Synthesis and transport of proteins

Question 1

Endoplasmic reticulum

forms

Transportation system

Answer 1

Forms a network of membrane tubules continuous with nuclear membrane.
Transportation system used to create and transport
- proteins
- enzymes
- and lipids.

Question 2

Rough ER

Answer 2

Cytosolic face covered with ribosomes, connected to the nuclear membrane and smooth ER, flattened sacs called cisternae.

Question 3

Smooth ER roles

Answer 3

No ribosomes,
- Synthesises lipids and proteins to be exported by cell
- controls calcium level in muscles
- detoxifies poisions.

Question 4

Synthesis of all proteins begins in

Answer 4

Cytosolic Ribosomes

Question 5

Cytosol

Answer 5

cytoplasm’s matrix, surrounds the cell organelles, fluid present in the cell membrane, while cytoplasm is all the contents of cell excluding nucleus.

Question 6

Proteins within the membrane

Answer 6

Intrinsic proteins and external

Question 7

Intrinsic proteins

Answer 7

Embedded in the membrane, from one side to the other

Question 8

Signal sequence

Answer 8

short stretch of amino acids at one end of polypeptide that determines final location of protein in a cell.

Question 9

Transmembrane protein

Answer 9

Inserted into phospholipid bi layer, permit the transport of specific substances across the membrane

Question 10

So what do transmembrane proteins do

Answer 10

Carry a signal sequence, which halts translation and directs the ribosome to dock with the ER, forming Rough ER!

Translation continues and protein is inserted into membrane of the ER

Question 11

Locations proteins can be taken to by vesicles

Answer 11

• Cytoplasm
• organelles like lysosomes
• cell membrane like receptor proteins
• secreted from the cell like hormones and antibodies.

Question 12

Vesicles

Answer 12

Transport materials between membrane compartments

Question 13

Movement of proteins between membranes

Answer 13

Proteins in the lumen of the ER are transported by vesicles that bud off and fuse with the golgie apparatus

Question 14

Golgi apparatus

Answer 14

Series of flattened membrane discs, stacks of single membrane compartments.

Question 15

Proteins moving through golgi discs

Answer 15

They do so in vesicles that bud off from one disc and fuse to the next one in the stack, undergoing post translational modification,

Question 16

What do enzymes catalyse while proteins move through golgi

Answer 16

The addition of various sugars in multiple steps to form the carbohydrates

Question 17

What is the major modification to proteins

Answer 17

addition of a carbohydrate group, now forming a fully functioning protein

Question 18

Vesicles leaving Golgie

Answer 18

Take proteins to the plasma membrane and lysosomes, they move along microtubulea and fuse with membranes within the cell.

Question 19

Secretory pathway

Answer 19

Secreted proteins are translated in ribosomes on the RER and enter its lumen, proteins move through Golgi and are packaged into secretory vesicles, which fuse with plasma membrane releasing the proteins from the cell.

Question 20

Examples of secreted proteins

Answer 20

peptide hormones and digestive enzymes

Many are synthesised as inactive precursors and require proteolytic cleavage to produce proteins

Question 21

Proteolytic cleavage

Answer 21

Process of breaking the peptide bonds between amino acids in proteins.

Type of PTM

Question 22

Digestive enzymes are an example of

Answer 22

Secreted proteins that require Proteolytic cleavage to become active!

Question 23

Proteome

Answer 23

Entire set of proteins expressed by a genome

Question 24

Why is the proteome larger thsan the genome

Answer 24

More than one protein can be expressed from a single gene because of Alternative RNA splicing. Though not all genes are expressed as proteins in a particular cell type.

Question 25

Genes that dont code for protein

Answer 25

Called non coding rna genes and include those that are transcribed to produce tRNA rRNA and RNA molecules that control the expression of other genes.

Question 26

Factors affecting the set of proteins expressed by a cell type are

Answer 26

The metabolic activity of a cell, cellular stress, response to signalling molecules, and diseased vs healthy cells