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Cell Biology > Definitions > Flashcards

Definitions Flashcards

1
Q

Glycosidic Bonds

A

Formed when monosaccharides join with a dehydration reaction (water removed)

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2
Q

Glycogen

A

A polysaccharide that stores glucose molecules in animal cells

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3
Q

Starch

A

A polysaccharide that stores glucose molecules in plant cells

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4
Q

Amylopectin

A

Another term for starch

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5
Q

Cellulose

A

Main structural component of plant cell walls

Carbohydrate

Made of glucose molecules linked together by a beta 1-4 linkage (which is very strong)

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6
Q

Chitin

A

Main structural component of animal cell walls

Carbohydrate

Forms exoskeletons of arthropods

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7
Q

Lipids

A

Fats

Used for energy storage
Major component in cell membranes
Steroid hormones important in cell signalling and messenger molecules

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8
Q

Fatty acids

A

Long hydrophobic hydrocarbon chains (16-18 carbons) with a carboxyl (COO-) group at one end

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9
Q

Unsaturated fatty acids

A

One or more double bonds

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10
Q

Saturated fatty acids

A

No double bonds

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11
Q

Triglycerides

A

Also known as fats

3 fatty acids linked to a glycerol molecule
Used as storage for fatty acids

Breaking them down yields energy

Insoluble in water

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12
Q

Phospholipids

A

Main component of cell membranes

2 non polar Fatty acids joined to a polar head group

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13
Q

Glycerol Phospholipids

A

2 non polar fatty acids bound to a glycerol, which is bound to a phosphate group, which is bound to a polar group

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14
Q

Sphinogomyelin

A

Only nonglycerol phospholipid found in cell membranes

Polar head group is formed from serine

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15
Q

Amphipathic

A

Molecules with a polar (water soluble) end and a non polar (hydrophobic) end

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16
Q

Glycolipids

A

Amphipathic

2 hydrocarbon chains and a carbohydrate polar head group

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17
Q

Cholesterol

A

Amphipathic

4 hydrophobic hydrocarbon rings and a polar hydroxyl (OH) group

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18
Q

Steroid hormones

A

Derivatives of cholesterol, act as chemical messengers

Ex. estrogen, testosterone

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19
Q

Nucleic acid

A

Principle informational molecule of the cell

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20
Q

Deoxyribonucleic acid

A

Genetic storage material

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21
Q

Ribonucleic acid

A

Genetic material with multiple purposes

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22
Q

mRNA

A

messanger RNA

carries genetic information copied from the original DNA to the ribosome

read in 5’ to 3’ direction

transport of mRNA out of the nucleus is independent of Ran and does not involve karyopherins

only RNA that does not require transport proteins!

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23
Q

rRNA

A

ribosomal RNA

involved in protein synthesis, reads the mRNA and puts the amino acids in the correct order

catalyzes peptide bond formation

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24
Q

tRNA

A

transfer RNA

involved in protein synthesis, brings amino acids to ribosome to be coded into proteins and aligns them with corresponding codons on the mRNA template

70-80 nucleotides long and are clover shaped

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25
Q

purine

A

nucleotides that make up DNA and RNA

adenine
guanine

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26
Q

pyrimidine

A

nucleotides that make up DNA and RNA

cytosine
thymine (dna only)
uracil (rna only)

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27
Q

nucleoside

A

nucleotide base linked to sugars

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28
Q

2’-deoxyribose

A

the sugar in dna

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29
Q

ribose

A

the sugar in rna

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30
Q

phosphodiester bond

A

bonds between nucleotides that make up dna/rna

form between 5’ phosphate of one nucleotide and the 3’ hydroxyl group of another

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31
Q

oligonucleotides

A

polymer of only a few nucleotides

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32
Q

polynucleotides

A

polymer of thousands or millions of nucleotides

rna and dna are polynucleotides

synthesized int he 5’ to 3; direction

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33
Q

complimentary base pairs

A

hydrogen bonds between nucleotides:

guanine - cytosine
adenine - thymine (dna)
adenine - uracil (rna)

