BECOM Exam #3 Flashcards
(211 cards)
1
Q
Helicase
A
separates the helix by breaking the hydrogen bonds between complementary bases
2
Q
Single Stranded Binding Protein (SSBP)
A
prevent reannealing of the duplex during DNA replication
-binds to split single stranded DNA once split by helices so it can not bind back together
3
Q
Topoisomerase
A
prevent DNA supercoiling during DNA replication
-doxorubicin poisens
4
Q
Primase
A
lays down DNA primer for DNA replication
5
Q
DNA Pol III
A
synthesizes daughter strand 5’-3’ direction (continuously on the leading strand, discontinuously on the lagging strand). This results in Okazaki fragments on the lagging strand.
6
Q
DNA Pol I
A
replaces the RNA bases of the primer with DNA bases in-between Okazaki fragments
7
Q
DNA ligase
A
facilitates the formation of phosphodiester bonds and joins Okazaki fragments
8
Q
ribonucleoprotein telomerase
A
synthesized telomeres
9
Q
telomeres
A
-are added to the 3’ end of the template strand so there is a over hang and no essential genes are effected
10
Q
T loop
A
- the over hating 3’ end loops around and inserts itself into a section of the double stranded telomere
- shelterin protein complexes that specifically bind to telomeric DNA repeats and protects them from being recognized by DNA repair proteins
11
Q
exonuclease DNA replication
A
- a section of DNA polymerase
- 3’-OH end of the daughter strand is displaced into exonuclease subunit because of mismatched base pairing
- removes mismatched base pair
- also used to remove primer from Okazaki fragments
12
Q
PCNA
A
sliding clamp that makes DNA polymerase more efficient
13
Q
DNA MYH glycosylase
A
recognizes and cleaves the damaged DNA bases in DNA excision repair leaving a sugar with no base
14
Q
AP endonuclease
A
recognizes sugar with no base during DNA excision repair and cleaves DNA chain
15
Q
Poly-ADP-ribose polymerase
A
binds to the strand break and recruits other repair proteins during DNA excision repair
16
Q
Nonhomologous End Joining
A
- is used in non dividing cells to repair double stranded breaks in DNA
- single stranded bases are removed by Artemis and the two stands are then put back together by DNA ligase
- Damaged DNA is removed no repaired
17
Q
Homologous Recombination Repair
A
- actively dividing cells
- sister is used as a template for repair
- MRN complex binds to end of DNA and activate ATM (Kinase)
- BRCA1, PALB2 and BRCA2 are recruited
18
Q
HATs
A
- transfer acetyl group from acetyl-CoA to lysine residues in histone tails
- loosens DNA
19
Q
HDAC
A
- removes acetyl group from acetyl-CoA to lysine residues in histone tails
- tightens DNA
20
Q
DNA Methyltransferase
A
- associates with the 6’ carbon of cytosine and adds a methyl group to the 5’ carbon
- This favors the incorporation of DNA into heterochromatin (tightly packed, no transcription)
21
Q
Silencer
A
- are DNA elements that act at a distance to repress transcription of their target genes
- Silencers bind transcription factors called repressor proteins that induce bends in DNA
22
Q
Enhancer
A
- Enhancer sequences increase the level of transcription of specific genes
- They bind proteins that interact with the proteins that are bound to gene promoters, and together the promoters and enhancers drive gene expression
23
Q
thyroid hormone receptor
A
- THR bound to RXR (heterodimer)
- Heterodimer bound to corepressor
- Thyroid hormone binds to THR and conformational change binds coactivator
24
Q
which end is capped and which end get a poly a tail
A
5’ cap 3’ poly a tail
25
Initiation
1. small ribosomal subunit binds to mRNA strand
2. UAC (methionine) bind to to AUG
3. large subunit binds and methionine is in the P site
26
eIF3
prevents premature association of 40S and 60S subunits
27
eIF2-GTP
- binds to initiator tRNA
- eIF2-GTP/tRNAmet join the 40S ribosomal subunit with participation of eIF3 and other eIFs
- inactive when phosphorylated
- heme dependent
28
Insulin activates
eIF4
29
Peptidyl transferase = aminoacyl-tRNA
catalyzes peptide bond formation between amino acids attached to tRNAs at the P and A sites
30
Using GTP hydrolysis, eEF2
translocates the ribosome, moving it three nucleotides toward the 3’ end of the mRNA
31
termination
release factors bind to stop codon at the A site he polypeptide bound to the tRNA at the P site is then released while the RF is ejected and the ribosomal subunits separate
32
Tetracyclines, including doxycycline
prevent the binding of aminoacyl-tRNA by blocking the A (aminoacyl) site of the 30S ribosome
33
Aminoglycoside antibiotics (Streptomycin, Kanamycin and tobramycin)
have an affinity for the 30S ribosome subunit and don't allow it to bind with 50s subunit
34
Erythromycin, roxithromycin, and clarithromycin (macrolides)
- prevent elongation at the transpeptidation step of synthesis by blocking the 50S polypeptide export tunnel.
