cell division, death, differentiation and embryonic development Flashcards
1
Q
what are the engines of the cell cycle?
A
cyclin-dependent kinases (Cdk)
2
Q
what does regulates CDK activity?
A
presence and absence of cyclin
3
Q
what are the phases of the cell cycle (mitosis)?
A
G1, S, G2, M
4
Q
in what phase the cell undergo checks for cell size and DNA damage?
A
End of G1
5
Q
in what phase the cell undergo checks for damaged or unduplicated DNA or centrosomes?
A
During G2
6
Q
in what phase the cell undergo checks for chromosome attachment to mitotic spindle?
A
End of M
7
Q
where does Taxol work in the cell cycle?
A
M phase, blocking the mitotic spindle
8
Q
where does etoposide work in the cell cycle?
A
Restriction point (R), inhibiting growth factor stimulation
9
Q
where does 5-flourouracil work in the cell cycle?
A
S phase, blocking DNA replication
10
Q
where does radiation work in the cell cycle?
A
S and G2 phases, damaging DNA and causes apoptosis
11
Q
when do nucleosomes become supercoiled? and why?
A
prior to mitosis, supercoiled DNA is inaccessible to proteins involved in transcription and replication.
12
Q
what is the location in which the mitotic spindle attach to the chromosome?
A
Kinetochore
13
Q
In what phase the nucleus and centrosomes replicate?
A
S phase
14
Q
in what phase the chromatin coils and supercoils to become chromosome and the centrosomes move to opposite poles?
A
prophase
15
Q
in what phase nuclear envelop breaks down and kinetochore microtubules appear?
A
prometaphase
16
Q
in what phase the centromeres become aligned at the cell equator?
A
metaphase
17
Q
in what phase the paired sister chromatids separate?
A
anaphase
18
Q
in what phase the nuclear envelope and nucleoli reform, chromatin decondenses and cytokinesis occurs?
A
telophase
19
Q
what drives cytokinesis in animal cells?
A
Acto-myosin ring
20
Q
what is the difference between apoptosis and necrosis?
A
apoptosis: programmed death
necrosis: death due to cell-damaging agents
21
Q
what are the markers of necrosis?
A
- cell swelling
- cell lysis
- inflammatory response
22
Q
what are the markers of apoptosis?
A
- cell condensation
- membrane blebbing
- nuclear shrinkage
- chromatin condensation and fragmentation
- formation of apoptotic bodies
*does not cause an inflammatory response
23
Q
who coined the term apoptosis?
A
Andrew Wyllie
24
Q
what are the functions of apoptosis?
A
- regulating cell numbers
- development processes
- removal of pathogenic cells
25
what type of pathogenic cells undergo apoptosis?
* virus-infected cells
* immune cells
* cells with DNA damage
26
how many gene mutations found to affect apoptosis?
at least 14
27
what are the genes that cause apoptosis?
* Ced-3 (caspase)
* Ced-4 (Apaf 1)
28
what are the genes that prevent apoptosis?
Ced-9 (Bcl-2)
29
What are caspases?
* A cysteine proteases enzyme (cleaves proteins)
* present in the cytoplasm and mitochondria
* Inhibited by IAP proteins
* need to be cleaved to become active (after aspartic acid residue)
30
what are the different types of caspases?
* initiator caspases (8, 9 and 10)
- activated by pro-apoptotic stimuli
- cleave and activate executor caspases
* Executor caspases (3, 6 and 7)
- cleave proteins including cytoskeletal and nuclear proteins
31
in which apoptosis pathway caspase 9 is activated?
* intrinsic pathway
32
in which pathway caspases 8 and 10 are activated?
* death receptor pathway
33
what is the role of mitochondria in apoptosis?
opening of pores in the mitochondria outer membrane triggers cytochrome C release and caspase activation.
34
How can Bcl-2 prevent apoptosis?
prevents the formation of pores in mitochondria's outer membrane.
35
what are the precursor cells that differentiate to specialized cells?
stem cells
36
what are stem cells?
* undifferentiated cells
* Ability for quiescence to enter dormant state
* capacity for self-renewal through asymmetric cell division
* capacity to differentiate into mature cells (potency)
37
what is the cellular differentiation hierarchy?
