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Biochemistry Flashcards

1
Q

Protein functions

A 
Catalytic
Structure
Transport
Mobility
Immunity
Communication
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2
Q

Primary protein structure

A

Unique sequence of amino acids arranged to form polypeptide chain

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3
Q

Secondary protein structure

A

Maintained by hydrogen bonds formed between carbonyl oxygen and amine hydrogen in the polypeptide backbone

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4
Q

Secondary protein structure no regular patterns

A

Bends
loops
Turns

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5
Q

Tertiary protein structure

A

Pattern of the secondary structural elements folding into unique 3D conformation.
Maintained by interactions between side chains of aa

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6
Q

Quaternary protein structure

A

Association of individual polypeptide chain subunits in a geometrically and stoichiometrically specific manner.
Dimer vs tetramers

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7
Q

Protein structural classification

A

Globular proteins- myoglobin
Fibrous protein - collagen
Transmembrane proteins - GPCR

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8
Q

Protein denaturation

A

Destruction of protein’s quaternary, tertiary and secondary structures
N

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9
Q

What affects protein denaturation

A

Nonenzymatic modifications (glycosylation, oxidation, etc)
High temperature
Very low or very high pH

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10
Q

Oxidoreductases

A

Catalyze oxidation reduction reactions

Lactate > pyruvate

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11
Q

Transferases

A

Catalyze transfer of c n or p containing groups

Serine> glycine

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12
Q

Hydrolases

A

Catalyze cleavage of bonds by addition of water

Urea> nh3 and co2

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13
Q

Lyases

A

Catalyze cleavage of cc CNS and certain cn bonds

Pyruvate> acetaldehyde

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14
Q

Isomerases

A

Catalyze arrangement of optical or geometric isomers

Methylmalony coa> succinylcholine coa

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15
Q

Ligases

A

Catalyze formation of bonds between carbon and o s and n. Couples to hydrolysis of high energy phosphates
Pyruvate> oxaloacetate

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16
Q

Synthase

A

No atp required

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17
Q

Synthetase

A

Requires atp

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18
Q

Oxidase

A

Uses o2 as acceptor without incorporating it

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19
Q

Oxygenase

A

One or both o2 atoms are incorporated

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20
Q

Phosphatase

A

Uses h2o to remove phospho group

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21
Q

Phosphorylase

A

Uses pi to break bond and generate phosphorylated product

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22
Q

Cofactors

A 
Non protein components
Inorganic substances that are required for or increase the rate of catalysis
Zn2+
Mg2+
Fe3+
Fe2+
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23
Q

Coenzymes

A 
Non protein enzyme component
Organic molecules that are required by certain enzymes to carry out catalysis
Vitamin derivatives 
NAD+
FAD
NADP+
CoQ
CoA
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24
Q

