Biology Final Chapter 16

G= ?

C

A photo suggested that the DNA molecule was made up of two strands, forming a __________________.

Double helix

Franklin's X-ray crystallographic images of DNA enabled Watson to deduce that DNA was ________

helical

enzymes that untwist the double helix at the replication fork

helicases

An enzyme called _________ can start an RNA chain from scratch and adds RNA nucleotides one at a time using the parental DNA as a template

primase

Synthesizes and RNA primer at 5' end of the leading strand and at the 5' end of each Okazaki fragment of the lagging strand

primase

The base composition of DNA varies between species and In any species the number of A and T bases are equal and the number of G and C bases are equal

2 of Chargaff's rules

The ___ ' end serves are the starting point for the new DNA strand

3'

DNA polymerases add nucleotides only to the free 3' end of a growing strand; therefore, a new DNA strand can elongate only in the __' to __' direction

5' ; 3'

The primer is ___-___ nucleotides long

5-10

Joins Okazaki fragments of lagging strand; on leading strand, joins 3' end of DNA that replaces primer to rest of leading strand DNA

DNA ligase

Removes RNA nucleotides primer from 5' end and replaces them with DNA nucleotides

DNA polimerase 1

Using parental DNA as a template, synthesizes a new DNA strand by adding nucleotides to an RNA primer or a preexisting DNA strand

DNA polimerase 3

DNA is copied during _____________, and cells can repair their DNA

DNA replication

In ___________, the parent molecule unwinds, and two new daughter strands are built based on base-pairing rules

DNA replication

__________ produced a picture of the DNA molecule using this technique.

Franklin

In 1953, ______________ and____________ introduced an elegant double-helical model for the structure of deoxyribonucleic acid, or DNA

James Watson and Francis Crick

__________ and ________ were using a technique called X-ray crystallography to study molecular structure

Maurice Wilkins and Rosalind Franklin

The lagging strand is synthesized as a series of segments called _______ fragments, which are joined together by DNA _______.

Okazaki ; ligase

A= ?

T

In has been proposed that the shortening of telomeres is connected to ______.

aging

Watson built a model in which the backbones were _____________.

antiparallel

The shortening of telomeres might protect cells from cancerous growth by limiting the number of _____ _________.

cell division

The basis for Charger's rules were not understood until the discovery of the ______________.

double helix

A __________ chromosome may have hundreds or even thousands of origins of replication

eukaryotic

To elongate the other new strand, called the _______ strand, DNA polymerase must work in the direction away from the replication fork

lagging

Replication proceeds in both directions from each _________, until the entire molecule is __________.

origin ; copied

Replication begins at particular sites called ______ __ ___________, where the two DNA strands are separated, opening up a replication "bubble"

origins of replication

Pairing a ______ with a pyrimidine resulted in a uniform width consistent with the X-ray data

purine

A Y-shaped region where new DNA strands are elongating is known as __________.

replication fork

Watson and Crick's ________________ ______ of replication predicts that when a double helix replicates, each daughter molecule will have one old strand (derived or "conserved" from the parent molecule) and one newly made strand

semiconservative model

bind to and stabilize single-stranded DNA

single-strand binding proteins

There is evidence of __________ activity in cancer cells, which may allow cancer cells to persist

telomerase

Eukaryotic chromosomal DNA molecules have special nucleotide sequences at their ends called _____________.

telomeres

________ do not prevent the shortening of DNA molecules, but they do postpone the erosion of genes near the ends of DNA molecules

telomeres

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

topoisomerase

An example of a MUTATION would be a _______

tumor

The X-ray images also enabled Watson to deduce the ______ of the helix and the spacing of the _______ bases

width ; nitrogenous