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Biology 201 > Lecture 2 > Flashcards

Lecture 2 Flashcards

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1
Q

Why are organelles compartmentalized?

A

It allows the specificity of function and the concentration of reactants to certain parts of the cell.

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2
Q

Where are mitochondrial proteins encoded?

A

The nucleus

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3
Q

Where are mitochondrial proteins translated?

A

The cytoplasm

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4
Q

What does mtDNA encode for?

A

RNA, mostly tRNA and rRNA

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5
Q

Why does the mitochondria have two membranes?

A

One is bacterial and the outer is eukaryotic because the ancestral mitochondria was absorbed by a eukaryotic cell.

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6
Q

What are cisternae?

A

The flattened sacs that make up the endoplasmic reticulum.

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7
Q

What is the difference between the rough and smooth ERs?

A

The rough ER is covered in ribosomes

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8
Q

What is the function of the rough ER?

A

The ribosomes attached to it translate proteins destined for within the endomembrane system.

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9
Q

What is the function of the smooth ER?

A

It is responsible for the synthesis of lipids and steroid hormones.

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10
Q

What is the function of the Golgi Body?

A

It processes and packages proteins, sythesizes polysaccharides, receives proteins from the ER, and modifies proteins by glycosylation (addition of sugars)

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11
Q

What is the function of lysosomes?

A

They digest all macromolecules.

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12
Q

How does the lysosome appear in microscopy?

A

It is a large, circular organelle with dense staining in the interior membrane, but is smaller than the nucleus.

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13
Q

What is the function of ribosomes?

A

To synthesize proteins.

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14
Q

Where can ribosomes be found?

A

They are free in the cytoplasm or bound to the ER.

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15
Q

Where does all translation begin?

A

In the cytoplasm.

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16
Q

What makes up a plasma membrane?

A

Phospholipids, other lipids, proteins, and carbohydrates.

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17
Q

What does amphipathic mean?

A

It has both hydrophilic and hydrophobic sections.

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18
Q

During centrifugation, what does a particle’s rate of movement depend on?

A

Size and density (larger or more dense particles have higher sedimentation rates)

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19
Q

What can centrifugation be used for?

A

Sibcellular fractionation- separates and purifies organelles.

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20
Q

How are samples prepared for centrifugation?

A

Cells are homogenized (broken up) to separate contents, then forced through narrow orifice or ultrasonic vibration or osmotic shock or enzymatic treatment or manual grinding

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21
Q

Define homogenate

A

A solution containing intracellular content that can be separated.

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22
Q

What is differential centrifugation?

A

Slowly increasing speed/duration of centrifugation while sequentially removing the pellet.

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23
Q

What is equilibrium/density gradient centrifugation?

A

Homogenate is spun until each component of the solution reaches their density equilibrium position which forms separate indentifiable layers.

24
Q

What is the nucleoplasm?

A

The fluid in the nucleus.

25
Q

What is the nuclear envelope?

A

The two lipid bilayers surrounding the nucleus.

26
Q

What is the nucleolus?

A

It is the site of rRNA synthesis (ball inside nucleus).

27
Q

What is the nuclear lamina?

A

A network of intermediate filaments that support the nuclear structure.

28
Q

What is Chromatin?

A

DNA

29
Q

What section of the nuclear double membrane do nuclear pores span?

A

They span the entire membrane (go all the way through).

30
Q

What are nuclear pores made of?

A

Proteins called nucleoporins that are arranged in to a very large complex.

31
Q

What can diffuse freely across the nuclear pores?

A

Small ions, metabolites, and small globular proteins.

32
Q

Where are cytoplasmic filaments found on nuclear pores?

A

The cytoplasmic side.

33
Q

What is needed for a protein to be sent to the nucleus?

A

A nuclear localization signal (NLS).

34
Q

Is NLS necessary and sufficient for nulear localization?

A

It is both necessary and sufficient for nuclear localization.

35
Q

Where is NLS generally located on a protein?

A

Usually near the N-terminus.

36
Q

What are importins?

A

Cytoplasmic proteins that recognize and bind to the NLS

37
Q

What is a nuclear import receptor (NIR)?

A

It is a heterodimer made from an alpha and beta subunit.

38
Q

In NIRs, which subunit binds which localization signal?

A

Alpha binds NLS and beta binds NPC

39
Q

What is Ran-GTP?

A

A G protein which acts as an on/off switch.

40
Q

Where are Ran-GTP and Ran-GDP found?

A

Ran-GTP is inside the nucleus, Ran-GDP is outside the nucleus.

41
Q

Where are Ran-GAP and Ran-GEF found?

A

Ran-GAP is in the cytoplasm and Ran-GEF is in the nucleus.

42
Q

What is Ran-GAP?

A

An enzyme that cleaves a phophate off of GTP making GDP.

43
Q

What does Ran-GEF do?

A

It exchanges GDP for GTP to reactivate Ran and it is only found in the nucleus.

44
Q

What affects the binding and release by importins?

A

Ran-GTP is bound in the nucleus and Ran-GDP is bound in the cytoplasm, which dictates what is bound and released by the imp

45
Q

What must a protein that shuttles into and out of the nucleus have?

A

A Nuclear Export Signal (NES)

46
Q

What has both NLS and NES?

A

Ribosomes

47
Q

What are the steps of nuclear export?

A

Exportin-1 forms a complex with Ran-GTP; Exportin-Ran-GTP complex binds NES containing protein; Entire exportin-Ran-cargo complex leaves nucleus; Ran-GAP in cytoplasmic filaments of NPC allow release of cargo

48
Q

What is the difference between protein import and protein export?

A

In export, Ran-GTP is part of the cargo complex that is transported.

49
Q

What is an interphase chromosome?

A

It is the DNA found during the period when the cell is not dividing.

50
Q

What is a condensed chromosome?

A

DNA when the cell is dividing.

51
Q

What are histones?

A

A group of basic protein found in chromatin.

52
Q

What are the five groups of histone?

A

H1, H2A, H2B, H3, and H4

53
Q

What is the function of histones?

A

They form a core that DNA wraps around to form a nucleosome

54
Q

Describe the packing of chromatin during interphase

A

DNA forms a double helix which wraps around histones (beads on a string), which then packs to form a solenoid and the solenoid folds into loops.

55
Q

Describe the packing of chromatin during mitosis

A

The whole chromosome is packed in loops

56
Q

What are non-histone scaffold proteins?

A

They assist in packing into loopsby associating with DNA

57
Q

What are the regions of DNA that associate with the scaffold?

A

Scaffold-associated regions (SARS)

Biology 201 (10 decks)

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