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34
Q

5’-triphosphate

A

ATP

main form of chemical energy in cells

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35
Q

protein

A

diverse macromolecules
polymers of amino acids

  • structural components
  • transport and storage of small molecules
  • transmit informtaion between cells (protein hormones)
  • defence against infection (antibodies)
  • enzymes
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36
Q

amino acids

A

consist of an alpha carbon bonded to a carboxyl group and an amino acid group, a hydrogen, and a side chain

4 categories:

  • non polar
  • polar
  • basic
  • acidic

20 amino acids

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37
Q

peptide bones

A

joins amino acids

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38
Q

polypeptides

A

chains of hundreds or thousands of amino acids

synthesized from n-terminus to c-terminus

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39
Q

n-terminus

A

an alpha amino group at the end of a polypeptide chain

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40
Q

c-terminus

A

an alpha carboxyl group at the end of a polypeptide chain

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41
Q

x-ray crystallography

A

way to analyze the 3D shape of proteins

used to understand protein folding

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42
Q

primary structure of proteins

A

sequence of amino acids in a chain

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43
Q

secondary structure of proteins

A

many chains of amino acids stuck together that conform to a structure

alpha helix
beta sheet (folded)

held together by hydrogen bonds between the peptide bonds

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44
Q

tertiary structure

A

side chains of amino acids interact with different regions of the polypeptide chain

made up of alpha helixes and beta sheets

shape determined by location of hydrophobic and hydrophilic amino acids

(hydrophobic amino acids folded to be on the inside of the protein, and hydrophilic amino acids are on the surface where they interact with water)

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45
Q

domain

A

the basic unit of tertiary structure

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46
Q

loop region of a protein

A

areas where secondary structures of a protein are connected

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47
Q

quarternary structure

A

composed of more than one polypeptide/protein

ex. hemoglobin is composed of 4 polypeptides

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48
Q

enzymes

A

catalysts that increase rate of chemical reactions

do not affect the amount of product, just the speed that you get it

(lowers the transition state/activation energy)

does not get ‘used up’ by the reaction

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49
Q

substrate

A

the reactants of a chemical reaction involving enzymes

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50
Q

transition state

A

a higher energy state that reactants need to reach before they can make the product

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51
Q

activation energy

A

amount of energy needed to reach the transition state

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52
Q

activation site

A

a site on an enzyme where a specific substrate binds to speed up the reaction

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53
Q

enzyme-substrate complex

A

the result of a substrate that has binded to its substrate

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54
Q

lock-and-key model

A

the substrate fits precisely into the active site

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55
Q

induced fit model

A

structure of both enzyme and substrate is modified after binding to make a perfect fit

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56
Q

prosthetic groups

A

small molecules that bind to proteins that allows them to bind with enzymes

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57
Q

coenzymes

A

small organic molecules that work with enzymes to enhance reaction rates

are not altered by reactions

almost always associated with vitamins

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58
Q

NAD+

A

nicotinamide adenine dinucleotide

a cozenzyme that carries electrons in an oxidation-reduction reaction

accept H+ (proton) and 2 electrons to form NADH

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59
Q

NADH

A

NAD+ plus an H+ proton

carries electrons and donates them to other substrates (this causes it to form NAD+ again)

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60
Q

vitamins

A

contribute part of all of the structure of coenzymes

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61
Q

feedback inhibition

A

the product of a metabolic pathway inhibits an enzyme involved in its own synthesis

a regulatory molecule binds to an enzyme site that is distinct from the catalytic site

changes confirmation of enzyme and prevents substrate from being able to bind to it

a type of allosteric regulation

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62
Q

allosteric regulation

A

controls enzyme activity by binding small molecules to the regulatory sites on enzymes

this results in the structure of enzymes, and thus the activation site to change

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63
Q

phosphorylation

A

a mechanism of enzyme regulation
either stimulates or inhibits the activities of many enzymes

phosphate groups are added to side chain of OH groups of serine, threonine, or tyrosine

