ proteins.
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Integral or peripheral
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Receptor proteins
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Proteins that are sensitive to the presence of specific molecules
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Carrier proteins
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Proteins that bind solutes and transport them across the cell membrane
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Channels
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Central pore that forms a passageway that permits the movement of water and other solutes across the cell membrane
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What does not dissolve in lipids?
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Ions
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What are the two major kinds of channels in membrane proteins?
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Leak channels and gated channels
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Leak channels
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Permit water and ion movement at all times
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Gated channels
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Can open or close to regulate ion passage
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Amphipathic
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Have hydrophilic and hydrophobic parts
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_______ are covalently bound to membrane lipids or proteins
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Carbohydrates
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Carbohydrates account for roughly what percentage of the cell membrane?
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3%
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Calyx
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Cup
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Cytoplasm
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General term for material located inside the cell membrane and outside the membrane surrounding the nucleus
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Cytoplasm contains many more __________ than does the extracellular fluid.
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Proteins
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What are the two major subdivisions of cytoplasm?
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Cytosol (intracellular fluid) and organelles
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Cytosol
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Contains dissolved nutrients, ions, soluble and insoluble proteins, and waste products
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Organelles
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Structures that perform specific functions within the cell
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The cytosol contains a relatively high concentration of ______ and a low concentration of ________.
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Potassium ions; sodium concentration
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Extracellular fluid contains a high concentration of ________ and a low concentration of ________.
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Sodium ions; potassium concentration
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What are the two categories of organelles?
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Nonmembranous organelles and membranous organelles
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What are the cell's nonmembranous organelles? (6)
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Cytoskeleton, microvilli, centrioles, cilia, flagella, and ribosomes
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Membranous organelles
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Surrounded by lipid membranes that isolate them from the cytosol
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What are the membranous organelles? (6)
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Mitochondria, endoplasmic reticulum, golgi apparatus, lysosomes, peroxisomes, and the nucleus
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Nucleus
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Control center of cellular operations
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Nucleolus
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Site of rRNA synthesis
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What is the function of the nucleus?
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To transmit and express genetic information in the form of DNA
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How does the nucleus determine the structural and functional characteristics of the cell?
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By controlling which proteins are synthesized and in what amounts
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Nuclear envelope
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Surrounds the nucleus and separates it from the cytosol
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________ is a double-layer membrane separated by a narrow perinuclear space.
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Nuclear envelope
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Chemical communication between the nucleus and cytosol occurs through _________.
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Nuclear pores
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Nucleoplasm
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Refers to the fluid contents of the nucleus
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DNA strands are located in complex structures known as _________.
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Chromosomes
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Endoplasmic Reticulum (ER)
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Network of intracellular membranes that is connected to the nuclear envelope surrounding the nucleus
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What are the two appearances of ER?
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Rough ER and smooth ER
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What are the main differences between rough ER and smooth ER?
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Rough ER contains ribosomes, and smooth ER does not.
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Cisternae
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Round chambers that act as a reservoir for water
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The endoplasmic reticulum forms what 3 things?
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Hollow tubes, flattened sheets, and cisternae
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What are the four major functions of the endoplasmic reticulum?
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Synthesis, storage, transport, and detoxification
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What does rough endoplasmic reticulum function in doing?
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In synthesis of proteins to be packaged into vesicles
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What does smooth endoplasmic reticulum function in doing?
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In lipid synthesis, including triglycerides and steroids
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Golgi apparatus
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Consists of 5-6 flattened membrane discs that communicate with the ER to help in movement of various synthesized chemicals
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Saccules
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Flattened membrane discs contained in the Golgi apparatus
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What are the three major functions of the Golgi apparatus?
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Synthesis and packaging secretions, renewal or modification of cell membrane, and packaging special enzymes
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Mitochondria
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Small organelles where ATP is created by means of the Krebs cycle
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Cristae
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Folds located in the inner membrane of the mitochondria
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Matrix
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Surface area exposed to the fluid contents of the mitrochondria
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Metabolic enzymes in the _______ perform the reactions that provide energy for cellular function.