- binds to the 23S rRNA component of the 50S ribosome and interferes with the assembly of 50S subunits.
35
Lincomycin and clindamycin
specific inhibitors of peptidyl transferase
36
B. pseudomallei toxin
targets the translation initiation factor 4A (eIF4A)
37
Shigella dysenteriae and enterohemorrhagic strains of E. coli
remove a specific adenine from 28S ribosomal RNA
38
Diphtheria toxin
- 0inactivate eukaryotic elongation factor eEF2, thereby inhibiting eukaryotic protein synthesis (prevents translocation)
- DT targets a PTM-modified histidine residue of EF2 called diphthamide, which is only present in eukaryotes and archaea
39
Mutation in coding region results in
abnormal protein
40
Regulatory region mutation results in
excessive amount of protein
41
Translocation results in
novel protein
42
Gene amplification results in
excessive amount of protein
43
Stop codons
UAA, UAG, UGA
44
BAD
proapoptotic
45
p21
universal cyclin/cdk inhibitor (CKI), it prevents the phosphorylation of Rb, keeping Rb bound to E2F
46
Rb/E2F
Rb usually sequesters the transcription factor E2F (family of transcription factors)
47
p53
1. stimulate transcription of p21
2. cyclin/CDK inhibitor
3. activates genes for apoptosis when DNA is not repaired
4. activates transcription of DNA repair enzymes
48
MDM2
- down regulation of p53
| - tags p53 for degradation when DNA is successfully repaired
49
β-catenin
- translocates to the nucleus and activates transcription of myc and cyclin D when not bound to APC
- when bound to APC --> degraded
50
HOXD13 mutations
causes webbed fingers, too many fingers, or not enough fingers
51
All axial and appendicular skeletal muscles, and all of the skeleton except the cranium, come from the
paraxial mesoderm
52
Limb skin, hair, skin glands, and nails
surface ectoderm
53
Proximodistal axes of development
pectoral/pelvic girdle -> digital tips
54
Dorsoventral axes of development
- spinal column (back/dorsum) -> belly (front/anterior)
| - Important for patterning the extensors dorsally and flexors ventrally
55
Anteroposterior axes of development
head -> tail (rostral -> caudal)
56
FGF10
- starts limb bud growth
| - FGF8 and FGF10 are important for continuing growth of the arm
57
Sonic hedgehog (Shh or SHH) is responsible for
Anteroposterior growth axis
58
apoptosis of hands and feet
loss of webbed fingers and toes
59
uplimb rotates
dorsally (laterally)
60
lower limb rotates
- ventrally (medially)
- so souls of feet will be on the ground
- most problem where legs don't rotate enough
61
what supplies the arteries of the upper and lower limb through development
primary axial artery
62
Amelia
Absence of limb(s)
63
Meromelia
- Absence of parts of limbs
| - Can be caused by HOX mutations and teratogens – remember thalidomide
64
Autosomal Recessive Inheritance
- If both parents have the disorder, all children will have
| - The sex ratio of affected offspring is expected to be equal
65
