Leys SG exam 2 Flashcards
(172 cards)
1
Q
how to cells acquire nucleotides?
A
de novo synthesis and salvage pathways
2
Q
result of denovo synthesis in purines?
A
synthesis of inosine
3
Q
can be converted into adenosine and guanosine
A
inosine
4
Q
derived from several sources including aspartate, glutamine, glycine, and methyl groups supplied by folic acid and carbon dioxide
A
atoms in newly synthesized purines
5
Q
regulate denovo synthesis of purines at multiple points in the pathway
A
ADP and GDP
6
Q
can be recycled through the salvage pathway with hypoxanthine guanine phosphoribosyl transferase (HGPRT)
A
hypoxanthine and guanine
7
Q
catalyzes a hydroxylase type reaction leading to formation of uric acid
A
xanthine oxidase
8
Q
cause of gout?
A
excess uric acid
9
Q
most often caused by low levels of the secretion of uric acid, but excess production as well
A
gout
10
Q
leads to localized inflammatory response in joints
A
crystallization of sodium urate
11
Q
used to treat gout by inhibiting xanthine oxidase (preventing uric acid formation)
A
allopurinol
12
Q
HGPRT deficiency resulting in severe retardation, crippling gouty arthritis and self-mutilation
A
lesch-nyhan syndrome
13
Q
occurs in males only because of the HGPRT gene location
A
lesch-nyhan syndrome
14
Q
location of HGPRT gene
A
X chromsome
15
Q
can replenish TCA cycle intermediates through the production of fumarate
A
breakdown of purines
16
Q
derived from aspartate and carbamoyl phosphate
A
atoms in a pyrimidine ring
17
Q
located on the same CAD protein
A
1st 3 enzymes in the synthesis of pyrimidines
18
Q
can be interconverted
A
pyrimidines U and C
19
Q
converted to TMP by thymidylate synthase
A
dUMP
20
Q
enzyme requiring the transfer of a methyl group from tetrahydrofolate
A
thymidylate synthase
21
Q
used as therapeutic agents for treating cancer and bacterial infections
A
inhibitors of tetrahydrofolate production
22
Q
used as anticancer agents
A
fluro substituted pyrimidine analogs that inhibit thymidylate synthase
23
Q
converts ribonucleotides to deoxyribonucleotides
A
ribonucleotide reductase
24
Q
A bonds with (in DNA)
A
T
25
G bonds with (in DNA and RNA)
C
26
A bonds with (in RNA)
U
27
can be compared in different species to determine phylogenetic relationships
homologous regions of DNA
28
contain similar DNA but often arranged differently on the chromosomes of each species
closely related organisms
29
3 divisions/domains of the living world?
bacteria, archaea, eukaryotes
30
4 main processes for generating change in a genome
- intragenic mutation (single base change)
- gene duplication
- DNA segment shuffling
- horizontal gene transfer
31
usually clustered into groups (operons) that are transcribed as one single unit
bacterial genes
32
often broken up with regions of noncoding DNA or introns between regions of coding DNA (exons)
eukaryotic genes
33
comparing exons and introns of closely related species:
exons will be similar (conserved) and introns will vary in size/content
34
densely packed with genes, leaving very little DNA that is non coding
bacterial chromosomes
35
do not code for proteins
most of the DNA in higher eukaryotes
36
made up of repeated sequences, many of which are mobile elements that can be moved around in the genome
most of human genome
37
linear chromosomes
eukaryotic
38
circular chromosomes
bacterial
39
have been completed including several bacteria that are found in the oral cavity
human genome and genomes of a large number of other organisms
40
possible to construct metabolic pathways and compare them with other organisms by:
examining their entire genome content
41
can be grouped into families based on similar (homologous) sequences found in different organisms
genes
42
can be found in genes of the same organism that carry out different but similar functions
homologous sequences
43
can have similar sequences (homology)
genes that have similar fans in very distantly related organisms
44
how can phylogenetic relationships of different organisms be compared?
by comparing the DNA sequences of similar genes in 2 organisms
45
DNA dependent (uses DNA as a template) DNA synthesizing enzymes
DNA polymerase
46
DNA dependent RNA polymerase
primase
47
synthesizes a small RNA primer that can be used by the DNA polymerase to elongate the chain
primase
48
RNA dependent DNA synthesizing enzyme
reverse transcriptase
49
minimizes the number of mistakes (mis-incorporated nucleotides) by using a 3- to 5 exonuclease (proofreading)
DNA polymerase
50
synthesize DNA in the 5' to 3' direction only
DNA polymerase as well as other nucleic acid polymerases
51
where are new nucleotides added during replication
to the 3' carbon on the last nucleotide of the new DNA chain
52
where are base components of each nucleotide connected to the sugar?
at the 1' carbon
53
where are adjacent nucleotides in a DNA chain attached to the sugar
5' and 3' carbons
54
which carbon differs between RNA and DNA?