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64
Q

phospholipid bilayers

A

2 layers of sheets of phospholipids with the hydrophobic tails facing each other, and the hydrophilic heads facing outwards
proteins are found within this structure

structure makes it selectively permeable

allows cell to control its internal composition

all cells membranes are like this

types of phospholipids, and number of lipids in a membrane varies

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65
Q

polar

A

hydrophilic

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66
Q

non polar

A

hydrophobic

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67
Q

mammal cell membranes

A

has 5 major types of phospholipids

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68
Q

animal cell membranes

A

contain glycolipids and cholesterol

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69
Q

membrane fluidity

A

determined by temperature and lipid composition

cholesteroles and other hormones affect this

unsaturated fats have kinks in their tails an reduces packing and increases fluidity

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70
Q

unsaturated fatty acids

A

have kinks in their tails

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71
Q

cholesterol

A

reduces interaction between fatty acids (comes inbetween)

and allows membrane to stay fluid at colder temperatures

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72
Q

fluid mosaic

A

our current understanding of the structure of phospholipid bilayers

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73
Q

Integral membrane protein

A

proteins embedded in the lipid bilayer

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74
Q

peripheral membrane protein

A

associated with the cell membrane indirectly

often by interactions with integral membrane proteins

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75
Q

transmembrane proteins

A

goes THROUGH the entire lipid bilayer, with exposed portions on both sides

usually has an apha helix structure and is made of 20-25 nonpolar amino acids

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76
Q

beta barrel protein structure

A

barrel shape made up of beta sheets that have folded into the tube structure

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77
Q

selectively permeable membrane

A

small, nonpolar molecules can diffuse across lipid bilayers

Ex. CO2, O2, H2O

ions and larger uncharged molecules cannot

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78
Q

channel proteins

A

transporter

act as open pores across the cell membrane, and can be selectively opened and closed in response to extra cellular signals

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79
Q

ion channels

A

allow passage of inorganic ions

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80
Q

carrier proteins

A

selectively bind and transport small molecules through the cell membrane

undergo conformation changes after binding to specific molecules that open its channel so that molecules can pass

ex. glucose can be transported with carrier proteins

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81
Q

passive transport

A

molecule movement across the membrane is determined by concentration and electrochemical gradients

no ATP required

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82
Q

active transport

A

molecules can be transported against a concentration gradient using energy from the hydrolysis of ATP

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83
Q

transcription

A

mRNA template made from DNA so that proteins can be made outside to nucleus without endangering the DNA

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84
Q

translation

A

tRNA and rRNA bind amino acids together to make polypeptide chains using mRNA template

first step of making proteins

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85
Q

gene expression

A

regulated during translation in both prokaryotic and eukaryotic cells

affects all aspects of cell behaviour and protein acivity

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86
Q

codon

A

3 bases in a row that code for a specific amino acid

codons tell the ribosome what amino acid needs to be attached next

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87
Q

aminoacyl rTNA synthestase

A

enzyme that attaches amino acids to specific tRNAs

20 different enzymes, one for each amino acid
each one recognizes a single type of amino acid, and the tRNA it should attach to

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88
Q

codon at 3’ end of tRNA

A

CCA

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89
Q

nonstandard codon

A

wobble

accounts for mistakes in mRNA sequence

each amino acid has multiple codons in case of coding error

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90
Q

70S ribosome

A

bacterial ribosome

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91
Q

80S ribosome

A

eukaryotic ribosome

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92
Q

UTRs

A

untranslated regions

noncoding regions at ends of mRNAs

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93
Q

monocistronic

A

encodes a single protein

common in most eukaryotic mRNAs

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94
Q

polycistronic

A

encodes multiple proteins

each are translated from an independent start site

common in most prokaryotic mRNAs

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95
Q

AUG

A

starting codon for
methionine

translation in both prokaryotes and eukaryotes

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96
Q

Shine-Dalgarno sequence

A

sequence before starting codon in bacterial mRNAs

initiates translation at 5’ end of monocistronic mRNAs and at an internal initiation site of polycistronic mRNAs

