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Biology Chapter 4 > Organelle functions > Flashcards

Organelle functions Flashcards

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0
Q

what category do the lipids in the plasma membrane belong to?

A

phospholipids

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1
Q

What is the plasma membrane mostly composed of?

A

lipids and proteins

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2
Q

What makes phospholipids different from dietary fats?

A

they have only two fatty acid tails instead of three

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3
Q

what does a phospholipid have in place of the third fatty acid tail?

A

a combination of phosphorus and oxygen, a phosphate group

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4
Q

what makes the phospholipid’s phosphate group hydrophilic?

A

the phosphate group is electrically charged

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5
Q

are the fatty acids in a phospholipid hydrophilic or hydrophobic?

A

hydrophobic

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6
Q

Why does this mixture of hydrophobic and hydrophilic form a two-layered membrane (phospholipid bilayer)?

A

the phosphate group mixes with water, while the fatty acids avoid it

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7
Q

What are embedded in the phospholipid bilayer?

A

proteins that perform various functions

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8
Q

what makes the membrane a fluid mosaic?

A

fluid because the molecules can move freely past one another and mosaic because of the diversity of proteins

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9
Q

what does the cell wall of plant cells that surrounds their plasma membrane do?

A

It protects cells, maintains their shape, and keeps the cells from absorbing too much water

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10
Q

What are plant cell walls made from?

A

cellulose fibrils embedded in a matrix of other molecules

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11
Q

How are plant cells attached to each other?

A

through channels that pass through cell walls and connect each cells’ cytoplasm to the next

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12
Q

What do the channels in plant cell walls do?

A

allow water and other small molecules to move between cells

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13
Q

What do animal cells have instead of a cell wall?

A

extracellular matrix

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14
Q

What does an animal cell’s extracellular matrix do?

A

it helps hold cells together and has supportive and protective functions

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15
Q

How are animal cells bound to the extracellular matrix?

A

by surface proteins in the plasma membrane

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16
Q

What is a cell junction?

A

structure that connects cells to cells

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17
Q

why do phospholipids organize into a bilayer?

A

the hydrophobic tails are shielded from the water and the hydrophilic tails are exposed to water

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18
Q

What is the nucleus’ double membrane called?

A

nuclear envelope

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19
Q

What are the membranes of the nuclear envelope similar to?

A

plasma membrane

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20
Q

What allows the passage of material between the nucleus and the plasma membrane?

A

pores through the nuclear envelope

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21
Q

What is chromatin?

A

Long DNA molecules and associated proteins

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22
Q

What does each long chromatin fiber constitute?

A

chromosome

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23
Q

What does the number of chromosomes in the cell depend on?

A

the species

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24
Q

What is the nucleolus made of?

A

ball like mass of fibers and granules

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25
Q

What does the nucleolus produce?

A

components of ribosomes

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26
Q

When do ribosomes begin to work?

A

once the components move through the pores of the nucleus into the cytoplasm

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27
Q

What do ribosomes do?

A

protein synthesis

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28
Q

Where are ribosomes located?

A

some in cytosol and some attached to ER

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29
Q

What happens to the proteins the ribosomes that are connected to the outside of the ER make?

A

they are incorporated into membranes or secreted by the cell

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30
Q

Are the ribosomes of prokaryotes and eukaryotes different?

A

yes, they differ considerably in their makeup

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31
Q

How does DNA program protein production in the cytoplasm?

A

By transferring its coded information to a molecule called messenger RNA

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32
Q

How does the mRNA exit the nuclear envelope to deliver its message?

A

exits through pores in the nuclear envelope and travels to the cytoplasm, where it binds to ribosomes

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33
Q

What happens as a ribosome moves along the mRNA?

A

genetic message is translated into a protein of specific amino acid sequence

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34
Q

What does the endoplasmic reticulum do?

A

produces a wide variety of molecules

35
Q

What is the ER’s structure?

A

membranous labyrinth of tubes and sacs running through the cytoplasm

36
Q

Why is the Rough ER rough?

A

ribosomes stud the outside

37
Q

What kind of proteins do the ribosomes on the outside of the rough ER produce?

A

membrane proteins and secretory proteins

38
Q

What is one thing that the rough ER produces?

A

new membrane

39
Q

What are cells that produce a lot of protein especially rich in?

A

rough ER

40
Q

How are some of the products produced by the rough ER transported to other parts of the cell?

A

transport vesicless

41
Q

what are transport vesicles?

