Biochem 1: Proteins Flashcards Preview

ABS > Biochem 1: Proteins > Flashcards

Flashcards in Biochem 1: Proteins Deck (46):
1

proteins are

polymers of 20 different amino acids (monomers) linked by peptide bonds

2

polypeptide chain is a

single unbranched polymer of amino acids

3

proteins consist of

one or more polypeptide chains folded into specific 3-D shapes

4

what defines the shape of the protein

the sequence of amino acids

5

polymers are formed by _____ reactions

condensation

6

monomers are joined by covalent bonds, energy must be added, and water is removed, this is also called a ______ reaction

dehydration

7

polymers are broken down into monomers in

hydrolysis reactions
(hydrolysis releases energy)

8

protein primary structure

is a polypeptide chain

9

protein secondary structure

occurs when the amino acid chain folds and coils in a helix or pleated sheet

10

protein tertiary structure

occurs when the helix or sheet fold irregularly, forming disulfide bridges, hydrogen bonds, hydrophobic interaction, and ionic bonds between amino acids in the chain

11

what 2 categories of proteins are there- divided into two large classes based on their three-dimensional structure

-fibrous proteins
-globular proteins

12

protein quaternary structure

consists of two or more polypeptides

13

proteins can undergo denaturation which is

occurs when proteins encounter hostile environments such as temperature and pH, and therefore lose their shapes and functions

14

what structure does hydrolysis destroy?
what structure does denaturation destroy?

-hydrolysis destroys primary structure
-denaturation destroys all other levels of structure (but not primary) - because primary has covalent bonds

15

globular proteins are proteins which are

folded to a more or less spherical shape

16

globular protein properties and example

-they tend to be soluble in water and salt solutions
example is hemoglobin

17

polar/nonpolar groups of globular proteins

-most of their polar side chains are on the outside and interact with the aqueous environment by hydrogen bonding and ion-dipole interactions
-most of their non polar side chains are buried inside

18

fibrous proteins contain

polypeptide chains organized approximately parallel along a single axis

19

properties of fibrous proteins

-consist of long fibers or large sheets
-tend to be mechanically strong
-are insoluble in water and dilute salt solutions
-play important structural roles in nature

20

examples of fibrous proteins

-keratin of hair and wool
-collagen of connective tissues of animals including cartilage, bones, teeth, skin, and blood vessels

21

collagen consists of

three polypeptide chains wrapped around each other in a replica twist to form a triple helix

22

collagen structure specifics

-30% of amino acids in each chain are Pro and hydroxyproline
-every third position is Gly
-each polypeptide chain is a helix
-the three strands are held together by hydrogen bonding

23

collagen fibers with age

with age, collagen helices become crossed linked by covalent bonds formed between Lys and His residues

24

where are crystallins found

in the epithelial and fiber cells of the ocular lens

25

what are crystallins and what do they maintain

crystallins are structural, water soluble proteins
-maintain the elongated shape of lens fiber cells and lens structure and affect refraction of light

26

crystalline proteins in the lens contain significant amounts of

Cys and Met

27

what do molecular chaperons maintain

maintain normal conformation of other crystallins to prevent aggregation

28

80-90% of the bulk of the eye contains

collagen

29

collagen in the eye helps to

forms and maintains tissue structure, scaffolding and adhesion
-makes up the semiliquid gel of the vitreous humor

30

in the corneal storm, collagen fibers form

lamellae sheets that impose cross-sectional strength

31

collagen is also in ____, ___.... of the eye

in the sclera, ocular basement membranes called descemet's membrane, lens capsule and blood vessels

32

anchoring collagen fibrils attach:

basal epithelial cells of cornea and outermost lamellae of corneal stroma

33

how senile cataracts form

-if oxidized, protein shape is altered through exposing more Cys sulfhydryl groups
-disulfide bonds form within and between crystallin protein
-high molecular weight aggregates are formed, which reduce the integrity and clarity of the lens itself

34

hemoglobin basic structure

tetramer of two alpha chains and two beta chains, a2b2
-each chain has 1 heme group

35

hemoglobin can bind up to __ molecules of ___

4 molecules of O2

36

what is O2 positive cooperativity in hemoglobin

when one O2 is bound, it becomes easier for the next O2 to bind

37

function of hemoglobin to

transport oxygen

38

what affects the ability of Hb to bind and transport oxygen

H+, Co2, Cl-, and 2,3-biphosphoglycerate (BPG)

39

the Bohr affect in binding affinity of O2 for Hb

H+ and CO2 bind to Hb and affect the binding affinity of Hb for O2

40

Bohr affect in lungs
when hemoglobin binds to O2

actively metabolizing muscle: Hb releases O2

41

Bohr affect in lungs
when hemoglobin releases H+

actively metabolizing muscle: Hb binds H+

42

what are antibodies

are Y-shaped molecules consisting of two identical heavy chains and two identical light chains held together by disulfide bonds

43

antibodies are classified as

glycoproteins

44

what is the variable region of an antibody

the variable region is found at the prongs of the Y and is the part of the antibody that binds to the antigen

45

the binding sites for the antibody on the antigen are called

epitopes

46

the importance of correct folding

proteins that do not fold correctly may interact with other proteins in an undesired manner and aggregates may results