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Matrix
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Where do most of the cellular activities that require energy occur in?
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The surrounding cytoplasm
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Energy is stored and transferred in the form of _________.
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High-energy bonds
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What kind of group do high-energy bonds generally attach to?
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Phosphate group
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What is the most important high-energy compound?
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Adenosine triphosphate (ATP)
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_______ break the high-energy bond under controlled conditions.
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Living cells
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In the mitochondria, living cells break the high-energy bond under controlled conditions. What does ATP become? (2 things)
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ADP and phosphate
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Most cells generate ATP and other high-energy compounds through the breakdown of _________, esp. glucose.
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Carbohydrates
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Lysosomes
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Vesicles filled with digestive enzymes
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Lysosomes are produced where?
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Golgi apparatus
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Primary lysosomes contain _______.
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Inactive enzymes
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When does enzyme activation occur?
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When the lysosome fuses with the membranes of damaged organelles
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What is the function of lysosomes?
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To contain enzymes that degrade cellular or extracellular debris
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What are the two types of lysosomes?
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Endocytosis and phagocytosis
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___________ perform essential cleanup and recycling functions inside the cell.
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Lysosomes
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Peroxisomes
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Organelles that are smaller than lysosomes and carry a different group of enzymes, usu. peroxide-based enzymes
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What is the function of peroxisomes?
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To degrade certain waste molecules
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Ribosomes
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Organelles that manufacture proteins using information provided by the DNA of the nucleus
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The number of ribosomes within a particular cell varies depending on _________.
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The type of cell
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A functional ribosome consists of _____ subunits and are normally separate and distinct.
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2; large and heavy or light and small
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What must happen before protein synthesis can begin?
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A light and heavy ribosomal subunit must join together with a strand of mRNA to create a functional ribosome
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What are the two major types of functional ribosomes?
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Free ribosomes and fixed ribosomes
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Where are the free ribosomes located?
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Scattered throughout the cytoplasm
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Where are the fixed ribosomes located?
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Attached to the endoplasmic reticulum
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Vaults
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Barrel-shaped organelles that may function in transport of molecules between nucleus and cytoplasm
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Centrioles
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Paired cylindrical structures that function in development of the mitotic spindle
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Cytoskeleton
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An internal protein framework that gives the cytoplasm strength and flexibility; the "backbone" of the cell
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What are the four major components of the cytoskeleton?
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Microfilaments, intermediate filaments, thick filaments, and microtubules
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Thick filaments only appear in _________ cells.
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Muscle
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What is the most common type of microfilament?
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Actin
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What are the functions of microfilaments?
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Separation of cytoplasm during cell division and structural support for cell projections
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Microvilli
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Small, finger shaped projections of the cell membrane that greatly increase the surface area of the cell exposed to the extracellular environment
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Cilia
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Appear as 9 pairs of microtubles surrounding a central pair (9+2 structure)
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Fagella
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Whip-like structure that allows for moving upstream (sperm)
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The _______ cell is the only cell that has a flagellum in humans.
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Sperm
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What are the functions of the microtubles?
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Mitotic spindle and major component of cilia and flagella
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Where can you find microtubles in the body? (3 places)
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Respiratory tract, oviduct, and sperm
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Cell adhesion molecules
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Send signals from cell to cell
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Tight junctions
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Cell adhesion molecule that causes transepithelial transport
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Desmosomes
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Cell adhesion molecule that binds cells together for strength
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Gap junctions
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Composed of membrane proteins that allow for ions and molecules moving between cells act as a signal of electricity
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Chromosomes
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Area where DNA is stored
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Histones
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Special proteins where DNA strands are bound
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DNA strands coil around _________ allowing a great deal of DNA to be packaged in a small space.
