Proteins Flashcards Preview

AP Biology 2014 > Proteins > Flashcards

Flashcards in Proteins Deck (28):
1

proteins are the links between

genotype and phenotype

2

gene expression

- process by which proteins are DNA directs protein synthesis

- two stages: transcription and translation

3

why can't proteins be directly translated from DNA

- use of RNA protects DNA and its genetic material

- allows more proteins to be created simultaneously

4

amino acid

- 20 types

- order determines the protein formed

5

peptide bond

- bonds between amino acids

- form between the hydrogen and carboxyl groups

6

polypeptide

- protein composed of one or more long chains

7

(blanks) provide the instructions to make certain proteins

genes

8

protein shape determines (blank)

function

9

primary structure

- describes order of amino acids

- any of 20 amino acids can appear at a position in the protein

- primary structure for protein antidiuretic hormone (ADH) can be written as Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg-Gly
 

* important to note side groups don't play a role in peptide strucutre, but do play a role in primary structure



 

10

secondary structure

- 3D shape

- results from hydrogen bonding between amino and carboxyl groups of adjacent amino acids

- bonding produces either

spiral (alpha helix): when hydrogen bonds form in a chain

OR

folded plane that looks like pleats on a skirt (beta pleated sheet): parallel chains linked into pleated shape 

- protein whose shapes are dominate by two patterns often form fibrous proteins

A image thumb
11

tertiary structure


 

- additional 3D shaping

- often dominates structure of globular proteins

- factors that contribute to tertiary

= hydrogen bonding between R groups of amino acids

= iconic bonding between R groups of amino acids

= hydrophobic effect: occurs when sulfur atom in amino acid cysteine bonds to sulfur atom in a nother cysteine (forming cysteine, kind of double amino acid); disulfide bridge helps maintain folds of amino acid chain

A image thumb
12

quaternary structure 

- describes protein that is assembled from two or more separate peptide chains

- ex. globular protein hemoglobin consists of four peptide chains that are held together by hydrogen bonding and interactions among R groups

A image thumb
13

structural -

1/7 major functions of proteins

support

keratin in the hair and horns of animals

collagen in connective tissues

silk in spider webs

14

storage -

2/7 major functions of proteins

holds/collects molecules like calcium and iron

casein in milk

ovalbumin in egg whites

zein in corn seeds

15

transport -

3/7 major functions of proteins

moves certain small molecules/ions

in membranes of cells that transport materials into and out of cells
oxygen carrying hemoglobin in red blood cells

proton pump

16

motion - 

6/7 major functions of proteins

contract muscles

actin

myosin

17

defense -

4/7 major functions of proteins

recognizes foreign substances; center of immune system

antibodies that provide protection against foreign substances that enter bodies of animals

immunoglobulins

18

regulation - 

7/7 major functions of proteins

receives or sends information to regulate body functions

hormones

19

enzyme catalysis -

5/7 major functions of proteins

facilitates or speeds up certain chemical reactions 

enzymes

20

denaturation

- proteins unfolding

- can occur if pH, ionic concentration, or temperature change

- leads to biologically inactive proteins

- most enzymes can only function in specific conditions

21

channel proteins

- provide open passageways through membrane for certain hydrophilic (water-soluable) substances such as polar and charged molecules

aquaporins are channel proteins of certain cells (such as those in kidneys and plant roots) that dramatically increase the passage rate of H2O molecules




 

22

ion channels

- allow passage of ions across membrane

in nerve and muscle cells, ion channels called gated channels open and close in response to specific chemical or electrical stimuli to allow passage of specific ions (like Na+ and K+)




 

23

carrier proteins

- bind to specific molecules
- transferred across membrane after carrier protein undergoes change of shape

passage of glucose into cells is by carrier protein






 

24

transport proteins

- use energy in form of ATP (adenosine triphosphate)
- transport materials across membrane

- when energy used, materials said to be actively transported through active transport

sodium potassium pump uses ATP to maintain higher concentrations of Na+ and K+ on opposite sides of plasma membrane








 

25

recognition proteins

- give each cell type unique identification
- identification provides for distinction between cell types
- between self and foreign cells, normal cells and those infected with a virus
- recognition proteins are actually glycoproteins, proteins with short polysaccharide chains that extend away from surface of membrane

differences between blood types are result of recognition proteins on surface of red blood cells










 

26

receptor proteins

- provide binding sites for hormones or other trigger molecules
- in response to hormone or trigger molecule, specific cell response is activated

27

adhesion proteins

- attach cells to neighboring cells
- also provide anchors for internal filaments and tubules that give stability to the cell

28

molecular chain of command in a cell

DNA ⇒ RNA ⇒ protein