A

membranous spheres that bud from the ER

42
Q

What does the smooth in smooth ER refer to?

A

lacks ribosomes on surface

43
Q

What enables the smooth ER to perform many functions?

A

diversity of enzymes in membrane

44
Q

What is one function of the smooth ER?

A

synthesis of lipids

45
Q

What is another function of the smooth ER? (in liver cells)

A

detoxification of drugs and other poisons that might be present in thee bloodstream

46
Q

What does the Golgi apparatus do?

A

receives, refines, stores, and distributes chemical products of the cell

47
Q

How do products made in the ER reach the Golgi?

A

transport vesicles

48
Q

How do Golgi mark a protein product’s final destination within the cell?

A

chemically tags it

49
Q

What do vesicles that bind with the plasma membrane do?

A

secrete chemical products to the outside of the cell

50
Q

What is a lysosome?

A

membrane enclosed sack of digestive enzymes

51
Q

What does the lysosome do?

A

break down macromolecules such as proteins, polysaccharides, fats, and nucleic acids. It also provides a compartment where the cell can digest macromolecules safely without unleashing digestive molecules and killing itself.

52
Q

What are food vacuoles?

A

tiny cytoplasmic sacs used for digesting nutrients

53
Q

How do lysosomes and food vacuoles interact?

A

lysosomes fuse with food vacuoles and expose the food to enzymes that digest it

54
Q

What happens to the small molecules such as amino acids that result from this digestion?

A

they leave the lysosome and nourish the cell

55
Q

What do lysosomes do with harmful bacteria?

A

rupture the bacterial cell walls with enzymes

56
Q

How does the lysosome “recycle” damaged organelles?

A

Without harming the cell lysosomes can engulf and digest parts of an organelle, making its molecules available for construction of new organelles

57
Q

What function do lysosomes have in embryonic development?

A

destroy the cells of the webbing joining the fingers of early human embryos by acting as “suicide packs” and breaking open to cause the programmed death of whole cells

58
Q

What are vacuoles?

A

membranous sacs that bud from the ER, Golgi, or Plasma Membrane

59
Q

What do certain freshwater protists use vacuoles for?

A

as pumps to expel excess water that flows into the cell

60
Q

What’s a type of vacuole found in a plant cell?

A

The central vacuole

61
Q

What do plant cells store in the central vacuole?

A

nutrients

62
Q

How do central vacuoles contribute to plant growth?

A

by absorbing water and causing cells to expand

63
Q

What do chloroplasts do?

A

perform photosynthesis

64
Q

What is photosynthesis?

A

conversion of light energy from the sun to the chemical energy of sugar and other organic molecules

65
Q

How is the chloroplast partitioned?

A

into three major compartments by internal membranes

66
Q

What is stroma in the chloroplast?

A

the thick fluid within the chloroplast

67
Q

How are the granum in chloroplasts shaped?

A

membrane-enclosed tubes and disks connected together

68
Q

How many membranes does a chloroplast have?

A

2

69
Q

What do the grana in chloroplasts do?

A

trap light energy and convert it to solar energy

70
Q

What are mitochondria?

A

The sites of cellular respiration

71
Q

What does cellular respiration do?

A

harvests energies from sugars and other food molecules and converts it to another chemical energy called ATP

72
Q

What do cells use ATP for?

A

direct energy source for most work

73
Q

Are chloroplasts found in plant or animal cells?

A

plant

74
Q

Are mitochondria found in plant or animal cells?

A

both

75
Q

How many membranes does a mitochondria have?

A

2

76
Q

What does the inner membrane of a mitochondria have and what are they called?

A

has numerous infoldings called cristae

77
Q

How does the cristae maximize ATP output?

A

by increasing the surface area of the membrane

78
Q

What do chloroplasts and mitochondria contain that most organelles don’t?

A

DNA that encodes some of their proteins

79
Q

What is the cytoskeleton?

A

a network of fibers extending throughout the cytoplasm

80
Q

In what two ways does the cytoskeleton function?

A

serves as both skeleton and muscle of cell

81
Q

What is one of the cytoplasm’s most important fibers?

A

microtubules

82
Q

what are microtubules?

A

Straight hollow tubes composed of globular proteins called tubulins

83
Q

What are the other kinds of cytoskeletal fibers?

A

filaments

84
Q

How is the nucleus often held in place?

A

cytoskeletal cage of filaments

85
Q

What else are microtubules used for?

A

organelles move along tracks made from microtubules

Biology Chapter 4 (4 decks)

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