2'
55
elongating enzyme, cannot initiate synthesis
DNA polymerase
56
required for elongation of a new strand using the DNA polymerase
a primer
57
contains one origin of replication
bacterial chromosomes
58
proceeds in both directions away from the origin until the 2 replication forks meet at a specific sequence on the other side of the chromosome
DNA synthesis
59
new rounds of DNA replication can begin before the previous round is completed
in bacteria
60
contain many origins of replication that may change during the development of the organism
eukaryotic chromosomes
61
each chromosome is replicated only once each cell division
in eukaryotes
62
new rounds of replication do not start until after the cell divides
in eukaryotes
63
linear and special structures in eukaryotic chromosomes placed on each end
telomeres
64
constructed with the enzyme telomerase
telomeres
65
uses an RNA template to synthesize a short repeated DNA sequence at the ends of chromosomes
telomerase
66
since polymerase must synthesize new DNA in the 5' to 3' direction,,,
the 2 polymerase molecules on opposite strands move away from each other
67
unwinds the 2 DNA strands before polymerization of new strands
helicases
68
keep the 2 complementary strands for reforming a double helix
single stranded binding proteins
69
moves toward replication fork
polymerase on leading strand
70
moves away from replication fork
polymerase on lagging strand
71
synthesized in short Okizaki fragments
the lagging strand
72
initiates synthesis of each Okizaki fragment by making a short RNA primer
Primase
73
synthesized by the continuous movement of the DNA polymerase along the template
leading strand
74
signals that the DNA is unreplicated and is ready to be used as a template for the next round of synthesis
methylation of the DNA
75
new or modified genes can be generated by 1 or a combination of 4 events:
1) point mutations
2) duplication of entire gene
3) segment shuffling
4) horizontal gene transfer
76
point mutation locations in new gene generation
in the coding region that change the amino acid composition of the protein
77
mixing the segments of one gene with segments of another gene
segment shuffling
78
horizontal gene transfer
acquisition of new activities by transfer of genes between 2 organisms
79
homologous that usually code for proteins that carry out similar functions
genes in gene families that share homologous regions
80
facilitate the initiation of recombination
breaks in the DNA (especially double stranded)
81
a defect in DNA ligase effects:
the joining together of adjacent segments of DNA on a chromosomes, causing abnormal amounts of recombination
82
the reciprocal exchange of genetic information
recombination
83
1) reciprocal exchange during cell division
2) DNA damage (x-ray)
3) introduction of foreign DNA
4) programmed recombination during the development/maturation of a cell type (antibody producing genes during B-cell maturation)
recombination can be the result of:
84
the non-reciprocal exchange of genetic information
gene conversation
85
recombination between direct repeated sequences on the same chromosome causes:
the loss of DNA that was between the 2 repeated segments
86
can be inserted in a chromosome by recombination between a region on a circular molecule and a homologous region on the chromosome
circular DNA
87
x rays and other agents that cause breaks in DNA
induce recombination
88
found in all species from bacteria to human
transposable elements
89
move from one location in the DNA to another location within that cell
transposable elements
90
can cause changes in the DNA at the sight of insertion
transposable elements
91
1st type of transposable element
contains inverted repeated sequences at the ends and causes a short region of the genome to be duplicated at the site of insertion
92
2nd type of transposable element
structurally similar to a retrovirus and transposes through an RNA intermediate
93
recombination resulted from imprecise pairing of tenderly repeated sequences
unequal crossing-over
94
results in the loss or gain of gene copies
unequal crossing-over
95
2 types of mutations
DNA rearrangements and base substitutions
96
many mechanisms for repairing DNA
in each cell
97
can either be repaired or lead to a permanent mutation
damage to a nucleotide (deamination)
98
can be caused either by errors during replication or by injury to the DNA from chemicals or radiation
mutations
99
made up of segmental duplications or large regions of DNA that are present in more than one copy
a small fraction of the genome (3% in humans)
100
duplicated DNA is generated by a process called:
gene amplification
101
can result in resistance to drugs, transformation into cancerous cells or other changes in the cell phenotype
gene amplification
102
due to defects in DNA repair enzymes
several human diseases
103
coenzymes in carboxylations
B1
104
oxidorectase coenzymes
B2/B3
105
transaminase coenzymes
B6
106
