Eukaryotes Flashcards
(123 cards)
1
Q
What are peroxisomes?
A
Site of oxidative metabolism
2
Q
Why are topologically equivalent pathways good?
A
As molecules can move between compartments without crossing a membrane
3
Q
What is the significance of the cristae and thylakoids?
A
extensive internal invaginations for max SA and capacity for energy metabolism
4
Q
Name for ETC supercomplex on cristae membrane
A
Respirasome
5
Q
How are cristae insulated?
A
Narrow junctions at neck = diffusion limitation
Densely packed with ETC complexes
6
Q
Name fro type of plastid from which many diff types are derived?
A
PROPLASTID
7
Q
What do gerontoplast plastids do?
A
senescing chloroplasts
8
Q
What do TOC and TIC stand fro in terms of chloroplasts?
A
TOC- translocase of outerchoroplast membrqne
TIC- translocase of innerchoroplast membrqne
9
Q
4 pathways fro thylakoid import
A
1- Sec pathway
2- SRP-like pathway
3-TAT
4- spontaneous insertion
10
Q
How are number of mitochondria and chloroplasts controlled?
A
Fission (Dynamin) and fusion (GTPase)
11
Q
Where does glycosylation occur and what happens?
A
In ER- ADDITION OF n-LINKED GLYCANS TO PROTEINS
12
Q
Name of flattened membrane sacks in golgi
A
Cisternae
13
Q
Primary function of golgi?
A
polysaccharide factory (processing of N-linked glycans on glycoproteins adn synthesis of glycolipids
14
Q
What are functional compartments of golgi?
A
Cis- Medial- Trans- cisternae
15
Q
function of endocytic pathway
A
transport macromolecules from external environemnt to lysosomes/vacuole for digestion
16
Q
What does cell wall affect in endocytic pathway?
A
precluded phagocytosis (but not endocytosis)
17
Q
2 layers of COPII transport vesicle coat
A
Adaptor proteins (interact with membrane) cage proteins (assembled in lattice)- deforms membrane
18
Q
what is characterisitc of ER resident proteins?
A
primary structure of short aa sequences
19
Q
effect of KDEL signals in ER residency
A
Necessary for residency of protein AND sufficient for causing residency of secreted protien if transplanted
20
Q
how do KDEL signals maintain ER proteins in the ER?
A
continuous retrieval from golgi
21
Q
How is cholesterol stransported?
A
As LDL (low density lipoprotein )particles
22
Q
`What are the 2 protein layers of CCV’s ?
A
clathrin complex adn Adaptin complex
23
Q
4 fates of proteins going to golgi
A
1- to PM/ secreted (default)
2- to CCV
3- return to ER
4- retention in golgi
24
Q
SNARES are present on which proteins?
A
ALL
25
What happens when v-SNARE matches t-SNARE?
compatible
forms complex
pulls closer to membrane
26
What is the acrosomal vesicle?
membranous organelle located over the anterior part of the sperm nucleus that is highly conserved throughout evolution. This acidic vacuole contains a number of hydrolytic enzymes that, when secreted, help the sperm penetrate the egg's coats.
27
In mammilian fertilisation what does the sperm first bind to?
Zona Pellucida
28
What event occurs after fertilisation of 1st sperm to prevent any more fertilising the egg? (mammals)
Membrane depolarisation
29
What triggers mulitple waves of calcium?
applications of a calcium ionophores
30
What is the consequence of positive feedback of calcium during mammalian fertilisation?
Calcium induced calcium release
31
What is released from corticol granules under PM to toughen up zygote in harsh condition?
polysaccharides- after fertilisation
32
3 functions of calcium wave following fertilisation?
1- depolymerise membrane potential = block polyspermy
2- harden zona pellucida
3- stimulate centrosome duplication and anaphase promoting factor
33
What are mendels 2 laws of assortment?
