Slide set 2 Flashcards
What is molecular genetics?
the study of how genes are turned on and off and how they affect phenotype
What is transcription?
DNA sequence is enzymatically copied by an RNA polymerase to produce mRNA
(RNA polymerase makes RNA!)
By what protein is DNA unbound?
DNA helicase
What RNA nucleotide is different from DNA nucleotide?
Uracil rather than thymine
What are transcription factors?
Proteins which assist the RNA polymerase in recognizing promoters thus activating the gene
What are the 2 types of transcription factors? Why are they called like that?
GENE SPECIFIC transcription factors => if they can activate specific genes
- like estrogen receptor=> estrogen target gene specific
GENERAL transcription factors => if tf that are required to activate all genes
What is the action of general transcription factors?
Bind to DNA regions within promoters and deliver the RNA polymerase to their respective promoter sites
What is CREM transcriptional activation good for? (what does it stand for…)
CREM: Camp responsive element modulator (transcription factor)
CREM binds to Camp responsive element area on mRNA . This is NECESSARY FOR TRANSCRIPTION
The CREM dependant transcription is regulated by KIF17b in nucleus, which binds to ACT (activator of CREM in testis) This is also necessary for CREM t
What is alternative splicing? what is it good for?
- Method of processing mRNA
- Occurs when enzymes clip out segments of the middel or off ends ot he mRNA trand
When alternative splicing occurs, what part is expressed?
Introns get chopped off, exons are expressed!
What are the 3 types of mRNA ?
- Messenger RNA
- Ribosomal RNA
- Transfer RNA
Where is mRNA processed after its made? What is done to it? Where does it go after?
Processed in the NUCLEUS!
- Editing of mRNA
- Removal of introns, addition of ply A tail and guanine cap.
- It then enters cytosol where it works with rRNA and tRNA to direct TRANSLATION
What happens to mRNA after being transported into the cytoplasm?
In the cytoplasm, mRNA associates with ribosome
- tRNA molecules transfer specific a.a. to the mRNA which is read in triplicate at the ribosome
- As a.a. are brought into place, peptide bonds join them - eventually producing an entire polypeptide chain
- tRNA is gonna come along with complementary codes and specific corresponding a.a.
What is the structure and role of rRNA ?
Ribosomal RNA has a LARGE and SMALL subunit
- Interacts with tRNA during translation
- mRNA can be found between the 2 subunits
- rRNA contains and enzyme that catalyzes the peptide bond between the new a.a. that are being formed
- So tRNA comes in, brings a.a. and than rRNA responsible to attach them together to create a new prot
What is a proteome?
- All the proteins synthesized by a cell- cell’s proteome- or by the whole body - human proteome
Where does a lot of the processing happen after proteins has been synthesized?
A lot happens in the Golgi, but also in ER and cytosol
True or false
The proteome is the same for every cell, as the genome is the same
False
Proteome is different for every cell, but the genome is the same
What are post-translational modifications? give exemples
Chemical modifications of a protein after its translation
Addition of:
- Sugars
- Lipids
- CH3
- Phosphate
What are the 5 steps for making a prot?
- Gene activation
- Transcription
- mRNA processing
- Translation
- Post-translation modifications
True or false
Homeostasis means equilibrium
False
What are the 3 body fluid compartments?
- Plasma (25% of ECF)
- Interstitial fluid (75% of ECF)
- Intracellular fluid
True or false
Water is able to move freely across membrane, but ions can’t
True
What is tonicity ?
how a solution would affect cell volume if the cell were placed in solution=> describes volume change of a cell
What ions are more found outside vs inside the cell?
Outside: Na+, Cl-, HCO3-
Inside: K+
True or false
The bigger the molecule the slower the diffusion
True
What are the 4 functions of membrane proteins? What are their roles/actions?
STRUCTURAL PROTS
- Connect membrane to cytoskeleton (integrity)
- Create cell junctions
- Attach cells to ECM
ENZYMES
- Catalyzes chemical reactions
MEMBRANE PROTEINS
- Part of body’s chemical signaling system
TRANSPORTERS (essential in maintaining osmolarity of many ions )
- Channel proteins
- Carrier proteins
What are the 2 properties of molecules that influence its movement across cell membranes?
- Size
- Lipid solubility
What are the 2 types of channels in membrane transporters?
Gated channels
Open channels
How can carrier proteins be classified?
Uniport carriers
Cotransporters
- Symport carriers
- Antiport carriers (Nees ATP!!)
Which of the membrane transporter change confirmation?
Carrier proteins (not the channel proteins)
What is the difference between active and diffusion transport?
- Active transport moves substances AGAINST contratration gradient.
- Active transport requires ENERGY
What is the most important transport protein in animal cells? What does it do?
Na+ K+ ATPase
Maintains concentration gradients of Na+ and K+
Pomp 2 potassium IN, 3 sodium OUT
NEEDS ENERGY => because goes against concentration gradient
True or false,
Primary active transport needs ATP, while secondary active transport doesn’t need ATP
true!
secondary active transport uses the POTENTIAL energy stored in Na+ concentration gradients to move glucose against its concentration gradient (SGLT- sodium glucose linked transporter- mechanism)
What is vesicular transport good for?
- Good for macromolecules that are too large to pass through protein channels or carriers
- Move in and out with the aid of vesicles created from the cell membrane
What are the 3 types of vesicular transport?
PHAGOCYTOSIS
- Cell engulfs bacterium or other particle into PHAGOSOME
- Creates vesicles using the CYTOSKELETON
ENDOCYTOSIS
- Membrane surface indents and forms vesicles
- Active process that can be nonselective (pinocytosis) or highly selective
ENDOCYTOSIS
- Uses CAVEOLAE (flask shaped indentations within plasma membrane to concentrate small molecules to help in transfer of macromolecules and to participate in cell signaling)
- Receptor mediated uses clathrin-coated pits
EXOCYTOSIS
- Releases molecules too large for transport proteins
- Is the opposite of endocytosis
What are the 2 basic types of endocytosis?
- PHAGOCYTOSIS : condition of cell-eating
- PINOCYTOSIS : condition of cell-drinking=> fluid and the substances dissolved in it enter the cell
What are the 2 type of epithelium, based on layor of cells and exchange/transport.
Leaky or tight epithelium
Leaky (SINGLE CELL LAYER): when there are a lot of exchanges => capillaries
Tight ( MULTIPLE LAYERS) : skin, cheek, mouth , throat
In what type of epithelium will there be exchange vs transport?
Exchange=> leaky
Transport=> tight
Read last slides of case study
Go
