Lesson 20 - Nucleic acids - RNA and DNA structure

Question 1

What do DNA and RNA stand for?

Answer 1

RNA (ribonucleic acid)
DNA (deoxyribonucleic acid)

Question 6

What are nucleotides made of?

Answer 6

• a phosphate
• a pentose sugar (deoxyribose sugar for DNA and ribose sugar for RNA)
• (monosaccharide with 5 carbons)
• a nitrogenous organic base

Question 6

What are nucleic acids?

Answer 6

‘Information carrying’ molecules
Two main types:
RNA (ribonucleic acid)
DNA (deoxyribonucleic acid)
Monomer = nucleotides
Polymer = nucleic acids

Question 7

what 3 bases are pyrimidines?

Answer 7

Cytosine, Thymine and Uracil

Question 7

which 3 bases are purines?

Answer 7

Adenine and Guanine

Question 8

which bond is formed by a condensation reaction between 2 nucleotides?

Answer 8

Phosphodiester bond

Question 9

structure of RNA

Answer 9

• Single stranded polynucleotide chain that is relatively short
• Pentose sugar - ALWAYS Ribose
• Bases - either A, G, C or U

Question 10

types of RNA

Answer 10

messanger RNA
ribosomal RNA
transfer RNA

Question 11

structure of DNA

Answer 11

• A double helix structure - made up of 2 polynucleotide strands
• DNA molecules are extremely long
• Pentose sugar - ALWAYS deoxyribose
• Bases - either A, T, C or G

Question 12

How are the two polynucleotide strands in a DNA molecule held together?

Answer 12

Complementary base pairing between bases (held together by hydrogen bonding). These make antiparallel DNA strands. Bases are held by a sugar phosphate backbone, making a dna ladder. Forms a dna double helix.

Question 13

Which bases pair up?

Answer 13

thymine/uracil with adenine and cytosine with guanine

Question 14

how is DNA adapted for it function?

Answer 14

• It has a very stable structure allowing it to pass from generation to generation without changing, rarely mutates
• Its 2 strands are held together by (weak) hydrogen bonds, allowing the strands to be separated during DNA replication and protein synthesis for the genes to be read (by the breaking of the hydrogen bonds)
• Extremely large molecule - can carry a huge amount genetic information
• The function of the gene/ protein made from that gene depends on the base sequence
  Complementary base pairs means the DNA is replicated ACCURATELY

Question 15

why is dna a very stable molecule?

Answer 15

• The sugar phosphate backbone (held together by phosphodiester bonds) protects the bases (the genetic code) inside the double helix (which carries the genetic code)
• Many hydrogen bonds are strong together

Question 16

what is the nucleus

Answer 16

Nucleus - the large, membrane-bounded organelle that contains the genetic material, in the form of multiple linear DNA molecules organized into structures called chromosomes.

Question 17

what is a chromosome

Answer 17

Chromosome - a structure found in the nucleus that consists of a single molecule of DNA bonded to proteins called histones (together these make chromatin). Chromosomes carry the genetic information in the form of genes.

Question 18

what is dna

Answer 18

DNA - Carries the genetic information. The hereditary material responsible for passing genetic information from cell to cell and therefore, generation to generation.