Cellular Level of Organization Flashcards

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1
Q

Cell

A

Smallest living unit in the body

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2
Q

Plasma membrane

A

Selectively permeable membrane that controls: Entry of ions and nutrients, elimination of wastes, release of secretions

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3
Q

Extracellular fluid

A

Watery medium surrounding cells; called interstitial fluid in most tissues

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4
Q

Glycocalyx (carbohydrate shell)

A

Superficial membrane carbohydrates

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5
Q

Proteoglycans

A

Carbohydrates with protein attached

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6
Q

Glycoproteins

A

Protein with carbohydrates attached

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7
Q

Glycolipids

A

Lipids with carbohydrates attached

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8
Q

Integral proteins

A

Part of cell membrane; cannot be removed without damaging cell; often span entire cell membrane; can transport water or solutes

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9
Q

Peripheral proteins

A

Attached to cell membrane surface; removable; fewer than integral proteins

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10
Q

Phospholipid bilayer

A

Mostly comprised of phospholipid molecules in two layers: hydrophilic heads at membrane surface, hydrophobic tails on the inside; isolates cytoplasm from extracellular fluid; cholesterol important for membrane fluidity

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11
Q

Plasma membrane functions

A

Physical isolation, regulation of exchange with external environment, sensitivity to environment, structural support

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12
Q

Anchoring proteins

A

Attach the plasma membrane to other structures and stabilize its position; inside the cell, membrane proteins are bound to the cytoskeleton

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13
Q

Recognition proteins

A

Detected by cells of the immune system; enzymes in plasma membranes may be integral or peripheral proteins

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14
Q

Receptor proteins

A

Bind to specific extracellular molecules called ligands

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15
Q

Ligand

A

Anything from a small ion like calcium, to a relatively large complex hormone

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16
Q

Carrier proteins

A

Bind solutes and transport them across the plasma membrane

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17
Q

Channels

A

Integral proteins containing a central pore (channel) that forms a passageway completely across the plasma membrane; the channel permits the passage of water and small solutes that cannot otherwise cross the lipid layers of the plasma membrane

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18
Q

Cytoplasm

A

Material between cell membrane and nuclear membrane; Colloid containing many proteins

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19
Q

Cytosol

A

Intracellular fluid

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20
Q

Organelles

A

Intracellular structures with specific functions

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21
Q

Cytoskeleton

A

Cellular framework components

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22
Q

Microfilaments

A

<6 nm in diameter; typically composed of actin; commonly at periphery of cell

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23
Q

Terminal web

A

Inside plasma membrane of cells forming a layer or lining

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24
Q

Intermediate filaments

A

7-11 nm in diameter; strongest and most durable cytoskeletal elements

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25
Q

Microtubules

A

~25 nm in diameter; largest components of cytoskeleton; extend outward from centrosome (near nucleus)

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26
Q

Cantrioles

A

Cylindrical structures; composed of microtubules (9 groups of triplets); two in each centrosome; control movement of DNA strands during cell division ( cells without centrioles cannot divide: red blood cells, skeletal muscle cells)

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27
Q

Cilia

A

Long, slender plasma membrane extensions; common in respiratory and reproductive tracts; also composed of microtubules: nine groups of two surrounding a central pair; anchored to cell surface with basal body; beat rhythmically to move fluids or secretions across cell

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28
Q

Ribosomes

A

Protein synthesis; two subunits (1 large, 1 small) containing special proteins and ribosomal RNA (rRNA): must join before synthesis begins; fixed ribosomes-attached to the endoplasmic reticulum; free ribosomes: throughout cytoplasm, manufactured proteins enter cytosol

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29
Q

Smooth endoplasmic reticulum

A

Lacks ribosomes; tubular cisternae

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30
Q

Rough endoplasmic reticulum

A

Has attached (fixed) ribosomes; modification of newly synthesized proteins; export to golgi apparatus

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31
Q

Functions of the smooth endoplasmic reticulum

A

Synthesis of the phospholipids and cholesterol needed for maintenance and growth of the plasma membrane, ER, nuclear envelope, and golgi apparatus; synthesis of steroid hormones, such as androgens and estrogens (the dominant sex hormones in males and females, respectively) in the reproductive organs; synthesis and storage of glycerides, especially triglycerides, in liver cells and fat cells; synthesis and storage of glycogen in skeletal muscle cells and liver cells