Holoenzyme

A

Enzyme + non protein component = active

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25
Apoenzyme
Enzyme without non protein component = inactive
26
Enzyme property function | Efficiency
Extremely high. 10^3 to 10^14 faster than uncatalyzed reactions
27
K cat
Turnover number. | Number of substrate molecules converted to product per enzyme molecule per second
28
Enzyme properties function | Specific
Highly specific Only one or a few substrates Only one type of chemical reaction Set of enzymes present in cell determines which reactions will occur in that cell
29
Free energy | Gibb’s free energy
Quantitative measure of the energy transfers between chemical reactions
30
Free energy of activation
Difference in free energy of reactants and high energy intermediate.
31
How do enzymes work
Enzymes work by lowering the free energy of activation without affecting the energies of the reactants and products. Do NOT change the equilibrium, but accelerate the rate at which equilibrium but accelerate the rate at which equilibrium is achieved
32
Factors affecting reaction velocity
Temperature Ph Substrate concentration
33
Reaction velocity ph
For human enzymes ph optimum is dependent on enzyme localization Affects ionization of the active site and enzyme integrity
34
Allosteric enzymes concentration curve
Allosteric enzymes show a sigmoidal curve. | Some enzymes have allosteric regulators that bind a different site on molecule and change enzyme activity
35
Michaelis menten kinetics
Model to describe how reaction velocity varies with substrate concentration at a given concentration of enzyme. Must assume: [s] is much greater than [e] [es] does not change with time. No pack reaction from product to substrate
36
What must you assume with the michaelis menten kinetics
[s] is much great than [e] [es] does not change with time There is no appreciable back reaction from product to substrate
37
Km
Defined as amount of substrate need to half maximal velocity
38
what only form of proteins are found in the human body
l amino acids
39
which amino acids are nonpolar alipathic
``` glycine alanine proline valine leucine isoleucine ```
40
which amino acids are aromatic
phenylalanin tyrosine tryptophan
41
which amino acids are sulfur containing
methioine | cysteine
42
which amino acids are polar uncharged
asparagne glutamine serine threonine
43
which amino acids are negative/ acidic
aspartate | glutamate
44
which amino acids are positive/basic
arginine lysine histidine
45
what is the 21st amino acid
seleniumcysteine modified aa posttranslational
46
nonpolar alipathic acids
``` highly hydrophobic glycine alanine proline caline leucine isoleucne ```
47
aromatic acids
hydrophobic, though try and trp and a little more hydrophilic phenylalanine tryptophan tyrosine
48
tyrosine is the precursor for
catecholamines
49
polar uncharged aa
``` highly hydrophilic groups can be modified (phosphorylation, glycosylation) asparagine glutamine serine threonine ```
50
sulfur containing groups
able to sulfide bond methione cysteine
51
methionine
serves as a methyl donor for methylation
52
cysteine
hghly reactive and easily oxidized
53
essential amino acids
``` cannot be synthesize in humans histidine methionine threonine valine isoleucine phenylalanine truptophan leucine lysine ```
54
Gluconeogenic
``` Alanine Arginine Asparagine Aspartate Cysteine Glutamate Glutamine Glycine Proline Serine Histidine Methionine Threonine Valine ```
55
Glucogenic and ketogenic amino acids
Tyrosine Isoleucine Phenylalanine Tryptophan
56
Ketogenic
Leucine | Lysine
57
DNA
Storage of genetic information
58
RNA
Mediator in the expression of genetic information
59
Purines
Adenine | Guanine
60
Pyrimidines
Cytosine Uracil Thymine
61
Nitrogenous bases
``` Adenine Guanine Cysteine Thymine Uracil ```
62
Nucleoside bases
``` Adenosine Guanosine Cytidine Thymine Uridine ```
63
3 5 phosphodiester bonds
Formed between the oh group on c3 of one sugar and c5 on next one Link nucleotides together forming backbone of rna and dna polymers
64
N glycosidic bonds
Formed between the nitrogenous bases and c1 of sugar
65
Orientation / directionality of dna rna
5’ end = phosphate group | 3’ end = hydroxyl end
66
Nucleoside
Ribose and nitrogenous base
67
N glycosidic bonds
Formed between nitrogenous bases and c1 of sugar
68
Double helix Watson and crick model
2 allele complementary strands 2 deoxyribose phosphate backbones N bases bond to one another by h bonds
69
B dna
Watson and crick Majority of dna Right handed helix 10 base pairs per turn
70
A form
Right handed helix 11 bp per turn More compact
71
