Cellular biology Flashcards
1
Q
What are the phases of cell cycle?
A
G1——>Go
S
G2
M
2
Q
What is M phase and its parts?
A
It is the shortest, most rapid phase of cell cycle
Prophase Pro metaphase Metaphase Anaphase Telophase
Cytokinesis
3
Q
Which phases are of variable duration?
A
G1 and Go
4
Q
What regulates the cell cycle?
A
Cyclins, CDK, and tumor suppressors
5
Q
What are the checkpoints?
A
G1—->S
G2—->M
M (prior to anaphase)
6
Q
How is G1—->S regulated?
A
Mitogens (extracellular proteins, stimulate cell division)
Interact with cell surface receptors
Increase phase sp cyclins
Increase cdk activity (constitutive and inactive, in G1 phase)
7
Q
What does cyclin cdk complexes do?
A
Phosphorylation of proteins to coordinate cell cycle progression, must be inactivated and activated at app times for cell cycle to progress
8
Q
What is the function of P53 gene?
A
DNA damage,
P53 (unstable protein, rapid breakdown)
P53 (becomes stabilised)
P53 stimulates p21 gene
P21 protein is formed
Inhibits cdk-cyclin complex
Hypophosphorylation (activation) of rb gene, e2f not activated, G1—->S
9
Q
What is retinoblastoma?
A
Rare child eye malignancy
Mutations in the Rb1 gene, which codes for abnormal Rb protein—-> unregulated cell growth via e2f
10
Q
What is the clinical correlation of p53 mutation?
A
Li Fraumeni syndrome (SBLA) (sarcoma, breast, leukaemia, adrenal gland)
Mutation in tp53, abnormal p53, cell cycle not arrested to allow for dna repair, accumulation, malignancy
11
Q
Permenant cell types are the types that remain in ___________, are terminally differentiated, and regenerate from _________
A
Go
Regenerated from stem cells
12
Q
What are the examples of permanent cell types?
A
Nerve tissue
Cardiac
Skeletal muscle
RBC
13
Q
What are stable cell types?
A
Enter G1 to Go when stimulated
14
Q
What are examples of stable cell types?
A
Liver cells, lymphocytes, pct, periosteal cells
15
Q
What are labile cell types?
A
Never go to G0, rapidly divide with short G1
16
Q
Which cell type was commonly affected by chemotherapy?
A
Labile
17
Q
What are examples of labile cell types?
A
Bone marrow, gut epith, skin, hair follicles, germ cells
18
Q
Which examples of cells enter and exit G0 many times in their lifetime?
A
Fibroblasts and lymphocytes
19
Q
Which growth factors have an effect on cell cycle?
A
Insulin, pdgf,epo,egf bind to tyrosine receptors to transition from the G1-S
20
Q
What is the function of RER?
A
Site of synthesis of exported secretory proteins and N linked oligosaccharide
21
Q
What are Nissl bodies?
A
They are the rer in neurones. They synthesise peptide neurotransmitters for secretion
22
Q
What is the function of free ribosomes?
A
Site of synthesis of proteins involved in metabolism and structure
23
Q
RER are abundant in which structures?
A
Plasma cells, goblet cells, and pancreatic B cells
24
Q
What are SER?
A
Site of synthesis of steroid, and detoxification of drugs and poisons
25
SER are abundant in which organelles?
Liver hepatocytes
Adrenal cortex
Gonads
26
What are the modifications that occur in Golgi apparatus?
Adding of oligosaccharides to extra N on asparagine
Adding of oligosaccharides to extra O on serine and threonine (mucins)
Adding of mannose 6 phosphate to proteins
27
What are the endosomes?
Sorting centres for material from membrane or Golgi apparatus, fuses with lysosomes, they go back to Golgi apparatus and membranes
28
What other name is for I cell disease?
Mucolipidosis type 11
29
I cell disease is of which type of genetic disorder?
Autosomal recessive
30
Which enzyme is deficient in I cell disease?