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32
Q

Golgi apparatus

A

Functions: renews or modifies plasma membrane, modifies or packages secretions for release from cell (exocytosis), packages special enzymes within vesicles for use in cytosol; typically consist of 5-6 flattened discs (cisternae); may be more than one in a cell; situated near nucleus

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33
Q

Membrane renewal vesicles

A

Add to plasma membrane

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34
Q

Secretory vesicles

A

Contain products to be discharged from the cell; fuse with plasma membrane and release contents into extracellular environment

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35
Q

Enzymes for cytosol

A

Contained within lysosomes: isolate damaging chemical reactions

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36
Q

Lysosomes

A

Isolated intracellular location for toxic chemicals involved in breakdown and recycling of large organic molecules

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37
Q

Lysosome functions

A

May fuse with another organelle to activate digestive enzymes; may fuse with another vesicle containing fluid or solid extracellular materials; may break down with cell injury or death causing autolysis (enzymes destroy cytoplasm)

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38
Q

Mitochondria

A

Produce energy (ATP) for cells through the breakdown of carbohydrates (glucose); vary widely in shape and number: red blood cells have none, cardiac muscle cells are 30% mitochondria by volume

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39
Q

Nucleus

A

Usually largest cellular structure; control center for cellular operations: can direct synthesis of >100,000 different proteins, coded in sequence of nucleotides, determines cells structure/function; usually only one per cell

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40
Q

Nucleoli

A

Transient, clear nuclear organelles; composed of: RNA, enzymes, proteins (histones)

41
Q

DNA

A

Instructions for protein synthesis; strands coiled: wrap around histone molecules forming nucleosomes, loosely coiled (chromatin) in nondividing cells, tightly coiled (chromosomes) in dividing cells: to begin, two copies of each chromosome held together at centromere, 23 chromosomes in somatic (general body) cells (one each from mother/father), carry instructions for proteins and RNA, also some regulatory and unknown functions

42
Q

Genetic code

A

Sequence of nucleotides

43
Q

Triplet code

A

Three nucleotides specify single amino acid

44
Q

Gene

A

Functional unit of heredity; all the DNA nucleotides needed to produce a specific protein; size varies (~300-3000 nucleotides)

45
Q

Transcription

A

Production of RNA from DNA template; all three types of RNA are formed

46
Q

Translation

A

Produces a typical protein in ~20 seconds; mRNA can interact with other ribosomes and produce more proteins; multiple ribosomes can attach to a single mRNA strand to quickly produce many proteins

47
Q

Step 1 of translation

A

mRNA binds to small ribosomal subunit: binding between mRNA and tRNA (mRNA codons with tRNA anticodons)

48
Q

Step 2 of translation

A

Small and large ribosomal subunits assemble around mRNA strand: Additional tRNAs arrive (there are more than 20 kinds: at least one for each amino acid)

49
Q

Step 3 of translation

A

Ribosome attaches to next complementary tRNA

50
Q

Step 4 of translation

A

Ribosome links amino acids forming dipeptide: more tRNAs arrive and continue forming polypeptide

51
Q

Step 5 of translation

A

Stops once stop codon is reached on mRNA: Ribosomal subunits detach (leaves intact mRNA and new polypeptide)

52
Q

Plasma membrane

A

Acts as a barrier separating cytosol and extracellular fluid (ECF); must still coordinate cellular activity with extracellular environment

53
Q

Permeability

A

Determines which substances can cross membrane

54
Q

Freely permeable

A

Any substances can cross membrane

55
Q

Selectively permeable

A

Some substances can cross membrane

56
Q

Impermeable

A

No substances can cross membrane; no living cell is impermeable

57
Q

Passive (do not require ATP)

A

Diffusion; carrier-mediated transport

58
Q

Active (require ATP)

A

Vesicular transport; carrier-mediated transport

59
Q

Diffusion

A

Continuous random movement of ions or molecules in a liquid or gas resulting in even distribution; at an even distribution, molecular motion continues but no net movement; slow in air and water but important over small distances

60
Q

Gradient

A

Concentration difference or when molecules are not evenly distributed

61
Q

Diffusion in extracellular fluid

A

water and solutes diffuse freely

62
Q

Diffusion across plasma membrane

A

Selectively restricted diffusion: movement across lipid portion of membrane, movement through membrane channel, movement using carrier molecules

