Biology I- chapter 11

DNA is the _______ material that provides the ___________ to produce an individual’s traits

genetic, blueprint

called _________________ acid or DNA for short

deoxyribonucleic

DNA carries the genetic ____________ for the traits of living organisms

information

Genetic material must meet the following criteria:

-Information: must contain the information __________ to construct the entire _________

-Replication: must be ________ copied

-Transmission: must be able to be passed on from ______ to _________ and cell to cell

-Variation: differences in the genetic material must account for known variations within each species and among different species

-necessary, organism -accurately, -parent, offspring,

DNA consists of ____________ (or bases), the building blocks of DNA

nucleotides

A nucleotide consists of a ___________ group, a pentose (five carbon) _____, and a nitrogen-containing (nitrogenous) ____

phosphate, sugar, base

The sugar for DNA is __________ (for RNA, it’s ______)

deoxyribose, ribose

The nitrogen-containing base could be: _______ (A), _______ (G), ________ (C), or _______ (T)

*In RNA there is ______ (U) instead of thymine

adenine, guanine, cytosine, thymine, uracil

DNA structural levels of complexity

-Nucleotides (or bases): the _________ blocks of DNA

-Strand: nucleotides that are _________ linked to one another producing a string of nucleotides

-Double helix: two strands of DNA bound to each other via _________ bonds twist to form structure that looks like a spiral staircase (a helix)

-Chromosomes: double stranded, helical DNA, associated with different proteins to form a more _______ ________

-Genome: complete complement of an organism’s _______ material

building, covalently, hydrogen, compact structure, genetic

Erwin Chargaff: analyzed the base composition of DNA _______ from different species

His results indicated that in any given species, the four bases are found in characteristic, but not necessarily _____, ratios

The amount of _______ was similar to the amount of thymine

The amount of _______ was similar to the amount of cytosine

These findings are known as Chargaff’s rules or the __/GC

isolated, equal, adenine, guanine, AT

Rosalind Franklin: initial evidence of the structure of DNA using a technique known as _-___ ___________

She concluded DNA was found in the shape of a _____ with a diameter that was too wide to be a ______-stranded helix

X-ray diffraction, helix, single

Watson and Crick: _____ Watson and _______ Crick began to work on a model of DNA with two strands, the double helix

They tried to put the nucleotides of DNA together like pieces of a puzzle however this did not fit the X-ray measurements from Rosalind Franklin and other information on the chemistry of DNA from known experimental observations at that time

The key breakthrough came in 1953 when they realized that the DNA molecule is made up of ___ chains of _____________ that are intertwined; i.e a ______ helix

James, Francis, two, nucleotides, double

The two strands of the DNA molecule are like a _____ staircase or twisted rope ladder

spiral

Each strand is composed of ____________ that are _________ attached to each other (as a result of dehydration reactions)

The _____-___________ component of each nucleotide make up the __________ or sides of the ladder

Pairs of __________ bases, one from each strand, oppose each other to form the steps

nucleotides, covalently, sugar-phosphate, handrails, nitrogenous

One end terminates in a _' OH and the other end terminates in a _’ PO4.

A strand has directionality based on the ___________ of the ____ molecules.

At one end of the DNA strand is an available _________ group attached to Carbon #5

At the other end of the DNA strand is an available ________ group attached to Carbon #3

3,5, orientation, sugar, phosphate, hyrdroxl

Due to the AT/GC rule, base pairing is ______________.

The bases are paired in _________ combinations

Adenine from one strand forms _________ bonds with a thymine from the other strand

Guanine from one strand forms ________ bonds with a cytosine from the other strand

the two strands are held together by ________ bonds

complementary, specific, hydrogen

As a result of the two strands being complementary to one another and the orientation of the nucleotides within each of the strands, the two strands of a DNA double helix are ____________

*The two strands run in ________ directions to one another

One strand goes in the 5’ to 3’ direction and the _____________ strand goes in the 3’ to 5’ direction

antiparallel, opposite, complementary

The DNA molecule is comprised of ___ strands that are ____________ to one another and form a double helix

The two strands of DNA are held together by the formation of ________ bonds between the ____ pairs

Adenine pairs with _______

Guanine pairs with ________

The nitrogenous base of each nucleotide face toward the ______ of the molecule, while the sugar and phosphate are facing the _______

DNA is __________

two, complementary, hydrogen, base, thymine, cytosine, middle, outside, antiparallel