N acetylglucosaminyl-1-phosphotransferase
31
What happens if the enzyme is deficient in I cell disease?
Failure of Golgi to phosphorylate mannose residues, so mannose 6 phosphate decreases
Proteins are secreted extra cellularly instead of being transported to lysosomes
32
What are the symptoms of I cell disease?
Coarse facial features, gingival hyperplasia, clouded corneas, restricted joint movements, claw hand deformities, kyphoscoliosis
33
What are the plasma levels of the lysosomal enzymes in I cell disease?
High
34
What is the future for children in I cell disease?
Often fatal in children
35
What are the functions of peroxisome? Oxidation, catabolism and synthesis wise
Beta oxidation of very long fatty acid chains (small in mito)
Alpha oxidation
Catabolism of branched chain fatty acids, aa and ethanol
Synthesis of cholesterol, bile acids and plasmalogens (phospholipid esp in white matter of brain)
36
Which type of oxidation strictly occurs in peroxisomes regarding fatty chains?
Alpha
37
What is the zell Weger syndrome? Genetic type, mutated gene, symptoms
It is an autosomal recessive disorder of peroxisome
Muted pex gene
Hypotonia, hepatotoxicity, seizures, early death
38
What is refsum disease? Genetic type, defective mechanism, symptoms
Defective alpha oxidation, so phytanic acid is not converted into pristanic
Autosomal recessive
```
Night blindness
Scaly skin
Ataxia
Shortening of 4th toe
Epiphyseal dysplasia
```
39
What is the treatment of refsum disease?
Diet, plasmapheresis
40
What is adrenoluekodystrophy? Genetic type, defective mechanism,
Defect in b oxidation—build up of vlcfa
X linked disorder
White matter of brain, adrenal gland, testes
Leads to adrenal crisis, coma and death
41
How do proteins from the ribosome go to RER?
______________ are ____________that recognise ____________ from ribosomes and traffic them into RER
Signal recognition particle (SRP) are ribonucleoproteins that recognise signal sequences on proteins from ribosomes and traffic them into RER
42
What would happen in SRPs were deficient?
Absent or dysfunctional SRP leads to protein accumulation in cytosol
43
What are the vesicular trafficking proteins?
COP 1, COP 11 and clathrin
44
What are COP 1?
Present on Golgi apparatus
Go from cis Golgi to ER retrograde
45
What are COP 11?
Present on RER
Go from ER to cis Golgi
Anterograde
46
What are clathrin?
Go from trans Golgi to lysosomes
From plasma membranes makes endosomes
LDL receptor on coated pits, plasma membrane invaginates, makes vesicle (receptor mediated endocytosis)
47
What is a proteasome and what is its use and clinical correlation?
Barrel shaped protein complex that degrades ubiquitin tagged proteins. Defects implicated in some cases of Parkinson disease
48
What are the types of filaments?
Microfilaments, intermediate filaments, microtubules
49
What is the predominant function of microfilament?
Muscle contraction, cytokinesis
50
What are the examples of microfilaments?
Actin, microvilli
51
What are intermediate filaments’ predominant function?
Maintaining cell structure
52
What is the use of intermediate filaments in laboratory?
Immunohistochemistry
Antibodies against intermediate filaments. Positive staining suggest tumour type/origin
53
What are the examples of intermediate filaments?
Vimentin, desmin, cytokeratin, lamins, GFAP (glial fibrillary acidic protein), nuerofilaments
VDCLGN
54
Where is vimentin and desmin found?
Z disks of sarcomere
55
Which tumors are vimentin implicated in?
Sarcoma(mesenchymal origin)(soft tissue)
Leiomyosarcoma, liposarcoma
Non sarcoma tissues
```
Renal cell carcinoma
CNS tumors (menangioma)
Endometrial carcinoma
```
56
Which cancer is desmin implicated in?
Positive for muscle tumors
Rhabdomyosarcoma
Leiomyoma
Leimyosarcoma
57
Which cancer is cytokeratin implicated in?
Squamous cell carcinoma
58
What is the purpose of lamins?
