Before Midterm Lecture 1-18 Flashcards
Secondary dna structure
Formed when the backbone of dna interacts non covalently
Tertiary structure of dna
Involves the r grips interacting with each other or the backbone structure
Quaternary structure of dna
Different polypeptide chains will come together to form a protein
Factors affecting membrane fluidity
- Degree of unsaturation
- Number of carbons in the chain
- Sterol content of the membrane
In high temperatures and sterol is added to the membrane the fluidity will
Decrease
Membrane rafts
Area of reduced fluidity that contains higher concentration of sterols
FRAP
fluorescence recovery after photobleaching
Integral proteins
Components of the membrane embedded in the phospholipid bilayer that are extractable with strong detergents
Peripheral proteins
Transiently attached to inner and outer surfaces that are held by non covalent interactions
Peripheral proteins can be displaced from the bilayer via
High salt concentrations
Transmembrane panel a proteins
Extend through the entire membrane
Lipid anchored panel c proteins
Will be covalently attached to fatty acids or diaglycerides
Monolayer panel B associated proteins
Proteins that will be held in place by an alpha helix
In electron microscopy the cells have to be
Dead
Functions of the membrane
- Serve as barrier to outside environment
- Form cellular compartments
- Control transport process
- Localize reactions
- Regulate cell communication
Sterols will interact to form
Stacking interactions via their polar alcohol group
Fatty acid interactions form
Micelles
Triglyceride interactions form
Oil droplets
How do phospholipids move across the membrane
Via lateral diffusion
Increased fatty acid saturation causes lipids to be
More ordered/ tightly packed
How does tail length affect membrane fluidity
Longer tails have a greater surface area, and thus more VWF that hold the tails tightly together making the membrane less fluid
Nuclear lamina
Lies directly under inner membrane of nuclear envelope, and is formed by intermediate filaments
Steps of active transport into the nucleus
- NLS signal/ KKKRK
- NLS protein import complex in cytosol
- Movement into nucleus through pore
- Receptor dissociates from nuclear protein
- NLS remains in nucleus
Overall charge on histones
Positive
In interphase, dna is known as
Chromatin or the 30 nm fiber
Steps of nuclease digestion
Chromatin will be lightly digested with nuclease, associated proteins will be removed, and dna molecules will be separated by size using gel electrophoresis
Assumptions of nuclease digestion
- If there is a repeating protein structure there will be pieces of dna left after digestion
- Pieces left will have a standard size if they are bound to the same type of structural complex
What is SDS-PAGE used to separate
Proteins
GEL- Electrophoresis is used to separate
DNA or rna
In SDS the gel is made of
Polyacrylamide
In electrophoresis the gel is made of
Agarose
Is proteins want to undergo gel electrophoresis what must be done first
Pre treatment with SDS and heat to denature and coat proteins will a uniform negative charge
Nucleolus is the site of
rRna synthesis and assembly of ribosomes
The outer membrane of the nuclear envelope is continuous with
The rough ER
Loss of function experiment
When a component from a system is removed and observed what happens to the systems function
Gain experiment
Adding a component that is not normally present in a system to see if it is sufficient to form a function
Euchromatin
Transcriptionally active chromatin that allows access to dna
Heterochromatin
Transcriptionally inactive dna that is tightly condensed
Constitutive vs facultative heterochromatin
Constitutive dna is always condensed and no genes are found, whereas facultative dna is not always condensed
Allowing access to dna is controlled by
Histone modifying enzymes, chromatin remodelling complexes
How are splicesomes formed
Introns are removed by SnRNPS and exons are linked together
Order of compacting dna
- Naked dna
- Nucleosomes (10-11 nm) no H1
- Beads on a string
- 30 nm fiber ( H1 histones condense fiber)
- Looping of 30 nm fiber
- High order chromatin folding
- Interphase chromosome
Endosymbiont theory
Structural and genetic similarities between mitochondria and chloroplasts
Inhibitory proteins
Competes with activator for the dna binding site
In alternative splicing
Introns are spliced out and exons are joined together, while reducing the number of genes needed to express different proteins
Lariat loop
A loop-like structure formed during RNA splicing, where an intron is cut and the 5’ end is covalently bonded to a conserved adenine residue, creating a “lasso” shape. This intermediate is released after the intron is removed, allowing exons to be joined together to form mature mRNA.
Theory of how genome size decreased
Gene loss and transfer of genes to the nucleus
Where does chloroplast protein synthesis occurs
Stroma if they are nuclear encoded and cytoplasm if chloroplast encoded