Autosomal Dominant Inheritance
- Fathers can give to DAUGHTERS and SONS
| - Males and females are affected in equal numbers
66
Autosomal Dominant Inheritance (Sex Limited)
Male-limited precocious puberty, a sex-limited autosomal dominant disorder expressed exclusively in males that affects secondary sex characteristics
67
Incomplete Penetrance
some individuals will not express the trait even though they carry the allele
68
X-linked Recessive Inheritance
- A recessive male mated to a homozygous dominant female produces all offspring with the dominant phenotype, and all female offspring are carriers
- Matings of recessive males with carrier females give half dominant and half recessive offspring of both sexes
- Matings of homozygous recessive females with dominant males produce all dominant (carrier) female offspring and all recessive male offspring
69
X-linked Dominant Inheritance
-Males cant pass X linked trait to son
| but all daughters will be effected
70
Random X-Chromosome Inactivation
one of two X chromosomes in each female somatic cell is randomly inactivated
71
HOX genes
a subset of homeotic genes, are a group of related genes that control the body plan of an embryo along the head-tail axis
72
Synpolydactyly mutation cause
HOXD13
73
Apical epidermal ridge
is a structure that forms from the ectodermal cells at the distal end of each limb bud and acts as a major signaling center to ensure proper development of a lim
74
what is derived from the paraxial mesoderm
All axial and appendicular skeletal muscles, and all of the skeleton except the cranium
75
what is derived from the surface ectoderm
Limb skin, hair, skin glands, and nails
76
Proximodistal
pectoral/pelvic girdle -> digital tips
77
Dorsoventral
spinal column (back/dorsum) -> belly (front/anterior)
78
Anteroposterior
head -> tail (rostral -> caudal)
79
Proximodistal growth axis of limb buds are induced by
FGF10 induction
| AER secretes FGF8, FGF4
80
Zone of Polarizing Activity
- is an area of mesenchyme that contains signals which instruct the developing limb bud to form along the anterior/posterior axis
- located posteriorly
- associated with Sonic hedgehog gene
81
apoptosis
loss of webbing
82
Upper limb rotates and movement
- dorsally (laterally)
| - Arm buds move cranially so the arm will get closer to the head w growth
83
Lower limb rotates
ventrally (medially)
84
Arterial supply to arm buds
primary axillary artery
85
Meromelia
Absence of parts of limbs
86
Intramembranous Ossification
- A mesenchymal stem cell, or MSC, is an unspecialized cell which can develop into an osteoblast.
- Flat bones of the skull
87
Endochondral Ossification
- In intramembranous ossification, bone develops directly from sheets of mesenchymal connective tissue. In endochondral ossification, bone develops by replacing hyaline cartilage. Activity in the epiphyseal plate enables bones to grow in length (this is interstitial growth).
