Biochem - Nucleic Acids

Question 1

What bond forms when nucleotides are polymerised?

Answer 1

Phosphodiester bonds

Question 2

tRNA anticodon sequence is the same as….

Answer 2

The template strand (With thymine switched to uracil)

Question 3

Helicase…

Answer 3

Helicase unzips and unwinds the DNA

Question 4

The template DNA is…

Answer 4

The DNA complimentary to the coding strand; it is the strand which complimentary nucleotides bond to the recreate the sequence of the coding strand

Question 5

Purine bases pair with…

Answer 5

Pyrimidine bases

Question 6

Phosphodiester bonds link…

Answer 6

adjacent nucleotides.

Question 7

Explain how nitrogenous bases allow identical copies of DNA to be made.

Answer 7

Adenine pairs with Thymine because of hydrogen bonding; Purine can only bond with pyrimidine because of their different sizes and-so bases can only pair with their one complimentary base.

Question 8

Outline protein synthesis:

Answer 8

mRNA transported out of nucleus.
mRNA transported to ribosome, where translation occurs.
tRNA brings specific amino acids, based on the complimentary anticodon on the tRNA.
Amino acids form peptide bonds - form polypeptide.
Polypeptide processed by golgi apparatus.

Question 9

What substance can be used to release DNA from nuclear envelope?

Answer 9

Detergent, because it works as an emulsifier (Attracts phospholipid molecules) and breaks open the nuclear membranes.

Question 10

True or False: Genetic code overlaps

Answer 10

True

Question 11

Helicase….

Answer 11

Unwinds the DNA molecule and breaks hydrogen bonds between base pairs.

Question 12

DNA polymerase…

Answer 12

Links new nucleotides together in DNA replication.

Question 13

RNA polymerase…

Answer 13

Links mRNA nucleotides in transcription

Question 14

How many nucleotide bases that code for a single amino acid.

Answer 14

3

Question 15

There is a maximum of….. different base combinations.

Answer 15

64

Question 16

Why are not all base combinations used to code for amino acids?

Answer 16

Some amino acids can be made from multiple base combinations.
Some amino acids are stop/start codons.

Question 17

What nucleotide bases are in both DNA and RNA

Answer 17

Adenine, Cyrosil and guanine

Question 18

What nitrogenous base changes between DNA and RNA?

Answer 18

Thymine is replaces with Uracil.

Question 19

Protease digests what proteins.

Answer 19

Histone proteins.

Question 20

DNA is wrapped around what protein?

Answer 20

Histone proteins.

Question 21

Nucleic acids are made from…

Answer 21

nucleotide monomers.

Question 22

Nucleotides consist of…

Answer 22

A phosphate group between pentose molecules. (forms ‘backbone’) and a nitrogenous base

Question 23

What causes the helix shape of DNA?

Answer 23

hydrogen bonding between the two antiparallel strands.

Question 24

Cytoplasmic ribosomes produce proteins for…

Answer 24

intra-cellular use

Question 25

RER ribosomes produce proteins for…

Answer 25

to export elsewhere.

Question 26

What do ribosomes consist of?

Answer 26

Large and small subunits.

Question 27

What are the subunits of ribosomes made from?

Answer 27

Proteins and ribosomal DNA.

Question 28

Where are ribosomes made?

Answer 28

The nucleolus

Question 29

Peptidyl transferase…

Answer 29

Catalyses formation of peptide bonds between amino acids in ribosome.

Question 30

Translation is dependant on…

Answer 30

Complimentary base pairing between codons on mRNA and anticodons on tRNA.

Question 31

Ribosome moves in a…. along the mRNA

Answer 31

5’ to 3’ direction

Question 32

What codon is the start codon?

Answer 32

Methionine (AUG)

Question 33

Which codons contain sulphur?

Answer 33

Methionine and Cysteine

Question 34

What 2 types of RNA bind to the ribosome?

Answer 34

mRNA and tRNA

Question 35

What form of RNA aids the accuracy of translation?

Answer 35

rRNA

Question 36

What phosphorylated nucleotide provides energy?

Answer 36

ATP - Adenosine triphosphate

Question 37

Why is the amino acid sequence important?

Answer 37

Form secondary and tertiary structure.

Question 38

What is the role of the nuclear envelope?

Answer 38

To prevent the DNA form being damaged by the cytoplasm.

Question 39

mRNA is complimentary to the …

Answer 39

template strand, making it a copy of the coding strand.

Question 40

What is the role of mRNA?

Answer 40

TO carry information outside of the nucleus.

Question 41

Where is the amino acid on tRNA

Answer 41

The amino acid is attached to the 3’ end on the ‘attachment site’

Question 42

Initiation of transcription:

Answer 42

RNA polymerase binds to DNA at a promoter.

Question 43

What direction is DNA in trancription?

Answer 43

3’ to 5’ and the RNA ploymerase moves in a 5’ to 3’

Question 44

Protein synthesis Outline:

Answer 44

mRNA formed by transcription of nuclear DNA passes through the pores of the nuclear envelope and attaches to ribosomes fixed to the RER. Specific amino acids are brought the the mRNA by molecules of tRNA which attach to the codons of the mRNA. Adjacent amino acids form peptide bonds, which are catalysed by peptidyl transferase. These assemble into polypeptides in spaces of vesicles of RER or transported to the Golgi Complex for processing

Question 45

Role of rRNA?

Answer 45

Provide structural stability to the protein synthesis sequence and helps to catalyze the reaction.

Question 46

Properties of ATP

Answer 46

small,
water-soluble
easily regenerated
releases energy in small quantities - from bonds between phosphates