SB3ci - DNA

how are chromosomes formed?

very long molecules of DNA are tightly coiled and packed up with proteins

what is the structure of DNA?

double helix

what does a molecule of DNA contain to form a helix?

two strands

what joins together the two strands to form a double helix?

pairs of substances called bases

what are the four bases in DNA?

adenine(A), thymine(T), cytosine(C) and guanine(G)

what always pairs with A?

T

what always pairs with C?

G

what are the matching bases called?

complementary base pairs

what is each base attached to?

a sugar

what is each sugar attached to?

a phosphate group

what is the sugar called?

deoxyribose

what is a nucleotide?

the grouping of a nitrogenous base(A/T/C/G), a carbon sugar and a phosphate

what forms the backbone of the DNA strands?

the sugars and phosphate groups

why is DNA a polymer?

because it is made of many similar units joined together in a long chain

Not a question but here is the structure of DNA as an image, hopefully if this comes up enough something will stick. This means you actually have to look thoroughly at it. Every single time. (answer = structure of DNA)

structure of DNA

what do parts of DNA have?

very slight electrical charges

what is an hydrogen bond?

a weak force of atraction

how do hydrogen bonds form?

a slightly negatively charged part of one base attracts a slightly positively charged part of another base

how many hydrogen bonds do adenine(A) and thymine(T) form?

2

how many hydrogen bonds do cytosine and guanine form?

3

what does the order of bases in a gene contain?

coded instructions for a protein

what does slightly different genes in each human (excluding identical twins) allow?

scientists to match DNA from cells to specific people

how can scientists find out if/how are people related?

by analysing DNA as it is passed down through families