97
Q

7-methylguanosine cap

A

found at the 5’ end of eukaryotic mRNAs

ribosome scans downstream from this cap to find initiation codon

98
Q

initiation

A

first stage of translation

methionyl tRNA, mRNA and a specific indicator bind to the small ribosomal subunit

the large ribosomal unit then joins and forms a functional ribosome

99
Q

elongation

A

connecting the correct amino acids together with peptide bonds in order to form the peptide chain

continues until a stop codon is found

100
Q

termination

A

a stop codon is found in the mRNA sequence and the chain is translocated into the A site

101
Q

elF

A

eukaryotic initiation factors

non ribosomal proteins involved in the initiation stage of translation in eukaryotes

102
Q

IRESs

A

internal ribosome entry sites

areas of eukaryotic mRNAs where translation can initiate without the 5’ cap

103
Q

elongation factor

A

forms a complex with GTP and brings aminoacyl tRNA to the ribosome

correct aminoacyl tRNA needed to synthesize the protein correctly

104
Q

EF-Tu

A

prokaryotic elongation factor

105
Q

eEF1 alpha

A

eukaryotic elongation factor

106
Q

P site

A

peptidyl binding site

initiator methionyl tRNA binds to p site

107
Q

A site

A

aminoacyl binding site

108
Q

E site

A

exit binding site

109
Q

decoding center

A

area in the small ribosomal subunit recognizes correct codon-anticodon base pairs and finds mismatches/mistakes

110
Q

translocation

A

ribosome moves 3 nucleotides along the mRNA, positioning the next codon in the A site

peptidyl tRNA is translocated from A to P
uncharged tRNA is translocated from P to E

111
Q

stop codon

A

UAA
UAG
UGA

stops the elongation stage of translation

112
Q

release factors

A

recognize stop codons and terminates protein synthesis

113
Q

RF1

A

release factor 1

recognizes stop codons:
UAA
and
UAG

114
Q

RF2

A

release factor 2

recognizes the stop codons:
UAA
and
UGA

115
Q

eRF1

A

recognizes all 3 stop codons in eukaryotic cells

116
Q

eRF1

A

recognizes all 3 stop codons in eukaryotic cells

117
Q

polysome

A

polyribosome

multiple ribosomes bound to the same mRNA molecule, translating at the same time

118
Q

global translational activity

A

modulated in response to stress, nutrient availability, and growth factor stimulation

119
Q

ferritin

A

protein that stores iron

120
Q

RNAi

A

RNA interference

short double-stranded RNAs is used to block gene expression at the level of translation

121
Q

siRNA

A

small interfering RNAs

produced from double-stranded RNAs by the nuclease dicer

pair with their targets and induce cleavage of the mRNA

122
Q

miRNA

A

microRNAs

transcribed by RNA polymerase II, then cleaved by nucleases Drosha and Dicer

1000 miRNAs in mammals
each target up to 100 different mRNAs

123
Q

RISC

A

RNA-induced silencing complex

represses translation and targets the mRNA for degradation by stimulating deadenylation

124
Q

miRNA

A

microRNAs

transcribed by RNA polymerase II, then cleaved by nucleases Drosha and Dicer

1000 miRNAs in mammals
each target up to 100 different mRNAs

up to one half of protein coding genes are regulated by miRNAs

important in embryonic development

play a role to cancer and other diseases

125
Q

RISC

A

RNA-induced silencing complex

represses translation and targets the mRNA for degradation by stimulating deadenylation

126
Q

modificated initiation factors

A

effects overall translational activity instead of targeting translation of specific mRNAs

127
Q

chaperones

A

proteins that facilitate folding of other proteins

catalysts that assist the self assembly process
do not become part of the folded protein

stabilize unfolded or partially folded polypeptides

128
Q

Hsp

A

Heat-shock proteins

Expressed in cells subjected to high temperatures

a type of chaperone that stabilize and facilitate refolding of proteins that have been partially denatured

129
Q

Hsp70

A

Stabilize polypeptide chains during tranlsation and transport by binding to short hydrophobic segments

Found in both prokaryotic and eukaryotic cells

130
Q

chaperonin

A

Consists of subunits arranged in two stacked rings to form a double-chambered structure

