Bio Hw due 9/15 Flashcards
A polypeptide is a long unbranched chain of
Amino acids
The shape of a protein determines its
function
Functions of proteins
- they catalyze chemical reactions
- they transport ions and molecules across the cell membranes
- provide structural support for many animal tissues
- play a key role in the contraction of muscles
Proteins are polymers made up of how many different amino acids?
20
Which part of an amino acid is ALWAYS acidic?
the carboxyl group
the chemical structure of a typical amino acid found in a protein:
A central carbon atom is bound to an amino group, carboxyl group, a side chain, and a hydrogen atom.
the 20 common amino acid are classified into 5 chemical classes based on their
R groups
What is responsible for linking amino acids together to form polypeptides?
Dehydration synthesis
Two _______ joined together by a peptide bond form a dipeptide.
amino acids
Where are the peptide bonds located in a polypeptide?
Between the amino group of one amino acid and the carboxyl group of another
Proteins that only have a single polypeptide chain what two terms are synonymous?
Protein and polypeptide
Each kind of protein has a single unique sequence of
amino acids
In general, where are nonpolar and polar amino acid found in a folded protein?
Non-polar - interior
Polar - exterior
Type of interaction involves the formation of a covalent bond between two different amino acid side chains?
Disulfide bridge
The structure of proteins is usually discussed in terms of a hierarchy of how many levels?
4
The amino acid sequence of its polypeptides is
primary structures
Altering the sequence of amino acids in a polypeptide chain by just a single amino acid can have drastic effects on which of the following ?
Proteins function and proteins shape
What is true about the relationship between enzymes and environmental conditions?
- the optimum conditions for enzyme activity are usually similar to the conditions where the enzyme normally functions
- changing environmental conditions may alter the structure of enzymes
- changing environment conditions may alter the activity of enzymes
Best describes the relationship between temp. and enzyme activity?
Each enzyme has an optimum temp. where it functions best
Proteins are made up of one or more unbranched chains of
amino acids
Denaturation
changes in a proteins environment cause the protein to unfold and lose its shape
Primary structure
Amino acid sequence
Secondary structure
Hydrogen bonding patterns. Alpha helices and Beta sheets
Tertiary structure
folds and links. 3D folding of a single peptide
Quaternary structure
interaction between 2 or more polypeptides to form a protein
A protein’s _____ structure refers to the final 3 dimensional shape of the polypeptide chains make up the protein.
tertiary
Interactions that help determine a protein’s tertiary structure
- Hydrogen bonds
- Disulfide bonds
- Ionic bonds
- Hydrophobic exclusion
When a protein spontaneously refolds back into its natural environment it is called :
renaturation
Protein denaturation may be caused by an increase in which of the following?
- Temperature
- Ionic concentration
- pH
Dissociation
observed when individual subunits making up a protein with quaternary structure separate without losing their tertiary structures
Dehydration synthesis
responsible for linking amino acids together to form polypeptides
The term ______ refers to a single, long chain of amino aicds, while a(n) _____ can be composed of one or more long amino acid chains.
polypeptide, protein
In general, where are nonpolar and polar amino acids found in a folded protein?
Non- Polar - interior
Polar - exterior
Hydrogen bonds between the amino and carboxyl groups of the polypeptide backbone help determine a proteins ____ structure while hydrogen bonds between the amino acid chains help determine protein _____ structure
secondary, tertiary
TRUE OR FALSE
A protein’s final structure can include either regions shaped like an alpha helix or regions shaped like a B- pleated sheet but not both?
FALSE
What are two basic types of secondary structure in proteins?
Alpha helix and B pleated sheet
Individual polypeptides within a protein are referred to as which of the following?
subunits
Most likely to be found in the interior of a protein:
Valine, Leucine, Phenylanine
The alpha helix and b pleaded sheets are maintained primarily by hydrogen bonds between which of the following?
The amino and carboxyl groups within the polypeptide backbone
A ____ is a substance or a mixture of substance’s pH
buffer
A substance that decreases (H+) and increases pH when it dissociates in water is called
base
A substance that increases (H+) and decreases pH when it dissociates in water is
acid
Disulfide bridge
formation of a covalent bond between 2 cysteine side chains
Ionic bond
formation of a bond between groups with opposite charge
Van der Waals attraction
weak attraction between atoms due to oppositely polarized electron clouds
Hydrophobic exclusion
hydrophobic portions of the protein gather in the interior of the protein
Diffusion that is assisted by a channel protein or carrier protein is called ___ diffusion
facilitated
channel proteins
have a hydrophilic interior that provides an aqueous channel through which polar molecules can pass when the channel is open
TRUE about ions
- They interact well with polar molecules
- They are repelled by the hydrophobic interior of the lipid bilayer
Channel proteins that can be opened or closed in response to specific stimilus are called ____ channels
gated
