Cellular Level of Organization Flashcards
1
Q
Cell
A
Smallest living unit in the body
2
Q
Plasma membrane
A
Selectively permeable membrane that controls: Entry of ions and nutrients, elimination of wastes, release of secretions
3
Q
Extracellular fluid
A
Watery medium surrounding cells; called interstitial fluid in most tissues
4
Q
Glycocalyx (carbohydrate shell)
A
Superficial membrane carbohydrates
5
Q
Proteoglycans
A
Carbohydrates with protein attached
6
Q
Glycoproteins
A
Protein with carbohydrates attached
7
Q
Glycolipids
A
Lipids with carbohydrates attached
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
9
Q
Peripheral proteins
A
Attached to cell membrane surface; removable; fewer than integral proteins
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
11
Q
Plasma membrane functions
A
Physical isolation, regulation of exchange with external environment, sensitivity to environment, structural support
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
13
Q
Recognition proteins
A
Detected by cells of the immune system; enzymes in plasma membranes may be integral or peripheral proteins
14
Q
Receptor proteins
A
Bind to specific extracellular molecules called ligands
15
Q
Ligand
A
Anything from a small ion like calcium, to a relatively large complex hormone
16
Q
Carrier proteins
A
Bind solutes and transport them across the plasma membrane
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
18
Q
Cytoplasm
A
Material between cell membrane and nuclear membrane; Colloid containing many proteins
19
Q
Cytosol
A
Intracellular fluid
20
Q
Organelles
A
Intracellular structures with specific functions
21
Q
Cytoskeleton
A
Cellular framework components
22
Q
Microfilaments
A
<6 nm in diameter; typically composed of actin; commonly at periphery of cell
23
Q
Terminal web
A
Inside plasma membrane of cells forming a layer or lining
24
Q
Intermediate filaments
A
7-11 nm in diameter; strongest and most durable cytoskeletal elements
25
Microtubules
~25 nm in diameter; largest components of cytoskeleton; extend outward from centrosome (near nucleus)
26
Cantrioles
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)
27
Cilia
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
28
Ribosomes
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
29
Smooth endoplasmic reticulum
Lacks ribosomes; tubular cisternae
30
Rough endoplasmic reticulum
Has attached (fixed) ribosomes; modification of newly synthesized proteins; export to golgi apparatus
31
Functions of the smooth endoplasmic reticulum
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
32
Golgi apparatus
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
33
Membrane renewal vesicles
Add to plasma membrane
34
Secretory vesicles
Contain products to be discharged from the cell; fuse with plasma membrane and release contents into extracellular environment
35
Enzymes for cytosol
Contained within lysosomes: isolate damaging chemical reactions
36
Lysosomes
Isolated intracellular location for toxic chemicals involved in breakdown and recycling of large organic molecules
37
Lysosome functions
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)
38
Mitochondria
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
39
Nucleus
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
40
Nucleoli
Transient, clear nuclear organelles; composed of: RNA, enzymes, proteins (histones)
41
DNA
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
Genetic code
Sequence of nucleotides
43
Triplet code
Three nucleotides specify single amino acid
44
Gene
Functional unit of heredity; all the DNA nucleotides needed to produce a specific protein; size varies (~300-3000 nucleotides)
45
Transcription
Production of RNA from DNA template; all three types of RNA are formed
46
Translation
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
Step 1 of translation
mRNA binds to small ribosomal subunit: binding between mRNA and tRNA (mRNA codons with tRNA anticodons)
48
Step 2 of translation
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
Step 3 of translation
Ribosome attaches to next complementary tRNA
50
Step 4 of translation
Ribosome links amino acids forming dipeptide: more tRNAs arrive and continue forming polypeptide
51
Step 5 of translation
Stops once stop codon is reached on mRNA: Ribosomal subunits detach (leaves intact mRNA and new polypeptide)
52
Plasma membrane
Acts as a barrier separating cytosol and extracellular fluid (ECF); must still coordinate cellular activity with extracellular environment
53
Permeability
Determines which substances can cross membrane
54
Freely permeable
Any substances can cross membrane
55
Selectively permeable
Some substances can cross membrane
56
Impermeable
No substances can cross membrane; no living cell is impermeable
57
Passive (do not require ATP)
Diffusion; carrier-mediated transport
58
Active (require ATP)
Vesicular transport; carrier-mediated transport
59
Diffusion
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
Gradient
Concentration difference or when molecules are not evenly distributed
61
Diffusion in extracellular fluid
water and solutes diffuse freely
62
Diffusion across plasma membrane
Selectively restricted diffusion: movement across lipid portion of membrane, movement through membrane channel, movement using carrier molecules
63
Factors that influence diffusion rates
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
Osmosis
Net diffusion of water across a membrane; maintains similar overall solute concentrations between the cytosol and extracellular fluid
65
Osmotic flow
Movement of water driven by osmosis
66
Osmotic pressure
indication of force of pure water moving into a solution with higher solute concentration
67
Hydrostatic pressure
fluid force; can be estimate of osmotic pressure when applied to stop osmotic flow
68
Osmolarity (osmotic concentration)
Total solute concentration in an aqueous solution
69
Tonicity
Effect of osmotic solutions on cell volume
70
Isotonic
Solution that does not cause osmotic flow across membrane
71
Hypotonic
Causes osmotic flow into cell
72
Hypertonic
Causes osmotic flow out of cell
73
Carrier-mediated transport
Hydrophilic or large molecules transported across cell membrane by carrier proteins; many move specific molecules through the plasma membrane in only one direction
74
Cotransport
>1 substance same direction
75
Countertransport
2 substances in opposite directions (carrier called exchange pump)
76
Facilitated diffusion
Requires no ATP (=passive); movement limited by number of available carrier proteins (=can become saturated)
77
Active transport
Requires energy molecule or ATP (=active); independent of concentration gradient
78
Secondary active transport
Transport mechanism does not require ATP; cell often needs ATP to maintain homeostasis associated with transport
79
Vesicular transport
Requires ATP
80
Endocytosis
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
Exocytosis
Vesicle discharges materials into ECF
82
Cell division
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
Mitosis
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
Meiosis
Sex cells, each with only 23 chromosomes
85
G0 phase
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
G1 phase
Normal cell functions plus cell growth, duplication of organelles, protein synthesis
87
S phase
DNA replication, synthesis of histones
88
G2 phase
Protein synthesis
89
Prophase
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
Metaphase
Chromosomes align at metaphase plate
91
Anaphase
Chromatids separate: drawn along spindle apparatus
92
Telophase
Cells prepare to enter interphase; cytoplasm constricts along metaphase plate (cleavage furrow); Nuclear membranes reform; chromosomes uncoil
93
Cytokinesis
Begins with formation of cleavage furrow; continues through telophase; completion marks end of cell division
94
Cancer
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
Benign
Remain in original tissue
96
Malignant
Accelerated growth due to blood vessel growth and supply to the area
97
Invasion
Cells migrating into surrounding tissues
98
Metastasis
Formation of secondary tumors