Folding of proteins takes place here

Isolates proteins from cytosol and other unfolded proteins

131
Q

chaperonin

A

Consists of subunits arranged in two stacked rings to form a double-chambered structure

Folding of proteins takes place here

Isolates proteins from cytosol and other unfolded proteins

132
Q

Protein misfolding diseases

A

Mutations and deformations caused by misfolded proteins

133
Q

Cystic fibrosis

A

Mutation that results in the deletion of one amino acid that leads to improper folding of protein CFTR

134
Q

CFTR protein

A

Transports Cl- ions across epithelial cell membranes

135
Q

Alzheimers Disease

A

Associated with 2 aggrigate types of misfolded proteins in brain tissue

neurofibrillary tangles (misfolded tau proteins)
amyloid plaques (aggregates of misfolded amyloid-beta protein)
136
Q

Parkinson’s Disease

A

Associated with aggregation of misfolded proteins

137
Q

Type 2 Diabetes

A

Associated with aggregation of misfolded proteins

138
Q

Amyloids

A

Fibrous aggregates caused by misfolded proteins

characterized by beta-sheet structures when the protein is not supposed to be in this shape

139
Q

prions

A

misfolded proteins that can self-replicate

140
Q

Scrapie

A

Disease in sheep caused by prions

141
Q

Mad Cow Disease

A

Disease caused by prions

142
Q

Creutzfeldt-Jakob disease

A

Disease caused by prions

143
Q

Kuru

A

Disease caused by prions

144
Q

PDI

A

protein disulfide isomerase

catalyzes disulfide bond formation

abundant in the ER, where the oxidizing environment allows S–S linkages

145
Q

peptidyl prolyl isomerase

A

catalyzes isomerization of peptide bonds that involve proline residues

146
Q

Proteolysis

A

Cleavage of a polypeptide chain removes portions such as the initiator methionine from the n-terminus

147
Q

signal sequences

A

sequence of amino acids that target the new protein for transport to a specific destination

148
Q

signal sequences

A

sequence of amino acids that target the new protein for transport to a specific destination

149
Q

signal peptidase

A

A membrane protease that cleaves off signal sequences

150
Q

signal peptidase

A

A membrane protease that cleaves off signal sequences

151
Q

glycosylation

A

adds carbohydrate chains to proteins to form glycoproteins

starts in the ER before translation is complete

152
Q

glycoproteins

A

Proteins with carbohydrate chains attached

The carbohydrate plays important roles in:
protein folding in the ER
targeting proteins for transport
and recognition sites in cell-cell interactions

153
Q

N-linked glycoproteins

A

glycoprotein where the carbohydrate is attached to the nitrogen atom in the side chain of asparagine

154
Q

O-linked glycoproteins

A

glycoprotein where the carbohydrate is attached to the oxygen atom in the side chain of serine/threonine

155
Q

dolichol phosphate

A

a lipid carrier

156
Q

N-myristoylation

A

a type protein modification where lipids are added

myristic acid (fatty acid) attached to an N-terminal glycine

associated with the inner face of the plasma membrane

157
Q

prenylation

A

a type protein modification where lipids are added

prenyl groups are attached to sulfur in the side chains of cysteine near the c-terminus

these proteins are involved in control of cell growth and differentiation

158
Q

Rasoncogene proteins

A

Proteins responsible for many human cancers

159
Q

palmitoylation

A

a type protein modification where lipids are added

palmitic acid (a fatty acid) is added to the sulfur in the side chains of internal cysteine residues

involved in association of some proteins with the cytosolic face of the plasma membrane

160
Q

GPI anchors

A

a type protein modification where lipids are added

glycosylphosphatidylinositol anchors

lipids linked to oligosaccharides

glycolipids are added to the c-terminus carboxyl groups

anchor proteins to the external plasma membrane

161
Q

Protein Regulation

A

Via activities, or the amounts of proteins

  • regulation by small molecules
  • phosphorylation and other modifications
  • protein-protein interactions
162
Q

Ras proteins

A

Rasoncogene proteins

Proteins responsible for up to 25% of human cancers

caused by small difference in protein conformatoin resulting in ras being able to interact with its target molecule, which signals the cell to divide
cancer = cells dividing out of control

