Nucleic acids, proteins and enzymes

Question 1

Define proteins and polypeptides

Answer 1

Protein- macromolecule made out of amino acid chains
Polypeptide- long chain of amino acids

Question 2

Difference between monomer and polymer

Answer 2

Monomer- smallest building block of a polymer
Polymer- made up of many monomers

Question 3

amino acid structure

Answer 3

Central carbon (CH)
amino group
carboxyl group
R-group- different structure for each amino acid, affects the way it bonds to other amino acids (hydrophobic and hydrophillic)

Question 4

Peptide bond

Answer 4

chemical bond between 2 amino acids

Question 5

condensation polymerisation reaction

Answer 5

Two monomers join by attaching carboxyl group to amino group, creating water as a by-product

Question 6

Primary structure

Answer 6

the sequence of amino acids

Question 7

Secondary structure

Answer 7

when hydrogen bonds are formed between amino acids to create alpha helices, beta pleated sheets or random coils.

Question 8

Difference between tertiary and quaternary structure

Answer 8

Tertiary- When secondary structure further folds to become a functional 3d protein
Quaternary- Multiple tertiary structure (polypeptide chains) joined together

Question 9

deoxyribose nucleic acid

Answer 9

double stranded nucleic acid chains (monomers=nucleotides)

Question 10

Ribonucleic acid

Answer 10

single stranded nucleic acid chain (monomers=nucleotides)

Question 11

nucleotide structure

Answer 11

Phosphate
Five carbon sugar
Nitrogenous base (GCAT)

Question 12

Explain why the direction of nucleotides is called 3’ and 5’

Answer 12

3’ and 5’ refer to the carbon number on the sugar, which are ordered in a clockwise direction. RNA has a 5’ to 3’ end because the 5’ carbon is at the top, 3’ is at the bottom

Question 13

Name all bonds present in DNA and its location

Answer 13

phosphodiester bond (formed via condensation reaction)- sugar-phosphate backbone
hydrogen bond- between base pairs

Question 14

Name 3 types of RNA and its functions

Answer 14

Messenger RNA- Carries genetic info from nucleus to ribosomes
Transfer RNA- Delivers anticodons to ribosomes
ribosomal RNA- the main structural component in RNA

Question 15

Gene structure and function

Answer 15

Promoter- enzyme where RNA polymerase binds to (eukaryotes- known as TATA box)
Operator- binding site for repressor proteins, inhibits gene expression
Leader (prokaryotes)-gene regulation
Introns- non-coding DNA that are spliced out in RNA processing
Exons- translated into final protein

Question 16

Process of transcription

Answer 16

RNA polymerase bind to promoter with the help of transcription factors, DNA unwinds
RNA polymerase creates pre-mRNA from a 5’ to 3’ direction that is complimentary to DNA template strand
RNA polymerase reaches termination sequence synthesis of mRNA is stopped

Question 17

RNA processing

Answer 17

methyl-G cap is attached to 5’
poly-A tail is attached to 3’
splicing of introns

Question 18

Translation

Answer 18

mRNA enters ribosomes, is read from 5’ to 3’ from start codon
Its read and tRNA brings amino acids until stop codon is reached
Adjacent amino acids are bonded via condensation reaction

Question 19

Structural and regulatory genes

Answer 19

Structural- Produces proteins that help with structure or function of cell
Regulatory- Produces regulatory proteins (e.g. repressor proteins)

Question 20

Explain the repression of trp operon

Answer 20

When trp level is high, trp binds to repressor protein causing conformational change, allowing it to bind to operator. Transcription is prevented

Question 21

Explain attenuation

Answer 21

When trp levels are high, there is a high presence of tRNA-bound trp. When ribosome arrives at attenuator sequence, 2 trp is added to mRNA, resulting it to fold into a terminator hairpin loop

Question 22

Identify and describe the function of organelles in the protein secretory pathway

Answer 22

Ribosomes- Synthesises proteins
RER- Folds and transports proteins
Vesicle- Transports proteins
Golgi apparatus- modifies and packages proteins

Question 23

catabolic vs anabolic reaction

Answer 23

catabolic- breaks molecules and releases energy
anabolic- uses energy to join molecules