carboxylase coenzymes
Biotin
107
coenzyme in single carbon transfers
folic acid/B12
108
causes angular stomatitis
lack of riboflavin
109
B1
thiamin
110
B2
riboflavin, FAD
111
B3
Niacin, NAD, NADP
112
B6
pyridoxine
113
B7
biotin
114
B12
folic acid-coalbumin
115
- act as coenzymes in many metabolic pathways
| - body has no way to store (except B12)
water soluble vitamins
116
excess can be excreted in the urine
B vitamins
117
a deficiency for any single one of these vitamins is rare
B vitamins
118
the greater the caloric intake, the larger the requirement for:
B vitamins
119
evidence is emerging that suggests that excess of ___can be toxic
B vitamins
120
measurements of vitamin levels in the blood relate to
recent intake, rather than overall body status
121
most are modified before they become active
vitamins
122
deficiency syndrome of inflammation of the corners of the mouth
angular stomatitis, caused by lack of riboflavin
123
found in egg whites, binds tightly to biotin preventing absorption
avidin
124
important for single C transfer reactions
folic acid
125
active form of folic acid
tetrahydrofolate
126
converts folate or dihydrofolate to THF
dihydrofolate reductase (DHFR)
127
oxidizes DHF to dihydrofolate
thymidylate synthase
128
inhibitor of folate reduction (DHFR) used as antibiotics
trimethoprim
129
inhibitor of folate reduction (DHFR) used for cancer therapies
methotrexate
130
increased demand during pregnancy and lactation due to fast growing cells
folic acid
131
one of most common vitamin deficiencies
folic acid
132
can cause megaloblastic anemia
deficiency in folic acid
133
difficult to distinguish from B12 deficiencies
folic acid
134
both involved in a methylation reaction
B12 and folic acid
135
concentrated in the liver
B12
136
deficiency causes scurvy, that results in defecting collagen synthesis
vitamin C
137
impairs immune function
vitamin C
138
not as readily absorbed, but can be stored in tissues
vitamins A, D, E K (fat soluble)
139
fat soluble vitamins that can be toxic in excess
A and D
140
teratogenic vitamin, should be avoided during pregnancy
vitamin A
141
signaling molecule that interacts with ligand-activated transcription factors
retinoic acid (vitamin A)
142
deficiency causes night blindness
vitamin A
143
regulates calcium and phosphorus homeostasis
vitamin D
144
majority is produced by UV exposure of skin
vitamin D
145
people in norther climates have a difficult time getting sufficient amounts of this vitamin in the winter
vitamin D
146
deficiency causes demineralization of bones with increased susceptibly to fractures
vitamin D
147
linked to early childhood caries
vitamin D
148
necessary for blood coagulation
vitamin K
149
no longer topologically inside the cell
proteins that have a crossed membrane
150
must recross the membrane to get back inside the cell
proteins that have a crossed membrane
151
move from compartment to compartment to get back within a cell
vesicles
152
vesicles get back into a cell by:
budding and membrane fusion
153
many proteins have signal sequences at their:
amino terminus
154
direct proteins to cross the membrane
signal sequences at amino terminus
155
fewer proteins have:
internal signal sequences
156
surrounded by a double lipid membrane bilayer
nucleus
157
allow molecules, including proteins to pass from the cytosol into the nucleus and back
nuclear pores
158
pass through nuclear pores by an active process
larger proteins
159
bind to nuclear transport signals found on some nuclear bound proteins and facilitate transport into the nucleus
nuclear import receptors
160
requires multiple signals
to transport proteins from the cytosol into the lumen of the mitochondria
161
multiple in the mitochondrial membrane
protein translators
162
each reacts with a specific set of proteins
translocator
163
requires energy
transport into the mitochondria
164
proteins enter ___ using a mechanism similar to mitochondrial entry
peroxisomes
165
proteins travel through this from the endoplasmic reticulum to many sites
golgi
166
binds to the signal sequence during translation and directs the nascent peptide to the ER membrane
signal recognition protein (SRP)
167
translated in the cytosol and then transported through the mitochondrial membrane (requires ATP)
proteins bound for the mitochondria
168
transported through the ER membrane during translation (no energy required)
proteins that are headed into or through the ER
169
helps direct proteins to their ultimate location
carbohydrate modification of proteins in the ER
170
if there are no other signals directing the protein to other locations, the "default pathway" is:
to send the protein to the cell surface
171
in regulated secretory pathways, cells store proteins in ____ until they are signaled to release them by fusion of vesicles with the cellular membrane
secretory vesicles
172
major intracellular components of an animal cell?
cytosol, mito, RER, SER, nucleus, peroxisomes, lysosomes, endoscopes
