Lesson 20 - Nucleic acids - RNA and DNA structure Flashcards
What do DNA and RNA stand for?
RNA (ribonucleic acid)
DNA (deoxyribonucleic acid)
What are nucleotides made of?
- a phosphate
- a pentose sugar (deoxyribose sugar for DNA and ribose sugar for RNA)
- (monosaccharide with 5 carbons)
- a nitrogenous organic base
What are nucleic acids?
‘Information carrying’ molecules
Two main types:
RNA (ribonucleic acid)
DNA (deoxyribonucleic acid)
Monomer = nucleotides
Polymer = nucleic acids
what 3 bases are pyrimidines?
Cytosine, Thymine and Uracil
which 3 bases are purines?
Adenine and Guanine
which bond is formed by a condensation reaction between 2 nucleotides?
Phosphodiester bond
structure of RNA
- Single stranded polynucleotide chain that is relatively short
- Pentose sugar - ALWAYS Ribose
- Bases - either A, G, C or U
types of RNA
messanger RNA
ribosomal RNA
transfer RNA
structure of DNA
- 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
How are the two polynucleotide strands in a DNA molecule held together?
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.
Which bases pair up?
thymine/uracil with adenine and cytosine with guanine
how is DNA adapted for it function?
- 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
why is dna a very stable molecule?
- 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
what is the nucleus
Nucleus - the large, membrane-bounded organelle that contains the genetic material, in the form of multiple linear DNA molecules organized into structures called chromosomes.
what is a chromosome
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.
what is dna
DNA - Carries the genetic information. The hereditary material responsible for passing genetic information from cell to cell and therefore, generation to generation.