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Histones
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Somatic cells
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All cells other than sex cells
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How many chromosomes do the nuclei of somatic cells contain?
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23 chromosomes
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One of each pair of chromosomes are derived from ________.
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Parents
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Nucleotide structure
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5-carbon carbohydrate that makes up chromosomes
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What are the two kinds of messenger molecules?
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cAMP and cGMP
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What are the 3 kinds of pyrimidines?
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Cytosine, thymine, and uracil
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What are the 2 kinds of purines?
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Adenine and guanine
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Nucleic acids are polymers of ________.
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Nucleotides
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What are the 2 kinds of nucleic acids?
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DNA and RNA
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What carbohydrate does DNA contain?
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Deoxyribose
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The DNA of the nucleus controls the cell by means of what?
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Protein synthesis
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What are the 2 levels of DNA control?
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Direct control and indirect control
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The nucleus can accelerate the rate of ________ by increasing the number of needed enzymes in the cytoplasm.
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Glycolysis
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Protein synthesis
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The role of the genetic code by means of transcription and translation
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What are the steps of protein synthesis? (3 steps)
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1. DNA ----- transcribed -----> mRNA
2. mRNA = nucleus -----> cytoplasm 3. mRNA ------ translated ------> cytoplasm to proteins |
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Gene
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Portion of DNA with code
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Triplet
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Nucleotide sequence that codes for particular amino acid
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Triplet is transcribed into ______.
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Codon
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______ is transcribed into codon.
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Triplet
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How many amino acids are there?
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20
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Each codon codes for how many amino acids?
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1
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One amino acid can be coded by how many codons?
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1+
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What is the role of RNA polymerase?
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To help with DNA's process of uncoiling (DNA sequencing) and to speed up processes
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A DNA molecule consists of a pair of DNA strands held together by what?
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Hydrogen bonding between complementary nitrogenous bases
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When does DNA replication begin?
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When various enzymes unwind and disrupt weak bonds between the nitrogenous bases
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Liga
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To tie
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Ligases
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Enzymes that link nucleotides together
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Spliced exons
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Contains code in processed mRNA
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5' CAP
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Necessary for initiation of translation of mRNA
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3' Poly A tail
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Protects mRNA from degration
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Translation requires what 3 things?
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mRNa, tRNA, and rRNA
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Where does translation occur?
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In the cytoplasm
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What are the two kinds of tRNA?
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Charged tRNA and free tRNA
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What's the difference between charged tRNA and free tRNA?
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Charged tRNA is amino-acid-bound, and free tRNA is not
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What are the 2 tRNA binding sites?
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P site and A site
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What is the difference between the P site and the A site?
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The P site holds tRNA with the last amino acid added to the polypeptide chain, and the A site hols tRNA with next amino acid to be added
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The ultimate destination of translation depends on _________.
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Leader sequence
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Mitosis
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Process that separates duplicated chromosomes of the original cell into two identical nuclei
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________ specifically refers to the division and the duplication of the nucleus of the cell.
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Mitosis
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_______ is the reproduction of the nucleus of the cell.
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Mitosis
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_________ is the reproduction of the cell itself.
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Cytokinesis
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Cytokinesis
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Division of cytoplasm to form new distinct cells
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What are the four stages of mitosis?
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Prophase, metaphase, anaphase, and telophase
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Prophase
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Phase of mitosis that begins when the chromosomes coil so tightly that they become visible as individual structures
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Metaphase
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Phase of mitosis that begins after the degeneration of the nuclear evelope
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Metaphase ends when _________.
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Chromatids are aligned
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Anaphase
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Phase of mitosis that begins when the chromatid pair splits
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Anaphase ends when ________.
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Daughter chromosomes arrive near the centrioles
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Telophase
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Phase of mitosis that begins when each cell prepares to return to the interphase state
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_______ marks the end of mitosis.
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Telophase
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_______ is the formation of two new cells; ______ is the formation of two new nuclei.
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Cytokinesis; mitosis
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