Z form dna
Left handed helix | 12 bp per turn
72
Chargaffs rule
Complementary A=t g= c
73
How many bonds does at have
2 h bonds
74
How many bonds does gc have
3 h bonds
75
DNA denaturing alkali
Remove surname contamination of dna
76
Denaturation of dna heat
Melt | Melting temperature temperature 50% of dna is separated
77
DNA packaging and organization nucleoside
DNA 146 bp Histidine proteins (arg and lys) 8 core histones H1 linker histone
78
Euchromatin
Relaxed transcriptionally active | Lightly stained
79
Heterochromatin
Highly condensed inaccessible for transcription | Dark stained
80
Chromosome
Highly condensed form | Visible in metaphase only
81
DNA accessibility
All cells within organism have same dna but different chromatin structure which determines tissue specific function Because different cells need different genes for different proteins and functions. When dont need the genes > heterochromatin
82
Control of dna accessibility further condense
Methylation of dna further condenses dna
83
How dna relaxes dna
Acetylation of histones | So dna relaxes and is able to be transcribed.
84
Mitochondrial dna
``` Circular double stranded High mutation rate Contains very few untranslated sequences Encodes 13 protein subunits - for etc Large and small MT rRNAs 22 MT tRNA molecules Genetic code differs slightly from standard code ```
85
Deviations of genetic code in mtDNA
Uga standard stop codon is read as trp | Aga and agg (standard codons for arg) are read as stop codons.
86
Rna general structure
Single stranded linear molecule 5>3 direction Uracil instead of thymine Hairpin loops (intramolecular double stranded regions)
87
Major types of rnas in human cells
``` Messenger rna Transport Ribosomal Micro Others- snRNA, snoRNA, piRNA, incRNA, siRNA ```
88
Messenger RNA
Coding RNA | Carries genetic info from DNA to ribosomes for use in protein synthesis
89
Transport RNA
No coding RNA | Present amino acids to the ribosomes for synthesis of polypeptide chain
90
Ribosomal RNA
No coding RNA | Together with ribosomal proteins form ribosomal usubunits
91
Micro RNA
No coding RNA Regulatory functions MiRNA precursor fragments associate with protein complex
92
MRNA structure
Mose diverse group in length and base sequence Monocystronic in eukaryotes Produced as larger precursor (hnRNA)
93
Common modifications of mRNA
5’ cap and 3’poly a tail for protection from cytoplasmic nucleases Splicing of introns 5’ and 3’ utr- regulate localization stability translation efficiency
94
mRNA function
Carries the genetic info from dna to ribosomes for use in protein synthesis
95
tRNA structure
Smallest in size More than 1 tRNA for each aa Extensive secondary and tertiary structures forming cloverleaf. 3’ acceptor end for aa attachment Anticodon loop - complementary to respective codon on mRNA Variable loop
96
tRNA function
Present aa to ribosomes for synthesis of polypeptide chain
97
rRna structure
80% of all rnas Four different sizes Produced from larger precursors in nucleolus and modified subsequently
98
Rrna function
Together with ribosomal proteins form small and large ribosomal subunits to carry on protein synthesis
99
Rna catalysts | Ribozymes
Small rna molecules with catalytic activity | Diverse structures and mods
100
Rybozymes function | Nuclease
Participate in processing of rrna, tRNA, and mRNA
101
Rna catalysts rybozymes | Peptides transferase
Part of large ribosomal subunit catalyze condensation condensation of amino acids to form polypeptides
102
Snrnas | Small nuclear rnas
100-300 nucleotides Rich in uracil Form small nuclear ribonucleoprotein particles
103
Small nucleolus rnas
In nucleolus
104
Piwi interacting rnas
Form complexes with piwi proteins
105
Diploid
2n Two sets of 23 homologous chromosomes Somatic cells
106
Haploid
N One set of 23 chromosomes Mature gametes
107
Karyotype analysis
Diagnostic tool to detect chromosome abnormalities in Genetic diseases Staging of tumor progression Gender identification
108
Structure of human genes
``` Regulatory region Promoter Exons Introns Terminator - poly a signal 3’ and 5’ utr ```
109
Single copy genes
Protein coding dna Tissue specific- only expresses in particular tissues House keeping - in all cells. Cytoskeleton.
110
Satellite dna
Generally not transcribed, highly repetitive cluster together Alpha Mini Micro - trinucleotide repeats > undergo expansion in certain diseases
111
Dispersed repetitive dna
Lines- long interspersed elements Sines- short interspersed elements Transposones
112
DNA replication cycle
``` Mitosis Nondividing >cell death G0 Stimulus G1 growth and metabolism dna =2n S dna replication dna = 2n >4n G2 preperation for cell division dna = 4n ```
