(Temporary) Unit 1 - Proteins

Question 1

What is Genomics?

Answer 1

The study of the genome

Question 2

What is the genome?

Answer 2

The total genetic material in a cell

Question 3

What is the proteome?

Answer 3

The entire set of proteins that can be expressed by a cell/genome/organism

Question 4

Why is the proteome bigger than the genome?

Answer 4

More than one protein can be produced from one gene due to alternative RNA splicing

Question 5

Factors that affect what proteins are expressed

Answer 5

-Metabolic activity of cell
-cellular stress
-response to signalling molecules
-diseased vs healthy cells

Question 6

function of endoplasmic reticulum

Answer 6

forms a network of membrane tubules continuous with nuclear membrane

Question 7

what is synthesised in the endoplasmic reticulum?

Answer 7

lipids and proteins

Question 8

difference between smooth endoplasmic reticulum and rough endoplasmic reticulum

Answer 8

rough (ER) has ribosomes on its cytosolic face while smooth (ER) lacks ribosomes

Question 9

what is the golgi apparatus?

Answer 9

series of flattened membrane discs

Question 10

what are lysosomes?

Answer 10

membrane-bound organelles containing a variety of hydrolases that digest proteins, lipids, nucleic acids and carbohydrates

Question 11

function of vesicles

Answer 11

transporting materials between membrane compartments

Question 12

what is synthesised in smooth endoplasmic reticulum?

Answer 12

lipids

Question 13

where does synthesis of all proteins begin?

Answer 13

ribosomes

Question 14

where is synthesis of cytosolic proteins completed?

Answer 14

ribosomes

Question 15

steps of protein synthesis

Answer 15

1. transmembrane proteins carry signal sequence
2. this halts transcription and directs ribosome to dock with ER, forming rough ER
3. translation continues after docking and protein is inserted into membrane of ER

Question 16

what is a signal sequence?

Answer 16

short stretch of amino acids at one end of the polypeptide that determines location of a protein

Question 17

steps after protein has been synthesised

Answer 17

1. once protein is in rough ER, transported by vesicles that bud off from ER and fuse with Golgi apparatus.
2. when moving through golgi apparatus, undergo post-translational modification ( e.g. major modification is addition of carbohydrate )
3. move through golgi discs in vesicles that bud off from one disc to next one.
   4.enzymes catalyse addition of various sugars
4. vesicles leave golgi apparatus take proteins to plasma membrane and lysosome.

Question 18

where are secreted proteins translated?

Answer 18

ribosomes on rough ER and enter its lumen

Question 19

examples of secreted proteins

Answer 19

-peptide hormones
-digestive enzymes

Question 20

what happens when secreted proteins are synthesised as inactive precursors?

Answer 20

require proteolytic cleavage to produce active protein

Question 21

what is proteolytic cleavage

Answer 21

type of post-translational modification

Question 22

what do all amino acids have?

Answer 22

-amine (NH2)
-carboxylic acid (COOH)
-hydrogen
-variable R group

Question 23

what bond are amino acids linked by?

Answer 23

peptide bonds

Question 24

what are the 4 R groups

Answer 24

-basic
-acidic
-polar
-hydrophobic

Question 25

acidic R groups

Answer 25

contain a carboxylic acid side chain (-COOH)

Question 26

basic R groups

Answer 26

contain a amine side group (-NH2)

Question 27

polar R group

Answer 27

hydrophilic, seek contact with aqueous solutions

Question 28

hydrophobic R groups

Answer 28

non-polar R groups, avoid contact with liquids

Question 29

what is the primary structure?

Answer 29

sequence in which amino acids are synthesised into polypeptide

Question 30

what is the secondary structure?

Answer 30

hydrogen bonding along backbone of protein strand.
known as:
- alpha helices
-beta pleated sheets

Question 31

what is tertiary structures?

Answer 31

polypeptide folds into tertiary structure
this is stabilised by interactions between R groups
e.g. hydrophobic interactions, ionic bonds, LDF, disulphide bridges

Question 32

what is quaternary structure?

Answer 32

exists in proteins with two or more connected polypeptide subunits.

Question 33

what is a prosthetic?

Answer 33

a non-protein unit which is tightly bound to a protein and necessary for its function