nucleic acids Flashcards
explain how pairing of nitrogenous basesd allows identical copies of DNA to be made (3)
- adenine pairs with thymine and cytosine pairs wit guanine because of H bonding
- purine can only bind wth pyramidine because they are diff sizes
- 2 H bonds between A and T and 3 between C and G
why is DNA described as a macromolecule ?
- a molecule of DNA is very large
why is DNA described as a polynucleotide
- polymer made of mady nucleotides
explain how nucleotides are important to cell metabolism other tan being part of nucleic acids (4)
- ATP is a phosphorolated nucleotide in all energy requiring metabollic reactions
- coenzymes all contain nucleotides
- many metabolic processed requaire these coenzymes
- ATP, ADP and AMP help regulate many metabolic pathways
a length of DNA was analysed and 23% of nucleotide bases were adenine. what % of bases were cytosine ? (3)
23% A = 23% T
= 54% C+G
= 27% C
how can simple nucleotide units combine to store genetic info (3)
- nucleotides stored in a specific sequance
- used by cell;ular machinery
- to code for AA’s that make proteins
Is only DNA or only RNA or both, DNA and RNA found in the nucleus and cytoplasm? (1)
Only RNA
Suggest now info obtained by DNA analysis can be useful to taxonomists (2)
- Compare with DNA
- Decide which group organism fits in
Explain why the mRNA molecule is shorter than a DNA molecule (2)
- Only copies 1 section of DNA
- DNA compromises many genes
Explain how amanitin stops the formation of an enzyme-substrate complex during RNA production (2)
• Non complementary inhibitor
• inhibitor fits into all ostrich site
Suggest now AMA nit in may lead to death of an organism (2)
• Inhibits production of mRNA
• prevents protein synthesis
When proteins are heated to a high temp their tertiary structure is disrupted.
Explain now this occurs (3)
• Bonds are overcome + broken
- change un 3D shape of protein
Denatures
Suggest 2 characteristics that researchers should look for when choosing an organism for research into now genes control development (2)
• small
• cheap
Name type of gene, which if mutated gives rise to dramatic changes in body plan (I)
Homeotic
Nice are used by scientists to find out how genes control development in animals,includinghumans. Suggest why info gained from studying such model organisms can be applied to humans. (2)
• Similar genes
- shared ancestor
True or false. Covalent bonds form between phosphate of one and pento se nucleotide sugar of the next nucleotide (1)
True
Describe now the information coded on genes is used to synthesise poly peptides and how these polypeptides control physical development of an organism (8)
- transcription
- complementary base pairing
- translation
. tRNA caries AA’s to ribosomes
• roles of polypeptides: structural - enzymes
•Hormones
• receptor proteins
Explain the use of the 44 remaining amino acid combinations (2)
- Several triplets code for 1 aa
Mutation may not result in change of aa
Fill the gap
The molecule that cables a gene and carries information to a… Is called RNA
Ribosome
Explain why DNA replication is considered to besemi Conservative (2)
• 1 strand from original DNA and one strand newly formed
. One strand acts as a template
Explain why complementary base pairing is important in DNA replication (3)
- DNA can be replicated without error
- Reduces occurrence of mutation
- allows reformation of H bonds
Describe the structural relationship between deoxyribose and other components of the DNA molecule (3)
- bonded to nitrogenous base and phosphate group
- part of backbone of DNA
- part of nucleotide
Suggest how changing sequence of nucleotides can affect final product DNA codes for (3)
• Different sequence of amino acids.
• different protein
• different function
Explain now the structure of DNA allows replication (5)
- Double stranded
• both strands act astemplate
• h-bonds easily break between bases
• complementary base pairing
• purine only binds to pyramiding
