2.4 Proteins

Question 1

What are proteins composed of

Answer 1

polypeptides -> composed of amino acids

Question 2

how many universal amino acids are there

Answer 2

20

Question 3

What are polypeptides

Answer 3

long chains of joined amino acids.

Distinct chemical properties, which affect fold and function.

Question 4

Peptide bonds - link 2 amino acids to form a polypeptide

Answer 4

covalent chemical bond linking two consecutive alpha-amino acids from C1 of one alpha-amino acid and N2 of another, along a peptide or protein chain.

Question 5

What composes an amino acid

Answer 5

amine group (NH2) + HC R-group + Carboxyl group (OHC=O)

Question 6

Primary structure (order of the amino acid sequence)

Answer 6

determines how the chain folds due to the chemical properties of the variable group. The order of amino acids determines all subsequent levels of protein folding.

Question 7

Secondary structure (stable configuration)

Answer 7

This is the result of the hydrogen bonds of non-adjacent amine and carboxyl groups.

Coil/spiral arrangement = alpha helices

Directionally oriented staggered strand conformation = beta-pleated sheets.

Random coil = no secondary structure exists.

Question 8

The tertiary structure (3D config.)

Answer 8

Overall 3D configuration is determined by the variable chain - the interactions are between hydrogen bonds, disulphide bridges, ionic interactions, polar association, etc.

Affinity/repulsion is determined by the overall shape of the polypeptide chain and the position of specific amino acids within the sequence.

Question 9

Quaternary Structure (multiple protein structures)

Answer 9

Found in proteins that consist of more than one polypeptide chain linked together, including inorganic prosthetic groups.

E.g. haemoglobin (carries oxygen) > composed of iron-containing haeme groups (prosthetic groups responsible for binding oxygen

Question 10

Denaturation

Answer 10

Structural change in a protein that results in the loss of its biological properties. Protein folds determine function - change or abrogation of the tertiary structure alter activity.

Question 11

Temperature

Answer 11

Disrupt the hydrogen bonds that hold the protein together. Bonds are broken, the protein will begin to unfold and lose its capacity to function as intended

Question 12

pH

Answer 12

Amino acids are zwitterions, neutral molecules possessing both negatively (COO–) and positively (NH3+) charged regions. Alters charge - protein solubility & shape

Question 13

zwitterions

Answer 13

neutral molecules possessing both negatively and positively charged regions

Question 14

Stages of DNA sequencing

Answer 14

1. Transcription

2. Translation

Question 15

Describe transcription

Answer 15

DNA template to make an mRNA transcript (occurs w/in nucleus)

Question 16

Describe Translation

Answer 16

instructions of mRNA transcript to link amino acids together (ribosome)

Question 17

What is the proteome

Answer 17

It is the totality of proteins expressed within a cell/tissue/organism at a certain time. It is significantly larger than the number of genes in an individual.

Question 18

Protein functions (SHITS ME)

Answer 18

STRUCTURE
HORMONES
IMMUNITY
TRANSPORT
SENSATION
MOVEMENT
ENZYMES

Question 19

Protein function: STRUCTURE

Answer 19

collagen (component of the connective tissue of animals)

spider silk (fibre spun by spiders).

Question 20

Protein function: HORMONES

Answer 20

insulin (produced by the pancreas = triggers a reduction in blood glucose levels)

glucagon (pancreas = triggers an increase in blood glucose levels)

Question 21

Protein function: IMMUNITY

Answer 21

immunoglobulins (Antibodies produced by plasma cells - targets specific antigens).

Question 22

Protein function: TRANSPORT

Answer 22

haemoglobin (found in red blood cells that is responsible for the transport of oxygen)

cytochrome (located in the mitochondria and involved in the electron transport chain).

Question 23

Protein function: SENSATION

Answer 23

rhodopsin (pigment - photoreceptor cells of the retina, detection of light).

Question 24

Protein function: MOVEMENT

Answer 24

actin (thin filaments involved in the contraction of muscle fibres)

myosin (thick filaments involved in the contraction of muscle fibres).

Question 25

Protein function: ENZYMES

Answer 25

rubisco (enzyme involved in the light independent stage of photosynthesis)

catalase (catalyses the decomposition of hydrogen peroxide to water and oxygen).