163
Q

Protein Regulation

A

Via activities, or the amounts of proteins

164
Q

regulation by small molecules

A

small molecules bind to enzymes to change their conformation.

common in controlling metabolic pathways by feedback inhibition

165
Q

protein kinases

A

transfer phosphate groups from ATP to the hydroxyl groups of side chains of serine, threonine, or tyrosine

often components of signal transduction pathways

can transmit a signal from the cell surface to target proteins in the cell, resulting in changes in call behavior in response to environmental stimuli

involved in DNA repair

166
Q

protein phosphatases

A

reverses phosphorylation

catalyze hydrolysis of phosphorylated amino acids

167
Q

epinephrine

A

signals the breakdown of glycogen to glucose-1-phosphate, providing energy for increased muscular activity

168
Q

glycogen phosphorylase

A

enzyme that catalyzes the breakdown of glycogen for energy for muscle activity

regulated by protein kinase

169
Q

protein-protein interactions

A

many proteins consist of multiple subunits, interactions between them can regulate protein activity

170
Q

protein ubiquitylation

A

regulates protein kinases

controls endocytosis and vesicle trafficking

171
Q

Ran GAP

A

Ran GTPase-activating protein

associated with nuclear pore complexes and is required for import of proteins

separates a Pi off of GTP, turning it to GDP

172
Q

ubiquitin-proteasome pathway

A

major pathway of protein degradation in eukaryotes

ubiquitin is attached to the amino group of the side chain of a lysine residue

173
Q

ubiquitin

A

highly conserved in all eukaryotes

attach to old or disfunctional proteins to signal them for deconstruction

tend to regulate proteins that control fundamental cell processes

174
Q

polyubiquinated proteins

A

recognized and degraded by large protease complex called the proteasome

175
Q

proteasome

A

large protease complex

176
Q

proteolysis

A

Degradation of old or defective proteins by the proteasome

177
Q

lysosomes

A

membrane-enclosed organelles that contain digestive enzymes, including proteases

digest extra cellular proteins taken up by endocytosis and help in turnover of organelles and proteins

178
Q

autophagy

A

Act of digesting and recycling non nessesary parts of a cell’s self

Activates during times of nutrient starvation
Recycles molecules from non essential proteins and organelles and use them for necessary processes

Vesicles called autophagosomes enclose small areas of cytoplasm or organelles then fuse with the lysosome

major role in developmental processes that involve extensive tissue remodeling
like insect metamorphosis

179
Q

Autophagosomes

A

Vesicles that form inside a cell and bring the parts of a cell to its own lysosome to recycle non nessesary parts during starvation

180
Q

Autophagosomes

A

Vesicles that form inside a cell and bring the parts of a cell to its own lysosome to recycle non nessesary parts during starvation

181
Q

nuclear envelope

A

seperates the nuclear contents from the cytoplasm

controls traffic of proteins and RNAs

critical role in regulating gene expression

  • 2 nuclear membranes
  • underlying nuclear lamina
  • nuclear pore complexes
182
Q

nuclear pore complexes

A

regulates traffic of proteins and RNAs into and out of the nucleus

channels for small polar molecules, ions, and macromolecules

large, made of 30 proteins (nucleoporins)
8 subunits organized around a large central channel

183
Q

outer nuclear membrane

A

phospholipid bilayers that are only permeable to small nonpolar molecules

continuous with the ER

184
Q

inner nuclear membrane

A

phospholipid bilayers that are only permeable to small nonpolar molecules

has integral proteins, including ones that bind to the nuclear lamina for stabilization

