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Block 1 -Test 1, (Biochem) > Lecture 1 (8/16) Cell Structure and Organelles > Flashcards

Lecture 1 (8/16) Cell Structure and Organelles Flashcards

1
Q

Non-membrane bound organelles

A 
Cytoskeleton 
 -MT
 -AF
 -IF
Proteosomes
Ribosomes
Centrioles and Basal Bodies
Cilia, Flagella
Inclusions

“CPR-CCI”

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2
Q

Membrane bound organelles

A 
PM
Peroxisomes
Lysosomes 
Mitochondria
ER, Endosomes
Golgi
Nucleus

“Please, please let me go now”

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3
Q

Glycoproteins will always face the?

A

Extracellular environment

Cytoplasm is a reducing environment and Extracellular fluid is an oxidizing environment.

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4
Q

Functions of the cell membrane

A 
Structure 
Control movement 
Regulates cell cell interaction 
Has receptors 
Transport
Transduces
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5
Q

Channels allow passage of

A

ions

-can be voltage, ligand, or mechanically gated.

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6
Q

Pumps and carriers

A

ions and molecules. Na/K. Ca. Glucose

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7
Q

Surface receptors

A

bind to a ligand to elicit a cellular response. Serve as signaling molecules which are kinases or are kinases themselves or are associated with kinases.

Also associated with G-proteins, cytokines, or steroid receptors.

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8
Q

Linkers and Structural Proteins

A

involved in cell-cell attachment; cell-matrix attachment

-serve as scaffolds for cytoskeleton

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9
Q

Major proteins in the nucleus

A

Replication and TF, Ribosomal proteins, histones, and fibrous proteins.

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10
Q

Outer nuclear membrane is contiguous with

A

RER

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11
Q

Constitutive vs facultative chromatin

A

C: remains transcriptionally inactive.

F: Can be decondensed and transcriptionally active, depending on cell type.

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12
Q

The interphase nucleus contains both transcriptionally inactive heterochromatin and also ?

A

Euchromatin

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13
Q

What goes in and out of nucleus

A

In:
DNA polymerase
Proteins made in the cytosol
Ribosomal proteins

Out:

mRNA to be translated
rRNA
ribosomes

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14
Q

Large molecules require a NLS to enter the nucleus such as

A

stretch of several basic amino acids such as Lysine and arginine

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15
Q

RNAs are transported through the NPC as ribonucleoproteins

A

THis requires energy provided by ATP hydrolysis. Nuclear transport proteins bring substances to the nuclear pore and facilitate movement across nuclear membrane and this requires energy provided by GTPase.

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16
Q

What happens in the nucleolus?

A

site of rRNA synthesis and ribosome assembly.

-Where rRNA and ribosomal particles come together to form the complete ribosome.

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17
Q

Dense fibrillar region

A

newly transcribed rRNA and ribosomal proteins

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18
Q

Granular component

A

assembly of RNA/ribosomal proteins into ribosomes

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19
Q

Metabolically active phase which may or may not lead to S phase

A

G1

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20
Q

Considered the committed step of of mitosis

A

S

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21
Q

Bulking up and proof reading phase

A

G2

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22
Q

Extended or non dividing phases

A

G0 and G1

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23
Q

Proteins that mediate apoptosis

A

caspases

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24
Q

Caspases begin to

A

digest the DNA as well as cytoplasmic proteins and organelles

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25
Q

Ribosomes can associate with ER membranes if the nascent polypeptide contains?

A

A signal sequence

26
Q

As many as 11-15 ribosomes can be on one mRNA. This structure is called a?

A

polyribosome.

27
Q

A free polyribosome with no signal sequence can go to

A

Mitochondria, Peroxisomes, Nucleus. (No sequence needed)

28
Q

ER bound polyribosomes target the protein to

A

Golgi , SV, Lysosomes, and protein either becomes part of membrane or secreted from the cell.

29
Q

Functions of the RER

A

Synthesis
Transport
Storage
Detox

30
Q

What binds to ER signal sequence?

A

SRP -signal recognition particle

and then binds to docking protein.

31
Q

Which proteins have an internal signal sequence?

A

Proteins that span the lipid bilayer.

