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BIOL 107 > Quiz #2 > Flashcards

Quiz #2 Flashcards

1
Q

What are proteins?

A

are involved in every biological task

polymers of amino acids

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2
Q

What are amino acids?

A

general structure consists of a nitrogen bonded to a carbon bonded to a carboxyl group
can exist as different enantiomers, but all proteins use L-enantiomers

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3
Q

What are the different characteristics a side chain in an amino acid can have?

A

non polar, hydrophobic
polar, hydrophilic
electrically charged (acidic/negative or basic/positive)

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4
Q

What is Primary Protein Structure?

A

the linear sequence of amino acids
polypeptides have an NH3+ (amino) end and a COO- (carboxyl) end and they can be composed of a few to more than a thousand monomers

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5
Q

What is Secondary Protein Structure?

A

the formation of alpha helices or beta pleated sheets due to hydrogen bonding between the O of carbonyl group and the H of the amino group

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6
Q

What is Tertiary Protein Structure?

A

the arrangement of the peptide chain due to interactions between R groups, that gives the protein it’s distinctive shape

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7
Q

What different bonds or interactions cause tertiary protein structures?

A 
hydrophobic interactions
van der waals interactions
ionic bonds
hydrogen bonds
disulfide bonds
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8
Q

What is Quaternary Protein Structure?

A

results from the aggregation of two or more polypeptide subunits
not all proteins exhibit these structures

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9
Q

What conditions can affect protein structure?

A

physical and chemical changes can affect structure

alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel

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10
Q

What is denaturation?

A

the loss of a protein’s native structure

biologically inactive

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11
Q

What are chaperonins?

A

are proteins that assist proper folding of other proteins

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12
Q

What are nucleic acids?

A

coded information that cells can transmit to future generations and the messages that determine protein production
DNA and RNA
each polynucleotide is made of monomers called nucleotides

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13
Q

What is a nucleotide?

A

consists of three different molecules joined together

phosphate, 5 carbon sugar, nitrogenous base

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14
Q

What is the 5 carbon sugar component of the nucleotide?

A

in RNA, the sugar is ribose

in DNA, the sugar is deoxyribose

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15
Q

What are the properties of the 1’C carbon in a nucleotide?

A

attaches to the base

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16
Q

What are the properties of the 2’C carbon in a nucleotide?

A

bonded to OH in RNA

bonded to H in DNA

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17
Q

What are the properties of the 3’C carbon in a nucleotide?

A

bonded to OH

important for polymer formation

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18
Q

What are the properties of the 4’C carbon in a nucleotide?

A

no special properties

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19
Q

What are the properties of the 5’C carbon in a nucleotide?

A

attaches to phosphate group

20
Q

What are the two groups of nitrogenous bases?

A

pyrimidines

purines

21
Q

What are pyrimidines?

A

single 6-sided ring

Cytosine, Uracil, Thymine

22
Q

What are purines?

A

6 and 5 sided rings fused

Adenine, Guanine

23
Q

What is the structure of DNA?

A

DNA molecules have two polynucleotides spiraling around an imaginary axis forming a double helix
two backbones run in opposite 5’ to 3’ directions from each other, and arrangement referred to as antiparallel
DNA bases pair by hydrogen bonding
A always with T
G always with C

24
Q

What is the structure of RNA?

A

RNA molecules are usually a single polynucleotide chain
complementary base-pairing can occur between RNA and DNA, other RNAs, and itself
A pairs with U
G pairs with C

25
Q

What is a plasma membrane?

A

a boundary that separates living cell from its surroundings
exhibits selective permeability
the spherical phospholipid bilayer is the basic structure of all biological membranes
membranes are made of proteins and lipids

26
Q

What is the fluid mosaic model?

A

membrane is a fluid structure with a “mosaic” appearance because it contains different types of protein embedded in it
different membranes contain different proteins

27
Q

Proteins in the bilayer can be classified into what two groups?

A

Integral (or intrinsic)

Peripheral (or extrinsic)

28
Q

What are integral membrane proteins?

A

embedded in the bilayer

at least one portion of the protein is hydrophobic

29
Q

What are peripheral membrane proteins?

A

attached loosely to the surface of the membrane (usually by interacting with an integral protein)

30
Q

What are glycoproteins?

A

membrane proteins that have a sugar attached

important function in cell regulation

31
Q

What are glycolipids?

A

membrane lipids that have a sugar attached

32
Q

What is cholesterol?

A

inserts between phospholipid molecules

influences membrane permeability and fluidity

33
Q

How does temperature affect membranes?

A

biological membranes are fluid at physiological temperature
high temperature will cause an increase in fluidity
gaps in membrane will form if temperature goes high enough
all membranes will turn solid if temperature goes low enough

34
Q

The temperature of a phase transition occurs depending on what properties of the membrane?

A

length of fatty acids in the phospholipid
shape of fatty acids in phospholipids
cholesterol also has an effect on membrane fluidity

35
Q

How does the length of fatty acids in the phospholipid impact the temperature a phase transition occurs at?

A

short chains have less stable interactions with each other, therefore a lower temperature is required to make them solid

36
Q

How does the shape of fatty acids in phospholipids impact the temperature a phase transition occurs at?

A

double bonds cause structural kinks, decreasing ability of chains to pack together

37
Q

How does cholesterol impact the temperature a phase transition occurs at?

A

acts as a “fluidity buffer” to maintain membrane fluidity at a greater range of temperatures
interferes with the lateral movement of phospholipids
it prevents close packing of phospholipids at lower temperatures

38
Q

What are the six major functions of membrane proteins?

A 
transport of molecules in or out of cell
enzymatic reactions near the membrane
signaling via receptors
cell-cell recognition
intercellular attachment
attachment of the cell to extracellular matrix proteins
39
Q

What is diffusion (passive transport)?

A

no energy required
occurs best with small hydrophobic molecules such as O2
when such a molecules is more concentrated on one side of a membrane, diffusion occurs until equilibrium is reached
molecules diffuse down their concentration gradient

40
Q

What is osmosis?

A

diffusion of water across a selectively permeable membrane

water (solvent) follows the solute

41
Q

What is facilitated diffusion?

A

passive transport aided by proteins
specific molecules are impeded by the membrane but diffuse passively with the aid of a transport protein
channel and carrier proteins help with this process

42
Q

What are channel proteins?

A

a specific channel protein usually allows only one type of molecule or ion to pass through
cellular conditions determine if the channel is open or closed

43
Q

What are carrier proteins?

A

undergo a subtle change in shape to translocate a solute across the membrane

44
Q

What is active transport?

A

energy is required
used to move a substance against the concentration gradient
requires energy, usually in the form of ATP
active transport allows cells to establish and maintain concentration gradients that might not occur naturally

45
Q

What is membrane potential?

A

all cells exhibit a voltage across their plasma membranes

the unequal distribution of anions across the plasma membrane

46
Q

What are electrogenic pumps?

A

responsible for creating electrochemical gradients

47
Q

What are cotransporters?

A

couple the “downhill” transport of a solute to the “uphill” transport of a second substance against its own concentration gradient

BIOL 107 (11 decks)

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