The Structure Of Dna

Front 1

What is DNA?

Back 1

DNA is a nucleic acid made up of nucleotides joined into long strands or chains by covalent bonds. Nucleotides may be joined in any order

Front 2

What is a DNA nucleotide?

Back 2

A DNA nucleotide is a unit made of a nitrogenous base, a 5 carbon sugar called deoxyribose and a phosphate group

Front 3

What are DNAs four nitrogenous bases?

Back 3

adenine, guanine, cytosine, and thymine

Front 4

Erwin Chargaff

Back 4

Showed the percentages of adenine and thymine are almost always equal in DNA. The percentages of guanine and cytosine are also almost equal

Front 5

Rosalind Franklin

Back 5

X-Ray diffraction studies revealed the double helix structure of DNA

Front 6

James Watson and Francis Crick

Back 6

They built a model that explained the DNA structure.

Front 7

The two strands in the double helix run in ______ directions, with the nitrogenous bases _______

Back 7

Opposite, in the center

Front 8

Each strand carries a sequence of ________, arranged almost like the letters in a fourletter alphabet for recording _________ information.

Back 8

Nucleotides, genetic

Front 9

___________ hold the strands together. The bonds are easily broken allowing DNA strands to seperate

Back 9

Hydrogen Bonds

Front 10

Hydrogen bonds form only between certain base pairs _______ with _______ and ________ with ________. This is called _________ pairing

Back 10

adenine & thymine, cytosine & guanine, base

Front 11

The building blocks of DNA are _________

Back 11

Nucleotides

Front 12

Nucleotides in DNA are made of three basic components, a sugar called _____ ,a ________and a nitrogenous ________

Back 12

deoxyribose, phosphate, base

Front 13

DNA contains four kinds of nitrogenous bases _______, _____, _____, and ________.

Back 13

adenine, thymine, guanine, and cytosine

Front 14

In DNA _______ can be joined in any order

Back 14

nucleotides

Front 15

The nucleotides in DNA are joined by ________ bonds

Back 15

covalent

Front 16

Store Information

Back 16

Each strand of the double helix carries a sequence of bases, arranged like something in a four letter alphabet

Front 17

Copy Information

Back 17

The base pairs can be copied when hydrogen bonds break and the strands pull apart.

Front 18

Transmit Information

Back 18

When DNA is copied the sequence of base pairs is copied, so genetic information can pass unchanged from one generation to the next

Front 19

Copying the Code

Back 19

Each strand of the double helix has all the information needed to reconstruct the other half by the mechanism of base pairing. Because each strand can be used to make the other strand, the strands are said to be complementary. DNA copies itself through the process of replication.

Front 20

The two strands of the double helix unzip, forming ____________.

Back 20

replication forks

Front 21

New ________ are added, following the rules of _________ pairing ( A with T & G with C )

Back 21

bases, base

Front 22

_____________ is an enzyme that joins individual nucleotides to produce a new strand of DNA.

Back 22

DNA Polymerase

Front 23

During replication, DNA may be lost from the tips of chromosomes, which are called ________

Back 23

telomeres

Front 24

Replication in Living Cells

Back 24

The cells of most prokaryotes have a singular, circular DNA molecule in the cytoplasm. Eukaryotic cells have much more DNA. Nearly all of it is contained in chromosomes, which are in the nucleus.

Front 25

_________ in most prokaryotic cells start from a single point and proceeds in two directions until the entire chromosome is copied.

Back 25

Replication

Front 26

In ________ cells, replication may begin at dozens or even hundreds of places on the DNA molecule, proceeding in both directions until each chromosome is completely copied.

Back 26

Eukaryotic Cells

Front 27

Why are the strands of a DNA molecule said to be complementary?

Back 27

Each strand can be used to make the other strand.

Front 28

What is the first step in eukaryotic DNA replication?

Back 28

The strands of three double helix seperate or unzip

Front 29

If the base sequence on a seperated DNA strand is CGTAGG, what will the base sequence on its complementary strand be?

Back 29

GCATCC

Front 30

What enzyme joins individual nucleotides to produce the new strand of DNA?

Back 30

DNA Polymerase

Front 31

What enzyme makes it less likely that DNA will be lost from telomeres during replication?

Back 31

telomerase

Front 32

How does this enzyme work (telomerase)

Back 32

Telomerase works by adding short repeated DNA sequences to telomeres

Front 33

What is a replication fork?

Back 33

A point in a DNA molecule where two strands separate during replication

Front 34

Does DNA replication take place in the same direction along both strands of the DNA molecule that is being replicated?

Back 34

No, replication proceeds in opposite directions between replication forks.

Front 35

Location of DNA in Prokaryotes

Back 35

singular circular molecule in the cytoplasm

Front 36

Location of DNA in Eukaryotes

Back 36

packaged in chromosomes in the nucleus

Front 37

Amount of DNA in Prokaryotes

Back 37

Less than Eukaryotes

Front 38

Amount of DNA in Eukaryotes

Back 38

Up to 1,000x more than prokaryotes

Front 39

Starting point(s) for replication in Prokaryotes

Back 39

Single starting point

Front 40

Starting point(s) for replication in Eukaryotes

Back 40

dozens or hundreds of starting points

Front 41

Is DNA replication always a foolproof process?

Back 41

No, many proteins check the DNA for damaged parts or errors. Damaged regions can still be replicated. This may result in gene alterations and serious complications for the organism.

Front 42

Why is the pairing of bases during replication essential for the transmission of inherited traits from parent to offspring?

Back 42

The match is almost always perfect between ATCG so that the code is copied correctly every time.