Chapter 16: The Molecular Basis of Inheritance

what did griffith discover

transformation

what is the pathogenic strain

s

what is the nonpathogenic strain

r

When he killed S cells with heat and mixed them with living R cells what happened to the mice

they died due to living S cells

what did hershey and chase study

bacteriophage

what are bacteriophages

viruses that infect bacteria

what did hershey and chase discover

that DNA, not proteins, encode genetic information

what two things did chargaff discover

dna composition varies between species

and number of adenine and thymine bases are equal and the number of guanine and cytosine bases are equal

what does a nucleotide contain

nitrogenous base, sugar, phosphate

what is the backbone of DNA

sugar-phosphate

what are the purines in DNA

adenine and guanine

how many rings do purines have

2

how many rings to pyrmidines have

1

what are the pyrimidines

thymine and cytosine

how many hydrogen bonds are between A-T

2

how many hydrogen bonds are between C-G

3

where are nitogenous bases found in DNA

they are inward

what allows the molecule to separate equally during replication

hydrogen bonds

what did rosalind franklin use

x-ray diffraction

what did rosalind franklin find out

the sugar phosphate backbones are on the outside of the helix

who worked with rosalind franklin and ended up giving her work away

maurice wilkins

what 3 things did watson and crick disover

double helix

complementary base pairing

antiparallel strands

what is the conservative model

parent strand rejoins after replication

what is the semiconservative model

each new DNA molecule has one old strand (parental) and one new strand

what is the dispersive model

each strand is a mix of old and new DNA segments

what did Meselson and stahl find out

the semiconservative model is correct

where does replication begin

origin of replication

what stands for origin of replication

ORI

what happens at the origin of replication

DNA strands separate

what is formed at the ori

replication bubble

what does each bubble have

2 replication forks

what is a replication fork

Y-shaped regions where DNA elongates

Untwists and separates the DNA double helix at the replication fork.

helicase

what does the helicase do

untwists and separated the dna double helix

where does helicase work

at the replication fork

Bind and stabilize single-stranded DNA.

single-strand binding proteins

Relieves strain and corrects overwinding ahead of replication forks by cutting and rejoining DNA strands.

topoisomerase

what does topoisomerase do

rejoin DNA strands

Synthesizes RNA primers to provide a 3′ end for DNA polymerase to start building from.

primase

what does primase do

makes RNA primer

Main enzyme that adds nucleotides to the 3′ end of a primer; synthesizes most of the new DNA strand.

DNA polymerase III

what does DNA polymerase III do

adds nucleotides

what end of the primer are nucleotides added to

3'

can DNA polymerase III just start adding nucleotides anywhere

no

Removes RNA primers and replaces them with DNA nucleotides.

DNA polymerase I

what does DNA polymerase I do

removes RNA primers and replaces them with DNA nucleotides

what does DNA polymerase I remove

RNA primers

what does DNA polymerase I add

DNA nucleotides

Joins Okazaki fragments and seals nicks in the sugar-phosphate backbone.

DNA ligase

what does DNA ligase to

join okazaki fragments together

what does DNA polymerase need to start synthesis

primer

what way does the new strand grow

5' to 3'

Synthesized continuously toward the replication fork.

leading strand

which strand is made toward the replication fork

leading strand

continuous synthesis

leading strand

Synthesized discontinuously away from the fork, forming short Okazaki fragments.

lagging strand

which strand is made away from the fork

lagging strand

what do lagging strand create

okazaki fragments

what does each okazaki fragment require

its own primer

what connects okazaki fragments

dna ligase

what do repair enzymes do

correct base-pair errors

what does a nuclease do

cut out damaged DNA

what type of living things run into the issue of having shorter DNA strands after replication

eukaryotes

what is the shape of eukaryotic DNA

linear

what is the shape of prokaryotic DNA

circular

Repetitive, noncoding DNA sequences at chromosome ends that protect genes from being eroded.

telomeres

protective caps at the ends of eukaryotic chromosomes

telomeres

what is the telomeres sequence

TTAGGG

Protect genes from being lost during DNA replication

telomeres

what do telomeres do

protect genes from being lost during DNA replication

what does telomerase do

extends telomeres

what does the shortening of telomeres lead to

aging

Molecule that stores and transmits hereditary information.

DNA

Segment of DNA coding for a specific trait or function.

gene

Process by which external DNA is assimilated by a cell, changing its genotype and phenotype.

griffith's trasnformation

Identified DNA as the substance that causes bacterial transformation.

avery, mccarty, macleod

Virus that infects bacteria.

bacteriophage

Proved DNA (not protein) is genetic material using radioactive labeling.

hershey-chase

Building block of DNA (base, sugar, phosphate).

nucleotide

Double-ring nitrogenous base (A, G).

purine

Single-ring nitrogenous base (C, T).

pyrimidine

A = T and G = C; DNA composition varies among species.

chargaff's rules

Produced X-ray image revealing DNA's helical structure.

rosalind franklin

Structure of DNA with two antiparallel strands twisted into a helix.

double helix

DNA strands run in opposite directions (5′→3′ vs. 3′→5′).

anitparallel

A pairs with T, G pairs with C via hydrogen bonds.

complementary base pairing

Weak attractions holding DNA bases together (2 for A-T, 3 for G-C).

hydrogen bonds

Each daughter DNA has one parental strand and one new strand.

semiconservative replication

Parental strands rejoin after replication (incorrect).

conservative replication

DNA strands are mixtures of old and new (incorrect).

dispersive replication

Proved semiconservative replication using isotopic labeling.

Meselson-Stahl experiment

Site where DNA strands separate and replication begins.

origin of replication

Opened region of DNA where replication occurs.

replication bubble

Y-shaped region where DNA strands are unwound and replicated.

replication fork

Enzyme that unwinds DNA strands.

helicase

Stabilize unwound DNA strands.

single-strand binding protein

Relieves strain by cutting and rejoining DNA strands.

topoisomerase

Synthesizes short RNA primers to start DNA synthesis.

primase

Short RNA segment that initiates DNA synthesis.

RNA primer

Enzyme that adds nucleotides to growing DNA strand (5′→3′).

DNA polymerase