1.5 - Nucleic Acids and Their Functions Flashcards
What is a nucleic acid made of?
Monomers called nucleotides
What is the term for many nucleotides?
Polynucleotide
What are the 3 components of nucleotides?
- phosphate group
- a pentose sugar
- a nitrogenous organic base
How are the compenents of nucleotides combined?
Combined by condensation reactions
What are the 2 types of bases?
Pyrimidine and purine
What is a pryrimidine base?
Single ring thymine cytosine and uracil
What is a purine base?
Double ring adenine and guanine
What are heterotrophic organisms?
Animals that get chemical energy from food
What are autotrophic organisms?
Plants that get chemical energy from light
What is ATP?
Stands for adenosine-triphosphate and is an energy carrier
What is ATP made up of?
Adenine, ribose sugar and 3 phosphate groups
How does ATP distribute energy?
- the enzyme ATPase hydrolyses the bond between the second and third phosphate groups in ATP, removing the 3rd phosphate group, leaving only 2
- turns into ADP (adenosine-diphosphate) and an inorganic phosphate ion, with the release of energy
- its an exergenic reaction releasing 30.6kj when this bond is broken
What are the advantages of having ATP as an energy supplier?
- single reaction that releases energy immediately, unlike glucoses many reactions
- only one enzyme ATPase is needed to break down ATP, whilst glucose has many
- ATP releases energy in small amounts, whilst glucose releases it all at once
- ATP provided energy for a range of reactions, increasing efficiency and control by the cell
What are the 5 roles of ATP?
- metabolic processes
- active transport
- movement
- nerve transmission
- secretion
What is the structure of DNA?
- 2 polynucleotide strands in a double helix
- pentose sugar is deoxyribose
- 4 bases = purine adenine and guanine, pyrimidine cytosine and thymine
- deoxyribose sugar and phosphate group forms backbone
- AT-GC complimentary base pairing (hydrogen bonds)
- DNA is tightly coiled within a chromosome
- the strands are antiparallel (parallel but facing in opposite directions)
Why is DNA suited to its function?
- very stable molecule so information remains unchanged
- large molecule so carries alot of information
- the 2 strands can separate as they are held together by hydrogen bonds
- base pairs are found in the inside, therefore are protected by the sugar-phosphate backbone
What is the structure of RNA?
- single stranded polynucleotide
- pentose sugar ribose
- purine base, adenine and guanine, pyrimidine base cytosine and uracil
What are the 3 types of RNA?
messenger RNA (mRNA)
ribosomal RNA (rRNA)
transfer RNA (tRNA)
What is messenger RNA?
- mRNA is along single stranded molecule
- synthesised in the nucleus
- carries the genetic code from the nucleus to the ribsomes in the cytoplasm
What is ribosomal RNA?
- rRNA is found in the cytoplasm
- large, complex molecules
- ribosomes are made of ribosomal DNA and protein
- they are the site of translation of the genetic code into protein
What is transfer RNA?
- tRNA is a small single stranded molecule
- cloverleaf shape
- molecules of tRNA transport specific amino acids to the ribosomes in protein synthesis
What are the 2 functions of DNA?
- replication
- protein synthesis
What is replication of DNA?
IF 2 strands of a double helix are separated , 2 identical double helixes can be formed, as each parent strand can act as a template for the synthesis of a new complimentary strand
What is protein synthesis in DNA?
The sequences of bases represents the information carried in DNA and determines the sequence of amino acids in proteins
What are the 3 types of DNA replication?
- Conservative replication
- Semi- conservative replication
- Dispersive replication
What is conservative replication?
Where the parental double helix remains intact, and a whole new double helix is made
What is semi-conservative replication?
The double helix separates into 2 strands, each of which acts as a template for synthesis of a new strand
What is dispersive replication?
The 2 new helixes contain fragments from both strands of the parental double helix
What is the genetic code?
- a triplet code
- 3 pairs of bases codes for one amino acid
How many possible amino codes are there?
64 (4 bases cubed)
What in mRNA ends the code?
Codons mark the end of a coding sequence
What is an intron?
Non-coding nucleotide sequence in DNA and pre-mRNA that is removed from pre-mRNa to produce mature mRNA (useless as its just separating code)
What is an exon?
Nucleotide sequence in RNA and pre-mRNA that remains present in the final mature mRNA, after introns have been removed (the important stuff)
What are the 2 stages of protein synthesis?
- transcription
- translation
What is transcription?
One strand of the DNA acts as a template for the production of mRNA, a complimentary part of the DNA sequence. It occurs in the nucleus
What is translation?
The mRNA acts a template to which complementary tRNA molecules attach, and the amino acids they carry are linked to form polypeptide
Occurs in ribosomes in the cytoplasm
