DNA + RNA

Question 1

compare DNA and RNA

Answer 1

DNA:
- deoxyribose sugar
- double stranded helix
- adenine, thymine, cytosine, guanine
- stores genetic information

RNA:
- ribose sugar
- single stranded
- adenine, uracil, guanine, cytosine
- transmits + stores genetic information

Question 2

compare mRNA and tRNA

Answer 2

mRNA:
- straight molecule
- longer chain molecule
- chemically unstable

tRNA:
- clover leaf shape
- shorter chain molecule
- chemically stable

Question 3

under a mciroscope, what is the dark material in the nucleus?

Answer 3

• DNA bound to histones

Question 4

under a microscope, why is it not possible to see any distinct chromosomes?

Answer 4

• because the chromosomes have a relatively open structure

at this point dna and histones are referred to as chromatin

Question 5

what is a chromatid?

Answer 5

• one of two identical strands of chromosome copied during cell replication
• attatched at centromere

Question 6

how many chromsomes are found in human cells?

Answer 6

• 46 (23 pairs)
• ## 23 chromsomes form father, 23 chromsomes from mother

Question 7

what are homogulous chromosomes

Answer 7

• a pair of chromosomes
• on inherited from each parent
• contain the same genes at the same loci

Question 8

define ‘gene’

Answer 8

gene= section of DNA which encodes the amino acid sequence of a polypeptide

Question 9

define ‘allele’

Answer 9

allele= version of a gene