DNA

Question 1

Describe how DNA is stored in Eukaryotes

Answer 1

Long
linear
associated with proteins called histones
tightly coiled into chromosomes

Question 2

How is DNA stored in Prokaryotes

Answer 2

Short
circular
not associated with
proteins/histones

Note:mitochondria and chloroplast are similar to prokaryotes

Question 3

Describe the molecular structure of DNA

Answer 3

Long polymer of nucleotides;

composition of a nucleotide (pentose sugar, phosphate and N containing base)

4 bases named (A, T, C and G) (Uracil (U) is a base in RNA that replaces T), A, G are purine bases (2 ring structure) T, C and U are pyrimidine bases (single ring structures)

sugar-phosphate ‘backbone’;

two (polynucleotide) strands;

specific base-pairing

hydrogen bonding between bases

Question 4

Describe two features of DNA which make it a stable molecule.

Answer 4

Two strands with specific base pairing

large number of hydrogen bonds (between strands);

helix/coiling reduces chance of molecular damage / protects H
bonds;

strong sugar-phosphate backbone;

Question 5

Explain how the structure of DNA is related to its function.

Answer 5

-sugar - phosphate backbone gives strength (phosphodiester bonds)
-(coiling gives) compact shape;
-sequence of bases allows information to be stored;
-long molecule stores large amount of information;
-information can be replicated/complementary base pairing;
-double helix protect weak hydrogen bonds prevents code being corrupted;
-chains held together by weak hydrogen bonds;
-chains can split for replication / transcription
-Complementary base pairing enables information to be replicated/transcribed
-Many hydrogen bonds together give molecule stability;
-Hydrogen bonding allows chains to split for replication/transcription