32
Q

In the ER…

A

New proteins move into ER cisternae

Mannnose rich oligosaccharides are added to specific asparagine residues (N-linked)

Proteins are folded

Disulfide bonds are formed between cysteine residues

33
Q

Cis Golgi events

A

Vesicle movement from RER through golgi network is promoted by COPII

Similarly , COPI controls retrograde vesicle movement

Mannose 6-phosphate is added to future lysosomal enzymes

N linked oligosaccharides are trimmed and other sugars are added

34
Q

Medial golgi events

A

New glycosylation occurs on -OH groups of some lipids and Serine and threonine residues (O-linked).

N-linked oligosaccharides on proteins are modified further.

Glycoproteins and glycolipids are sorted into specific vesicles.

35
Q

Trans golgi events

A

Sialic acid is added as the terminal sugar to certain oligosaccharides

Sulfation of tyrosine residues and some sugars

Specific vesicles with different destinations are separated and sorted.

36
Q

Where are sugars added ?

A

ER and modified in the golgi

37
Q

Default from the TGN is the

A

Plasma membrane

38
Q

Proteins destined for the lysosome contain a recognition site consisting of ?… and delivered by vesicular transport from the TGN.

A

Phosphorylated mannose … M6P

39
Q

Material is delivered to the lysosomes in two ways.

A
  1. Vesicular transport by the TGN

2. By vesicles derived from the PM.

40
Q

3 types of alternative transport pathways to the lysosome ?

A

Phagocytosis (bulk material-bacteria, cell debris)
Endocytosis
Autophagy

41
Q

In receptor mediated cytosis, what helps “direct traffic”

A

Coat proteins

42
Q

What happens to the receptors and ligands in the case of LDL?

A

Receptor recycles

Ligand degraded

43
Q

What happens to the receptors and ligands in the case of transferrin?

A

Both receptor and ligand are recycled

44
Q

What happens to the receptors and ligands in the case of EGF?

A

Both receptor and ligand are degraded

45
Q

What happens to the receptors and ligands in the case of IgA

A

Both receptor and ligand are transported (“transcytosis”)

46
Q

Where are peroxisomal proteins synthesized?

A

cytoplasm - they are transported into the organelle using a specialized targeting amino acid sequence.

47
Q

One major function of the peroxisomes is?

A

Oxidation of LCFA, but the energy generated is not used to synthesize ATP

48
Q

Hydrogen peroxide is broken down by?

A

Catalase

49
Q

Where is the proteasome located?

A

Cytoplasm and the nucleus

50
Q

Proteins that are destined for destruction are tagged with a 76 AA peptide called ?

A

Ubiquitin

51
Q

Degradation via the secretory pathway ends up at the

A

Lysosome

52
Q

Degradation via the cytosol ends up at the

A

Proteasome

53
Q

All of the MT, AF, and IF are held together by

A

non-covenant bonds

54
Q

Functions of the cytoskeletal system

A 
Pulls chromosomes apart 
Guides intracellular traffic 
Supports the PM
Swim and crawl (sperm)
Muscle contraction 
Maintains diversity
55
Q

Microtubules

A

Mechanical reinforcement
Tracks for motor proteins
Chromosomal moment during mitosis
Tracks for movement along axons (neurotubules)
** Cilia and Flagella
Organized around centrioles or basal bodies.

Tubulin is a heterodimer

56
Q

AF

A

cross linked, anchored to the PM to reinforce the surface of the cell.

57
Q

What supports microvilli?

A

Actin fillaments

-Genetic defects in the actin binding protein, dystrophin cause most of the common forms of muscular dystrophy.

58
Q

Intermediate filaments

A

strong and flexible.

59
Q

All IF are related to the ? molecule.

A

Keratin

60
Q

IF link the

A

PM to the nucleus

some reinforce the nuclear envelope

61
Q

Genetic defects in certain IF cases a severe ?

A

Blistering of the skin, along with other disorders.

62
Q

Inclusions

A 
Glycogen 
Lipids (stores to make hormones on demand when needed because storing hormones would diffuse into the cells when not supposed to because they are lipid soluble).
Lipofuscin
Hemosiderin 
Melanin 
Crystals

Block 1 -Test 1, (Biochem) (12 decks)

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