Quiz 4 BIOL 111 Flashcards
Lectures 17 & 18 Development Lab
How are secondary structures formed?
Hydrogen bonding in peptide backbone
Tertiary structure
- highest level of structure for a single protein
- Stabilized by interactions between the R-groups of the amino acids
Electrostatic interactions
H-bonds and ionic bonds between R-groups
Disulfide bridges
SH groups of cysteine can form covalent bonds called disulfide (S-S) bridges
Van der Waals Interactions
weak interactions between nonpolar molecules due to charge fluctuations in the electron clouds of atoms
Hydrophobic interactions
hydrophobic R groups fold to the interaction of the protein to avoid contact with the aq environment
Domains
subunits within a protein that carry out specific functions
Activating the transcription of a gene requires
transcriptional activation domain (TAD) to attract/interact w/ RNA polymerase
function of a protein depends on
what domain it has
Quaternary structure
interaction of 2 or more proteins to form a multi-protein complex
Chaperone proteins
enzymes that help proteins fold/refold into the proper shape
Epigenetic Modifications
modifications that change the expression of genes w/ out changing the DNA sequence of the gene
* Often change the chromatin structure of a gene
* Epigenetic modifications can change how tightly DNA and histones bind to each other
Euchromatin
DNA & histones are loosely associated and DNA very accessible to transcription factors/RNA pol. binding
Heterochromatin
DNA & histones are tightly associated and DNA is not very accessible to transcription factors/RNA pol.
Histone acetylation
acetyl groups are covalently bound to lysines located in the amino-terminal tails of histones
Histones are acetylated
HATs
Histones are deacetylated
by (HDACs)
Methyl group
physical barrier to binding of transcription factors (inhibits gene transcription)
Cytosines methylated by
DNMTs
Cytosines demethylated
DNA demethylases
fertilization membrane
lifts off the surface of the egg soon after the first sperm makes contact
polyspermy
the entrance of more than one sperm into the egg.
holoblastic
Cleavage in the sea urchin
How do sea urchin eggs show polarity?
- nucleus is away from the bottom and close to the top.
- The nucleus is offset toward the animal pole.
How do amphibian (frog) eggs show polarity?
they have a distinct animal vegetal polarity, have
* more yolk that is concentrated in the vegetal hemisphere than in the animal hemisphere, and
* the nucleus is also offset towards the vegetal pole. There is no cell division in the animal pole.
How do chicken eggs show polarity?
small portion of the cell is at animal polarization of yolk
- Cell division is a major event during development. How does the amount of yolk in echinoderm, frog and chicken eggs influence cell division?
*having less yolk allows the eggs to develop quicker
* Echinoderms develop the quickest, then frogs, and then chicken eggs.
- What do the blastulas of echinoderms, frogs and chickens have in common? In terms of the blastocoel, how are they different?
hollow space and develop the notochord and have blastocoel
- On the cellular level, how is gastrulation accomplished in echinoderms, amphibians, and birds? In general terms what does gastrulation accomplish?
Echinoderms → cells of vegetal plate migrate to the center of the embryo
Amphibians → cells at ventral margin of gray crescent migrate to center of embryo
Birds → initiated by separation of cells from the lower surface of the blastoderm