1. symmetric stem cell division
2. asymmetric stem cell division
3. progenitor cell division
4. differentiation
38
the ability of a single cell to give rise to all the embryonic and extra-embryonic cell types refers to..
totipotency
39
the ability of a single cell to give rise to all of the cell types found in the complete adult organism refers to...
pluripotency
40
the ability of a single cell to give rise to multiple, but not all, cell types found in the complete adult organisms refers to...
multipotency
41
what is an example of a totipotent cell?
fertilized egg
42
what is an example of a pluripotent cell?
embryonic stem cells (ESCs)
43
what are the types of germ layers?
* Ectoderm
* Mesoderm
* Endoderm
44
what is an example of multipotent cells?
somatic stem cells:
* hematopoietic SCs
* Neural SCs
* Mesenchymal SCs
45
what determines what genes are to be expressed in a cell?
transcription factors (master regulators) by inducing or suppressing transcription
46
when misexpressed, what can the master regulators do?
prespecify the fate of the cell or transdifferentiate mature cells.
47
can cell differentiate while undergoing cell division?
no, cell division must be shut down
48
what mechanisms determines cell fate?
* cytoplasmic segregation (asymmetric cell division)
* induction
49
what are the factors the play a role in the fate of the cell intracellularly called?
cytoplasmic determinants
50
what are the factors the play a role in the fate of the cell extracellularly called?
inducers
51
can mature plant cell be induced to dedifferentiate into a totipotent cell?
yes
52
what organism is considered to be the closest unicellular relative to humans?
choanoflagellates
53
did animals, plants and fungi have a single multicellularity evolution?
no, multicellularity of each type had an independent evolutionary path.
54
what is the road to multicellularity?
1. colony formation
* cells stick together
2. true multicellular organism
* selective cell adhesion
* cells have different properties
* composed of genetically identical cells
55
does mutation in somatic cells affect germ line?
no
56
does mutation in germ cell affect germ line?
yes
57
where does the cytoplasm in the zygote come from?
Egg
58
where does the centrioles in the zygote came from?
sperm
59
what is the name of the process of rapid cell division in the early embryonic development?
cleavage
60
what is the difference between cleavage cycle and somatic cell cycles?
cleavage cycle doesn't have G1 and G2 phases
61
why doesn't the size of the early embryonic dividing cells increase?
because they don't have G1 phase
62
cleavage results in the formation of the....
blastula
63
how is cleavage in mammals different from other species?
* occurs slowly
* asynchronous
* rotational
* results in blastocyst
64
what does the blastocyst consist of?
* inner cell mass - form the embryo
* trophoblast - placenta and umbilical cord
* blastocyst cavity - factors for cellular differentiation
65
what is gastrulation?
transformation of the the blastula to gastrula.
66
what is organogenesis?
transformation of gastrula to fully-formed organism.
67
what is the outer germ layer?
Ectoderm
68
what is the intermediate germ layer?
Mesoderm
69
what is the inner germ layer?
endoderm
70
what will the ectoderm give rise to?
epidermal layer of the skin, the nervous systom
71
what will the mesoderm give rise to?
muscles, bones, kidneys, blood, gonads, connective tissue
72
what will the endoderm give rise to?
lining of the gut, liver and lungs
73
what pole of the embryo will form the meso- and endoderm
vegetal pole
74
what pole will form the ectoderm?
animal pole
75
what is the name of the process when cells move inward in gastrulation?
involution
76
.......... describes the flattening and extension of cells that occurs on the outside of the blastula.
Epiboly
77
........... describes the intercalation of cells in the direction of movement that drives involution.
convergent extension
78
how is the gray crescent formed?
rotation of the cortical cytoplasm after fertilization
79
whose experiments proved that the gray crescent is crucial for gastrulation?
Hans Spemann
80
what is the organiser in gastrulation?
the dorsal lip
81
How is the organiser established?
1. After fertilization, Dsh move to the dorsal side as the embryo rotate.
2. Dsh inhibits GSK-3 (inhibition lead to maintaining B-catenin in the dorsal side and degradation in the ventral side)
3. B-catenin is a transcription factor that regulates the activity of organiser genes.
82
what is the first process of organogenesis?
neurulation
83
what does the formation of somites induce?
body segmentation
84
the three division of somites will form
1. upper: ..........