113
DNA replication
Semiconservative Origin Replication fork
114
S phase of cell cycle
DNA replication
115
DNA replication steps
1. DNA strands separate at origin, creating 2 replication forks 2. Primers req’d to initiate dna synthesis leading strand begins in direction of replication fork. Lagging strand opposite direction in Okazaki fragments 3. Leading strand elongates and second Okazaki fragment made 4. Leading strand continues to elongate. Third Okazaki fragment made. First and second Okazaki are connected
116
DNA polymerase iii
Elongates a new dna strand by adding dNTPs to end of growing chain
117
Primase
Synthesizes short stretches of rna on lagging strand
118
Topoisomerase i and I (gyrase)
Remove super oils in helix by transiently cleaving one for both dna strands Gyrase is bacterial prokaryotes Target for anticancer drugs and antibiotics
119
DNA helical
Unwinds short segments of parental duplex dna
120
DNA ligase
Catalyzes sealing of nicks / breaks remaining in dna on lagging strand
121
Single strand binding proteins
Prevent premature annealing of ssdna to dsdna
122
Dnt
Deoxynucleotides
123
Direction of fork movement
5’ to3’
124
5’ to 3’ polymerase activities
Free end of new strand 3’ end has free oh. Phosphate is then attached to dnt
125
3-5 exonuclease activity
DNA polymerase activity Take out the mistakes of base pairing Proof reading
126
Polymerase alpha function
Replication (in a complex with primase and aids in starting primer) DNA repair No exonuclease activity
127
Polymerase delta function
Replication (processive dna synthesis on lagging strand) DNA repair 3’ to 5’ exonuclease activity
128
Polymerase epsilon function
Replication (DNA synthesis on leading strand) DNA repair 3’to 5’ exonuclease activity
129
Telomerase
Complex of protein test and short piece of rna template Tert acts as reverse transcriptase Translocates to the newly synthesized end and process is repeated multiple times When 3’ overhang is elongated, primase binds and synthesis of the complementary strand is initiated
130
Telomerase TERT
Active in germ line cells and stem cells Not activated in somatic cells Reactivated in disease states Telomere repeat adds to end of telomere
131
Reverse transcriptase
Found in retroviruses (rna viruses) Uses single stranded rna template to make a dna copy (complementary dna) cDNA is then used to produce complementary strand of double stranded cDNA Once ds cDNA is produced it can become integrated into human genome. Upon integration viral genes may be inactive or transcribed - causing diseases (AIDS) Integration event may also disrupt an adj cellular gene and lead disease
132
Inhibitors of dna replication
Nucleoside analogs that dont allow nucleotides to be added so cant continue replication
133
enzyme properties : regulation
``` availability of substrates post translational modifications enzyme protein production regulation through specific local environment enzyme compartmentalization regulation by allosteric effectors ```
134
effectors / modifiers
bind to sites other than the active site noncovalently alter the affinity of the enzyme for its substrate (affect km) alter the max catalytic activity (vmax) alter both
135
Mutation
Change in genomic sequence | Generally used for disease causing genetic variants
136
Point mutation
Single base change
137
Silent mutation
Changes that specifies the same amino acid
138
Missense mutation
Change that specifies different amino acid
139
Nonsense mutation
Change that produces stop codon
140
Insertion mutation
An addition of one or more bases
141
Deletion mutation
Loss of one or more bases
142
Polymorphism
Genetic variant in which the rare allele occurs with a frequency of at least 1% in population Independent of the functional or pathogenic relevance of this alteration
143
Single nucleotide polymorphism Snps Number of alleles
Substitution of one or another base pair at a particular location in genome Number of alleles: usually 2
144
Insertion/deletion polymorphism Indels Simple vs microsatellites Number of alleles
Simple: presence or absence of short segment. Number of alleles:2 Microsatellite: generally 2,3,4 nucleotide unit repeated in tandem 5-25 times. Number of alleles: typically 5 or more
145
Copy number variants | Number of alleles
Typically presence / absence of 200 bp to 1.5 mb segments of dna. Although tandem duplication of 2,3,4 or more copies can occur 2 or more alleles
146
Inversions | Number of alleles
A dna segment present in either two orientations with respect to surrounding dna 2 alleles.
147
