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Life Science > Life on This Rock: Section 2 -3 > Flashcards

Life on This Rock: Section 2 -3 Flashcards

1
Q

What is the nucleus?

A

A membrane enclosed area within the cell that houses the cell’s DNA.

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2
Q

True or false? DNA never leaves the nucleus.

A

True.

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3
Q

Although DNA never leaves the nucleus, what sometimes happens to the DNA?

A

Copies are made of portions of it.

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4
Q

Why does DNA never leave the nucleus?

A

So that DNA can be protected and preserved.

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5
Q

What are the nucleus’ copies of DNA made of?

A

RNA (Ribonucleic acid)

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6
Q

Why is RNA much shorter than DNA?

A

Because it is a copy of only a particular section.

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7
Q

Where do RNA messages leave the cell?

A

Through nuclear pores.

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8
Q

What are nuclear pores?

A

Donut-shaped transmembrane proteins in the cell’s plasma membrane.

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9
Q

What is the endoplasmic reticulum?

A

A branching, interconnecting series of tubes that go throughout the membrane of the nucleus.

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10
Q

Where does the endoplasmic reticulum spread out to after it leaves the nuclear membrane?

A

The cytoplasm.

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11
Q

What is the first portion of the endoplasmic reticulum covered by on the outside?

A

Ribosomes.

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12
Q

What is the term for the first portion of the endoplasmic reticulum?

A

Rough endoplasmic reticulum.

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13
Q

What marks the transition into the second part of the endoplasmic reticulum and what is this portion called?

A

The disappearance of ribosomes and it is called the smooth endoplasmic reticulum.

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14
Q

What are ribosomes?

A

Little factories that assemble proteins from their amino acid monomers.

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15
Q

What carries the code that allows a ribosome to assemble a protein?

A

The RNA message that left the nucleus.

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16
Q

How does an RNA message reach the nucleus?

A

It moves through a channel in the center of the ribosome.

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17
Q

What happens once an RNA message reaches the center of a ribosome?

A

The proper amino acids are brought together and assembled into a protein.

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18
Q

True or false? All of the cell’s ribosomes are on the rough endoplasmic reticulum.

A

False. Some are floating free in the cytoplasm.

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19
Q

Why do some ribosomes float free in the cytoplasm?

A

To allow certain proteins to remain in the cytoplasm and other to be sent along the passageway of the endoplasmic reticulum to the golgi apparatus.

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20
Q

What is the golgi apparatus and what is it shaped like?

A

It is an area where different proteins gather to be modified and transported to different areas of the cell and it is shaped like a stack of pancakes.

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21
Q

What are lysosomes?

A

They are the waste disposal units of the cell and recyclers.

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22
Q

How do lysosomes destroy waste?

A

They have a very high or very low level of pH and special enzymes.

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23
Q

What do lysosomes do with incoming vesicles containing food particles?

A

They break down the particles into amino acids and other monomers to be used by the cell to build things.

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24
Q

How do lysosomes recycle old organelles?

A

They break down the old organelles into monomers the cell can use.

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25
Q

Where do the destructive enzymes within lysosomes come from?

A

The Golgi apparatus.

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26
Q

What would happen if the lysosome enzymes were not contained within the Golgi apparatus?

A

They would degrade everything they encountered and eventually destroy the cell.

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27
Q

What is the purpose of mitochondria?

A

They create energy for the cell.

28
Q

Where do cells begin to break down sugars?

A

Within the cytoplasm.

29
Q

Where are the products of a cell’s breakdown sent?

A

The mitochondria.

30
Q

What do the mitochondria do with the products of the cell’s breakdown?

A

They break them down completely.

31
Q

How do mitochondria capture and store energy?

A

Through a series of reactions.

32
Q

How many membranes do mitochondria have and why?

A

Two, so that they may organize the steps of the reactions that allow them to store energy.

33
Q

What do mitochondria use to power their reactions?

A

Oxygen.

34
Q

What do mitochondria create as a waste product?

A

Carbon dioxide.

35
Q

What does the extracellular matrix allow animal cells to do?

A

Form tissues and organs.

36
Q

What is a desmosome?

A

A structure formed by the transmembrane proteins holding each other together.

37
Q

What is the extracellular matrix?

A

A complex array of fibers and proteins that bind cells together.

38
Q

What does the extracellular matrix assemble from?

A

Proteins secreted from the cells themselves.

39
Q

What is collagen?

A

The material that helps to make cartilage and bone.

40
Q

True or false? Collagen is not one of the proteins that makes up the extracellular matrix.

A

False.

41
Q

What is the extracellular matrix used for in stem cell therapy?

A

It helps to coax stem cells into action.

42
Q

What are chloroplasts?

A

They are the energy factories of plant cells and algae.

43
Q

How do chloroplasts create energy for the cell?

A

They capture the sun’s energy and use it to build sugars.

44
Q

Where do chloroplasts get the carbon they need to make sugars?

A

The carbon dioxide that plants take in from the atmosphere.

45
Q

What happens to the oxygen from the carbon dioxide taken in by the plant?

A

It is ejected back into the atmosphere.

46
Q

What is the series of membranes within the outer membrane of a chloroplast used for?

A

The process of building sugars.

47
Q

True or false? Plant cells have lysosomes.

A

False.

48
Q

what do plant cells have that replace lysosomes?

A

A central vacuole.

49
Q

What is the purpose of the central vacuole?

A

They store water and pump in enzymes that degrade o;d molecules for recycling.

50
Q

What helps a plant cell to maintain its shape during periods of too little or too much water?

A

The cell wall.

51
Q

True or false? Animal cells do not have a cell wall.

A

True.

52
Q

What are bacteria?

A

Single-celled organisms with only one chromosome of DNA and no nucleus.

53
Q

How do bacteria reproduce?

A

Binary fission.

54
Q

What is binary fission?

A

When a single-celled organism splits into two halves and each half becomes a new organism.

55
Q

How often do bacteria reproduce?

A

At least every twenty minutes.

56
Q

True or false? Bacteria have a cell wall and ribosomes.

A

True.

57
Q

What do many bacteria use to propel themselves?

A

Flagellum.

58
Q

Are bacteria prokaryotes or eukaryotes?

A

Prokaryotes.

59
Q

Are animal and plant cells prokaryotes or eukaryotes?

A

Eukaryotes.

60
Q

What is the main difference between prokaryotes and eukaryotes?

A

Prokaryotes do not have membrane-bound organelles.

61
Q

Did prokaryotes or eukaryotes come first?

A

Prokaryotes.

62
Q

What is it thought that mitochondria may be the descendants of?

A

Bacteria that were engulfed by primitive eukaryotes.

63
Q

What are algae?

A

Single-celled prokaryotes that carry the machinery necessary for photosynthesis.

64
Q

What is the theory that mitochondria and chloroplasts evolved from engulfed prokaryotes called?

A

Endosymbiosis.

65
Q

What are some lines of evidence that support endosymbiosis?

A

Mitochondria and chloroplasts contain their own DNA that creates proteins for these organelles. We also cannot make more mitochondria or chloroplasts.

66
Q

What did the engulfed bacteria and algae gain from endosymbiosis?

A

Protection.

67
Q

What did the eukaryotes gain from endosymbiosis?

A

Nutrients.

Life Science (5 decks)

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