1- alleles separate in equal proportion
2- alleles at diff. loci assort independantly
(2nd law should state UNLINKED characters assort independently)
34
What are dimorphic chromosomes?
diff. length e.g. Sex chromosomes-
35
What is result of linked alleles not assorting independantly?
Parental characters remain together in progeny
36
What does hemizygous mean?
posseses a single allele at a locus
37
What are polytene chromosomes?
large chromosomes which have thousands of DNA strands e.g. in Drosophila
38
Difference between coupled and repulsed alleles?
Coupled- WT on 1 chromosome and mutant on the other
| Repulsed- each chromosome carries 1 of each
39
What is recombination?
exchange of genetic material between the maternal and paternal chromosomes
40
When does recombination happen?
meiosis prophase 1
41
What is a holliday junction?
4 strands containing branched intermediate
42
What can suppress recombination?
Chromosomal inversions
43
What is a nucleosome?
DNA wrapped twice around histone protein
44
What are the 5 elements of a protein coding gene (RNA)?
cap, 5' UTR, coding sequence, 3' UTR, poly-A tail
45
Whats the modal length of an exon?
111bl (37 codons)
46
What are centromeres mostly composed of?
alpha-satellites
47
How do spindle fibres attach to centromere during mitosis?
Using kinetochore
48
What is the repeated sequence in telomeres and how long are they?
TTAGGG- 10,000 bp long
49
What to retrotransposons exist to do?
Reproduce themselves
50
What happens to density of genes on chromosomes near centromeres and telomeres?
```
centromere = low/none
telomere = high
```
51
How many exons in the average gene?
4
52
What is average length of exons with respect to histones?
Approx same length as DNA wrapping round histones
53
What is satallite DNA?
Repetitive elements only simple sequence repeats (1-6bp long)
54
What does CDK stand for?
cyclin dependent kinases
55
What is MPF and what does it do?
maturation promoting factor- stimulates mitotic and meiotic phases
56
why is fission yeast good for studying the cell cycle
can tell where it is in the cell cycle by its size
57
What are the 2 subunits of MPF?
CDK and cyclin B
58
What does cdk actually do?
its a kinase so adds a phosphate onto a serine or threonine group
59
What are the 2 approaches to genetic studies?
Forward and reverse genetics
60
What are 3 methods of identifying mutant genes?
1) insertion mutagenesis
2) linkage mapping and map based cloning
3) whole genome sequencing
61
What does insertion mutagenesis rely on?
transposons
62
What is the hypothesis of linkage gene mapping?
Recombination frequency of a gene pair is related to the distance between them on a chromosome
63
What is the equation fro recombination frequency?
total number of recombination events/ total no. of gametes tested X100
64
how are linkage maps generated?
combination of recombination frequencies of different genes
65
What does it mean that genetic and linkage maps are COLINEAR?
same order
66
What are 2 types of molecular markers?
INDELS (insertion/deletion)
| SNP's (single nucleotide polymorphism)
67
what is cosegregation?
transmission, together, of 2 or more genes on the same chromosome, as a result of their being in very close physical proximity to one another
68
What does map based cloning eliminate?
Estimation
69
What are steroid hormones used for?
long, slow pathways, activating gene regulatory proteins
70
What are the 3 types of cell surface receptors?
enzyme-linked, G-protein coupled and ion channel
71
What are enzyme linked surface receptors capable of?
MASSIVE AMPLIFICATION
72
What type of surface receptors are used as major drug targets?
G-protein coupled receptors
73
How can GABA ion channel recreptors be used as muscle relaxants?
as they inhibit action potential by maintaining membrane hyperpolarisation
74
What does adrenaline use to trigger specific tissue responses?
cAMP
75
What is a method of visualising ion channels using a specific probe?
transgenic chameleon probes = colour change detected by ratiometric sensors
76
What can be used to measure ion channels?
Patch clamp
77
What is ion selectivity determined by?
ionic radius and hydration energy
78
What are the 2 types of post synaptic potentials?
excitatory e.g. glutamate channels and inhibitory e.g. GABA
79
What are the 3 types of synapse?
neuromuscular, neurone-neurone, neuroglandular
80
How are voltage gated channels associated with movement of charges within a protein?
helices move with change i membrane potential as contain charged residues
81
How many proteins per cell?