- all but flat bone of the skull
88
Secondary ossification centers
- Tip of spinous and on each transverse process
| - Two annular epiphyses in vertebral bod7
89
two primary ossification centers
- Dorsal and ventral
- Fuse to form one center
- Primary ossification centers on either side of neural arch
90
Spina Bifida
- Failure of vertebral arch to fuse
| - Spinal cord, spinal nerves and meninges vulnerable to injury
91
lateral mesoderm forms
Sternum
92
Synaptotagmin
where Ca2+ binds to initiate SNARE protein -> exocytosis
93
Synaptobrevin
runs through vesicle and attaches to membrane bound SNARE complex
94
Acetylcholinesterase
Breaks down ACh to acetate and choline
95
Ryanodine Receptors
- receptor connecting t tubule and sarcoplasmic reticulum
| - can be activated by calmodulin
96
Troponin I
inhibits binding of myosin
97
Troponin T
binds to tropomyosin
98
Troponin C
binds to calcium
99
H band
middle (myosin only)
100
light I band
actin in between two myosin
101
A band
actin and myosin overlap
102
Role of ATP in skeletal muscle action
- Myosin ATPase
- Ca+2 pump in SR
- Na+/K+ pump in sarcolemma
103
Twitch
- single stimulation of a muscle fiber
| - short depolarization and short period of crossbridging => short weak contraction
104
Treppe
- staircase increase in muscle contraction as more and muscle fibers are stimulated
- increase in force produced with each contraction
105
tetany
- fatigue
- continued stimulation of maximal force
- maximum speed of contraction, max force, inability to maintain force (fatigues)
- Intracellular Ca2+ levels remain high or rise during tetany
106
Incomplete tetany
repeated rapid contraction, recovery tension increases with each contraction
107
Longer length muscle
greater velocity and less force
108
Shorter length muscle
less velocity and greater force
109
Slow vs Fast twitch ranking
Slowest Type 1 < Type 2a < Type X < Fastest Type 2b
110
Power Output =
force X velocity
111
High intensity exercise (sec-minutes) fatigue
Lack of blood flow: lack of O2Anaerobic metabolism formation of lactic acid and depletion of ATP
112
Moderate intensity exercise(20-120min) fatigue
- Lack of adequate blood flow: lack of O2Anaerobic metabolism formation of lactic acid and depletion of ATP
- Glycogen depletion
113
Low intensity exercise (2hr-days) fatigue
- CNS fatigue: decrease in neurotransmitter in CNS leading to difficulties in maintaining muscle contraction, prolonged exercise
- Glycogen depletion (CHO store within muscle)
- Electrolyte depletion (Na+, K+, Ca2+)
114
Myosin light chain phosphatase
- smooth muscle relaxation
| - force decreases
115
Myosin light chain kinase
- smooth muscle contraction
| - force increases
116
Unitary smooth muscle vs. multi unit smooth muscle
Unitary: single neuron (varicosity) innervation -> gap junction passes cellular response
Multi Unit: each cell must come in contact with a varicosity
117
Tetrodotoxin
| Local anesthetics
Nerve action potential
118
Hemicholinium
| Botulinus toxin
ACh release
119
Curare
| Succinylcholine
Endplate Potential
120
```
Organophosphates
Pyridostigmine (Myasthenia gravis)
```
Acetylcholinesterase
121
Veratridine
| Quinine
Muscle action potential
122
Metabolic poison
| Procaine
Muscle Contraction
123
Phosphodiesterase
breaks down cAMP
124
RYR1 vs RYR2
skeletal
| cardiac
125
lamellar granules
water-resistant glycolipid slows water loss
126
type I keratins
acidic keratins
127
type II keratins
basic keratins
128
How does melanin protect skin
- absorb energy with double bonded ring structure
| - provide site for free radical binding
129
Alternative splicing
processing of identical transcripts in different cells can lead to mature mRNAs with different combinations of exons and thus different polypeptides
130
start codon (Kozak sequence)
AUG
131
eIF4
is bound to the mRNA and bind it to the 40s subunit
132
Release Factor (RF)
- bind a stop codon in the A site
- The polypeptide bound to the tRNA at the P site is then released while the RF is ejected and the ribosomal subunits separate
- bacteria: multiple RF eukaryotes: single RF
133
Rb gene
-sequesters trans factor eF2 by binding to it
134
APC mutation lead to
- colon cancer (Familial adenomatous polyposis)
