Cells and proteins

Question 1

The proteome?

Answer 1

The entire set of proteins that is, or can be expressed by a certain genome.

Question 2

More than one protein can be produced from a single gene due to…

Answer 2

Alternative gene splicing.

Question 3

Non coding RNA genes

Answer 3

Genes that do not code for proteins transcribed to produce tRNA, rRNA and RNA molecules that control the expression of other genes.

Question 4

The set of proteins expressed by a given cell type can vary over…

Answer 4

Time and under different condition

Question 5

4 factors affecting the set of proteins expressed by a given cell type are:

Answer 5

Metabolic activity of the cell
Cellular stress response to signalling molecules
Diseased vs healthy cells

Question 6

Because of their size, eukaryotes have a relatively small…

Answer 6

Surface area to volume ratio

Question 7

The plasma membrane of eukaryotic cells is too small to…

Answer 7

Carry out all the vital functions of the cell

Question 8

Name 13 parts of the cell

Answer 8

Cell membrane
Golgi apparatus
Golgi vesicles
Nucleus
Lysosome
Ribosome 
Microtubules
Pinocytotic vesicles 
Endoplasmic reticulum 
Centrioles
Vacuole 
Mitochondria
Smooth endoplasmic reticulum

Question 9

Endoplasmic reticulum

Answer 9

Forms a network of membrane tubules continuous with the nuclear membrane

Question 10

Golgi apparatus

Answer 10

A series of flattened membrane discs

Question 11

Lysosome

Answer 11

Membrane bound organelles containing a variety of hydrolyses that digests proteins lipids, nucleic acids and carbohydrates

Question 12

Vesicles

Answer 12

Transport materials between membrane compartments

Question 13

Parts of the cell involved in synthesis of membrane components

Answer 13

Ribosomes
Rough endoplasmic reticulum
Smooth endoplasmic reticulum

Question 14

Lipids and proteins are synthesised in the…

Answer 14

Endoplasmic reticulum

Question 15

What is the difference between rough endoplasmic reticulum and smooth endoplasmic reticulum?

Answer 15

RER has ribosomes on its cytosolic face while SES does not

Question 16

Lipids are synthesised in…

Answer 16

The SER and inserted into its membrane

Question 17

The synthesis of all proteins begins in the…

Answer 17

Cytosolic ribosomes

Question 18

The synthesis of cytosol proteins is completed in the…

Answer 18

Cytosolic proteins, these proteins remain in the cytosol (liquid part of the cytoplasm)

Question 19

Transmembrane proteins

Answer 19

Carry a signal sequence which halts translation and directs the ribosome synthesising the protein to dock with the ER forming RER

Question 20

Signal sequence

Answer 20

A short stretch of amino acids at one end on the polypeptide that determines the eventual location of a protein in a cell

Question 21

What are many secreted proteins synthesised as

Answer 21

Inactive precursors and require proteolytic cleavage to produce active proteins

Question 22

What is proteolytic cleavage

Answer 22

Another type of post-translational modification

Question 23

Example of secreted proteins

Answer 23

Digestive enzymes that requires proteolytic cleave to become active, another is insulin

Question 24

Proteins are polymers of…

Answer 24

amino acid monomers

Question 25

What are enzymes linked by

Answer 25

Peptide bonds to form polypeptides

Question 26

Amino acids have the same basic structure, differing only in the...

Answer 26

R group present

Question 27

What can R groups vary in

Answer 27

``` size shape charge hydrogen bonding capacity chemical reactivity ```

Question 28

Amino acids are classified according to their R groups. What are they

Answer 28

basic (positively charged) acidic (negatively charged) polar (hydrophilic) hydrophobic (non polar)

Question 29

What does the diversity of amino acid R groups result in

Answer 29

Wide range of functions carried out by proteins

Question 30

What is the primary structure

Answer 30

The sequence in which the amino acids are synthesised into the polypeptide

Question 31

where are secreted proteins translated?

Answer 31

they are translated in ribosome on the RER and enter it’s lumen

Question 32

Describe how vesicles are able to move around the cell

Answer 32

Along microtubules (to other membranes)

Question 33

Describe the differences between the various protein synthesised in cells in terms of their final destinations

Answer 33

Cytosolic proteins are synthesised in cytosolic ribosomes; transmembrane proteins start in cytosolic ribosomes and finish in docked ribosomes/ RER; secretory proteins start in cytosolic ribosomes and finish in docked ribosomes/ RER

Question 34

Describe TWO different types of post-translational modification

Answer 34

Addition of carbohydrate in golgi apparatus; proteolytic cleavage of digestive enzymes in gut

Question 35

Name the FOUR different types of R groups and describe the characteristics of each.

Answer 35

hydrophobic are uncharged; basic are positively charged/ hydrophilic; acidic are negatively charged/ hydrophilic; polar have small balanced charges/ no net charge

Question 36

Describe the primary and secondary level of protein structure.

Answer 36

primary is the sequence of amino acids; secondary is folding to produce helices/sheets/turns; held in shape by H bonds

Question 37

Name FIVE types of bond that can hold the tertiary structure of protein in shape.

Answer 37

``` hydrophobic interactions ionic bonds disulfide bridges London dispersion forces hydrogen bonds ```

Question 38

Describe the quaternary structure of a protein

Answer 38

arrangements of subunits; may have prosthetic groups

Question 39

Explain what is meant by co-operativity between subunits of a protein

Answer 39

binding or dis-binding of substances at subunits; affects affinity of these substances for further subunits