185
Q

space between inner and outer nuclear membranes

A

connected with the lumen of the ER

186
Q

nuclear lamina

A

fiberous mesh that provides structural support to the nuclear envelope

consists of fiberous proteins (lamins) and other proteins

187
Q

lamins

A

a class of intermediate filament proteins that associate to form higher order structures (lamina)

bind to inner membrane proteins such as emerin, LBR, and chromatin

188
Q

lamin dimer

A

alpha-helical regions of lamins wind around each other to form a coilerd coil

associate with each other to form the lamina

189
Q

LBR

A

lamin B receptor

inner membrane protein

190
Q

emerin

A

inner membrane protein

191
Q

LINC protein complexes

A

connect the lamina to the cytoskeleton of the cell

192
Q

passive diffusion

A

small molecules pass freely in either direction through pore complexes

no ATP needed

193
Q

selective transport

A

proteins and RNAs selectively transported through pore complexes

requires ATP

194
Q

nuclear localization signals

A

amino acid sequences on proteins that must enter the nucleus

195
Q

nuclear transport receptors

A

recognize nuclear localization signals

196
Q

NLS

A

nuclear localization signals

amino acid sequences on proteins that must enter the nucleus

197
Q

nuclear transport receptors

A

recognize NLS

198
Q

importins

A

receptors that recognize NLS and carry proteins through the nuclear pore complex

bind to the NLS of a protein then to the nuclear pore proteins and the complex is transported across the membrane

work in conjunction with GTP-binding protein Ran
Ran controls direction of movement

GTP/Ran binds to the importin and brings it back outside the nucleus

199
Q

NES

A

nuclear export signals

amino acid sequence that targets for transport out of the nucleus

200
Q

exportins

A

recognizes NES and direct protein transport to the cytoplasm

201
Q

karyopherins

A

family of nuclear transport receptors

most importins and exportins fall into this family

202
Q

exportins

A

recognizes NES and direct protein transport to the cytoplasm

form stable complexes with cargo proteins in association with Ran/GTP in the nucleus

In the cytoplasm, cargo protein disassociates from complex when GTP hydrolyzes and into Ran/GDP

203
Q

karyopherins

A

family of nuclear transport receptors

most importins and exportins fall into this family

204
Q

RNP

A

ribonucleoprotein complexes

Transports RNA to the cytoplasm

karyopherin exportins transport tRNA, rRNA, and miRNA

205
Q

RNP

A

ribonucleoprotein complexes

Transports RNA to the cytoplasm

karyopherin exportins transport tRNA, rRNA, and miRNA

206
Q

snRNA

A

small nuclear RNA

_____

initially exported from the nucleus by exportin Crm1

in the cytoplasm, snRNA associate with proteins to form snRNP, which is recognized by an importin and brought back into the nucleus

function within the nucleus

207
Q

snRNA

A

small nuclear RNA

initially exported from the nucleus by exportin Crm1

in the cytoplasm, snRNA associate with proteins to form snRNP, which is recognized by an importin and brought back into the nucleus

function within the nucleus

208
Q

snoRNA

A

small nuclear RNA

guide RNA to direct specific base modifications of pre-rRNA

2 families associate with different proteins, which catalyze ribose methylation or pseudouridine formation

have sequences complementary to 18S or 28S rRNA, including the sites of base modification

function in pre-rRNA processing
form complexes with proteins, forming snoRNPs, which function similar to spliceosomes on pre-mRNA

associated with nucleoli

function within the nucleus

209
Q

protein transport regulation

A

regulation of import and export of transcription factors controls gene expression

  • proteins associate with cytoplasmic proteins and mask their NLS, causing proteins to remain in the cytoplasm
  • phosphorylation of transcription factors can interfere with import
210
Q

chromatin

A

bundles of genetic information

highly condensed during mitosis to form compact metaphase chromosomes

loose and distributed throughout the nucleus during interphase

chromatin stays within distinct regions of the nucleus

211
Q

chromosomes

A

some human chromosomes are rich in transcribed genes, whereas others contain very few genes

gene-rich chromosomes tend to be located in the center of the nucleus, and gene-poor chromosomes near the edges

212
Q

chromosome territory

A

descrete area in the nucleus where chromosomes tend to occupy

213
Q

euchromatin

A

decondensed and transciptionally-active genetic informatoin

distributed throughout the nucleus

214
Q

heterochromatin

A

highly condensed and not trsncribed

often associated with the nuclear envelope or periphery of the nucleolus
found at the edges