Form nuclear envelope
59
Which cancers is GFAP implicated in?
Astrocytoma, glioblastoma
60
Which cancers is neurofilaments implicated in?
Nueroblastoma, medulloblastoma, retinoblastoma
61
What is predominant funtion of microtubules?
Movement, cell division
62
What are the examples of microtubules?
Centrioles, cilia, flagella, mitotic spindle, axonal trafficking
63
What is the basic structure of microtubule?
Heterodimer (alpha tubulin, beta tubulin)
Polymerizes into protofilaments
Each dimer has 2 GTP attached
64
What is dynamic instability of microtubules?
Grow very slowly
| Collapses very quickly
65
What are the microtubule motor proteins?
Dynein and kinesin
66
What is dynein?
Transports cellular cargo in retrograde fashion (positive to negative) Negative End is Near Nucleus
Involved in axonal flow
67
What is kinesin?
Transports cellular cargo in anterograde fashion (negative to positive) postive end points to periphery
Movement of vesicles
Localization of golgi apparatus towards cell centre
68
What is the structure of cilia?
Arranged into axonemes:
9 periphery doublet with 2 central doublet
Basal body: it is the base and it is below cell membrane
9 periphery triplet with no central doublet
69
What makes the cilia bend?
Axonemal dynein bridges microtubules together, they use atp to pull on neighbouring microtubules——sliding
70
What is the clinical correlation of cilia?
Kartagener syndrome (1 ciliary dyskinesia)
71
What is the genetic type disorder of kartagener syndrome?
Autosomal recessive
Dynein arm defect
72
What are the symptoms of kartagener syndrome?
Recurrent sinusitis
Otitis media (conductive hearing loss)
Female and Male infertility due to immotile sperm and dysfuntional tube
Bronchiectasis
Situs inversus
73
What is the complication of kartagener syndrome?
Ectopic pregancy
74
Which is the most abundant protein in the human body?
Collagen
75
What are the types of collagen?
Type 1, type 11, type 111, type 1V
76
Which type of collagen is the most adundant?
Type 1
77
Where is type 1 collagen found in the body?
Be So Totally Cool, Chill, Read Books
Bone, Skin, Tendon, Cornea- dentin, fascia
Late wound repair
78
Where is type 11 collagen found in the body?
Be So Totally Cool, Chill, Read Books
Cartilage, virtreous body, nucleus pulposus
79
Where is type 111 collagen found in the body?
Be So Totally Cool, Chill, Read Books
Reticulin, Blood vessels—-uterus, fetal tissue
Granulation tissue
80
Where is type 1V collagen found in the body?
Be So Totally Cool, Chill, Read Books Love
Basement membrane, lens
81
Which collagen type is deficient in Alport syndrome?
Type 1V
82
What does the alport syndrome present as?
Triad: haemturia, hearing loss, ocular disturbances
83
Which collagen type is targeted by autoantibodies in good pasture syndrome
Type 1V
84
What are the steps of collagen synthesis?
Synthesis, hydroxylation, glycosylation, exocytosis, proteolytic cleavage, cross linking
Guests, water and lemon, sweets, guests leave
85
What happens in the synthesis step in collagen synthesis?
Translation into preprocollagen which is made of alpha chains. Alpha chains Gly-X-Y. Most consists of glycine
86
What happens in the hydroxylation step in collagen synthesis?
Hydroxylation of proline and lysine, vitamin c requirement
87
Def of vitamin c will lead to?
Scurvy
88
What happens in the glycosylation step in collagen synthesis?
Glycosylation of the preprocollagen. Makes good bonds with guests i.e hydrogen and sulphide bonds between preprocollagen into procollagen (triple helix)
89
In which step is the osteogensis imperfecta implicated in collegen synthesis?
Glycosylation
90
What happens in the exocytosis step in collagen synthesis?
Exocytosis of the procollegen into extra cellular space
91
What happens in the proteolytic cleavage step in collagen synthesis?
Cleavage of the C and N terminal ends of the procollagen—-insoluble tropocollagen
92
In which step is the Ehlers Danlos implicated in collegen synthesis?