Types of point mutations
Base substitution Transition Transversion - Base addition , base deletion
148
Transition base substitution
One purine is changed to the other purine or one pyrimidines is changed to other pyrimidine
149
Transversion
Purine is changed to pyrimidine or vice versa
150
Types of mutations and their frequency | Missense
50% | Deleterious with medical significance
151
Mutation and frequency | Nonsense
10% Produces truncated protein Deleterious with medical significance
152
Mutation and frequency | Frameshift
25% | Deleterious with medical significance
153
Mutations that are deleterious with medical significance
``` Missense Nonsense Frameshift Rearrangements Dynamic mutations Rna processing ```
154
Clinical consequences of mutations | Somatic vs Germline
Somatic cells - made lead to cancer | Germline cells - transmitted to offspring
155
Molecular consequences of dna mutations
Gain of function mutation produces novel or excess protein product Loss of function mutation reduces or eliminates protein product - need 2 alleles for complete loss of function Dominant negative mutation (allele 2) produces abnormal protein product that interferes with normal protein produced by allele 1
156
Sources of dna damage | Endogenous
Mistakes during replication Basal mutation rate Tautomeric shift
157
Sources of dna damage | Exogenous
Ionizing radiation - uv sunlight, x ray, radioactive agents Hydrocarbons - cig smoke Reactive oxygen species Chemotherapy agents
158
Types of mutation consequence | Lethal and silent
No medical significance Happen early in development but as so detrimental that there is no more organism development Miscarriage
159
Basic mechanisms of dna repair
DNA proofreading Mismatch repair Excision repair Dsdna repair
160
DNA repair: proofreading | Polymerase function
Incoming nucleoside triphosphate is correctly matched to its complementary base on dna template and is added to monophosphate to growing dna chain Enzyme advances
161
DNA repair: proofreading | Proofreading function
If DNA polymerase mispairs nucleotide with template, uses 3’>5’ exonuclease activity to excise mismatched nucleotide
162
DNA repair | Mismatch repair
Newly replicated daughter strand contains g mismatched to t in parent strand (g and t not hydrogen bonded) DNA mismatch Repair proteins Removal of newly synthesized strand and DNA polymerase and ligase repair
163
Dysfunctional dna mismatch repair Hereditary nonpolyposis colorectal cancer (aka hnpcc or lynch syndrome) Features and type of repair defect
Proximal bowels tumors, increased susceptibility to several other type of cancer Mutations in any of 6 dna mismatch repair genes
164
Mismatch repair | Repair proteins
``` Msh2 Mlh1 Msh6 Pms1 Pms2 ```
165
Trinucleotide repeat expansion | Huntington’s disease
Tandem repeats of cag, coding for glu. | Aggregated protein polyglu
166
Trinucleotide repeat expansion | Fragile x
Cgg repeat in utr
167
Trinucleotide repeat expansion | Monotonic dystrophy
Cug repeat in utr
168
Trinucleotide repeat expansion diseases
Huntington’s disease Fragile x Monotonic dystrophy (classic / type1)
169
DNA excision repair options
Nucleotide excision | Base excision
170
Tautomeric shift
Isomerize of nitrogenous base
171
Dysfunctional dna repair | Xeroderma features and repair defect
Features: skin tumors, photosensitivity, cataracts, neurological abnormalities Type of repair defect: nucleotide excision repair defects, including mutations in helicase and endonuclease genes
172
Dysfunction dna repair Cockayne syndrome Features and type of repair defect
Features: reduced stature, skeletal abnormalities, optic atrophy, deafness, photosensitivity, mental retardation Type of repair defect: defective repair of uv induced damage in transcriptionally active dna, considerable etiological and symptomatic overlap with xeroderma pigmentosum and trichothiodystrophy
173
Nucleotide excision
``` Pyrimidine dimer Uv specific endonuclease Nicks strand Removal of damaged oligonucleotide DNA polymerase places deoxynucleotides DNA ligase seals up ```
174
Base excision
Switches only the base out.
175
DNA replication
Makes dna copies that are transmitted from cell to cell and from parent to offspring.
176
Transcription
Produces rna copy of a gene
177
Messenger rna
Temporary copy of a gene that contains info to make polypeptide
178
Translation
Produces a polypeptide using information in mrna
179
Central dogma
Replication (DNA) Transcription (RNA) Translation (protein)
180
Transcription steps
Initiation Elongation Termination
181
Difference between structures of prokaryotes and eukaryotes
