structure of nucleic acids

What do nucleotide consist of?

• pentose sugar

• phosphate

• nitrogenous base

What is the sugar and base in DNA?

• sugar - deoxyribose

• base - adenine, thymine, guanine or cytosine

What is the sugar and base in RNA?

• sugar - ribose

• base - adenine, uracil, guanine, cytosine

What is the sugar and base in ATP?

• sugar - ribose

• base - adenine and 3 phosphate groups

How is ATP formed?

• endergonic reaction ( reaction that uses energy)

• ADP + phosphate

Where does the energy to form the bonds come from?

• exergonic reaction (energy releasing) reactions - condensation

What enzyme catalyses an exergonic reaction in ATP?

• ATP synthetase

Advantages of ATP?

• small and soluble

• easily be transported into cells - can be synthesised when energy is available - converts energy into single usable form

Why is ATP a universal energy currency?

• provides energy to ask reactions in cells in all species

explain how ATP is formed and released.

• energy is released when ATP is broken down to ADP and phosphate and this is an exergonic reaction: this is linked to energy requiring reactions eg. active transport, muscle contraction, synthesis of organic molecules.

• energy is require to combine ADP and phosphate to form ATP and this is an energetic reaction, organisms use the energy stored in food ( released by respiration) or light energy too form ATP from ADP

What are the two main categories of base in nucleic acids?

• purines

• pyrimidines

What are the purine bases?

• guanine and adenine - double ring in structure

What are pyrimidines bases?

• thymine, cytosine, uracil - single ring

How are guanine and cytosine linked?

3 hydrogen bonds

How are adenine and thymine linked?

2 hydrogen bonds

What are the two functions of DNA in cells?

• carrying instructions for protein synthesis in all living cells

• replicating prior to cell division so that each daughter cell gets equal DNA

Describe DNA structure

• 2 complimentary polynucleotide strand - polynucleotide is a polymer of nucleotides

• held in double helix via hydrogen bonds

• sugar phosphate molecules are joined by condensation reactions, making phosphodiester linkage

• sugar phosphate molecules form two sugar phosphate backbones

• strands of DNA run antiparallel to each other

What are exons?

regions that code for proteins

What are introns?

regions of non-coding DNA

Is RNA single stranded or double stranded?

single stranded polynucleotide

What are the three types of RNA?

• rRNA

• tRNA

• mRNA

Describe the structure of rRNA.

• found in nucleolus - component of ribosomes

• single polynucleotide strand - folded - globular structure

Describe the structure of mRNA.

• single stranded - made in nucleus

• helix shape

How is mRNA manufactured?

• complimentary base pairs of of RNA base pairs using strands of DNA as a template - 3 base codes for 1 amino acid

• T replaced by U

What are the 3 bases called in mRNA?

codons

What is mRNA function?

carries code from DNA in the nucleus out o the nuclear pore and into the cytoplasm where the mRNA attaches to ribosome

Describe the structure of tRNA.

• single stranded polynucleotide - clover leaf shape

What is the function of tRNA?

• carried amino acids to mRNA and ribosomes for it to create a protein

how is the type of amino acid carried determined in tRNA?

• anticodon - sequence of three unpaired bases on middle leave of clover shape - complimentary to codons

Why are anticodons complimentary to codons in tRNA ?

to ensure that amino acids lined up in the correct order for the primary structure of protein