Chromosomes, Genes And DNA

Question 1

Genes

Answer 1

Have a specific chromosomal location - same position in everyone
Humans have about 25,000 genes

Question 2

Human Genome

Answer 2

The entire DNA sequence

22 autosomes plus 2 sex chromosomes (X and Y)

Question 3

Nucleoside

Answer 3

Base and sugar

Question 4

Nucleotide

Answer 4

Base and sugar and phosphate

Question 5

RNA

Answer 5

Ribose sugar has 2 -OH groups
Contains uracil instead of thymine
mRNA, tRNA, rRNA

Question 6

DNA

from 5’ to 3’ is L to R

Answer 6

2-deoxyribose contains one less -OH 
Contains thymine instead of uracil 
Anti-parallel strands 
Right Handed Double Helix 
Minor groove is more flexible than the major group 
5'Phosphate 
3'OH

Question 7

Nitrogenous bases

Answer 7

Purines (2 ring structure) - Adenine and Guanine
Pyrimidines (1 ring structure) - thymine and cytosine
A to T (U in RNA) double bond
G to C triple bond

Question 8

DNA packaging

Answer 8

Nucleosome - DNA and histone core
Beads on a string - loosely packed - EUCHROMATIN - genes expressed (lighter staining)
Solenoid (30nm fibre) - densely packed - HETEROCHROMATIN - genes not expressed (darker staining)