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Flashcards in Lecture 1 Deck (41)
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0
Q

What are the main functions of the plasma membrane?

A
  • Acts as a selective barrier
  • Contains ion channels and transporters
  • Active transport and facilitated diffusion
1
Q

What are the functions of the nucleus

A
  • Location of gene replication
  • Location of transcription
  • Holds all genetic information (Euchromatin and Heterochromatin)
2
Q

What are the main functions of mitochondria?

A
  • Oxidative phosphorylation for ATP synthesis

- Involved in cell signalling and the cell cycle

3
Q

What are the main functions of the golgi?

A
  • Modifies, packages and secretes proteins

- Involved in lysosome formation and the secretory pathway

4
Q

What is the main function of lysosomes?

A
  • Contains hydrolytic enzymes to degrade proteins and other large molecules
  • Used in immune defences to degrade pathogens
5
Q

Describe rough endoplasmic reticulum and state its function

A

Interconnected network of flattened membrane enclosed sacs.
Studded with ribosomes on its outer surface which is the location of late-phase protein synthesis.
Involved in transport of proteins to golgi

6
Q

What is the function of Smooth Endoplasmic Reticulum and how does it differ from Rough Endoplasmic Reticulum?

A
  • Does not contain ribosomes on its outer membrane.

- Involved in lipid and carbohydrate metabolism as well as detoxification and transport of proteins to golgi.

7
Q

What is the function of ribosomes?

A
  • Location of protein synthesis
8
Q

What is meant by the macromolar structure of a protein?

A

It’s primary, secondary, tertiary (and sometime quaternary) structure

9
Q

When do hydrogen bonds occur and why?

A
  • When a H atom is bound to a highly electronegative atom such as O, N or F.
  • Electronegative atom decentralises the electron cloud, pulling it towards itself. This creates partial charges (dipoles) on the atoms
10
Q

When do zwitter ions arise in proteins and how? What benefit does this have to the protein?

A
  • When to R groups are in close proximity and one has COOH and the other NH2.
  • The H of the carboxyl group transfers to the amine group (COO- and NH3)
  • Increases stability of the protein
11
Q

Describe a peptide bond

A
  • Carboxyl group of one a’a is linked to the amino group of the next via a condensation reaction
  • The bonds around the peptide bond are in trans formation
12
Q

What is a hydrophobic interaction and at what level of macromolar structure are they found?

A
  • When two hydrophobic R groups are in close proximity they interact and repel water. Adds to the stability and function of a protein.
  • Found in the tertiary structure of a protein
13
Q

What are van der waals and how are they formed?

A
  • Weak interactions between atoms which aid stability
  • Formed as the electrons in an electron cloud are constantly mobile. This creates partial charges on the atoms in the compound (d+/d-). When two atoms with partial charge are in close proximity they attract/repel each other.
14
Q

How do hydrogen bonds affect solubility of proteins?

A

-Atoms with a high potential to form hydrogen bonds will be highly soluble

15
Q

Are polar molecules soluble or insoluble and why?

A

Polar molecules contain electronegative atoms, giving the compound the ability to produce hydrogen bonds and thus are soluble

16
Q

Are non-polar molecules soluble or insoluble? Can they contain electronegative atoms?

A

Non-polar molecules are insoluble as they do not have the ability to form hydrogen bonds. They may contain electronegative atoms, however it is not in a high enough proportion to make the entire molecule soluble

17
Q

Are molecules which contain both polar and non-polar regions soluble or insoluble?

A

Soluble - they form micelles with hydrophobic, non-polar regions on the inside and the hydrophillic polar regions on the outside

18
Q

What is pH?

A

-Measure of the acidity/basicity of an aqueous solution

19
Q

What is pK?

A
  • A measure of how likely a molecule is to accept or donate a proton
20
Q

In terms of pH and pK, when is a molecule likely to be protonated/deprotonated?

A
  • If pHpK then the molecule will be deprotonated
21
Q

What is a buffer?

A

An aqueous solution with a highly stable pH

22
Q

What are buffers made from?

A

An acid/base with its conjugate

23
Q

What are the non-polar hydrophobic amino acids?

A

Glycine, Alanine, Valine, Leucine, Isoleucine, Methionine, Proline, Phenylalanine, Tryptophan.

24
Q

What amino acids are polar, uncharged?

A

Serine, Threonine, Asparigine, Glutamine, Tyrosine, Cysteine

25
Q

Which amino acids are Polar and charged?

A

Lysine, Arginine, Histidine, Aspartate, Glutamate

26
Q

What is an isoelectric point?

A

The point at which a protein has no overall charge

27
Q

Will the isoelectric point of an acidic protein by high or low and why?

A
  • Low

- Acidic proteins contain many negatively charged amino acids

28
Q

Will the isoelectric point of a basic protein be high or low and why?

A
  • High

- Basic proteins have many positively charged amino acids

29
Q

What is primary protein structure?

A
  • The linear sequence of amino acids
30
Q

What is secondary protein structure? List two types

A
  • The local spatial arrangement of the polypeptide back bone
  • Doesn’t involve R groups
  • a-helix and b-strand
31
Q

Describe the features of an a-helix

A
  • Right handed helix
  • 3.6 a’a/ complete turn
  • 0.54nm pitch (vertical distance in one turn)
  • Stabilised by H bonds
32
Q

Describe a b-strand

A
  • Has an extendeed conformation due to the R groups being on alternate sides
  • multiple multidirectional strands held together through H bonds form B-pleated sheets
33
Q

Which bonds are involved in tertiary structures of proteins?

A
  • Disulphide Bonds
  • Hydrophobic interactions
  • Ionic bonds
  • Salt bridge
34
Q

What is a quaternary protein structure?

A

Two or more polypeptides non-covalently and covalently linked
Eg, Hb, ribosomes

35
Q

How does heat denature proteins?

A

Increases Vibrational Energy

36
Q

How does pH denature proteins?

A
  • Alters ionisation states of a’a which breaks bonds
37
Q

How do detergents/solvents denature proteins?

A
  • Disrupt hydrophobic interactions

- Change oxidation states

38
Q

What would cause the formation of amyloid fibres?

A
  • Misfolding of proteins resulting in an insoluble long fibrous structure
39
Q

Describe globular proteins

A
  • Contain several secondary structures

- Compact

40
Q

Describe fibrous proteins

A
  • single type of secondary structure - usually B strand

- involved in support, eg collagen