Biology: Ch. 2 Cells Flashcards
(95 cards)
1
Q
Cell
A
Basic functional unit of all living things
2
Q
Plasma membrane (Cell membrane)
A
- Bounds the cell & encloses the nucleus and cytoplasm
- Separates internal metabolic events from external environment
- Controls movement into and out of the cell
- Phospholipid bilayer
3
Q
Cytoplasm
A
Consists of organelles suspended in the cytosol
4
Q
Cytosol
A
Consists of water and dissolved substances such as proteins and nutrients
5
Q
Peripheral proteins
A
Attach loosely to the inner or outer surface of the protein
6
Q
Integral proteins
A
Extend into the membrane; amphipathic
7
Q
Transmembrane proteins
A
Integral proteins that span across the membrane and appear at both surfaces
8
Q
Fluid mosaic model
A
Mosaic nature of scattered proteins within a flexible matrix of phospholipid molecules
9
Q
Phospholipid membrane
A
- Selectively permeable
- Allows small, uncharged, polar molecules (H2O & CO2), hydrophobic molecules (O2 & lipid-soluble molecules) to pass
10
Q
Channel proteins
A
Open passageways for hydrophilic substances (polar and charged molecules)
11
Q
Ion channels
A
Passage of ions
12
Q
Gated channels
A
Ion channel in nerve and muscle cells that responds to chemical or electrical stimuli
13
Q
Porins
A
Allow passage of certain ions and small polar molecules
14
Q
Aquaporins
A
Increase passage rate of H2O molecules in kidneys and plant roots
15
Q
Carrier proteins
A
Binding to specific molecules (glucose) induces change of shape which transfers the molecule across
16
Q
Transport proteins
A
Use ATP
17
Q
Active transport
A
When energy is used to transport materials
18
Q
Na+-K+ pump
A
Uses ATP to maintain higher concentrations of Na+ and K+ on opposite sides of the membrane; active transport
19
Q
Recognition proteins
A
Gives each cell a unique identification which allows them to make a distinction between self and foreign; glycoprotein
20
Q
Glycoprotein
A
Protein with a short polysaccharide chain attached
21
Q
Adhesion proteins
A
- Attach cells to neighboring cells
- Provide anchors for internal filaments and tubules
22
Q
Receptor proteins
A
Binding sites for hormones or other trigger molecules
23
Q
Cholesterol
A
Distributed throughout lipid bilayer providing rigidity to the plasma membranes of animal cells; sterols provide similar function in plants
24
Q
Glycocalyx
A
- Carbohydrate coat covering the outer face of the cell wall (some bacteria) or plasma membrane (certain animal cells)
- Consists of various oligosaccharides attached to membrane phospholipids and proteins
- Can provide adhesive capabilities, barrier to infection, cell-to-cell recognition
25
Organelles
Bodies within the cytoplasm that physically separate the various metabolic reactions
26
Nucleus
- Bounded by nuclear envelope
- Contains DNA in form of chromatin
- One or more nucleoli
- Site for separation of chromosomes
27
Nuclear envelope
Consists of 2 phospholipid bilayers
28
Chromatin
DNA which is spread out within the nucleus as a threadlike matrix
29
Chromosomes
Condensed form of chromatin when cell begins to divide; made up of two long DNA molecules and various histone molecules
30
Histones
Organize the DNA into bundles (nucleosomes)
31
Nucleosomes
Bundles of DNA which make up the histones
32
Nucleoli
Concentrations of DNA in the the process of manufacturing the components of ribosomes
33
Ribosomes
- Subunits are manufactured in the nucleus and consist of RNA molecules and proteins
- 60S + 40S = 80S
- Assist in the assembly of amino acids into proteins
34
S value (Svedberg unit)
How readily a product forms a sediment in a centrifuge; larger value = larger heavier products
35
Endoplasmic reticulum (ER)
- Stacks of flattened sacs that produce various materials
| - Smooth and rough
36
Rough ER
- Ribosomes are present
| - Create glycoproteins by attaching polysaccharide groups to polypeptides
37
Smooth ER
- Synthesis of lipids and hormones
| - Breakdown of toxins, drugs, and toxic by-products in liver cells
38
Golgi apparatus (Golgi complex or Golgi body)
- Group of flattened sacs arranged like a stack of bowls
| - Modify and package proteins and lipids into vesicles
39
Vesicles
Spherical sacs that bud from the Golgi apparatus which migrate to and merge with the plasma membrane to release contents outside the cell
40
Lysosomes
Vesicles from Golgi apparatus the contain digestive enzymes (low pH) that break down food, cellular debris, and foreign invaders (bacteria)
41
Peroxisomes
- Breakdown H2O2, fatty acids, and amino acids
- Liver and kidney cells: breakdown toxic substances
- Plant cells: modify by-products (CO2) of photorespiration
- Germinating seeds: (called glyoxysomes) breakdown stored fatty acids to help generate energy for growth
42
Mitochondria
Carry out aerobic respiration
43
Aerobic respiration
Process in which energy (ATP) is obtained from carbohydrates
44
Chloroplasts
Carry out photosynthesis
45
Photosynthesis
Plant process of incorporating energy from sunlight into carbohydrates
46
Three protein fibers & function
- Microtubules, intermediate filaments, microfilaments
| - Establish shape of or coordinate movements of the cytoskeleton
47
Cytoskeleton
Internal structure of the cytoplasm
48
Microtubules
- Made of protein tubulin
- Provide support and motility for cellular activities
- Found in the spindle apparatus and flagella and cilia
49
Spindle apparatus
Guides the movement of chromosomes during cell division
50
Intermediate filaments
Provide support for maintaining the shape of the cell
51
Microfilaments
- Made of protein actin
- Involved in cell motility
- Found in muscle cells and cells that move by changing shape (phagocytes)
52
Flagella
Long, few, move in snake-like motion
53
Cilia
Short, many, move in back-and-forth movement
54