2. middle: ........
3. lower: .........
1. contribute to skin
2. muscles
3. cartilage of the vertebrates and ribs
85
what are Hox genes?
group of genes that control the body plan of an embryo along the anterior-posterior axes.
86
in what direction the Hox genes are expressed?
anterior to posterior
87
what are the two meristems of plant zygote?
apical and basal daughter cells
88
what are the three permanent tissue layers in plant?
* Dermal
* ground
* vascular
89
what is the name of the gene that has more than one allele?
polymorphic gene
90
choose haploid or diploid:
1. gamete is .......
2. zygote is .......
1. haploid
2. diploid
91
what is a monogenic condition?
disease caused by one gene
92
law of independent assortment applies for genes on the same chromosome? (true/false)
false
93
what are the non-Mendelian inheritance types?
* multiple alleles
* incomplete dominance
* co-dominance
* pleiotropic alleles
* Epistasis
* Polygenic traits
* Incomplete penetrance
94
what does the A allele of the ABO gene adds to the H antigen?
N-Acetylgalactosamine
95
what does the B allele of the ABO gene adds to the H antigen?
Galactose
96
what does ABO gene encodes?
an enzyme that adds sugars to the H antigen: glycosyltransferase.
97
what is the Bombay blood phenotype?
no antigen on RBCs surface because of the hh FUT1 alleles that encodes for inactive enzyme that cannot adds fucose to the precursor
98
what are the sources of genetic variation?
* Mutation
* Rcombination
99
what causes mutation?
* Spontaneous (internal effect)
* induced (external effect)
100
what are the types of molecular mutation?
* point mutation: silent, missense, nonsense, frame-shift.
* chromosomal mutation : deletion, duplication, inversion, insertion, translocation
101
what type of mutation that doesn't affect the encoded amino acid?
synonymous, silent, mutation
102
what type of mutation that changes the amino acid encoded?
missense
103
what type of mutation that changes the codon of the amino acid to a stop codon?
nonsense
104
what type of mutation in which insertion or deletion of one or two bases will alter the reading frame of the entire sequence.
frame-shift
105
loss of function mutation frequently shows (recessive/dominant) inheritance?
recessive
106
gain of function mutation frequently shows (recessive/dominant) inheritance?
dominant
107
what is the gene that induces testicular development?
SRY
108
what it is the name of the syndrome that is a result of XX male?
De la Chapelle
109
what is the name of the syndrome that is a result from the missing of the gene SRY in the Y chromosome?
Swyer stndrome
110
what is the sex determining chromosome in:
1. mammals
2. Birds
3. African pigmy mice
1. Y (male)
2. W (female)
3. Y (male) unless W is present
111
what are the downsides of sexual reproduction?
* maintenance of the molecular machinery for sexual reproduction.
* need to find a mating partner.
* decreased reproductive capacity
112
what are the benefits of sexual reproduction?
* high genetic variability aids evolution
* brings together advantageous alleles
* paired chromosomes allow deleterious mutations to be masked
113
in what phase of meiosis the cross over occurs?
late prophase (prometaphase)
114
does the DNA replicate pre-meiosis II?
no
115
in what phase the secondary oocyte arrest?
metaphase II
116
what is the name of the crossing over region?
Chiasma
117
what causes the incompleteness of gene linkage on the same chromosome?
cross-over
118
what indicates the recombination frequency?
distance between genes
119
what is the unit of the distance between genes?
centimorgan
120
what does hemizygous mean?
having one copy of a gene
121
what is the result offspring of hemizygous recessive male + homozygous dominant female?
offspring showing the dominant phenotype
122
what is the result offspring of hemizygous dominant male + homozygous recessive female?
* male offspring showing the recessive phenotype
* female offspring showing the dominant phenotype
123
what is it called when there is an abnormal number of chromosomes in an organism?
aneuploidy
124
what causes aneuploidy?
non-disjunction
125
examples of autosomal chromosome aneuploidy...
* Down syndrome (21)
* Edward Syndrome (18)
* Patau syndrome (13)
126
examples of sex chromosome aneuploidy...
* Klinefelter syndrome XXY
* XYY
* XXX
* Turner syndrome XO
