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BIOL I > CHAPTER 5 > Flashcards

CHAPTER 5 Flashcards

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1
Q

cell theory

A

Important unifying theory of biology:
- Cells = fundamental units of life
- Organisms composed of cells
- Cells come from preexisting cells
- Modern cells envolved from a common ancestor

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2
Q

surface area-to-volume ratio

A

As cell volume increases = chemical activity, need for resources, and waste removal increases
Surface area becomes limiting = large organisms have many small cells

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3
Q

magnification

A

Increases apparent size

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4
Q

resolution

A

Clarity of magnified object (minimum distance between two objects so they can still be seen as two objects)

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5
Q

microscopes

A

-Light = glass lenses and light; resolution 0.2 um
-Electron = electromagnets focus an electron beam; resolution 0.2 nm

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6
Q

bright-field microscopy

A

Light passes through cells with little contrast and details (when natural pigments are not present)

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7
Q

cell membrane

A

outer boundary of the cell; similar structure in all cells; phospholipid bilayer with embedded proteins; selectively permeable barrier; allows homeostasis; important in communicating and receiving signals; has protein for binding and adhering to adjacent cells

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8
Q

cytoplasm

A

everything in the cell except the nucleus

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9
Q

cytosol

A

fluid cytoplasm (not contained in another compartment)

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10
Q

prokaryotic

A

no membrane-enclosed internal compartments; enclosed by a cell membrane; DNA located in nucleoid; have rigid cell wall (bacteria have peptidoglycan and capsule of polysaccharides)

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11
Q

eukaryotic

A

have membrane-enclosed organelles in which different functions occur

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12
Q

ribosomes

A

sites of protein synthesis; consist of two subunits which are ribosomal RNA (rRNA) and more than 50 different protein molecules

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13
Q

internal membrane

A

system that contains the molecules needed for photosynthesis in bacteria

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14
Q

cytoskeleton

A

system of protein filaments that maintain cell shape and play roles in cell movement and division; holds organelles in position; moves organelles; involved in cytoplasmic streaming; interacts with extracellular structures to hold cell in place; composed of three types of filaments

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15
Q

flagella

A

used by prokaryotes to swim; made of the protein flagellin

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16
Q

Pili

A

hairlike structures projecting from the cell surface; help bacteria adhere to cells

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17
Q

Fimbriae

A

shorter pili that help cells adhere to surfaces such as animal cells

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18
Q

nucleus

A

largest organelle
- contains most DNA
- site of DNA replication
- site where gene transcription is turned on or off
- surrounded by nuclear envelope (double membrane)

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19
Q

nucleolus

A

region where the assembly of ribosomes begins

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20
Q

chromosomes

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A

DNA combines with proteins to form chromatin in these long, thin threads; individual are visible in the light microscope

21
Q

endomembrane system

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A

interconnected system of membrane-enclosed compartments

22
Q

endoplasmic reticulum

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A

network of membranes in the cytoplasm; large surface area

23
Q

rough endoplasmic reticulum

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A

ribosomes are attached, newly made proteins enter through here and are modified, folded, and transported to other regions in vesicles that pinch off

24
Q

smooth endoplasmic reticulum

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A

no ribosomes
-chemically modifies small molecules
-site of glycogen degradation in animal cells
-synthesis of lipids and steroids
-stores calcium ions

25
golgi apparatus
flattened sacs (cisternae) and small vesicles -receives proteins from the RER -modifies, concentrates, packages, and sorts proteins -in plant cells, where polysaccharides for cells walls are synthesized
26
lysosomes
contain digestive enzymes that hydrolyze macromolecules into monomers PRIMARY: originate from the Golgi apparatus SECONDARY: phagosomes + primary lysosomes
27
phagocytosis
how food molecules enter the cell and a phagosome is formed
28
exocytosis
how wastes are ejected
29
mitochondria
energy in fuel molecules such as glucose is transformed to the bonds of energy-rich ATP (cellular respiration); can reproduce, divide independently of the central nucleus; two membranes (LEER INFO EN POWERPOINT ADICIONAL)
30
plastids
only in plants and some protists
31
chloroplasts
site of photosynthesis; have a double membrane; divide independently of the nucleus
32
thylakoids
contain chlorophyll and other pigments that harvest light energy; membranous sacs, stacked to form a granum
33
stroma
the internal fluid of chloroplasts
34
peroxisomes
collect and break down toxic byproducts of metabolism such as H2O2, using specialized enzymes; specialized metabolic compartments bounded by a single membrane; produce H202 and turn it to H20; perform reactions with many different functions
35
glyoxysomes
only in plants; where lipids are converted to carbohydrates for growth
36
vacuoles
provide structure for plant cells; water enters through osmosis creating turgor pressure; store anthocyanins (pink and blue pigments) in flowers and fruits (colors attract pollinators); in seeds they have digestive enzymes to hydrolyze stored food for early growth; store waste products and toxic compounds such as tannins (stored by tannosomes) ; some may deter herbivores
37
microfilaments
help a cell or parts of a cell to move; determine cell shape; made from the protein actin (polymerizes to form long helical chains which are reversible); have distinct ends: plus and minus; involved in the formation of pseudopodia; in some cells they form a meshwork just inside the cell membrane which provides structure
38
intermediate filaments
50 different kinds in 6 molecular classes; tough, ropelike protein structures; anchor cells structures in place; resist tension
39
microtubules
long, hollow cylinders; form a rigid internal skeleton; act as a framework for motor proteins; made from dimers of the protein tubulin; can change length rapidly by adding or losing dimers at plus or minus ends (Cilia and eukaryotic flagella are made from these in "9 + 2" array)
40
motor proteins
move vesicles or organelles from one part of a cell to another
41
plasmodesmata
cell membrane-lined channels that permit movement of water, ions, small molecules, RNA, and proteins
42
cell wall
provide rigid yet flexible support for the plant; barrier to disease organisms; contribute to plant form as growing cells expand
43
What are the three types of cell junctions?
TIGHT junctions - membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid ANCHORING junctions (desmosomes) - fasten cells together into strong sheets GAP junctions - provide cytoplasmic channels between adjacent cells
44
extracellular matrix
composed of fibrous proteins such as collagen, gel-like proteoglycans, and other proteins; covered the animal cell; its proteins bind to receptor proteins in the plasma membrane called integrins; holds cells together in tissues; contributes to properties of bone, cartilage, skin, etc.; filters materials passing between different tissues; orients cell movements in development and tissue repair; plays a role in chemical signaling
45
symbiosis
how some organelles arose PARASITISM - negative relationship where only one organism is benefitted MUTUALISM - positive relationship where both organisms are benefitted
46
theory of endosymbiosis
proposes that mitochondria and plastids arose when one cell engulfed another cell; many of the ingested cell's genes were transferred to the host's DNA but the symbionts retained specialized functions
47
How are mitochondria and chloroplasts have similar to bacteria?
both enveloped by a double membrane; both contain free ribosomes and circular DNA molecules; grow and reproduce somewhat independently in cells
48
endosymbiont theory
suggests that an early ancestor of eukaryotes engulfed an oxygen-using nonphotosynthetic prokaryotic cell; then, the engulfed cell formed a relationship with the host cell, becoming an endosymbiont which evolved into mitochondria; one of these took up a photosynthetic prokaryote which evolved into a chloroplast
49
cellular respiration
a metabolic process that uses oxygen to generate ATP that happens in the mitochondria

BIOL I (12 decks)

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