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Cell Biology > Cell Membranes, Nucleus > Flashcards

Cell Membranes, Nucleus Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Actin (microfilaments) characteristics

A

Flexible
High tensile strength
Able to withstand low levels of compression
Tracks for molecular motors

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2
Q

When ______ via filamen, actin bundles can withstand moderate levels of compression

A

crosslinked

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3
Q

Intermediate filament characteristics

A

Similar to flexible cables
Possess high tensile strength
Don’t resist compression

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4
Q

Microtubule characteristics

A

Rigid
Hollow
Can withstand considerable compression AND tension loads
Tracks for molecular motors

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5
Q

Most abundant protein in cell

A

actin

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6
Q

Actin is formed by polymerization of monomeric actin, and this process relies on the _________ of ____

A

hydrolysis of ATP

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7
Q

Growth of actin is much faster on the ____ end

A

barbed (compared to pointed end)

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8
Q

____________ orientation of actin is important because it tells motors and other components where to go

A

asymmetrical

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9
Q

Microtubules are formed by the polymerization of __ and __ ______

A

alpha and beta tubulin

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10
Q

the addition of tubulin dimers to form microtubules relies on ____

A

GTP

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11
Q

T/F microtubules posses structural and functional polarity

A

True

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12
Q

microtubule functions

A

important components of cilia, mitotic spindle, and other cellular structures

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13
Q

Dyneins characteristics

A

Responsible for movement of cilia
Move toward minus-end of microtubules (retrograde transport)
Move incoming cargo from the cell membrane to the center of the cell

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14
Q

Kinesins characteristics

A

Aid in neuronal axon transport
Move protiens from the “middle” of cell to the membrance
Move toward the microtubules plus end (anterograde transport)

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15
Q

Although not usually considered to be molecular motors, ______ _____, _______, and ______ also use ATP hydrolysis to move along polymers of DNA or RNA

A

nucleic acid, polymerases, helicases

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16
Q

microtubule _____ is important

A

polarity

17
Q

Intermediate filament examples

A

Keratins, lamins, neurofilaments, vimentins

18
Q

nuclear _____ form a meshwork that stabilizes the inner portion of the nucleus

A

lamins

19
Q

The ____ _____ must be disassembled during mitosis

A

nuclear lamina

20
Q

___________ _____ _______ aid in regulating trafficking of both proteins and nucleic acids in and out of the nucleus

A

Nuclear pore complexes

21
Q

3 distinct regions of the nucleolus

A

Fibrillar center
Dense fibrillar component
Granular component

22
Q

contains rRNA, RNA polymerase, and other transcription factors

A

fibrillar center

23
Q

this is thought to be the site of active ribosomal RNA transcription

A

dense fibrillar component

24
Q

the site in the nucleolus of pre-ribosomal particles and ribosomal assembly

A

granular component

25
Q

Seen as dense patches (often against the nuclear membrane), it is the condensed form of chromatin organization and is considered transcriptionally inactive

A

heterochromatin

26
Q

this is a thread-like form of chromatin. because the DNA must be unwound for access by transcriptional machinery, this represents a transcriptionally active area of the genome

A

euchromatin

27
Q

Key features of the nuclear membrane (4)

A

Provides a selectively permeable barrier
Possesses 2 membranes, outer one contiguous with ER
Has a perinuclear space
Possesses a protein meshwork that lines the inner surface of the inner nuclear membrane

28
Q

Nuclear lamina helps support pores and is comprised of _____ __, __ ,__

A

lamin A, B, and C

29
Q

directs newly translated lamins back to where they belong

A

nuclear localization sequence (NLS)

30
Q

phosphorylation site that is involved in the regulation of lamina disassembly during mitosis

A

P-site

31
Q

Nuclear pores possess an _______ symmetry with __ spoke proteins

A

octagonal, 8

32
Q

This sequence can function autonomously or can be recognized by carrier proteins for transport into the nucleus

A

Nuclear localization sequence (NLS)

33
Q

This sequence acts as a signal for nuclear export

A

Nuclear export sequence (NES)

34
Q

This is primarily present on proteins that bind to immature mRNAs

A

Nuclear retention signal (NRS)

35
Q

What 3 mechanisms have been proposed for the regulation of nuclear trafficking

A

Changing the number of nuclear pore complexes
Masking of NLSs (i.e. phosphorylation)
Addition of NRSs or binding proteins in the cytoplasm

36
Q

What animals have nucleated RBCs for their entire life?

A

fish, amphibians, reptiles, and birds

37
Q

Why should you care about lamins?

A

since lamin assembly and disassembly are crucial for cell division, this process might represent a logical pathway to target with chemotherapeutic drugs

Cell Biology (2 decks)

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