Chapter 13 Flashcards by Kyler Zimmerman

DNA is a polymer of what?

Nucleotides

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What does nucleotide consist of?

Deoxyribose, a phosphate group, and a nitrogen-containing base

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What are the four different nucleotides different in only the bases?

Purines - adenine and guanine
Pyrimidines - cytosine and thymine

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What is chargaff rule?

% of adenine = % of thymine
% of cytosine = % of guanine

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Adenine pairs with

Thymine

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Cytosine pairs with

Guanine

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Pyrimidines are…. And what is the structure?

DNA - cytosine and thymine
RNA - uracil and cytosine
They are a single ring structure

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Purines are …… and what is the structure?

adenines and guanine
Double ring structure

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Nucleotide base are where on DNA structure?

The interior of the two strands

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Sugars-phosphate is where on the DNA strand…

Is backbone

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The two DNA strand run….

In opposite directions - they are anti parallel

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What are the four key features of DNA

1 it’s a double stranded helix
2 it’s a right handed helix
3 is has antiparallel strands
It’s has major and minor grooves

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A key feature - double-stranded helix

Sugar-phosphate backbone forms a coil around the outside of the helix; the bases points towards the center
Strand are held together by
- hydrogen bond between the bases
- van der waals forces between adjacent bases on the same strand

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A key feature - Right handed helix

Clockwise turning motion moves the helix away from the observer

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A key feature - antiparallel strands

Direction is determined by sugar - phosphate bonds
Phosphate groups connect the 3’ C of one sugar with the 5’ C of the next
One strand has a free 5’ phosphate groups (the 5’ end)
One strand has a free 3’ hydroxyl group (the 3’ end)

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The key feature - major and minor grooves

Backbones of the DNA strands are closer together on one side (forming the minor groove) than on the other (forming the major groove)

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The double-helix structure is…

Essential to DNA function

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Genetic material stores an organism’s …..

Genetic information

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The average gene contains….

Thousands of nucleotides

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What stores the genetic information

The sequence of the base pairing contain large amount of genetic information

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Genetic information is susceptible to ….. in the information it encodes

Mutations

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Mutations can be …..

Positives, negative, or neutral, the environment will determine this

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Genetic information is ….. in the cell division cycle

Precisely replicated

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Genetic material (the coded of information in DNA) is expressed as the ……

Phenotype

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Replication pattern is …..

Semi conservative

Each parents strand is a template; new molecule have one old and one new strand

Semi conservative DNA replication involves ……

Several different enzymes and other proteins

What are the three steps of DNA replication?

Initiation Elongation Termination

Initiations is ….

Double helix is unwound, separating the two templates strands and making them available for new base pairing

Elongation is ….

Additional of nucleotides that form complementary base pairs with template DNA; incoming nucleotides are covalently linked together by phosphodiester bonds

Termination is …..

DNA synthesis ends when all DNA regions have been replicated

DNA helicase

Unwinds the double helix and separates the two strands

Single-strand binding proteins

Bind to separate strands and prevent them from re-forming the double helix

DNA primase

Creates an RNA primer (5-10 nucleotides long)

DNA polymerase

Links new nucleotides to form the new DNA strands and removes the primers

DNA ligaments

Connects Okazaki fragments made by DNA polymerase to one another

DNA replication begins when a large protein complex binds to a region called the ….

Original of replication

The origin of replication ….

Is a sequence of muclogicex on the DNA molecule that tell all all of the enzymes in replication where to start

Eukaryotes chromosomes have ….. otherwise it would take week to replicate chromosomes

Multiple origins of replication

DNA has to have what to begin replications

Has to have a primer which is a short “starter” strand which is usually RNA.

What makes the primer to start DNA replication

Primate catalyzes the synthesis of the primer

What does DNA helicase do?

It uses energy from ATP hydrolysis to unwind the double helix

What to the single-strand bonding protein do?

Keep the template strands separated

The leading strand grows at the

3’ end as the fork opens up

The lagging strand,

the exposed 3’ end gets farther from the fork and an unreplicated gap forms

Okazaki fragments

Synthesis of the lagging strand occurs in small, discontinuous stretches of

Each Okazaki fragment has its own….

Primer

The final phosphodiester linkage between fragments is catalyzed by

DNA ligase

Why is the only way for a nucleotide to attach to the polypeptide at the 3’ end?

Because that is the only place the condensation reaction can occur to make that phosphodiester bond.

The template strand is build in what way?

5’ to 3’

The leading strand is synthesized….. in the ….. direction by DNA polymerase

Continuously in the 5’ to 3’ direction

The lagging strand is synthesized…..

Discontinuously

What does DNA polymerase 3 do?

Add nucleotides to the 3’ end, until reaching the primer of the previous fragment.

What does DNA polymerase 1 do?

Replaces the primer with DNA

Telomeres

Repeated DNA sequences at the end of eukaryotic chromosome, they prevent the DNA repair system from recognizing the chromosomes ends as breaks

Telomerase

An enzyme that catalyzes addition of lost telomere in continuously dividing cells

DNa must be accurately —- and —-

Replicated and maintained

DNA bring copied accurately is essentials for….

The proper functioning of every cell

What are ways DNA can make a mistake?

DNA polymerase makes mistakes in assembling polynucleotide strands DNA can be damaged by chemicals, UV radiation and other treats

Mismatched and damaged bases can lead to …

Mutations

What are the cells three repair mechanisms?

Proofreading Mismatch repair Excision repair

What’s is proofreading?

Is an incorrect nucleotide is added, DNA polymerase recognizes the mismatched pairs and removed incorrectly paired bases

What is mismatch repair?

New replicated DNA is scanned for mismatched pairs missed in proofreading: enzyme detectors “bulges” where the wrong base is inserted (purine/pyrimidine match) When mismatch repair fails, DNA sequences are altered (occurs after replication)

What is excision repair?

DNA is scanned for damaged nucleotides- they are removed and replaced with functional nucleotides

Polymerase chain reaction (PCR)

An enzymatic technique for the rapid production of million of copies of a particular stretch of DNA where only a small amount of the parents molecule is available

Chapter 13 Flashcards

(65 cards)