Proteolytic cleavage, and cross linking
93
What happens in the cross linking step in collagen synthesis?
Cross linking (lysine hydroxylysine by lysyl oxidase, copper requirement) between tropocollagen—-collagen fibril
94
In which step is the Menkes disease implicated in collegen synthesis?
Cross linking
95
What type of genetic disorder is osteogenesis imperfecta?
Autosomal dominant is most common form
96
What mutation occurs in osteogenesis imperfecta?
COL1A1 and COL1A2
97
Which type of osteogensis imperfecta is more common?
Type 1, with decreased production of type 1 collagen
98
What is the severity of the types of OP?
Type 2 (lethal in uterus), type 3 and 4, type 1
99
What are the symptoms of OP?
Patients cant BITE
bone fractures with minimal trauma—-may occur during birth
Eye- blue sclera, due to translucent sclera over choroidal veins
Teeth- dental imperfections, opalescent teeth that wear easily due to lack of dentin in some forms (dentinogenesis imperfecta)
Ear- hearing loss abnormal ossicles
100
What is Op confused with?
Child abuse
101
What can be used to reduce risk of fractures in OP?
Bisphosphonates
102
What are the different types of Ehlers Danlos syndrome
Classical type, vascular type
103
What mutation occurs in the classical type of Ehlers Danlos?
COL5A1 and COL5A2, type 5 mutation
104
What are the symptoms in classical type of ehlers danlos
Hypermobile joints, hyperextensibility of skin, easy bruising, mitral valve collapse, thin wide scars
The symptoms may vary in degrees across the types, as they are seen in other types
105
What is deficient in the vascular type of Ehlers Danlos?
Type 111 procollagen
106
What are the symptoms in vascular type of ehlers danlos
Berry and aortic aneurysm, rupture of large arteries, uterus and intestinal ( hollow) viscera prone to rupture
107
Which form of Ehlers danlos most life threatening?
Vascular type
Median age 48
108
What is the inheritance pattern of ED?
May be autosomal dom or recessive
109
What inheritance pattern is Menkes disease?
X linked recessive
110
What is the mutation in the Menkes disease?
The mutation is in the ______, which leads to decreased _______ protein. This is needed for ________ absorption, needed for ______ activity. There is defective ________
ATP7A gene—->ATP7A protein decreased
Needed for copper absorption, low copper, then decreased lysl oxidase activity, defective collagen
111
What are the symptoms in Menkes disease?
Brittle kinky hair, hypotonia, growth retardation
112
Where are the elastin located?
Skin, lungs, large arteries, elastic ligaments, vocal cords, ligamenta flava
113
What makes elastin different from collagen?
Proline, glycine, lysine—-nonhydroxylated
Not glycosylated
114
Where does crosslinking of elastin occur and what does it do?
Extra cellular and gives it its elastic properties
115
Which enzyme breaks down elastin?
Elastase
116
Which enzyme inhibits elastase?
Alpha anti trypsin
117
What occurs in alpha antitrypsin deficiency?
Elastase works, which can cause emphysema
118
What changes occur in aging?
Decreased dermal collagen and elastin, decreased collagen fibrils
119
Is crosslinking normal in aging?
Yes
120
What inheritance pattern is marfan syndrome?
Autosomal dominant
121
What mutation occurs in marfan syndrome?
FBN1 gene mutation on chromosome 15—-defective fibrillin
122
What is fibrillin?
A glycoprotein that forms a sheath around elastin
123
What are the symptoms of marfan syndrome?
Skelelton: tall, increased wingspan
Pectus carinatum, pectus excavatum
Arachnodactyl
Heart: floppy mitral valve
Cystic medial necrosis of aorta
Aortic aneurysms
Eye: subluxation of lenses, upward and temporally
(look UP at a ceiling FAN)
124
What is the similarities btw symptoms of marfan and ehlers danlos syndrome?
Hypermobile joints
Floppy mitral valve
Aortic aneurysms
