Lecture 6: Microbial Genetics

Question 1

A ____ is the basic unit of heredity. It is the segments of DNA (RNA for some viruses) that code for functional products (proteins, RNAs). It is DNA sequences that are required to produce a polypeptide chain.

Answer 1

Gene

Question 2

____ is the macromolecule composed of repeating units called nucleotides.

Answer 2

DNA

Question 3

DNA is composed of: (3)

Answer 3

Nitrogenous Base
Deoxyribose
Phosphate Group

Question 4

A ____ is a sequence of DNA or RNA that codes for a molecule that has a function. The transmission of genes to an organism’s offspring is the basis of the inheritance of phenotypic traits.

Answer 4

Gene

Question 5

____ is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning of all known living organisms.

Answer 5

DNA

Question 6

The primary structure of DNA: (3)

Answer 6

1. a string of nucleotides joined together by phosphodiester linkages
2. a macromolecule
3. a deoxyribonucleoside 5-monophosphate

Question 7

The secondary structure of DNA: (3)

Answer 7

1. a three-dimensional configuration of DNA
2. a double helical structure
3. two polynucleotide strands wound around each other

Question 8

The two long polynucleotide chains of DNA are coiled around a central axis, forming a _____.

Answer 8

right-handed double helix

Question 9

The two chains of DNA run in an _____ direction.

Answer 9

antiparallel

Question 10

Two molecular forces that hold the two strands of DNA together: (2)

Answer 10

1. Hydrogen Bonds
2. Hydrophobic interactions between stacked base pairs.

Question 11

How are prokaryotic chromosomes different from eukaryotic chromosomes? (5)

Answer 11

1. found in the cytoplasm
2. circular
3. single chromosome plus a plasmid
4. made up of only DNA
5. copy their chromosomes and divide them immediately

Question 12

How are eukaryotic chromosomes different from prokaryotic chromosomes? (5)

Answer 12

1. found in the nucleus
2. linear
3. many chromosomes, usually 10-50 chromosomes in somatic cells
4. made up of DNA and histone proteins
5. copy their chromosomes, grow cells, and divide them equally through mitosis

Question 13

Bacteria typically have a ____ chromosome, consisting of a single circular molecule of DNA with associated proteins.

Answer 13

single, circular

Question 14

Chromosomes of bacteria are ____ and ____ and attached to one or several points to the plasma membrane.

Answer 14

looped and folded

Question 15

The DNA of E. coli has about _____ base pairs and is ____ long– 1000 times longer than the entire cell.

Answer 15

4.6 million; 1mm

Question 16

Chromosomes only take up about ___ of a cell’s volume because the DNA is ____.

Answer 16

10&; twisted, or supercoiled