DNA & RNA

Question 1

What are the components of DNA?

Answer 1

DNA is composed of nucleotides consisting of 3 components: a phosphate (attached at carbon 5), a 5 carbon pentose sugar ring (deoxyribose), and a nitrogenous base (attached at carbon 1)

Question 2

Which bases are purines?

Answer 2

Adenine

Guanine

Question 3

Which bases are pyrimidines?

Answer 3

Cytosine
Thymine (in DNA)
Uracil (in RNA)

Question 4

What is the difference between purine and pyrimidine bases?

Answer 4

Purines have 2 rings

Pyrimidines have 1 ring

Question 5

What are the base pairs?

Answer 5

Adenine and thymine or uracil (2 hydrogen bonds)

Cytosine and guanine (3 hydrogen bonds)

Question 6

What are the differences between DNA and RNA?

Answer 6

Thymine base in DNA, uracil base in RNA
The sugar in is deoxyribose in DNA (missing a OH group on carbon 2) , Ribose in RNA
DNA is a double helix. RNA is a single helix
DNA is only found in the nucleus

Question 7

What is the structure of DNA backbone?

Answer 7

The backbone is covalent bonds between deoxyribose and phosphate. DNA strands run antiparallel to each other. Each strand runs from 3 prime carbon to 5 prime carbon. The 3 prime carbon forms a covalent bond to the neighbouring phosphate which is attached to the 5 prime carbon on the adjacent nucleotide

Question 8

What is transcription and where does it occur?

Answer 8

Formation of a section of messenger RNA from DNA. It occurs in the Nucleus

Question 9

What is translation and where does it occur?

Answer 9

The formation of proteins from messenger RNA, in the cytoplasm

Question 10

What does RNA polymerase do?

Answer 10

Makes messenger RNA from DNA

Question 11

What are introns?

Answer 11

Long sections of DNA that do not code for protein- these are spliced out of mRNA before translation

Question 12

What are exons?

Answer 12

Coding areas of DNA for the protein that the gene encodes

Question 13

What is a codon?

Answer 13

Codons are part of the genetic code. They are made of RNA. They consist of 3 nucleotides and code for specific amino acids that form part of a specific protein. They are degenerate (more than one codon can code for the same amino acid but no codon can code for more than 1 amino acid)

Question 14

How many possible codons are there?

Answer 14

64

Question 15

What is transfer RNA?

Answer 15

Transfer RNA transfers amino acids to ribosomes so that proteins can be made during translation from the code in messenger RNA

Question 16

What is an anti-codon?

Answer 16

It is the code on transfer RNA that attaches to the codon on messenger RNA in ribosomes during translation to make sure the right amino acid is joined in the polypeptide chain

Question 17

What does DNA helicase do?

Answer 17

Unwind the double DNA strand so that it can be replicated (copied)

Question 18

What does DNA polymerase do?

Answer 18

Joins DNA nucleotides together during replication to form a new replicate DNA strand

Question 19

How are chromosomes best visualised?

Answer 19

Chromosomes are best visualised in metaphase of mitosis. Giesma staining is used to identify them by a process called G-banding