Cells And Proteins

Question 1

Why is having a cytoskeleton important to a cell?

Answer 1

Retains cell shape, keeps structure of cell and things in the correct place.

Question 2

What is the cytosol and what cellular functions take place there?

Answer 2

Metabolism, contains cytoskeleton so allows things to move through the cell

Question 3

Why do cells need lysosomes and peroxisomes?

Answer 3

Lysosomes- mainly degrade proteins
Peroxisomes- remove H2O2 and other toxic substances, as well as lipids

Question 4

Why does a mitochondrion need a double membrane to produce energy for the cell?

Answer 4

To set up a Proton gradient, for the ETC. Inner membrane increases SA for ETC, in cellular respiration

Question 5

Why are the functions of the Golgi apparatus required in a cell?

Answer 5

Needed to package proteins and add components to proteins, finishing protein synthesis. Makes lysosomes

Question 6

What are the functions of the endoplasmic reticulum and what is the difference in function between “rough” and smooth endoplasmic reticulum?

Answer 6

Smooth has no ribos; rough does.
Smooth- processes lipids

Question 7

What cellular functions does the nucleus perform ?

Answer 7

Stores DNA in form of chromatin. Most of the DNA in a eukaryotic cell is stored inside of it.

Question 8

What do microtubules do?

Answer 8

Provide a structure for things to prove through or from

Question 9

What is the primary structure of a protein?

Answer 9

Aa sequence

Question 10

What’s the secondary structure of a protein?

Answer 10

Initial folding of pp chain

Question 11

What’s the tertiary structure of a protein?

Answer 11

The overall shape

Question 12

What are chaperones?

Answer 12

Proteins that help other proteins fold

Question 13

How are peptide bonds between amino acids formed?

Answer 13

Carboxylic acid group of 1 aa reacts w amine group of another

Question 14

Types of R group

Answer 14

Charged, non-polar aliphatic, polar uncharged (hydrophobic), aromatic

Question 15

What determines amino acid properties

Answer 15

The R group

Question 16

What determines protein structure?

Answer 16

R groups, environment, chaperones

Question 17

What type of bond stabilises alpha helixes (and beta pleated sheets) within the secondary protein structure?

Answer 17

H bonds. R groups face outwards

Question 18

How is the tertiary structure of a protein determined?

Answer 18

By the lowest energy route. Ie not -ve and -ve, or hydrophobic and hydrophilic next to each other

Question 19

What’s the quaternary structure of a protein?

Answer 19

A complex of 1 or more pp chain

Question 20

Types of tertiary protein structures

Answer 20

Beta pleated sheet, fibrous, globular, helix

Question 21

How do we determine protein structure (shape)?

Answer 21

X ray cystallography, NMR

Question 22

Why may proteins be globular?

Answer 22

For secretion

Question 23

Why may proteins be elongated?

Answer 23

For strength

Question 24

What do multi-polypeptide complexes contain?

Answer 24

Homomers or Heteromers. Eg haemoglobun

Question 25

Describe how proteins aren’t rigid structures

Answer 25

Conformation is flexible and dynamic Post translational modification (phosphorylation) Function due to changes in conformation- eg enzyme and substrate

Question 26

Protein functions (4)

Answer 26

Binding- ligands, receptors Catalysis Switching- cell signalling pathways Structural- cytoskeleton

Question 27

What’s the regulatory protein for the cell cycle’s CdK?

Answer 27

Cyclin

Question 28

What’s CdK?

Answer 28

Cyclin dependent kinase. The catalytic protein in regulating the cell cycle.

Question 29

Where does P53 tumour suppressor protein bind?

Answer 29

To DNA, to control transcription

Question 30

Why do we need to know about proteins?

Answer 30

To target them with drugs. Eg blocking active site

Question 31

Where are most proteins synthesised?

Answer 31

On ribosomes on the rER

Question 32

What directs proteins to the correct site in the cell as part of localisation?

Answer 32

Sorting signals

Question 33

What transports proteins from 1 compartment to another?

Answer 33

Transport vesicles

Question 34

What do specialised cells have for carrying the secretions?

Answer 34

Secretory vesicles . They store hormones, enzymes,. They require an extracellular signal for exocytosis

Question 35

What are the 3 aa that phosphate covalently bonds to on the side chains?

Answer 35

Tyrosine, serine, Theronine