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BIOL I > CHAPTER 5 > Flashcards

CHAPTER 5 Flashcards

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

A

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

21
Q

endomembrane system

A

interconnected system of membrane-enclosed compartments

22
Q

endoplasmic reticulum

A

network of membranes in the cytoplasm; large surface area

23
Q

rough endoplasmic reticulum

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

A

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

25
Q

golgi apparatus

A

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
Q

lysosomes

A

contain digestive enzymes that hydrolyze macromolecules into monomers
PRIMARY: originate from the Golgi apparatus
SECONDARY: phagosomes + primary lysosomes

27
Q

phagocytosis

A

how food molecules enter the cell and a phagosome is formed

28
Q

exocytosis

A

how wastes are ejected

29
Q

mitochondria

A

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
Q

plastids

A

only in plants and some protists

31
Q

chloroplasts

A

site of photosynthesis; have a double membrane; divide independently of the nucleus

32
Q

thylakoids

A

contain chlorophyll and other pigments that harvest light energy; membranous sacs, stacked to form a granum

33
Q

stroma

A

the internal fluid of chloroplasts

34
Q

peroxisomes

A

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
Q

glyoxysomes

A

only in plants; where lipids are converted to carbohydrates for growth

36
Q

vacuoles

A

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
Q

microfilaments

A

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
Q

intermediate filaments

A

50 different kinds in 6 molecular classes; tough, ropelike protein structures; anchor cells structures in place; resist tension

39
Q

microtubules

A

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
Q

motor proteins

A

move vesicles or organelles from one part of a cell to another

41
Q

plasmodesmata

A

cell membrane-lined channels that permit movement of water, ions, small molecules, RNA, and proteins

42
Q

cell wall

A

provide rigid yet flexible support for the plant; barrier to disease organisms; contribute to plant form as growing cells expand

43
Q

What are the three types of cell junctions?

A

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
Q

extracellular matrix

A

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
Q

symbiosis

A

how some organelles arose
PARASITISM - negative relationship where only one organism is benefitted
MUTUALISM - positive relationship where both organisms are benefitted

46
Q

theory of endosymbiosis

A

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
Q

How are mitochondria and chloroplasts have similar to bacteria?

A

both enveloped by a double membrane; both contain free ribosomes and circular DNA molecules; grow and reproduce somewhat independently in cells

48
Q

endosymbiont theory

A

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
Q

cellular respiration

A

a metabolic process that uses oxygen to generate ATP that happens in the mitochondria

BIOL I (12 decks)

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