DNA is precisely __________

DNA is susceptible to ________

DNA is passed on from ______ to _________

DNA is expressed as the _________

*The DNA molecule stores an organism’s genetic information

replicated, mutation, parent, offspring, phenotype

Simplistically when a cell copies a DNA molecule, the two strands separate (_________ strands) and each strand serves as a template for ordering nucleotides into a new _____________ strand (daughter strands)

One at a time, nucleotides line up along the template strand according to the base pairing rules, and are joined together by a _________ (phosphodiester) bond via the hydration reaction

When the double helix is replicated that daughter molecules will have one ___ strand and one ______ made strand

parental, complementary, covalent, old, newly

E.coli can copy each of the _ million base pairs in single chromosome and divide to form two identical cells in ____ than an hour

A human cell can copy its _ billion base pairs and divide into daughter cells in approximately __ hours

5, less, 6, 24

The first event in DNA replication is the __________ and unwinding of the two strands of DNA (__________)

*Occurs by the enzymes DNA ________ and DNA _____________

Special proteins called DNA ______-________ binding proteins then bind to the separated strands to keep them from re-forming the double helix

This results in ___ single strands of DNA (the parental strands) that can then be replicated

separation, denaturation, helicase, topoisomerase, single-stranded, two

Once the strands are separated the enzyme DNA __________ is then able to catalyze the elongation of new DNA

As nucleotides align with complementary bases (according to the AT/GC rule) along the template strand, they are added to the _______ end of the new strand by the polymerase

*The rate of elongation is about 500 nucleotides per second in bacteria and 50 nucleotides per second in human cells

polymerase, growing

DNA __________ has two important features that affect how DNA strands are made

-DNA polymerase cannot _______ synthesis of new DNA on a bare template strand, can only ___ nucleotides to the end of an ________ chain that is base-paired with the template strand

-i.e. DNA polymerase ______ start a new strand from scratch

-To start a new strand requires a ______, a short, complementary segment of ___

-Primer is about __ to 12 nucleotides long in eukaryotes

-DNA ______, a type of RNA polymerase, makes the primer

polymerase, initiate, add, existing, cannot, primer, RNA, 10, primase

After formation of the ______, DNA polymerase can add DNA nucleotides to the _’ end of the ___ nucleotide chain

Another type of DNA polymerase later removes the RNA nucleotides of the primer and replaces them with DNA nucleotides complementary to the template strand

Lastly, an enzyme called DNA ______, catalyzes the formation of the ________ bond between the last replaced nucleotide of the primer with the pre-existing nucleotide in front of it

primer, 3, RNA, ligase, covalent

Keep in mind that the two strands of DNA are ____________

The _____-_________ backbones run in opposite directions

-Each DNA strand has a _’ end with a free hydroxyl group attached to deoxyribose and a _’ end with a free phosphate group attached to deoxyribose

-The 5’→3’ direction of one strand runs counter/________ to the 5’→3’ direction of the other strand

antiparallel, sugar-phosphate, opposite

The second feature that affects how DNA __________ replicates DNA pertains to the _____________ of the DNA

-DNA polymerase can only ____ (or elongate) a new DNA strand in the _’→_’ direction

This creates a problem at the replication fork because one parental strand is oriented 3’→5’ into the fork, while the other antiparallel parental strand is oriented 5’→3’ into the fork

At the replication fork, one parental strand (3’→5’ into the fork), the leading strand can be used as polymerase as a template for continuous replication

polymerase, directionality, 5, 3

The other parental strand (5’→3’ into the fork), the lagging strand, is copied away from the fork in short segments called _______ fragments

Okazaki fragments, each about ___ to 200 nucleotides, are joined by DNA ______ to form the sugar-phosphate backbone of a single DNA strand

Okazaki, 100, ligase

DNA __________ has a proofreading capability that ______ (and corrects) each new nucleotide against the template nucleotide as soon as it is added

*It’s not 100% accurate and errors do occur

DNA errors can also be created by other means

DNA can be damage (_______) by agents called ________; UV light, X-rays, and chemicals

There are other types of repair mechanisms that can fix DNA errors/damage

Any error or alteration to the DNa can be deadly

polymerase, checks, mutated, mutagens

Human cells contain __ chromosomes consisting of 23 “______” pairs

Each eukaryotic chromosome consists of a complex of a long, linear, double-stranded DNA molecule and specific proteins called ________ (__% of chromosomes)

*Helps maintain the chromosome structure and controls gene activity

The DNA and protein complex is called _________, and is organized into a long fiber that can then take on more compacted structures

Each chromosome has hundreds or thousand of genes, the units that specify an organism’s inherited traits

46, identical, histones, 50, chromatin