The cell as a Unit of health and disease Flashcards
1
Q
Pathology literally translates as _______
A
The study of suffering
2
Q
He was prescient in assrting that disease originates at the cellular level.
A
Virchow
3
Q
Human genome contains some ________ billion DNA base pairs
A
3.2
4
Q
Within the genome there are only about _____ protein-encoding proteins.
A
20000
5
Q
These are the blueprints that instruct the assembly of enzymes, structural elements, and signalling molecules within the 50 trillion cells that make up the human body.
A
Noncoding DNA
6
Q
___% of the human genome does not encode proteins
A
98.5
7
Q
Regions that provide binding sites for transcription factors
A
Promoter and enhancer
8
Q
2 best-studied varieties of noncoding regulatory RNA
A
MicroRNA
long noncoding RNA
9
Q
jumping genes, can move around the genome during evolution, resulting in variable copy number and positioning even among closely related species.
A
mobile genetic elements
10
Q
special structural regions of DNA
-chromosome ends
A
telomeres
11
Q
special structural regions of DNA
-chromosome tethers
A
centromeres
12
Q
Major component of centromere
A
satellite DNA
13
Q
is also important in maintaining the dense, tightly packed organization of heterochromatin
A
satellite DNA
14
Q
T or F
Variation in gene regulation may prove to be more important in disease causation than structural changes in specific proteins
A
True
15
Q
Individual variation, including differential susceptibility to diseases and environmental stimuli, is encoded in less than __% of our DNA
A
0.5
16
Q
2 of the most common forms of DNA variation in the human genome
A
- SNP
2. CNV
17
Q
Variants at single nucleotide positions and are almost always biallelic
A
SNP
18
Q
Roughly ___% of SNPs occur in coding regions
A
1
19
Q
T or false
SNPs located in noncoding regions can occur within
genomic regulatory elements, thereby altering gene
expression; in such instances, SNPs influence disease
susceptibility directly.
A
T
20
Q
are thought
to have no effect on gene function or individual
phenotype.
A
Neutral variants
21
Q
are a form of genetic variation consisting of different
numbers of large contiguous stretches of DNA; these
can range from 1000 base pairs to millions of base pairs.
A
CNVs
22
Q
Approximately __% of CNVs involve gene-coding
sequences; thus CNVs may underlie a large portion
of human phenotypic diversity.
A
50
23
Q
Nucleosomes consist
of DNA segments 147 bp long that are wrapped around
a central core structure of highly conserved low molecular
weight proteins called ____
A
histones.
24
Q
. The naked DNA of a single human cell is about
___long
A
1.8 m
25
In
general, only the regions that are ____ are available
for transcription.
“unwound”
26
T or False
| Histones are static
False
Histones are not static, but rather are highly dynamic
structures regulated by a host of nuclear proteins.
27
____ complexes, on the other hand, carry out over 70
different histone modifications generically denoted as
“marks.”
“Chromatin
| writer”
28
are associated with histone marks that make the DNA accessible
to RNA polymerases.
Actively transcribed genes
29
____ have
| histone marks that enable DNA compaction into heterochromatin
inactive genes
30
Histone marks are reversible through the
| activity of ____
“chromatin erasers.”
31
Histone methylation. Both ___ and ___can be
| methylated by specific writer enzymes.
lysines; arginines
32
Lysine residues are acetylated by _____, whose modifications
tend to open the chromatin and increase transcription.
histone acetyltransferases (HATs)
33
changes can be reversed by histone deacetylases (HDACs), leading to chromatin ____
condensation.
34
Histone phosphorylation. ____residues can be modified
| by phosphorylation
Serine
35
High levels of DNA methylation in
| gene regulatory elements typically result in ____
transcriptional
| silencing
36
are believed to bind to noncoding
regions and control long-range looping of DNA, thus
regulating the spatial relationships between enhancers
and promoters that control gene expression.
Chromatin organizing factors
37
T or F
| Genes can also be regulated by noncoding RNAs.
