Chapter 16 - The Molecular Basis of Inheritance

Question 1

thomas hunt morgan

Answer 1

(1910)
genes are on the chromosome (chromosome = DNA + protein)

Question 2

frederick griffith

Answer 2

(1928)
he discovered that it is a heritable factor that can “transform” bacteria (he did the mouse and S/R cells experiment)

Question 3

oswald avery, colin macleod, & maclyn mccarty

Answer 3

(1944)
discovered that the “transforming” agent is DNA

Question 4

what is a bacteriophage? what is it made of?

Answer 4

also known as “phage” is a duplodnaviria virus that is made of protein and DNA

a virus that parasitizes a bacterium by infecting it and reproducing inside it

a virus that infects bacteria

Question 5

alfred hershey & martha chase

Answer 5

(1952)
DNA, not protein, is the genetic material of bacteriophages

Question 6

erwin chargaff

Answer 6

(1952)
base composition varies between species
(base composition = proportions of the 4 nucleotides/bases, could be percentages)

found that in DNA, the ratios of adenine (A) to thymine (T) and guanine (G) to cytosine (C) are equal

Question 7

rosalind franklin & maurice wilkins

Answer 7

(1952)
they found out from an X-ray diffraction photo of DNA that the DNA is a double helix (2 strands rather than 1)

DNA => uniform diameter, base-spacing
=> phosphates are on the outer part of the DNA while bases are on the inner part

Question 8

james watson & francis crick

Answer 8

based on rosalind franklin and wilkin’s data they concurred that A is attached to T and G is attached to C

Adenine = Thymine
Guanine = Cytosine

Question 9

what are the 3 key features of DNA?

Answer 9

1.) anti-parallel strands
(strand C: 3’ => 5’)
(strand W: 5’ => 3’)

2.) sugar phosphate “backbones”

3.) bases “glue” strands together with H-bonds

Question 10

does DNA start at 3’ or 5’ end?

Answer 10

starts at 5’ end, 5’ end to 3’ end

Question 11

what are the 3 possible models for DNA replication?

Answer 11

(look in notes for a picture)

1.) conservative = parents re-associate

2.) semi-conservative model (most accurate model of what actually happens) = parents serve as templates
=> produces hybrids; 1 parent, 1 new

3.) dispersive = each product strand is a mix of parent & new hybrid

Question 12

matthew meselson & franklin stahl

Answer 12

(1958)
determined that the semiconservative model was most accurate

Question 13

parent molecule

Answer 13

2 strands

Question 14

new strand synthesis

Answer 14

nucleotides line up along the template according to base-pairing rule

Question 15

DNA polymerase

Answer 15

type of enzyme that is responsible for forming new copies of DNA, in the form of nucleic acid molecules

adds nucleotides to a strand based on a template

Question 16

what are the limitations of DNA polymerase?

Answer 16

1.) cannot open double-stranded DNA (needs helicase to open it)
2.) cannot keep single-stranded DNA (needs single-stranded binding protein to stabilize the single-strand DNA)
3.) requires existing strand to extend (needs primase to attach onto template so it can attach onto primase and continue its job)

Question 17

true or false: several proteins help prepare template strands for replication

Answer 17

true

Question 18

helicase

Answer 18

(enzyme, protein)
unwinds parental double helix at replication fork

Question 19

single-stranded binding proteins

Answer 19

stabilize parental strands, preventing re-annealing (renaturation of a DNA sample that has been dissociated by heating)

binds to and stabilizes single-stranded DNA until it is used as a template

Question 20

re-annealing

Answer 20

renaturation of a DNA sample that has been dissociated by heating

Question 21

topoisomerase

Answer 21

relieves strain caused by strand unwinding by breaking, swiveling, & rejoining DNA strands

Question 22

primase

Answer 22

synthesizes RNA primer at 5’ end of leading strand and at 5’ end of Okazaki fragment of lagging strand

Question 23

leading strand of DNA

Answer 23

continuous strand

Question 24

lagging strand of DNA

Answer 24

discontinuous strand (in fragments) and literally lagging behind the leading strand

synthesized away from the replication fork (DNA polymerase III)

series of segments called Okazaki fragments

Question 25

DNA pol I

Answer 25

replaces RNA primers with DNA essentially

takes out RNA primers, reads DNA, and adds in complementary DNA sequence

removes RNA nucleotides of primer from 5’ end and replaces them with DNA nucleotides

Question 26

lagging strand of DNA

Answer 26

discontinuous strand (in fragments) and literally lagging behind the leading strand

Question 27

Okazaki fragments

Answer 27

(during replication of DNA)
short sections of DNA formed at the time of discontinuous synthesis of the lagging strand

Question 28

DNA pol III

Answer 28

using parental DNA as a template

synthesizes new DNA strand by adding nucleotides to an RNA primer or a pre-existing DNA strand

Question 29

DNA pol I

Answer 29

removes RNA nucleotides of primer from 5’ end and replaces them with DNA nucleotides

Question 30

DNA ligase

Answer 30

seals gaps

joins Okazaki fragments of lagging strand

joins 3’ end of DNA that replaces primer to the rest of leading strand DNA

Question 31

telomeres

Answer 31

non-protein coding repetitive sequence found at the ends of the chromosome

it acts as a buffer to protect protein coding genes

shortens with each replication

Question 32

linear DNA starts shortening during replication

Answer 32

true

Question 33

telomerase

Answer 33

protein-RNA complex, DNA synthesis (RNA-directed)

serves as a template for extending the 3’ end of the telomere

Question 34

central dogma

Answer 34

a theory stating that genetic information flows only in one direction, from DNA to RNA to protein or RNA directly to protein

DNA => RNA => protein

RNA => protein

Question 35

what are the main differences between DNA and RNA?

Answer 35

DNA
function: contains genetic information/instructions needed for organisms to develop, survive, and reproduce
location: nucleus
sugar: deoxyribose
length: several million base pairs (ATGC)
replication: self-replicating
strand: double-stranded

RNA
function: creates proteins via translation
location: nucleolus => cytoplasm
sugar: ribose
length: several thousand base pairs (AUGC)
replication: synthesized by transcription
strand: single-stranded

Question 36

what is the relation between DNA and RNA?

Answer 36

RNA carries the information from the DNA and transforms that information into proteins that perform most cellular functions

DNA => RNA = makes proteins