Bio Chapter 16

Front 1

transformation

Back 1

change in genotype and phenotype due to the assimilation of external DNA by a cell

Front 2

bacteriophages (phages)

Back 2

viruses that infect bacteria as a tool in molecular genetic.

Front 3

DNA vs. Protein in Phage cells

Back 3

DNA of the virus is injected into the host cell, while proteins remain outside. The injected DNA causes the cells to produce new viral DNA and proteins

Front 4

double helix

Back 4

the form of native DNA, referring to its 2 adjacent polynucleotide strands wound into a spiral shape

Front 5

purines

Back 5

adenine and guanine are nitrogenous bases with two organic rings (2x as wide as pyrimadines)

Front 6

pyrimidines

Back 6

thyamine and cytosine nitrogenous bases with single rings

Front 7

bonding

Back 7

A-T are bonded by 2 H bonds, G-C are bonded by 3 H bonds. Van der Waals attractions between the stacked pairs holds molecules together.

Front 8

semiconservative model

Back 8

each of the two daughter molecules will have one old strand, derived from the parent moelcule, and one newly made strand

Front 9

conservative model

Back 9

parent molecule remains intact and the new molecule is formed entirely from scratch

Front 10

dispersive model

Back 10

each strand of both daughter molecules contains a mixture of old and newly synthesized parts

Front 11

origins of replication

Back 11

specific sequence of nucleotides that proteins recognize and separate the strands to open the bubble.

Front 12

replication

Back 12

DNA replication begins where 2 parental strands of DNA eparate to form replication bubbles. There are thousands of origin sites along the DNA molecule of each chrom that expand laterally in both directions as DNA replicates. The bubbles fuse to separate the two daughter strands.

Front 13

replication fork

Back 13

Y shaped region where the two strands of DNA are elongating, catalyzed by DNA polymerases

Front 14

DNA polymerase

Back 14

as nucleotides align complementary bases along a template strand of DNA, nucleotides are added by polymerase, one by one, to the growing end of the DNA strand
50 nucleotides/second

Front 15

Energy for nucleotide addition

Back 15

nucleoside triphosphate links to the sugar phosphate backbone of a growing DNA strand and loses 2 of its phosphates as a pyrophosphate molecule. hydrolysis of the bonds between the phosphate groups provides the energy for the reaction

Front 16

Antiparallel

Back 16

The 5'-3' strand runs counter to the 3'-5' strand, creating distinct polarity. The 3' end has a hydroxyl group on the end, the 5' end ends with a phosphate. Nucleotides are only added to the 3' end, so DNA elongates in the 5'->3' direction.

Front 17

leading strand

Back 17

the new continuous completmentary DNA strand synthesized along the template strand in the 5'->3' direction

Front 18

lagging strand

Back 18

a discontinuously synthesized DNA strand that elongates in a direction away from the replication fork (3'->5')

Front 19

okazaki fragments

Back 19

how the lagging strand grows. they individually grow in the 5'->3' direction,but work their way in in the opp. direction connected by DNA ligase (enzyme)

Front 20

primer

Back 20

a short stretch of RNA that signals where replication should begin

Front 21

primase

Back 21

enzyme that joins RNA nucleotides to make the primer

Front 22

priming DNA synthesis

Back 22

DNA polymerase cannot initiate a polynucleotide strand. After elongation, RNA is replaced with DNA

Front 23

helicase

Back 23

an enzyme that untwists the double heliz at the replication fork, separating the 2 old strands

Front 24

single strand binding protein

Back 24

line up along the unpaired DNA strands and holds them apart while they serve as templates for the synthesis of new complementary strands

Front 25

mismatch repair

Back 25

fixes mistakes that are made when DNA is copied. DNA polymerase proofreads each nucleotide against the template, and deletes (and replaces with the correct base) the mistake

Front 26

excision repair

Back 26

cutting out and replacing the DNA strand that is damaged

Front 27

nuclease

Back 27

DNA cutting enzyme that cuts out the section of the strand with the damage. DNA polymerase and ligase re-fill this deletion

Front 28

Limitations of 3' end

Back 28

a gap is left at the 5' end of each new strand because DNA polymerase can only add nucleotides to a 3' end. Each round of replication results in shorted daughter strands.

Front 29

telomeres

Back 29

special nucleotide sequences (DNA) that consists of multiple repetitions of one short nucleotide sequence AAAAAAA (polyA strand). because primer is cut out, there are extra base pairs on the template end. to make them match up, the extras must be cut out so they are made of only one base nucleotide

Front 30

telomerase

Back 30

enzyme that catalyzes the lengthening of telomeres in gametes, so that the strands dont get shorter with each generation. has a molecule of RNA along with its protein