True
38
do not encode proteins; they modulate translation
| of target messenger RNAs (mRNAs)
Micro-RNA
39
T or F
Posttranscriptional
silencing of gene expression by miRNA is a fundamental
and well-conserved mechanism of gene regulation present
in all prokaryotes
False
| -Eukaryotes
40
The human genome encodes almost ____ miRNA genes
6000
41
_____ are short RNA sequences
| that can be introduced experimentally into cells where they
Small interfering RNAs (siRNAs)
42
finer granular structures of the nucleus
Euchromatin
43
means
| that histones are not tightly wound.
Finely granular chromatin
44
```
■ cytochemically dense and
transcriptionally inactive (they
are not transcribed)
■ Coarsely granular structures of
the nucleus
```
HETEROCHROMATIN
45
■ cytochemically dispersed and
transcriptionally active
■ Finely granular structures of the
nucleus
EUCHROMATIN
46
Functions primarily to modulate the translation of
| target mRNA into their corresponding proteins
Micro-RNA (miRNA)
47
Transcription of miRNA genes produces a
primary transcript (pri-miRNA) that is
processed into progressively smaller segments,
including trimming by the ___
Dicer
48
they serve as
substrates for Dicer and interact with RISC,
thereby reproducing endogenous miRNAs
function.
Small interfering RNAs (siRNAs)
49
The number of lncRNAs may exceed coding
| mRNAs by 10- to 20- fold
LONG NON-CODING RNA (lncRNA)
50
LONG NON-CODING RNA (lncRNA) modulate gene expression in many ways:
○ Gene activation
○ Gene suppression
○ Promote chromatin modification
○ Assembly of protein complexes
51
T or F
Many normal housekeeping functions are
compartmentalized within membrane-bound
intracellular organelles
True
52
synthesizes new proteins destined for
the plasma membrane or point beyond
which are physically assembled in the
Golgi apparatus
Rough endoplasmic reticulum (RER)
53
Synthesizes proteins intended for the
| cytosol
Free ribosomes
54
SER may be abundant in ___ and ___
where it is used for steroid hormone and
lipoprotein synthesis;
gonads; liver
55
“Disposal” complexes that degrade
denatured or otherwise “tagged”
cytosolic proteins.
-can trigger initiation or suppression of signalling pathways
PROTEASOMES
56
```
Are intracellular organelles containing
degradative enzymes that permit
digestion of a wide range of
macromolecules (proteins,
polysaccharides, lipids, and nucleic
acids.
```
LYSOSOMES
57
```
○ Contain catalase, peroxidase, and other
oxidative enzymes
○ They play a specialized role in the
breakdown of very long-chain fatty
acids, generating hydrogen peroxide in
the process.
```
PEROXISOMES
58
Shuttle internalized material to the
| appropriate intracellular sites
Endosomal vesicles
59
Most of the adenosine triphosphate
(ATP) that powers cells is generated
via_____
Mitochondrial oxidative phosphorylation
60
also serve as an important source of
metabolic intermediates needed for
anabolic metabolism
Mitochondria
61
contain important sensors of cell
damage that can initiate and regulate
programmed cell death (e.g.,
apoptosis).
Mitochondria
62
Movement of both organelles and proteins within
the cell, as well as the entire cell in its
environment is accomplished by the
_____
cytoskeleton.
63
Cytoskeleton is composed of:
Filamentous actins (microfilaments), Keratins(intermediate filaments), and microtubules
64
○ 5 to 9nm diameter
○ formed from the globular protein actin
(G-actin)
○ most abundant
Actin microfilaments
65
New subunits are typically added at the
“positive” end of the strand and
removed from the “negative” end—a
process referred to as____
actin
| treadmilling
66
```
○ 10nm diameter
○ predominantly form ropelike polymers
and do not usually actively reorganize
like actin and microtubules
○ provide tensile strength so that cells
can bear mechanical stress, e.g., in
epithelia
○ They form the major structural proteins
of skin and hair.
```
Intermediate filaments
67
in mesenchymal
| cells
Vimentin
68
in muscle cells forms
the scaffold on which actin
and myosin contract.
Desmin
69
are critical for
neuronal axon structure and
confer both strength and
rigidity.
