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Organelle functions Flashcards

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
What is the nucleolus made of?
ball like mass of fibers and granules
25
What does the nucleolus produce?
components of ribosomes
26
When do ribosomes begin to work?
once the components move through the pores of the nucleus into the cytoplasm
27
What do ribosomes do?
protein synthesis
28
Where are ribosomes located?
some in cytosol and some attached to ER
29
What happens to the proteins the ribosomes that are connected to the outside of the ER make?
they are incorporated into membranes or secreted by the cell
30
Are the ribosomes of prokaryotes and eukaryotes different?
yes, they differ considerably in their makeup
31
How does DNA program protein production in the cytoplasm?
By transferring its coded information to a molecule called messenger RNA
32
How does the mRNA exit the nuclear envelope to deliver its message?
exits through pores in the nuclear envelope and travels to the cytoplasm, where it binds to ribosomes
33
What happens as a ribosome moves along the mRNA?
genetic message is translated into a protein of specific amino acid sequence
34
What does the endoplasmic reticulum do?
produces a wide variety of molecules
35
What is the ER's structure?
membranous labyrinth of tubes and sacs running through the cytoplasm
36
Why is the Rough ER rough?
ribosomes stud the outside
37
What kind of proteins do the ribosomes on the outside of the rough ER produce?
membrane proteins and secretory proteins
38
What is one thing that the rough ER produces?
new membrane
39
What are cells that produce a lot of protein especially rich in?
rough ER
40
How are some of the products produced by the rough ER transported to other parts of the cell?
transport vesicless
41
what are transport vesicles?
membranous spheres that bud from the ER
42
What does the smooth in smooth ER refer to?
lacks ribosomes on surface
43
What enables the smooth ER to perform many functions?
diversity of enzymes in membrane
44
What is one function of the smooth ER?
synthesis of lipids
45
What is another function of the smooth ER? (in liver cells)
detoxification of drugs and other poisons that might be present in thee bloodstream
46
What does the Golgi apparatus do?
receives, refines, stores, and distributes chemical products of the cell
47
How do products made in the ER reach the Golgi?
transport vesicles
48
How do Golgi mark a protein product's final destination within the cell?
chemically tags it
49
What do vesicles that bind with the plasma membrane do?
secrete chemical products to the outside of the cell
50
What is a lysosome?
membrane enclosed sack of digestive enzymes
51
What does the lysosome do?
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
What are food vacuoles?
tiny cytoplasmic sacs used for digesting nutrients
53
How do lysosomes and food vacuoles interact?
lysosomes fuse with food vacuoles and expose the food to enzymes that digest it
54
What happens to the small molecules such as amino acids that result from this digestion?
they leave the lysosome and nourish the cell
55
What do lysosomes do with harmful bacteria?
rupture the bacterial cell walls with enzymes
56
How does the lysosome "recycle" damaged organelles?
Without harming the cell lysosomes can engulf and digest parts of an organelle, making its molecules available for construction of new organelles
57
What function do lysosomes have in embryonic development?
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
What are vacuoles?
membranous sacs that bud from the ER, Golgi, or Plasma Membrane
59
What do certain freshwater protists use vacuoles for?
as pumps to expel excess water that flows into the cell
60
What's a type of vacuole found in a plant cell?
The central vacuole
61
What do plant cells store in the central vacuole?
nutrients
62
How do central vacuoles contribute to plant growth?
by absorbing water and causing cells to expand
63
What do chloroplasts do?
perform photosynthesis
64
What is photosynthesis?
conversion of light energy from the sun to the chemical energy of sugar and other organic molecules
65
How is the chloroplast partitioned?
into three major compartments by internal membranes
66
What is stroma in the chloroplast?
the thick fluid within the chloroplast
67
How are the granum in chloroplasts shaped?
membrane-enclosed tubes and disks connected together
68
How many membranes does a chloroplast have?
2
69
What do the grana in chloroplasts do?
trap light energy and convert it to solar energy
70
What are mitochondria?
The sites of cellular respiration
71
What does cellular respiration do?
harvests energies from sugars and other food molecules and converts it to another chemical energy called ATP
72
What do cells use ATP for?
direct energy source for most work
73
Are chloroplasts found in plant or animal cells?
plant
74
Are mitochondria found in plant or animal cells?
both
75
How many membranes does a mitochondria have?
2
76
What does the inner membrane of a mitochondria have and what are they called?
has numerous infoldings called cristae
77
How does the cristae maximize ATP output?
by increasing the surface area of the membrane
78
What do chloroplasts and mitochondria contain that most organelles don't?
DNA that encodes some of their proteins
79
What is the cytoskeleton?
a network of fibers extending throughout the cytoplasm
80
In what two ways does the cytoskeleton function?
serves as both skeleton and muscle of cell
81
What is one of the cytoplasm's most important fibers?
microtubules
82
what are microtubules?
Straight hollow tubes composed of globular proteins called tubulins
83
What are the other kinds of cytoskeletal fibers?
filaments
84
How is the nucleus often held in place?
cytoskeletal cage of filaments
85
What else are microtubules used for?
organelles move along tracks made from microtubules

Biology Chapter 4 (4 decks)

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