MOST LIKELY TO COME UP IN PAPER 1 Flashcards
What is the primary structure of a protein?
What type of bond is involved?
The order of specific amino acids, held by peptide bonds
What is the secondary structure of a protein?
H-bonds form between the amino causing either:
an alpha-helix shape
or a beta-pleated sheet
what is the tertiary structure of a protein? what bonds are involved?
The 3d shape of the polypeptide is dependent on the secondary structure (R group interactions)
- h bonds
- ionic
- disulfide
Draw the structure of a protein
Go online :)
describe and explain the INDUCED-FIT MODEL
The active site and substrate have complementary shapes, active site must change slightly to bind to fit the substrate and form ENZYME-SUBSTRATE COMPLEX.
Change in shape of active site puts pressure on bonds of substrate, easier to break (less energy needed)
Describe the quaternary structure of proteins.
Association of multiple polypeptide chains and non-protein (prosthetic) groups.
Describe the biuret test
Equal volumes sample and sodium hydroxide at room temp.
Add a few drops of copper 2 sulfate, mix
purple coloration indicates presence of peptide bonds, blue if negative.
Name the bond and reaction that joins amino acids together.
Peptide, Condensation
Explain the effect that a high PH has on an enzyme controlled reaction
PH alters charges of amino acids, substrate cannot bind to active site
Tertiary structure may be changed, active site changed shape (ionic bonds)
formula for magnification
m= image/object
what must be prepared before cell fractionation and why (3)
must be in a cold, isotonic (same water potential), buffer solution
cold;
reduce enzyme activity
isotonic;
no osmotic effect
buffered;
ph stays the same, which might affect cell and enzymes
describe the two steps of cell fractionation
cells are broken up by homogenizer resulting in homogenate, which is filtered
the homogenate is spun at different speeds, resulting in:
- at a slow speed, the heaviest organelles (nucleus) are forced to the bottom forming a pellet
- the (supernatant) is removed and spun at a high speed the next heaviest organelles (mitochondria) are forced to the bottom
process repeats, separating smaller and smaller organelles
explain the main differences between TEM and SEM
TEM transmits beams of electrons through the specimen, denser=darker
SEM scans a beam of electrons that bounce off the specimen and are detected producing 3d image
give advantages and disadvantages of TEM
advantage- high resolution, internal structures can be seen
disadvantages- only very thin specimens can be used, cannot use live specimens, black and white
give advantages and disadvantages of SEM
advantages- 3d, used on 3d specimens
disadvantages- lower resolution (compared to TEM) , dead specimens, black and white
Describe the structures of the mitochondrion (2)
Double membrane, the inner membrane is folded to form cristae, providing a large SA
Matrix, contains proteins, lipids, DNA, and ribosomes. Proteins involved in respiration
Describe the structure of the chloroplasts
grana
- stacks of thylakoids which are filled with chlorophyll
- absorption of light (first stage)
the stroma
- fluid filled matrix
- production of sugars (second stage)
Prokaryotic cells have cell walls which contain …
murein, a glycoprotein
Structure of nucleus
surrounded by nuclear envelope, contains nucleolus and chromatin
Give function of the nucleolus.
Synthesis of ribosome
Structure and function of rough endoplasmic endoreticulum
Membranes folded into cisternae, attached to nuclear membrane. Ribosomes attached
Synthesis of transport proteins
function of smooth endoplasmic reticulum
synthesis and absorption of lipids and carbs
Structure and function of golgi apparatus
Stacks of membrane bound sacs and vesicles.
modification, packaging and transportation of proteins (via vesicles)
transportation of lipids
function of vacuole
water and solutes provide turgid structure