Neurofilaments
70
is expressed in glial cells
Glial fibrillary acidic protein
71
are expressed in
| epithelial cells
cytokeratins
72
```
are
intermediate filament proteins
that form the nuclear lamina,
define nuclear shape, and
can regulate transcription.
```
Lamins (A, B, and C) 7
73
```
○ 25nm thick
○ composed of noncovalently polymerized
α- and β-tubulin dimers organized into
hollow tubes
○ These fibrils are extremely dynamic
and polarized, with “+” and “−” ends.
```
Microtubules
74
```
is typically embedded
in a microtubule organizing
center (MTOC or centrosome)
near the nucleus, where it is
associated with paired
centrioles
```
“−” end
75
elongates or recedes
in response to various stimuli by
the addition or subtraction of
tubulin dimers
“+” end
76
anterograde (− to
| +)
Kinesins
77
retrograde (+ to −)
Dyneins
78
```
PLASMA MEMBRANE
● a fluid bilayer of amphipathic phospholipids —
hydrophilic head groups that face the
_____ and hydrophobic lipid
tails that ______
```
aqueous environment; interact with each other
79
○ inner membrane leaflet
○ serving as an electrostatic scaffold for
intracellular proteins
PHOSHATIDYLINOSITOL
80
```
polyphosphoinositides can be
hydrolyzed by ______to
generate intracellular second signals
like diacylglycerol and inositol
trisphosphate
```
phospholipase C
81
○ inner face
○ confers a negative charge involved in
electrostatic protein interactions
PHOSPHATIDYLSERINE
82
○ extracellular face
○ They are important in cell-cell and
cell-matrix interactions
GLYCOLIPIDS AND SPHINGOMYELIN
83
```
is involved in specialized
pathways of protein/lipid transport and
signaling. They also act as vesicular
carriers for membrane trafficking in T
lymphocytes.
```
Lipid raft
84
that binds one
| cell to another
Cell-adhesion molecule
85
```
special integral
membrane proteins called ____
form transmembrane channels for
water, H2O2, and other small
molecules.
```
aquaporins
86
```
T or F
Larger hydrophobic molecules, (e.g.,
steroid-based molecules like estradiol
or vitamin D) can also cross lipid
bilayers with relative impunity
```
True
87
create hydrophilic
pores, which, when open, permit rapid
movement of solutes (usually restricted
by size and charge).
Channel proteins
88
```
bind their specific
solute and undergo a series of
conformational changes to transfer the
ligand across the membrane; their
transport is relatively slow.
```
Carrier proteins
89
pumps polar compounds (e.g.,
chemotherapeutic drugs) out of cells
and may render cancer cells resistant to
treatment.
multidrug
| resistance (MDR) protein
90
causes net movement
| of water out of the cells.
Hypertonicity
91
causes net movement
| of water into cells.
Hypotonicity
92
_____are most active at pH 7.4
and are often regulated by Ca2+, whereas
_____ function best at pH 5
or less.
Cytosolic enzymes ; lysosomal enzymes
93
○ For smaller molecules
| ○ “little caves”
Caveolae-mediated endocytosis
94
the major structural
protein of caveolae, which, like
membrane rafts, are enriched in
glycosphingolipids and cholesterol.
Caveolin
95
Internalization of caveolae along with
bound molecules and associated
extracellular fluid is called _____
potocytosis
96
```
Macromolecules bound to membrane
receptors (such as transferrin or
low-density lipoprotein [LDL] receptors)
are taken up at specialized regions of
the plasma membrane called
____
```
clathrin-coated pits.
97
```
T or F
The vesicles then rapidly lose their
clathrin coating and fuse with a basic
intracellular structure called the early
endosome
```
False
| -not acidic, basic
98
```
In this process, proteins synthesized
and packaged within the RER and
Golgi apparatus are concentrated in
secretory vesicles, which then fuse with
the plasma membrane to expel their
contents.
```
exocytosis
99
is the movement of endocytosed
vesicles between the apical and
basolateral compartments of cells
Transcytosis
100
Ganda ni quen no?
TRUE, siz!
