Molecular Inheritance

Question 1

Bacteriophages (phages)

Answer 1

Viruses that specifically infect bacteria; store genetic information in their protein head and inject it into host cells

Question 2

Viruses

Answer 2

Non-living infectious particaled made of genetical material (DNA or RNA)

Question 3

Chargaff’s rules

Answer 3

Discovered that adenine (A) always pairs with Thymine, and cytosine always pair with guanine, A+G = Purine, T+C = pyrimidines

Question 4

Double Helix

Answer 4

The twisted-ladder structure of DNA formed by two complementary strands, base pairs form the “rungs,” and the sugar-phasephate backbone forms the “sides.”

Question 5

DNA Replication

Answer 5

The process of copying DNA to produce identical genetic material for new cells.

Question 6

Anti-parallel

Answer 6

The two DNA strands run in opposite directions (one 5’ –> 3’, and the other 3’–>5’) this arrangement is key for replication and base pairing

Question 7

Semi-Conservative

Answer 7

Each new DNA molecule has one old (parental) strand, and one new strand

Question 8

Conservative

Answer 8

The original DNA molecule is completely conserved, and an entirely new molecule is made

Question 9

Dispersive

Answer 9

Each strand is a random mix of old and new DNA segments (this model was later disproven)

Question 10

Origins of Replication

Answer 10

Specifc DNA sequences where replication begins, proteins recognkize these sites and open up the DNA to start copying

Question 11

Replication Fork

Answer 11

The Y-shaped region where the double helix is unwound so replication can occur.

Question 12

Helicase

Answer 12

The enzyme that unwinds and separates the two DNA strands at the replication fork.

Question 13

Single-Stranded Binding Proteins (ssts)

Answer 13

Bind to separate strands to prevent them from repairing or folding back on themselves

Question 14

Topoisomerase

Answer 14

Enzyme that relives strain and prevents DNA form over twisting (supercoiling) ahead of the replication fork

Question 15

DNA Polymerase III

Answer 15

The main enzyme that adds new nucleotides to the growing DNA strand in the 5’3 direction

Question 16

DNA Polymerase I

Answer 16

Removes RNA primes and replaces them with DNA nucleotides; also repairs errors

Question 17

Primer

Answer 17

The short RNA segment made by primase; necessary for DNA synthesis to begin

Question 18

Primase

Answer 18

Synthesizes short RNA primes that provide a starting point for DNA polymerase

Question 19

Leading Strand

Answer 19

The strand of DNA synthesized continuously in the 5’3 direction toward the fork.

Question 20

Lagging Strand

Answer 20

The strand synthesized discontinuously in short fragments (Okazaki fragments) away from the fork in the 5’3

Question 21

Okazaki Fragments

Answer 21

Short DNA segments formed on the lagging strand; named after the Okazakis who discovered them

Question 22

DNA ligase

Answer 22

Enzymes that join Okazaki fragments and seals breaks in the sugar-phosphate backbone

Question 23

Mismatch Repair

Answer 23

Corrects incorrectly paired nucleotides after replication

Question 24

Nucleotide Excision Repair

Answer 24

Damaged DNA sections are cut out and replaced using the undamaged strand as a template

Question 25

Nuclease

Answer 25

The enzyme that cuts out damaged or mismatched DNA segments during repair

Question 26

Telomere

Answer 26

The protective end region of chromosomes made of repetitive DNA sequences

Question 27

Telomerase

Answer 27

An enzyme that extends telomeres, preventing chromosome shortening (active in stem and cancer cells)

Question 28

Euchromatin

Answer 28

Loosely packed chromatin, DNA here is active and accessible for transcription

Question 29

Heterochromatin

Answer 29

Tightly packed chromatin; DNA here is inactive and not easily transcribed.