Chapter 12 - DNA Flashcards

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1
Q

Who concluded that bacteria could be transformed from harmless to disease causing by an unknown factor?

A

Griffith

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2
Q

Who concluded that DNA was the factor that caused one bacterium to transform into another?

A

Avery

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3
Q

Who concluded that the genetic material of a bacteriophage is DNA?

A

Hershey and Chase

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4
Q

Who discovered that percentages of Adenine and Thymine were almost the same in any sample of DNA. and the same occurred for Guanine and Cytosine?

A

Chargaff

called “Chargaff’s rule”

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5
Q

Who concluded using an x-ray that DNA was in the shape of a double helix and that nitrogenous bases are near the center of the DNA molecule?

A

Franklin

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6
Q

Who discovered the structure of the DNA molecule (based of Franklin’s work)?

A

Watson and Crick

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7
Q

What did Watson and Cricks model show about DNA?

A

The two strands of DNA run in anti parallel
Hydrogen bonds held together the two strands of DNA
Explained and gave proof to Chargaff’s rule

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8
Q

During DNA replication, the DNA molecule does what?

A

It separates into two strands

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9
Q

At the end of DNA replication how many NEW strands of DNA are there?

A

Two new strands

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10
Q

At the end of DNA replication, how many strands (new and original) are there?

A

Four strands

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11
Q

New DNA is replicated in strands complimentary to the Original DNA, because production of new DNA follows the rules of

A

base parings

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12
Q

What are DNA’s 3 jobs

A

Give instructions to assemble proteins
Direct REPLICATION of genes (meiosis)
Direct process of how genes pass from parent to offspring

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13
Q

What is DNA

A

a nucleic acid (polymer) made of nucleotides (monomers)
The nucleotides are joined by covalent bonds (sugar to phosphate)
Can be thousands of nucleotides long

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14
Q

What is a nucleotide made of

A

sugar, deoxyribose (a phosphate group), and a nitrogenous base

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15
Q

What are the four Nitrogenous bases?

A

Adenine (A), Thymine (T),

Cytosine (C), Guanine (G)

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16
Q

What bases always go together and have the same percentage (Chargaff’s rule)

A
A = T
C = G
17
Q

How do two strands of DNA join

A

They join by hydrogen bonds, because they are strong enough to hold it together, but weak enough to break apart when needed

18
Q

what is the shape of DNA

A

double helix (twisted ladder)

19
Q

What bases are Pyrimidines

A

Cytosine and Thymine. They both have one ring

1y=1 ring

20
Q

what bases are Purines

A

Adenine and Guanine. They both have two rings.

2ns’=2 rings

21
Q

why are the “rungs of the ladder” 3 bases wide?

A

so that DNA is more stable, more integrity, and resists damage. (A=2 + T=1 = 3) (G=2 + C=1 = 3)

22
Q

what is the backbone of DNA made of?

the outside sticks of ladder

A

alternating sugars and phosphates

23
Q

How are the DNA strands Anti parallel

A

3 prime on one end and 5 prime on other end of one strand means on other strand; 5 prime on end opposite of other 5 prime, and 3 prime on other end of strand, opposite of 3 prime of other end

24
Q

How does the original strand act as a template for new strand?

A

the original is a template because the new strand must be complementary (using Chargaff’s rule) to original strand

25
Q

First step of DNA replication

A

Enzymes identify DNA that needs to be replicated and unwinds double helix

26
Q

what does the Helicase do? (step 2 in DNA replication)

A

Helicase “unzips” DNA by breaking the hydrogen bonds between the two Original strands. Creating two replication forks

27
Q

what does DNA polymerase do? (step 3 in DNA replication)

A

attaches the complementary base to the template strand. It also “proofreads” the forming strand

28
Q

Step four of DNA replication

A

The leading strand (the original 5’ to 3’ - nucleotides begin attached at the 3’ end of new) will build in a smooth progression

29
Q

Step five of DNA replication

A

the lagging strand (the original 3’ to 5’ - nucleotides cant be attached at the 5’ end) builds piecemeal

30
Q

what are okazaki fragments (step 6 in DNA replication)

A

short sections of bases brought together by DNA polymerase. (lagging side)

31
Q

what are ligase (step 6.5 in DNA replication)

A

ligase bring together Okazaki fragments (lagging side)

32
Q

step seven of DNA replication

A

When the replication is complete, the two new molecules of DNA are identical to each other. They then wind up and take the double helix form.

33
Q

What are telomeres

A

the DNA at chromosome tips, they’re very delicate and can be damaged during replication

34
Q

Replication in Prokaryotes

A

replication starts at one point and moves in both directions until ends meet and DNA separates. one origin two forks

35
Q

Replication in Eukaryotes

A

starts at many points and all move in both directions until completely copied. many origins many forks