Lecture 3: Cell Growth and Ribosomes Flashcards
Cell’s ability to divide (grow in number)
proliferation
cell death
apoptosis
Proteins that link proliferation and apoptosis (also link cell growth to proliferation)
morphogens (and modulators)
Enlargement of individual cells
Cellular growth
True or false: Cellular growth equals cellular proliferation.
False
What two thing do cells need to grow?
1) Growth factors
2) Nutrients
Small proteins on the outside of the cell that bind to receptors and signal to the inside of the cell.
Growth factors
What 4 types of nutrients do cells need to grow?
1) Oxygen
2) Glucose
3) Amino Acids
4) Nucleic Acids
What links cell growth and proliferation?
morphogens (proteins that drive both proliferation and growth)
Process of making proteins from RNA
Translation
What is needed for translation to take place?
1) mRNA
2) tRNA
3) ribosomes/rRNA
What is the rate-limiting step in protein formation (making proteins from RNA)?
Making ribosomes
Where are ribosomes made?
Nucleolus
What are ribosomes made from?
rRNA and proteins
Which two enzymes catalyze the transcription of rDNA into rRNA?
Pol I and Pol III
This enzyme catalyst makes a single RNA transcript that is turned into 3 RNAs (this occurs in the nucleolus).
Pol I (RNA polymerase I)
This enzyme catalyst makes rRNA in the nucleoplasm, then brings it into the nucleus.
Pol III (RNA polymerase III)
What is the part of the nucleus outside of the nucleolus?
nucleoplasm
How many subunits form the ribosomal complex? What are these subunits composed of?
2; rRNA molecules and r-proteins
What does the small (40s) ribosomal subunit do?
Reads the RNA
What does the large (60s) ribosomal subunit do?
Joins amino acids to form a polypeptide chain
True or false: rRNA is never translated (proteins are never made out of it).
True
What encodes for rRNA?
rDNA
True or false: rDNA has the potential to become an oncogene.
True
The process of ribosome production starts in the ________ and ends in the __________.
Nuclolus; cytosol
True or false: Cells can divide quickly even if they do not grow quickly.
False. Cells must grow quickly to divide quickly.
What is the oncogene that functions to export the ribosome from the nucleolus to the cytosol?
NPM
Where do oncogenes tend to be (upstream or downstream) in a reaction pathway? Why?
Upstream. Because mutations only affect processes downstream, there is no selective pressure for the development for mutations downstream.
Which tumor suppressor halts or turns off transport, transcription, and assembly of ribosomes? Where does it reside?
ARF; in the nucleolus
Where do ARF and p53 reside in the pathways of the processes they regulate?
Downstream.
How much of the ATP in the cell is utilized in the production of ribosomes?
70%
True or false: Growth factors have the ability to become oncogenes.
True
What type of mutation is caused by centrosome amplification?
Intrinsic
True or false: Cells with ATM inhibitiion can’t repair DNA.
True
What enzymes carry out apoptosis?
Caspaces