Prokaryotes: structural genes transcript multiple proteins (polycistronic) Eukaryotes: monocystronic.
182
How does initiation start in eukaryotes
Proteins are bound at the promoter region so polymerase can bind there and transcribe
183
Which direction is transcription happen
5’ to 3’
184
Prokaryotic transcription elongation enzyme
Rna pol holoenzyme (4 subunits core)
185
Rna polymerase i product
Ribosomal rna
186
Rna polymerase ii product
Messenger rna
187
Rna polymerase iii product
Transfer rna
188
Which stand do you use for template strand
Antisense strand | Goes 3’ to5’
189
mRNA matches which strand
Matches sense strand, the nontemplate strand. Goes from 5’ to 3’. Same code (except u)
190
Transcription termination prokaryotic 2 ways
Rho dependent - requires protein rho Rho independent - spontaneous doesn’t need additional enzymes. Nascent rna has regions that are complementary to itself so forms hairpin loop, strand separates then.
191
Rho independent termination pathway
spontaneous doesn’t need additional enzymes. Nascent rna has regions that are complementary to itself so forms hairpin loop, strand separates then.
192
Eukaryotic transcription termination
Contain poly a polymerase signal Poly a sequence is transcribed Termination factors help free rna from poly a site - cpsf cstf
193
Inhibitors of transcription | Prokayotic
Actinomycin d -antibiotic. Intercalated between dna bases inhibits initiation and elongation Rifampin binds to rna polymerase and percents chain growth beyond 3 nucleotides.
194
Eukaryotic inhibits
``` A amanitin Inhibits rna polymerase ii From mushrooms. No antidote Death ```
195
Capping of mRNA | mRNA processing in eukaryotes
``` mRNA processing Occurs co transcriptionally Decreases rate of degradation Recognition site for binding to ribosome. 5’ end ```
196
mRNA processing in eukaryotes
Capping of mrna 5’ end Poly a tail 3’ end Removal of introns
197
Addition of poly a | mRNA processing in eukaryotes
3’ end Poly a polymerase adds a with atp used. 40-100 adenosine added Protects rna from degradation
198
Removal of introns | mRNA processing in eukaryotes
Splicing Rich in uracil. Form snurps Small nuclear rnas.
199
Translation genetic code characteristics
``` Specific Universal Degenerative Continuous Non overlapping ```
200
tRNA structure
High % of unusual bases | Extensive secondary and tertiary structures- cloverleaf
201
Cloverleaf parts on tRNA | 3’ acceptor end
- site for aa attachment
202
Cloverleaf trna structure | Anticodon loop
Complementary to respective codon on mrna.
203
Codons for start signal
Aug | Methionine
204
Codon for stop signal
Uaa Uag Uga
205
rRNA function
Together with the ribosomal proteins form the small and large ribosomal subunits to carry on protein synthesis
206
Unusual bases in trna
Play role in recognition of trna
207
3 steps of translation
Initiation Elongation Termination
208
Sequences in translation in prokaryotes
Shine delgarno sequence 3 initiation factors Formulated met
209
Translation characteristics in eukaryotes
5’ cap directs binding | Many initiation factors.
210
Protein folding | Spontaneous
Many proteins | Require suitable physiological conditions
211
Protein folding | Chaperone assisted
Large number heat shock proteins and chaperonins Funciton as molecular chaperones Require atp
212
Proteasomal degradation
Selectively degrade damaged or short lived proteins Uses ubiquitous modification to target proteins for degradation by cytosol by proteasomes Energy dependent
213
Post translational modifications
Carbohydrate addition | Lipid addition
214
I cell disease
Caused by deficiency in enzyme that phosphorylates mannose at c6. Autosomal recessive inheritance Protein mistargeting
215
Inducible operon
Transcription is usually off but can be stimulated or induced.
216
Repressible operons
Transcription is usually on but can be inhibited or repressed
217
Gene expression
Formation of Functional product. Rna or protein.
218
Prokaryotic regulation
Only at transcription.
219
Eukaryotic levels of regulation
``` Epigenetic Transcription Post transcription Translation Post translation ```
220
Lac operon cell type
In prokaryotic cells
221
Lac operon | Glucose only present
Lac operon is off/ repressed 1. Repressor protein encoded by lacl gene is always present and bound to operator - blocks rna polymerase 2. Glucose inhibits ardently cyclase, cannot form camp complex, cannot initiate transcription.
222
Lac operon | Lactose only present
Lac operon is on/ induced 1. When glucose absent adenylyl cyclase makes camp, camp complex forms, binds to cap binding site, rna can efficiently initiate transcription 2. When lactose present - small amount of allolactose (lactose isomer) is produced that binds to repressor and prevents binding to operator