215
Q

TADS

A

topologically associating domains

how genomes are divided

regions with a domain interact frequently with one another, but only rarely with regions in other domains

216
Q

LADs

A

lamina-associated domains

chromosomes associated with the nuclear lamina

genes within LADs are generally transcriptionally repressed - LADs are heterochromatin

217
Q

NADs

A

nucleolus-associated domains

chromosomes associated with the nucleolus

DNA sequences found in NADs substantially overlap with those in LADs

NADs are heterochromatin

218
Q

LADs

A

lamina-associated domains

chromosomes associated with the nuclear lamina

genes within LADs are generally transcriptionally repressed - LADs are heterochromatin

DNA sequences found in LADs substantially overlap with those in NADs

219
Q

NADs

A

nucleolus-associated domains

chromosomes associated with the nucleolus

NADs are heterochromatin

DNA sequences found in NADs substantially overlap with those in LADs

220
Q

replication factories

A

large complexes where DNA replication occurs

221
Q

transciption factories

A

clustered sites where transcription occurs

contain newly synthesized RNA

coregulated genes from different chromosomes may be transcribed in the same factory

222
Q

nuclear bodies

A

organelles within the nucleus that concentrate proteins and RNAs for specific processes

not enclosure by membranes
dynamic structures maintained by protein-protein and protein-RNA interactions

223
Q

nucleolus

A

involved in rRNA synthesis and ribosome production

actively growing mammal cells have 5-10 million ribosomes that must be synthesized each time the cell divides

224
Q

RNA polymerase I

A

unit in the nucleolus that transcribes 5.8S, 18S, and 28S rRNAs

yields a 45S ribosomal precursor RNA

225
Q

RNA polymerase III

A

unit outside the nucleolus that transcribes and catalyzes the 5S rRNA

226
Q

nucleolar organizing regions

A

SLIDE 86 ??

227
Q

nucleoli

A

3 regions, the all represent the progressive stages of rRNA transcription, processing, and ribosome assembly

have over 300 proteins and 200 snoRNAs

228
Q

spacer DNA

A

seperates clusters of tandemly repeated rRNA genes

229
Q

45S pre-rRNA

A

____

primary transcript of rRNA genes in higher eukaryotes

processed via a series of cleavages and substantial base modification

  • addition of methyl groups to bases and ribose residues
  • conversion of uridine to pseudouridine
230
Q

snoRNP

A

complexes that function similar to spliceosomes on pre-mRNA

231
Q

snoRNP

A

complexes that function similar to spliceosomes on pre-mRNA

232
Q

polycomb proteins

A

repress transcription of genes via methylation of histone H3 lysine 27 residues

some contain clusters of repressed domains from different chromosomal regions

233
Q

cajal bodies

A

involved in assembly of snRNPs and other RNA-protein complexes

play a role in assembly of telomerase
promotes assembly of the RNA-protein telomerase complex and facilitates its delivery to the telomeres

enzyme for RNA methylation (fibrillarin) is found in cajal bodies

234
Q

scaRNA

A

RNA specific to cajal bodies

related to snoRNA, and similarily serve as guides to direct ribose methylation and pseudouridylation of snRNA

235
Q

telomerase

A

replicates the ends of chromosomal DNA

prevents aging -> the shorter the telomeres, the older you are

236
Q

speckles

A

after assembly and maturation in cajal bodies, snRNPs are transported here

speckles contain splicing factors
recruited to actively transcribed genes where pre-mRNA processing occurs

237
Q

NTF2

A

A protein involved in export and important proteins to and from the nucleus.

In both processes, it binds to Ran/GDP, and brings it back into the nucleus from the cytoplasm through the nuclear pore complex (NPC)
With export, the Ran/GDP is attached to an exportin

238
Q

Ran/GEF

A

Located in the nucleus

Removes GDP from Ran, and adds a GTP to form Ran/GTP

This is a process in both protein import and export used to reuse the Ran for transporting exportin/importin out of the nucleus

239
Q

adhesion proteins

A

link components of the extracellular matrix to each other and to attach to cells

Cell Biology (6 decks)

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