| - cant bind β-catenin
135
Autosomal Dominant Inheritance
- Each individual who has the disease has at least one affected parent
- Males and females are affected in equal numbers
136
Autosomal Recessive Inheritance
- If both parents have the disorder, all children will have it
- Individuals who have the disease are often born to parents who do not
- Fathers can give to DAUGHTERS and SONS
- If father gives to all his sons sex limited
137
X-linked Dominant Inheritance
-Dominant males mated to homozygous recessive females pass the trait to all their daughters and none of their sons
138
DHPR (Dihydropryidine receptor)
voltage sensitive receptor in the t tubule
139
Role of ATP in skeletal muscle
1. Myosin ATPase
2. Ca+2 pump in SR (Sequesters Ca+2 )
3. Na+/K+ pump in sarcolemma (Establishes resting membrane potential)
140
Action Potential vs End Plate Potential
- Action Potential is all-or-none response
| - End Plate Potential is a graded potential
141
Longer muscle length (ML) and fiber length (FL)
| fusiform
Greater velocity
142
Shorter muscle length (ML) and fiber length (FL)
| pennate
Greater force
143
Power output =
force x velocity
- more force = less velocity
- less force = more velocity
144
isotonic
same force
145
isometric
same length
146
Connexins
channels in the gap junction of cardiomyocytes that allow electrical connection
147
preload
amount of force/stress applied to muscle before contraction
148
afterload
amount of force the muscle must contract against in order to shorten
149
NE/EPI vs ACh effect on heart contraction
NE/EPI: inc contractile force
| ACh: dec contractile force
150
Inc in afterload
dec velocity
151
inc in preload
inc in contractile force up to a certain point
152
vernix caseosa
Exfoliated peridermal cells and sebum that covers infant and protects developing skin from constant exposure to amniotic fluid with its urine content during the fetal period
153
melanocyte location and embryological origin
- basal layer
| - neural crest cells migrate into mesenchyme of developing dermis (neural crest -> melanoblasts ->melanocytes)
154
thick skin lacks
Lacks hair follicles, arrector pili muscles and sebaceous glands but contains sweat glands
155
epidermis and dermis origin
epidermis: ectoderm
dermis: somatic layer of lateral mesenchyme
156
Ichthyosis
is a general term applied to a group of skin disorders resulting from excessive keratinization
157
collodion
infant is covered by a thick, taut membrane that resembles collodion (a protective film) or parchment
158
Nevus flammeus
denotes a flat, pink or red, flamelike blotch that often appears on the posterior surface of the neck
159
Sebaceous glands
- develop as cellular buds from the sides of developing epithelial root sheaths of hair follicles
- secrete sebum
160
Eccrine sweat glands
They develop as cellular buds from the epidermis that grow into the underlying mesenchyme
161
apocrine sweat glands
- The glands develop from downgrowths of the stratum germinativum of the epidermis
- As a result, the ducts open into the canals of the hair follicles superficial to the entry of the sebaceous gland ducts
- found in pubic, axilla, and areolae region
162
mammary glands
- specialized sweat glands, multiple buds come off forming lactiferous ducts
- The breasts of newborns contain lactiferous ducts but no alveoli
163
witch's milk
-These transitory changes are caused by maternal hormones passing through the placental membrane into the fetal circulation
164
Gynecomastia
refers to the development of the rudimentary lactiferous ducts in the male mammary tissue
165
Athelia
Absence of Nipples
166
Amastia
Absence of breast
167
hair bulb (epithelial cells) are invaginated a small mesenchymal cell called
hair papilla
168
Arrector pili muscles and origin
are small bundles of smooth muscle fibers that differentiate from mesenchyme surrounding hair follicle
169
Alopecia
is the absence or loss of hair
170
Nail growth
nail plate grow over the nail field (keratinized)
171
Congenital anonychia
is the absence of nails at birth and is a permanent abnormality
172
skin physical barriers
resistance to mechanical stress and absorption/evaporation of substances (water)
173
skin biological barriers
