Proteins

Question 1

what happens to the proteins once they are in the ER

Answer 1

Once the proteins are in the ER, they are transported by vesicles that bud off from the ER and fuse with the Golgi apparatus

Question 2

what happens to the proteins as they move through the Golgi apparatus

Answer 2

As proteins move through the Golgi apparatus they undergo post-translational
modification

Question 3

secreted proteins include…

Answer 3

digestive enzyme
peptide hormones

Question 4

what is another type of post transitional modification

Answer 4

proteolytic cleavage

Question 5

where are secreted proteins translated

Answer 5

in the ribosomes on the RER and enter its lumen

Question 6

digestive enzymes are an example of what

Answer 6

Digestive enzymes are one example of secreted proteins that require proteolytic cleavage to become active.

Question 7

what is a proteome

Answer 7

The proteome is the entire set of proteins
expressed by a genome

Question 8

why is the proteome larger than the number of genes

Answer 8

The proteome is larger than the number of genes, particularly in eukaryotes, because more than one protein can be produced from a single gene as a result of alternative RNA
splicing

Question 9

are all genes are expressed as proteins in a
particular cell type

Answer 9

No. not all genes are expressed as proteins in a
particular cell type

Question 10

what can the set of proteins expressed by a given cell type do over time

Answer 10

The set of proteins expressed by a given cell
type can vary over time and under different conditions

Question 11

what are genes that do not code for proteins are called

Answer 11

Genes that do not code for proteins are 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 12

what are some factors affecting the set of proteins
expressed by a given cell type

Answer 12

Some factors affecting the set of proteins expressed by a given cell type are the metabolic activity of the cell, cellular stress, the response to signalling molecules, and diseased versus healthy cells.

Question 13

what is the system of eukaryotic cells

Answer 13

Eukaryotic cells have a system of internal
membranes, which increases the total area of
membrane

Question 14

why do eukaryotes have a
relatively small surface area to volume ratio.

Answer 14

Because of their size, eukaryotes have a relatively small surface area to volume ratio

Question 15

why cant the plasma membrane of eukaryotic cells not carry out vital functions that other membranes can

Answer 15

The plasma membrane of eukaryotic cells is therefore too small an area to carry out all the vital functions carried out by membranes.

Question 16

what does the endoplasmic reticulum (ER) do

Answer 16

The endoplasmic reticulum (ER) forms a network of membrane tubules continuous with the nuclear membrane

Question 17

what is the Golgi apparatus

Answer 17

The Golgi apparatus is a series of flattened membrane discs

Question 18

what are lysosomes and what is there function

Answer 18

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

Question 19

what do vesicles do

Answer 19

Vesicles transport materials between
membrane compartments

Question 20

what is the difference between rough & smooth ER

Answer 20

Rough ER (RER) has ribosomes on its cytosolic face while smooth ER (SER) lacks ribosomes.

Question 21

what is synthesised in the ER

Answer 21

Lipids and proteins are synthesised in the ER

Question 22

which type of ER are lipids synthesised

Answer 22

Lipids are synthesised in the smooth endoplasmic reticulum (SER) and inserted
into its membrane

Question 23

where does the synthesis of all proteins begin

Answer 23

The synthesis of all proteins begins in cytosolic ribosomes

Question 24

synthesis of cytosolic proteins

Answer 24

The synthesis of cytosolic proteins is completed there (cytosolic ribosomes) , and these proteins remain
in the cytosol

Question 25

what do transmembrane proteins do

Answer 25

Transmembrane proteins carry a signal sequence, which halts translation and directs the ribosome synthesising the protein to dock with the ER, forming RER

Question 26

what is a signal sequence

Answer 26

A signal sequence is a short stretch of amino acids at one end of the polypeptide that determines the eventual location of a protein in a cell.

Question 27

what does translation continue after

Answer 27

Translation continues after docking, and the protein is inserted into the membrane of the ER

Question 28

how do molecules move through the Golgi discs

Answer 28

Molecules move through the Golgi discs in vesicles that bud off from one disc and fuse to the next one in the stack. Enzymes catalyse the addition of various sugars in multiple steps to form the carbohydrates.

Question 29

where are secreted proteins translated in

Answer 29

Secreted proteins are translated in ribosomes
on the RER and enter its lumen

Question 30

what happens after the proteins are secreted

Answer 30

The proteins move through the Golgi apparatus and are then packaged into
secretory vesicles

Question 31

how are proteins released from the cell

Answer 31

These vesicles move to and fuse with the plasma membrane, releasing the proteins out of the cell

Question 32

what are many proteins synthesised as

Answer 32

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

Question 33

what is proteolytic cleavage

Answer 33

Proteolytic cleavage is another type of post-translational modification. Digestive enzymes are one example of secreted proteins that require proteolytic cleavage to become active.

Question 34

what are some examples of secreted proteins

Answer 34

Peptide hormones and digestive enzymes
are examples of secreted proteins.