Transformation Lab

Question 1

Frederick Griffith

Answer 1

studied strains of pneumonia in mice (S) Smooth Strain, (R) Rough Strain

Question 2

Alfred Hershey, Martha Chase

Answer 2

studies showing that DNA is the genetic material of phage known as T2

Question 3

Edwin Chargaff

Answer 3

analyzed base (ATCG) to prove DNA is the genetic material

Question 4

Rosalind Franklin

Answer 4

Took photo 51, showing the double helix, a discovery that was essential in unlocking the mystery of how life is passed down from generation to generation.

Question 5

Structure of DNA

Answer 5

AT CG sugar attached to phosphate group through covalent bonds. Hydrogen bonds (weak) connect the two nitrogenous bases together

Question 6

Semi-conservative

Answer 6

after one round of replication, every new DNA double helix would be a hybrid that consisted of one strand of old DNA bound to one strand of newly synthesized DNA.

Question 7

Process of DNA replication

Answer 7

1) DNA double helix
2) Hydrogen bonds break and the helix opens
3) Each strand of DNA acts as a template for the synthesis of a new, complementary strand
4) Replication produces two identical DNA double helicases, each with one old and one new strand

Question 8

Leading and Lagging

Answer 8

During DNA replication, one new strand (the leading strand) is made as a continuous piece. The other (the lagging strand) is made in small pieces.

Question 9

5’ and 3’ carbon ends

Answer 9

For instance, if you know that the sequence of one strand is 5’-AATTGGCC-3’, the complementary strand must have the sequence 3’-TTAACCGG-5’. This allows each base to match up with its partner:

DNA polymerase only synthesizes DNA in the 5’ to 3’ direction only

5’ ends with the phosphate, and 3’ ends with the deoxyribose sugar.

Question 10

Helicase

Answer 10

untwists and separates strands

Question 11

single strand binding proteins

Answer 11

holds DNA strands apart

Question 12

primase

Answer 12

enzymes whose continual activity is required at the DNA replication fork

Question 13

DNA polymerase

Answer 13

adds DNA nucleotides to new strand

Question 14

DNA ligase

Answer 14

joins DNA fragments together

If two pieces of DNA have matching ends, ligase can link them to form a single, unbroken molecule of DNA

Question 15

DNA pol 1

Answer 15

removes RNA primer and replaces with DNA

Question 16

Okazaki fragments

Answer 16

segments of lagging strand

Question 17

Gel electrophoresis

Answer 17

a technique used to separate DNA fragments according to their size

Question 18

DNA primer

Answer 18

a short nucleic acid sequence that provides a starting point for DNA synthesis

Question 19

Mismatch repair enzymes

Answer 19

detect distortions caused by mismatched bases inserted during DNA synthesis

Question 20

nuclease in DNA proofreading and repair

Answer 20

A nuclease enzyme cuts the damaged DNA strand at two points and the damaged section is removed. Repair synthesis by a DNA polymerase fills in the missing nucleotides. DNA ligase seals the Free end of the new DNA To the old DNA, making the strand complete.

Question 21

telomeres

Answer 21

A telomere is a region of repetitive DNA sequences at the end of a chromosome. Telomeres protect the ends of chromosomes from becoming frayed or tangled. Each time a cell divides, the telomeres become slightly shorter. Eventually, they become so short that the cell can no longer divide successfully, and the cell dies.

Question 22

significance of telomeres in regular and cancerous cells

Answer 22

Dont contain genes; DNA typically consists of multiple repetitions of one short nucleotide sequence

Question 23

Distinguish between heterochromatin and euchromatin.

Answer 23

More condensed, non-transcribed = heterochromatin
Less condensed, transcribed = euchromatin

Question 24

Describe how the packing of chromatin changes during the course of the cell cycle

Answer 24

In interphase, the chromatin is highly extended. Preparing for mitosis, the chromatin coils or condenses and forms chromosomes in metaphase.

Question 25

Topoisomerase

Answer 25

relieves strain caused by unwinding