```
Dendritic cells of epidermis
-Present foreign antigens to white blood cells
DNA
-Its electrons absorb UV radiation
-Radiation converted to heat
```
174
skin chemical barrier
```
Skin secretions
-Low pH retards bacterial multiplication
-Sebum and defensins kill bacteria
Melanin
-Defense against UV radiation damage
```
175
skin pH, weight, and percent of body
- pH 4.7
- 6,20 lbs
- 15%
176
epidermis cells
keratinocytes, melanocytes, dendritic cells, tactile (Merkel) cells
177
dermis cells
primarily fibroblasts
178
Hypodermis cells and function
- adipocytes
| - Insulates body, Energy reserve, Cushions and protects skin, Mobility over underlining structures
179
Stratum granulosum contain
- lamellar granules that secrete lipids (water-resistant)
- everything dead above
- beginning of keratinization
180
Keratinocytes
Produce fibrous protein keratin (more produce as you get closer to surface)
Most cells of epidermis
Tightly connected by desmosomes
181
stratum spinosum mostly contain
melanosomes and dendritic cells
182
Dermis layers
- Papillary
| - Reticular: provide strength and resiliency bind water
183
Epidermis fuel source
- Blood glucose diffusing from dermis to epidermis is primary fuel source
- Extracellular glucose is greater than intracellular glucose suggesting lack of active transport i.e. insulin mediated uptake and more likely passive diffusion
- Upon enter keratinocytes, glucose is metabolized primarily anaerobically via glycolysis to produce lactic acid
184
↑ Body Core temp
Thermoreceptors in hypothalamus (primary driver) and skin (secondary) respond -> cholinergic stimulation -> vasodilation of blood vessels in dermis
185
↓ Body temp
Thermoreceptors in hypothalamus (primary driver) and skin (secondary) respond -> adrenergic stimulation -> vasoconstriction of blood vessels in dermis
186
Eccrine Sweat Glands are found where
Abundant on palms, soles, and forehead
187
Modified apocrine glands
- Ceruminous glands—lining of external ear canal; secrete cerumen (earwax)
- Mammary glands – secrete milk
188
type I keratin
acidic keratins (contain acidic acids)
189
type II keratin
basic keratins (contain basic amino acids)
190
Transglutaminase
lysine + glutamine forms amide bond
- gives structural stability to keratins int. filaments
- doesn’t just happen in keratin
- Ca2+ DEPENDENT
191
keratin is made up of and give it
Intermediate filaments provide mechanical strength and resistance to shear stress
192
UVA vs. UVB
UVB: skin cancer, cataracts and sun burn
-damage sup. epiderms
UVA: longer wavelength penetrate deeper
into dermis
193
Brown, Black, Pheomelanin (red/yellow tint) melanin structure
double bonded ring absorbs energy and provides site for free radicals to bind
194
melanin is derived from
tyrosine which can be derived from phenylalanine
195
enzyme used to convert tyrosine to melanin and what is it dependent on?
- Phe -> tyr -> Dopa -> melanin
| - tyrosine hydroxylase Cu2+
196
What happens to DNA when exposed to UV radiation
- Cyclobutane pyrimidine dimers
| - Two adjacent pyrimidines form a covalent dimer
197
nucleotide excision repair fixes
UV damaged DNA that as been dimerized
198
Nonhomologous end joining occurs in
non dividing cells
199
homologous recombination repair occurs in
actively dividing cells
200
Zone of Polarizing Activity (ZPA) is responsible for establishing
the anterior-posterior (dorsal-ventral) axis
201
lanugo hair
Help hold vernix caseosa on the skin, which protects the skin
202
Hypertrichosis
is growth of hair in excess of normal
203
vellus hair
Pale, fine body hair of children and adult females
204
Terminal hair
arse, long hair of eyebrows, scalp
At puberty
Appear in axillary and pubic regions of both sexes
Face and neck of males
205
methylation amino acid
cytosine
206
Acrania
Complete or partial absence of
| neurocranium
207
Meroencephaly
Failure of cranial end of neural
tube to close
• Failure of neurocranium to form
208
Microcephaly
Small calvaria
• Brain and neurocranium fail to
grow
209
hemivertebra
improper migration of sclerotomal cells
210
BAX
If DNA not repaired, p53 activates genes involved in apoptosis
211
ACTH
protein from POMC that helps release cortisol for anti inflammatory
