Final - Midterm 1 Flashcards
what are the tenets of the cell theory
- all living things are composed of cells
- all cells arise from pre-existing cells
- cells are the structural unit of life
which of the following structures is the smallest: eukaryote, prokaryote, nucleus, protein, neuron
protein
what are the characteristics of model organisms
- fast generation time
- large number of offspring
- easy to manipulate in the lab
- short lifespan
- fast to mature
polar molecules are ______; non polar molecules are _____
hydrophilic, hydrophobic
what are characteristics of water
- the water molecule is asymmetric (has a dipole due to differences in electronegativities between H and O)
- covalent bonds in water are polarized
- all 3 atoms can form hydrogen bonds
what is a characteristic of hydrogen bonds
hydrogen must be covalently bonded to an electronegative atom in order to form a hydrogen bond
what is the hydrophobic effect
aggregation of nonpolar molecules to decrease entropy (disorder) of water
which polysaccharide bond cannot be broken by mammalian enzymes that normally digest polysaccharides
Beta (1—>4) glycosidic linkages
in a polypeptide, when peptide bonds are formed between adjacent amino acids:
the carboxyl group of one amino acid joins with the carboxyl group of the adjacent amino acid
what are domains:
two or more distinct modules that fold up independently of one another that often represent parts of a protein that have a specific function.
what are functional groups:
particular groupings of atoms that often behave as a unit and give organic molecules their physical properties, chemical reactivity, and solubility in aqueous solution
what varies in biomembranes of cells:
the composition and ratio of lipids and proteins
what is an example of an amphipathic molecule
a fatty acid with a polar carbonyl head group and a nonpolar hydrocarbon chain
what is a sphingolipid/membrane lipid:
a sphingosine backbone with an attached fatty acid and an attached oligosaccharide
what are the building blocks of phosphatidic acid
glycerol, one phosphate group, 2 fatty acid tails
what directly or indirectly determines the transition temperature of a molecule
- the chain length of the fatty acids
- whether the fatty acid chains of the lipids are saturated or unsaturated
- the extent to which the fatty acid chains of the lipids contain double bonds
a bacterial culture growing at 15C is transferred to a culture room and maintained at a temperature of 40C. what would you expect to see?
enhanced rate of synthesis of saturated fatty acids for membrane incorporation
what are lipid rafts
contains higher concentrations of sphingolipids and cholesterol and certain proteins becomes concentrated within them
what is the role of acyl transferases in the synthesis of of a membrane lipid in the ER:
add 2 fatty acids to glycerol-3-phosphate
the orientation of a protein attached to the plasma membrane via acylation is:
always cytosolic
integral membrane proteins can consist of:
- just one transmembrane alpha-helix
- one single polypeptide with multiple membrane spanning alpha helices
- multiple polypeptides with individual membrane spanning alpha helices
a molecule normally enters a cell by diffusion through the lipid bilayer. what happens if you artificially reverse the molecules concentration gradient by adding all of the molecule to the inside of the cell at the start of the experiment
the molecule moves out of the cell until equilibrium concentrations have been reached
the net driving force of a charged molecule across the plasma membrane consists of:
a combination of concentration and voltage
with respect to carriers (transporters):
- molecules go down their concentration gradient
- they alternate between two conformations
GLUT4:
is a uniporter
an antiport will:
transport one molecule down its concentration gradient and one molecule, in a different direction, against its concentration gradient
with respect to the Na+/K+ ATPase:
- K+ is pumped into the cell
- both Na+ and K+ are pumped against their concentration gradients
- it is an example of direct active transport
the Na+/glucose symporter moves ____ down its gradient and drives the transport of ____ against its gradient
Na+ ions, glucose
potassium and sodium cannot move through the cell membrane into the cell on their own because:
these ions are charged
