Introduction Flashcards
In humans, like in other organisms, ____ is the carrier of genetic information and has a structure that is ideally suited to this function.
nucleic acid
There are 2 main types of nucleic acid,
_____ and _____, w/c each consist of a sugar – phosphate backbone w/ projecting nitrogenous bases.
DNA (deoxyribonucleic acid); RNA (ribonucleic acid)
There are 2 main types of nucleic acid,
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), w/c each consist of a _____ w/ projecting _____.
sugar – phosphate backbone; nitrogenous bases
The nitrogenous bases are of 2 types, _____ & _____. In DNA, there are 2 purine bases, ____, and 2 pyrimidine bases, _____.
purines; pyrimidines; adenine (A) and guanine (G); thymine (T) and cytosine (C)
RNA also contains A, G and C, but contains ____ (U) in place of T. In DNA, the sugar is _____, whereas in RNA it is _____.
uracil; deoxyribose; ribose
The nitrogenous bases are attached to the _____ position of each sugar, & the phosphate links _____ of two succeeding nucleotide.
1 ′ (one prime); 3 ′ and 5 ′ hydroxyl groups.
Each unit of purine or pyrimidine base together w/ the attached sugar and phosphate group(s) is called a ______.
nucleotide
A molecule of DNA is composed of 2 nucleotide chains, w/c are coiled _____ around one another to form a _____ with _____ nucleotides per complete turn of DNA
clockwise; double helix; 10 nucleotides
The 2 chains run in opposite directions (i.e. 5 ′ to 3 ′ for one and 3 ′ to 5 ′ for the other) & are held together by _____ between A in one chain and T in the other or between G & C.
hydrogen bonds
DNA/RNA base pairing is very specific, although rarely erroneous combinations may occur. As A:T & G:C pairing is obligatory, the parallel strands must be _____ to one another.
complementary
The ratio of A to T is 1:1 and of G to C is likewise 1:1. This is also called the _____.
Chargaff ’ s rule
Wide variation exists in the AT:GC ratio. Higher plants & animals tend to have an excess of ____ & in humans the ratio is _____.
A + T ; 1:4:1
The unit of length of DNA is the _____ w/ 1000 bp in a _____ & 1,000,000 bp in a ______.
base pair (bp); kilobase (kb); megabase (Mb)
The total length of DNA in a half (haploid) set of human chromosomes is approximately _____ &, as the distance between base pairs in the DNA helix is _____. The total length of haploid DNA if extended, per cell, would be 1 m.
3280 Mb (3.28 × 10^9 bp); 0.34 nm; 1 m
Each protein - coding gene usually possesses only _____ in the haploid genome but with well - known exceptions being the _____ genes, and the average gene size is _____ with an average intergenic distance of _____.
one copy; α - globin genes, histone genes and ubiquitin genes; 53.6 kb; 60 – 70 kb