Final review 3 Flashcards
What is the site of controlled ubiquination called?
degron
What are degrons controlled by?
Phosphorylation
What is the phase known as “point of no return”?
S phase
What is highly precise when copying DNA?
DNA polymerase
Explain okazaki fragments
at the lagging strand DNA polymerase synthesize DNA fragment by a back stitching mechanism
What provides starting primer for DNA polymerase?
Primase
What helps extend the template to the 3’ end of the DNA?
Telomerase
What are histones?
help package genome
What ties together the sister chromatids?
cohesion
What initiates microtubule formation?
centrosome
What is the microtubule system that forms between the two centrosomes
spindle
The ends of the microtubules attach to what of the sister chromatids?
kinetochores
How are the chromosomes pulled by the centrosome?
By microtubule shortening
Describe microtubule disassembly
microtubules disassemble at the kinetochores which moves a system of sliding rings towards the centrosome
What is DNA damage checkpoint initiated by?
p53
Why is p53 known as a Tumor Suppresor gene?
because a mutation to the p53 gene can cause increase in cancer
Germ cells vs stomatic
germ cells are gametes
stomatic cells are the rest of the organism
What is apoptosis?
programed cell death
what is Necrosis?
Bursting of cell due to damage, causes inflamation
What morphology changes occurs during apoptosis?
Chromatin compaction, condensation of cytoplasm, the break of the nuclear envelope, nuclear fragmentation, blebbing, cell fragmentation
How is DNA fragmentation obeserved?
Agarose gel electrophoresis
What occurs during DNA fragmentation during apoptosis?
Apoptosis activates nucleases that cleave off DNA
Where do the nucleases cut the DNA?
Between the nucleosomes
What is apoptosis executed by?
Caspases
How is apoptosis activated from inside the cell? (intrinsic pathway)
cytochrome C
Explain apoptosis from outside the cell (extrinsic pathway)
The killer lymphocyte with a Fas ligand comes to the target cell and connect to the Fas death receptor
What are villi?
specialized epithelial areas of the gut that function in the absorption of nutrients
Why must villi cells be constantly replaced?
because of the high turnover rate
In the intestine, new cells are produced, where and by what?
bottom of the crypt by a set of stem cells
What directly links the cytoplasm of neighboring cells?
gap junctions
What forms a strong physical connection between cells?
Desmosomes
What forms the extracellular matrix?
proteins and polysaccharide
Regulatory steps of a protein in order
DNA, RNA transcript, mRNA in nucleus, mRNA in cytosol, protein, degraded protein
What are transcription factors?
DNA binding proteins that regulate transcription initiation
Homeodomains form what type of bonds?
Hydrogen bonds with nucleobases
What is a transcription activator?
DNA binding protein that increases transcription of a gene
What is a transcription Repressor ?
DNA binding protein that decreases transcription of a gene
What is an enhancer?
DNA sequence that is recognized by a transcription activator
What is a silencer?
DNA sequence that is recognized by a transcription repressor
What occurs during DNA methylation?
suppresses gene expression by attracting transcription reppresors
What are the characteristics of cell-surface receptors?
signaling molecule are hydrophilic and requires signal transduction mechanism
What are intracellular receptor characteristics?
signal is a hydrophobic molecule and binds directly to the intracellular receptor which often acts as a transcriptional regulator
Nuclear hormone receptors are regulated by what
ligand-regulated transcription factors.
What is the signal transduction pathway?
- rapid relay of extracellular signal to the intracellular target
- amplification of the signal
- modulation of signal
- integration of different signals
Relaying signal by:
- protein phosphorylation
- GTP-binding proteins
- protein-protein interaction
- second messenger molecules such as cAMP, Calcium, IP3
GPCRs have how many transmembrane domains?
7 domains
The activated GPCR acts as what?
GEF
What is a messenger in cell signaling?
Ca2+
Why does Ca2 have a large affect on the cell?
Naturally Ca2+ levels are low so when raised cell is not adjusted
What is caused by fertilization of an egg by a sperm?
Calcium influx resulting a response in plasma membrane that blocks a second fertilization
