2.1.2 & 2.1.3 Biological Molecules Part 2 COMPLETE

Question 1

Proteins

Answer 1

Can be structural or functional and they provide building materials.
Also vital in metabolic activity, made up of amino acids

Question 2

Testing for Proteins

Answer 2

Biuret Solution
Mix with equal volume of the sample, swirl and look for colour changes
The chemicals react with the peptide bonds

Question 3

Amino Acids

Answer 3

Have an Amine group, an acid group and an R group

Animals and plants use them to make larger proteins

Question 4

Primary Structures

Answer 4

Condensation occurs in protein synthesis to create amino chains
Hydrolysis breaks them down with the aid of enzymes (Protease) used in ageing, hormone regulation and digestion

Question 5

Secondary Structure

Answer 5

Polypeptides fold to produce alpha helices or beta plead sheets
H bonds form between the differences in charge and help stabilise the structure.
Not very strong but lots of them, they’re sensitive to temp and pH

Question 6

Tertiary Strucure

Answer 6

3D shape of the protein, and created by the interaction of alpha helices and beta pleated sheets
Four main type of bonds include: Disulfide, ionic, hydrogen and hydrophobic and phillic interactions. All form between the R groups from the functional group

Question 7

Quaternary Structure

Answer 7

Determined by the tertiary structure and is the proteins final 3D structure
Either Globular or Fibrous

Question 8

Globular

Answer 8

Rolled into balls
Precise non repeating amino sequences of equal length
Water soluble
Used in metabolic reactions e.g. enzymes

Question 9

Fibrous

Answer 9

Form fibres
Often repeating amino sequences with varying length
Usually insoluble
Used for the structures

Question 10

Examples of Globular proteins

Answer 10

Haemoglobin
Insulin
Pepsin

Question 11

Examples of Fibrous proteins

Answer 11

Collagen
Keratin
Elastin

Question 12

Computer Modelling

Answer 12

Predict the structure of proteins using AB initio (based on physical or electrical properties) , or Comparative techniques

Question 13

TLC

Answer 13

Thin layer chromatography
Used to separate a mixture into its constituents
Has a mobile and stationary phase

Question 14

Visualisation

Answer 14

Cant always see the molecules used in TLC, can add UV light to see fluorescent parts
Ninhydrin to see amino acids

Question 15

How TLC works

Answer 15

The speed which a molecule moves along the plate depends on their solubility and polarity. The less polar the faster it’ll travel as won’t stick to the OH groups by forming H bonds

Question 16

Types of Nucleic Acid

Answer 16

DNA- Deoxyribonucleic Acid

RNA- Ribonucleic Acid

Question 17

DNA structure

Answer 17

A double helix made of two polynucleotide strands that are antiparallel to each other
They have complimentary base pairs that are attached to the sugar phosphate back bone

Question 18

Nucleotides

Answer 18

Monomer unit of nucleic acids

Made of three subunits, the Phosphate, a five carbon sugar and a base

Question 19

DNA Bases

Answer 19

Four types of nitrogenous base two purines (A and G) with two rings, and two pyrimidines (T and C) with one ring

Question 20

Making DNA

Answer 20

Phosphodiester bonds form in condensation reactions
The DNA is made of a double helix, the strands are made of a sugar phosphate backbone with a nitrogenous base attached
Not at right angles so form a helix

Question 21

Base Pairing

Answer 21

Hydrogen bonds form between the bases on the polynucleotides
A-T
G-C
They are complimentary

Question 22

DNA in Eukaryotes

Answer 22

Majority of DNA is in the nucleus
They’re wound around Histone proteins that forms chromosomes
There’s a loop of DNA inside the mitochondria and chloroplast

Question 23

DNA in Prokaryotes

Answer 23

DNA is a loop within the cytoplasm

There’s no nucleus and its classed as being naked

Question 24

DNA extraction

Answer 24

Add Ethanol and a strong detergent to the mixture.

To further purify add salts

Question 25

Semi Conservative Replication

Answer 25

1. Double Helix untwists in sections
2. The H bonds are broken by DNA helicase and the DNA unzips, exposing the nucleotide bases
3. Free nucleotides associate with the exposed ones
4. Unzipped strands are used as a template, DNA polymerase is used to catalyse the addition
5. Phosphodiester bonds form

Question 26

Other uses of Nucleotides

Answer 26

• Become phosphorylated, e.g. to make ATP
• Help regulate metabolic pathways
• Be components of coenzymes

Question 27

Describe Genetic Code

Answer 27

Its universal as the same triplet of bases codes all the amino acids
Triplets as three bases code for one amino acid, rehire called codons
Degenerate all amino acids have more than one base triplet
Non Overlapping as the code is read from a fixed point that ensure they’re read in the correct order

Question 28

Mutation

Answer 28

Errors sometimes occur when the wrong nucleotide is inserted. They are random and spontaneous
They aren’t always harmful and can be advantageous

Question 29

How is RNA different to DNA

Answer 29

• Single not double stranded
• Ribose sugar not deoxyribose sugar
• Uracil replaces Thymine

Question 30

Different forms of RNA

Answer 30

• Messanger RNA
• Ribosomal RNA
• Transfer RNA

Question 31

Protein Synthesis

Answer 31

Occurs in the ribosome
Has two main stages Transcription and Translation
Instructions for proteins can’t pass out the nucleus so are carried by mRNA

Question 32

Transcription

Answer 32

mRNA is formed in the nucleus
DNA unzips and the RNA nucleotides form complimentry bases on the template strand
RNA polymerase checks for mistakes
The mRNA breaks off and leaves the nucleus via a pore

Question 33

Ribosomes

Answer 33

Made in the nucleolus from ribosomal RNA, exits via the pores
Moves into the cytoplasm and two subunits come together
In the groove mRNA is translated into a protein

Question 34

Transfer RNA

Answer 34

tRNA
Made in the nucleolus and passes into the cytoplasm
Has four prolonged polynucleotides that join with amino acids

Question 35

Translation

Answer 35

mRNA attaches onto ribosomes with 2 free codons
tRNA in the cytoplasm has a specific amino acid attached to it so the tRNA attaches to the mRNA
The first codon is always AUG
Peptide bonds form requiring ATP
mRNA components are recycled after