Molecular Basis of Inheritance Flashcards Preview

BIOL-L 112 Exam 3 > Molecular Basis of Inheritance > Flashcards

Flashcards in Molecular Basis of Inheritance Deck (67)
Loading flashcards...
1

What technique was used to study molecular structure?

X-Ray Crystalography

2

Franklin's X-Ray Crystallographic images of DNA enabled Watson to deduce that DNA was

helical

3

X-Ray images also enabled Watson to deduce the

width of the helix and the spacing of the nitrogenous bases

4

Pattern in the photo suggested that the DNA molecule was made up of _____ , forming a ______

Two Strands
Double Helix

5

Watson and Crick built models of a double helix to conform to the _____ and _____ of DNA

X-Rays
Chemistry

6

Franklin had concluded that there were two outer ______, with the Nitrogenous ______

Sugar-Phosphate backbones
Nitrogenous bases paired in the molecule's interior

7

Watson built a model in which the backbones were ____

antiparallel (their subunits run in opposite directions)

8

Pairing a ___ with a ____ resulted in a uniform width consistent with the X-Ray Data

Purine
Pyrimidine

9

Purine + Purine =

Too wide

10

Pyrimidine + Pyrimidine =

Too Narrow

11

DNA Base Parings

Adenine - Thymine
Guanine - Cytosine

12

Watson - Crick Model explains

Chargaff's Rules

13

Chargaffs Rules

In any organism, the amount of A=T will be equal to the amount of G=C

14

Since the two strands of DNA are complementary, ____

each strand acts as a template for building a new strand in replication

15

In DNA replication, the parent molecule unwinds, and two new daughter strands are built based on ____

base-pairing rules

16

Semiconservative Model

Predicts that when a double helix replicates, each daughter molecule will have one old strand (derived or "conserved" from the parent molecular) and one newly made strand

17

Conservative Model

Two parent strands rejoin

18

Dispersive Model

Each strand is a mix of old and new

19

Replication begins at particular sites called _____

Origins of Replication

20

What happens at the origin of Replication?

Two DNA strands are separated, opening up a replication "bubble"

21

A eukaryotic chromosome may have _____ origins of replications

hundreds or even thousands

22

Replication proceeds in ____ , until the entire molecule is copied

both directions from each origin

23

At the end of each replication bubble is a ____

replication fork, a Y-shaped region where new DNA strands are elongating

24

____ are enzymes that untwist the double helix at the replication forks

Helicases

25

_____ bind to and stabilize single-stranded DNA

Single-strand binding proteins

26

______ corrects "overwinding" ahead of replication forks by braking, swiveling, and rejoining DNA strands

Topoisomerase

27

DNA polymerases cannot initiate synthesis of a polynucleotide; they can only ____

add nucleotides to an existing 3' end

28

The initial nucleotide strand is a short ____

RNA primer

29

what does Primase do?

Can start a RNA chain from scratch and adds RNA nucleotides one at a time using the parental DNA as a template

30

The primer is _______ and the _ end serves as te starting point for the new DNA strand

short (5-10 nucleotides long)
3'