223
Lac operon | Glucose and lactose are present
Lac operon is off/ uninduced. 1. When glucose is present it inhibits adenylyl cyclase, no camp, cant form camp complex, cannot initiate transcription 2. When lactose is present - small amount of allolactose is produced that binds to repressor and prevents binding to operator. 3. Although repressor is inactive, transcription cannot be initiated because cap site is empty
224
Transcriptional regulation - eukaryote Regulatory molecules Cis acting elements
Part of dna Core promoter Regulatory - distal and proximal
225
Transcriptional regulation - eukaryote Regulatory molecules Trans acting
Proteins: transcription factors General - required to initiate transcription Specific - regulate how much to be transcribed
226
Transcriptional regulation by steroid hormones steps
1. Binding of steroid hormone to its nuclear receptor causes a conformational change in the receptor that uncovers its zinc finger dna binding domain. 2. Hormone receptor complex interacts with specific regulatory DNA sequences such as gre 3. Hormone receptor complex in association with coactivator proteins controls the transcription of targeted genes
227
Post transcriptional regulation
Alternative splicing Alternative polyadenylation mRNA editing mRNA stability
228
Alternative polyadenylation
mRNA with different 3’ ends, altering. | Ex: prod of 2 different if molecules - igm, igd
229
mRNA editing
Modification in which 1 base in mrna is altered. | Example: liver and small intestine cells produce apoBs of different length
230
Rna interference
Mechanism of reducing gene expression by either: Repressing translation Increasing degradation of specific mrna s
231
Rna interference mediated by
Endogenously produced short micro rna - mirna | Exogenous short interfering rnas siRNA
232
Roles of rna interference
Fundamental role in cell proliferation, differentiation and apoptosis Widely used as tool in research Huge therapeutic potential
233
Translational regulation
Phosphorylated - translation is blocked Not phosphorylated then translation occurs. Examples aa starvation, heme deficiency, accumulation of misfolded proteins in rer
234
Posttranslational regulation
``` Phosphorylation Hydroxylation Carboxylation Biotinylated enzyme Farnesylated protein Glycosylation ```
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Epigenetic changes to chromatin may result from
``` Development Environmental chemicals Drugs/ pharmaceuticals Aging Diet ```
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Epigenetic changes may result in
Cancer Autoimmune disease Mental disorders Diabetes
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Variations in dna
Transposition | Rearrangements in dna
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Transposition
``` Mobile segments of dna that move in random manner from one site to another on the same or different chromosome Enzyme mediated (transposase) Movement can be direct or replication In genome structural variations ```
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Rearrangements in dna
Play a role in generation of a lot of different immunoglobulins from single gene, providing the diversity needed for the recognition fo an enormous number of antigens.
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Transposition clinical correlation
Duchenne muscular dystrophy Rare cases of hemophilia a Antibiotic resistance in bacteria
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Clinical correlation of rearrangements in dna
Pathological dna rearrangement is seen with chromosomal translocations in which 2 different chromosomes exchange dna segments.
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Nonreducing sugar
Both rings are locked
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Dietary macronutrients Carbohydrate Starch
Polysaccharide - ALL glucose
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Dietary macronutrients | Sucrose
Disaccharide - glucose and fructose
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Dietary macronutrients | Lactose
Disaccharide - glucose and galactose
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Dietary macronutrients | Lipids
Mostly triacylglycerols | Essential fatty acids
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Dietary macronutrients | Protein
Non essential and essential amino acids

Clinical Foundations (10 decks)

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