3.4.1-DNA,genes And Chromosomes

Question 1

What is the difference between the DNA in a prokaryotic cell and a eukaryotic cell?

Answer 1

In prokaryotic DNA molecules are short,circular and not associated with proteins
In the nucleus of eukaryotic cells DNA molecules are very long, linear and associated with histones

Question 2

Other than the nucleus where else in a eukaryotic cell is DNA found?

Answer 2

Mitochondria and chloroplasts-The DNA is short,circular and not associated with proteins

Question 3

What is a gene?

Answer 3

A base sequence of DNA that codes for:
-the amino acid sequence of a polypeptide
-a functional RNA

Genes occupy a fixed position called a locus on a particular DNA molecule

Question 4

What is a triplet?

Answer 4

A sequence of 3 DNA bases that codes for a specific amino acid

Question 5

What is the genetic code?

Answer 5

Degenerate-More than one triplet can code for the same amino acid
Universal-The same triplet codes for the same amino acid in almost all living things
Non overlapping-Each base is only part of one triplet

Question 6

Define non-coding base sequences and describe where the non-coding multiple repeats are positioned in the genome

Answer 6

DNA that does not code for sequences of amino acids positioned between genes

Question 7

What is a codon?

Answer 7

Three bases on mRNA that code for amino acid

Question 8

What is an allele?

Answer 8

An alternative form of a gene

Question 9

Explain how the considerable length of a DNA molecule is compacted into a chromosome

Answer 9

The double helix is tightly coiled around histone proteins

Question 10

What is the function of a histone protein?

Answer 10

to assist in the tightly coiling of DNA to fit chromosomes into the nucleus