key area 1.1 - structure of DNA Flashcards
1
Q
what is the function of DNA
A
- DNA is a substance that encodes the genetic information of heredity in a chemical language
2
Q
describe the structure of DNA
A
- DNA is a very long double stranded molecule in the shape of a double helix
- each strand is made up of chemical units called nucleotides
3
Q
name the 3 parts of a nucleotide
A
- a deoxyribose sugar
- a phosphate
- a base
4
Q
what is the sugar phosphate backbone
A
- nucleotides are linked together to make a long strand of DNA
- the deoxyribose sugar of one nucleotide is linked to the phosphate of the next nucleotide to form a sugar phosphate bond
5
Q
how are the two strands of DNA linked
A
hydrogen bonds
6
Q
complementary base pairing rule
A
- the base adenine always pairs with thymine
- the base guanine always pairs with cytosine
7
Q
3’ end and 5’ end
A
- refers to the direction of a DNA strand
- deoxyribose is at the 3’ end and phosphate is at the 5’ end
- nucleotides can be added to 3’ end only
8
Q
what is meant by anti parallel
A
- the strands run in opposite directions to each other
9
Q
prokaryotic cells
A
- cells such as bacteria with no discrete nucleus
- DNA organised into circular chromosomes and plasmids
10
Q
eukaryotic cells
A
- contain a nucleus
- DNA is tightly coiled into linear chromosomes
- the chromosomes are wrapped around proteins called histones to stop strands getting tangled
- also contain circular chromosomes in their mitochondria and also in chloroplasts of green plants
11
Q
why are yeasts special eukaryotes
A
- it also contains plasmids in the cytoplasm
12
Q
what is a plasmid
A
- circular loop is genetic material found in prokaryotic cells and yeasts