1,000,000,000
82
What are the 3 distinct regulation stages of transcription?
Initiation, Elongation. Termination
83
What is the function of transcription factors?
recruit/ block recruitment of other proteins + recruits initiation complex
84
What is the function of the capping enzyme during transcription?
Cps first nucleotide to exit polymerase which protects RNA from degradation
85
What is the rate of transcription (nucleotides per second)?
72
86
What is the average time taken to transcribe a gene?
4.5 mins
87
What happens to nucleosomes during transciption?
dissociate and associate
88
How many protein coding genes in human genome?
20,000
89
what brings polymerisation to a halt during transcription
cleavage and poly adenylation complex
90
what does the pre-initiaion complex recruit during transcription?
polymerase
91
What do miRNA's do?
can degrade /inhibit mRNA
92
Why is miRNA ability to degrade/inhibit mRNA useful in genome?
defence against retrotransposons and viral infection
93
What is an oocyte?
cell in an ovary which may undergo meiotic division to form an ovum.
94
What type of cleavage is it when the whole cell divides?
holoblastic cleavage
95
What does the first division after fertilisation determine in many bilaterians?
radial symmetry
96
What is teloblastic cleavage?
only part of fertilised egg divides (as seen in teleost fish)
97
What organ systems does the ectoderm go on to make?
nervous system + epidermis
98
What organ systems does the endoderm go on to make?
gut +associated digestive and respiratory organs
99
What organ systems does the mesoderm go on to make?
muscle, skeleton, excretory system and gonad
100
What is myogenesis?
formation of muscle tissue from myoblast precursors
101
What is a syncytium?
a single cell or cytoplasmic mass containing several nuclei
102
What is the difference between symmetric and asymmetric stem cell division?
symmetric= either 2 x commited or 2 x stem cell- asymmetric = 1 of each
103
what can a totipotent stem cell differentiate into?
everthing inc. extra-embryoninc tissue
104
what can a pluripotent stem cell differentiate into?
all cells in embryo and adult
105
what can a multipotent stem cell differentiate into?
all cell types in a tissue or organ
106
what can a oligopotent stem cell differentiate into?
several related cell types
107
what can a unipotent stem cell differentiate into?
one 1 type of cell
108
What regulate stem cells and maintain in stable undifferentiated state?
TF, Epigenetics, microRNA
109
What does in vitro mean?
it happens outside of a living organism
110
What does in vivo mean?
with or within an entire, living organism.
111
What type of stem cell produce red blood cells?
Haematopoietic (very productive)
112
Overexpression of what can reprogram differentiated cells to a pluripotent state?
Yamanake /OSKM transcription factors
113
What generates the polar ejection force during mitosis?
plus end motors of the microtubules
114
what synchronises spindle formation, chromosome condensation, NEB and motor protein localisation to initiate mitosis?
CDK
115
What is the name for the stable attachment of microtubules to the kinetochore?
amphitellic
116
What acts as chromosome glue between sister chromatids?
cohesins and condensins (SMC proteins)
117
What is the name of ring the structure stabilsing siser chromatids make of SMC proteins?
Solenoid
118
What is transdifferentiation?
with or within an entire, living organism.
119
What is a neoblast?
non-differentiated cells found in flatworms called planarians
120
What are 2 methods of cells changing fate during regenration?
transdifferentiation and undifferentiation to a pluripotent state
121
What happens during methylation?
charge left intact - methyl groups recruit diff diff/ set of proteins which interact with DNA in a diff. way-generally tightening
122
What happens during acetylation?
K and R basic residues are affected- their chatge is removed and the interaction between histone tails and DNA loosens = ready for transcription
123
Are epigenetics inherited?
YES- methylation points inherited therfore have same genetic profile as parent cell or organism