63
Q

Factors that influence diffusion rates

A

Distance (inversely related), molecule size (inversely related), temperature (directly related), gradient size (directly related), electrical forces: attraction of opposite charges (+,-), repulsion of like charges (+,+ or -,-)

64
Q

Osmosis

A

Net diffusion of water across a membrane; maintains similar overall solute concentrations between the cytosol and extracellular fluid

65
Q

Osmotic flow

A

Movement of water driven by osmosis

66
Q

Osmotic pressure

A

indication of force of pure water moving into a solution with higher solute concentration

67
Q

Hydrostatic pressure

A

fluid force; can be estimate of osmotic pressure when applied to stop osmotic flow

68
Q

Osmolarity (osmotic concentration)

A

Total solute concentration in an aqueous solution

69
Q

Tonicity

A

Effect of osmotic solutions on cell volume

70
Q

Isotonic

A

Solution that does not cause osmotic flow across membrane

71
Q

Hypotonic

A

Causes osmotic flow into cell

72
Q

Hypertonic

A

Causes osmotic flow out of cell

73
Q

Carrier-mediated transport

A

Hydrophilic or large molecules transported across cell membrane by carrier proteins; many move specific molecules through the plasma membrane in only one direction

74
Q

Cotransport

A

> 1 substance same direction

75
Q

Countertransport

A

2 substances in opposite directions (carrier called exchange pump)

76
Q

Facilitated diffusion

A

Requires no ATP (=passive); movement limited by number of available carrier proteins (=can become saturated)

77
Q

Active transport

A

Requires energy molecule or ATP (=active); independent of concentration gradient

78
Q

Secondary active transport

A

Transport mechanism does not require ATP; cell often needs ATP to maintain homeostasis associated with transport

79
Q

Vesicular transport

A

Requires ATP

80
Q

Endocytosis

A

Into cell using endosomes; Receptor-mediated endocytosis; Pinocytosis: formation of endosomes with ECF, no receptor proteins involved; Phagocytosis: Produces phagosomes containing solids, phagocytes or macrophages perform phagocytosis

81
Q

Exocytosis

A

Vesicle discharges materials into ECF

82
Q

Cell division

A

Production of daughter cells from single cell; important in organism development and survival; cells have varying lifespans and abilities to divide: often genetically controlled death occurs (apoptosis)

83
Q

Mitosis

A

Pair of daughter cells half the size of parent cell: grow to size of original cell before dividing; identical copies of chromosomes in each; ends at complete cell separation (cytokinesis) followed by nondividing period (interphase): cells perform normal activities or prepares to divide again (chromosomes duplicated, associated proteins synthesized)

84
Q

Meiosis

A

Sex cells, each with only 23 chromosomes

85
Q

G0 phase

A

Not preparing for division, but is instead performing all of the other functions appropriate for that particular cell type; some mature cells, such as skeletal muscle cells and most neurons, remain in G0 indefinitely and never divide; in contrast, stem cells, which divide repeatedly with very brief interphase periods, never enter G0

86
Q

G1 phase

A

Normal cell functions plus cell growth, duplication of organelles, protein synthesis

87
Q

S phase

A

DNA replication, synthesis of histones

88
Q

G2 phase

A

Protein synthesis

89
Q

Prophase

A

Paired chromosomes tightly coiled: chromatid (each copy), connected at centromere with raised area (kinetochore); replicated centrioles move to poles: astral rays (extend from centrioles), spindle fibers (interconnect centriole pairs)

90
Q

Metaphase

A

Chromosomes align at metaphase plate

91
Q

Anaphase

A

Chromatids separate: drawn along spindle apparatus

92
Q

Telophase

A

Cells prepare to enter interphase; cytoplasm constricts along metaphase plate (cleavage furrow); Nuclear membranes reform; chromosomes uncoil

93
Q

Cytokinesis

A

Begins with formation of cleavage furrow; continues through telophase; completion marks end of cell division

94
Q

Cancer

A

Illness that disrupts normal rates of cell division; characterized by permanent DNA sequence changes (mutations); most common in tissues with actively dividing cells; compete with normal cells for resources

95
Q

Benign

A

Remain in original tissue

96
Q

Malignant

A

Accelerated growth due to blood vessel growth and supply to the area

97
Q

Invasion

A

Cells migrating into surrounding tissues

98
Q

Metastasis

A

Formation of secondary tumors