Structure of flagella and cilia
Microtubules arranged in a "9+2" array--nine pairs of microtubules arranged in a circle surrounding a pair of microtubules
55
Function/structure of centrioles and basal bodies
- Act as microtubule organizing centers (MTOCs)
| - 9 triplets of microtubules arranged in a circle
56
Centrioles
- Pair of centrioles in centrosome gives rise to the microtubules that make up the spindle apparatus
- Lacking in plant cells
57
Basal bodies
- Organize the development of flagellum and cilium
| - Present in lower plants
58
Vacuoles and vesicles
Fluid-filled, membrane-bound bodies
59
Transport vesicles
Move materials between organelles or between organelles and the plasma membrane
60
Food vacuoles
Temporary receptacles of nutrients; merge with lysosomes which break down the food
61
Storage vacuoles
In plants; store starch, pigments, and bacteria
62
Central vacuoles
- Large bodies occupying most of the interior of certain plant cells
- Exert turgor (pressure) on cell wall which fully filled which maintains rigidity
- Store nutrients and carry out lysosome-like functions
63
Cell walls
- Found in plants, fungi, protists, and bacteria
- Develop outside the plasma membrane and provide support
- Made of cellulose in plants and cellulose or chitin in fungi
64
Extracellular matrix
- In animals; area between adjacent cells
- Provides mechanical support and helps bind adjacent cells together
- Occupied by fibrous structural proteins, adhesion proteins, and polysaccharides secreted by the cell (common substance is collagen)
65
Cell junctions
Anchor cells to one another or provide passageway for cellular exchange
66
Anchoring junctions
- Protein attachments between adjacent animal cells
| - Ex. desmosome
67
Desmosome
- Consists of proteins that bind adjacent cells together
- Provides mechanical stability to tissues
- Associated with protein filaments that extend into the cell and hold cellular structures together
68
Tight junctions
- Tightly stitched seams between animal cells
- Junction completely encircles each cell producing seal that prevents passage of materials between cells
- Present in lining of digestive tract
69
Communicating junctions
- Allow the transfer of chemical or electrical signals
| - Types: Gap junctions and plasmodesmata
70
Gap junctions
- Narrow tunnels between animals cells consisting of proteins called connexins, which prevent the cytoplasms of each cell from mixing but allow passage of ions and small molecules
- Allow communication through exchange of materials or transmission of electrical impulses
71
Plamodesmata
- Narrow channels between plant cells
- Narrow tube of ER, called a desmotubule, surrounded by cytoplasm and the plasma membrane, passes through the channel (material exchange occurs through this cytoplasm)
72
Present in plant cells, absent in animals cells
Cell walls, chloroplasts, central vacuoles
73
Present in animal cells, absent in plant cells
Lysosomes, centrioles, cholesterol
74
Eukaryotes
All organisms except for bacteria, cyanobacteria, and archaebacteria (prokaryotes)
75
Prokaryotes
Lack all organelles; consist of plasma membrane, DNA molecule, ribosomes, cytoplasm, and often a cell wall
76
Difference of prokaryotes
- No nucleus
- Hereditary material: single "naked" DNA molecule
- Ribosomes are smaller (50S + 30S = 70S)
- Cell walls made from peptidoglycans (except archaebacteria which contain polysaccharides)
- Flagella are not constructed of microtubules
77
Selectively permeable membrane
Allows only specific substances to pass
78
Hypertonic
Higher concentration of solutes
79
Hypotonic
Lower concentration of solutes
80
Isotonic
Equal concentration of solutes
81
Bulk flow
Collective movement of substances in the same direction in response to force or pressure; blood in blood vessel
82
Passive transport
Movement down concentration gradient; no energy required
83
Simple diffusion
Net movement of substances from an area of higher concentration to an area of lower concentration as a result of random and constant motion of molecules
84
Osmosis
- Diffusion of water across selectively permeable membrane
| - Hydrostatic pressure (or osmotic pressure) may build up; turgor pressure in plants
85
Dialysis
Diffusion of solutes across selectively permeable membrane which different solutes are separated
86
Plasmolysis
Movement of water out of a cell (osmosis) that results in the collapse of the cell
87
Facilitated diffusion
- Diffusion of solutes or water through channel proteins in the plasma membrane
- Aquaporins increase the rate of transfer of water by facilitated diffusion
88
Countercurrent exchange
Diffusion of substances between two regions in which substances are moving by bulk flow in opposite directions
89
Active transport
- Movement of solutes against a gradient; requires energy
| - Transport proteins transfer small ions, amino acids, and monosaccharides
90
Vesicular transport
Uses vesicles or other bodies in the cytoplasm to move macromolecules or large particles across the plasma membrane
91
Exocytosis
Vesicles fuse with plasma membrane and release contents to the outside of the cell
92
Endocytosis
Capture of a substance outside of the cell when the plasma membrane merges to engulf it; enters cytoplasm enclosed in a vesicle
93
Phagocytosis
Cellular eating; when undissolved material enters the cell--plasma membrane wraps around the solid material and engulfs it
94
Pinocytosis
Cellular drinking; when dissolved substances enter the cell--plasma membrane folds inward to form a channel allowing the liquid to enter
95
Receptor-mediated endocytosis
- Form of pinocytosis when specific molecules bind to specialized receptors in coated pits
- Pits, receptors, and molecules (ligands) fold inward and formation of a vesicle follows
