Biology DNA Replication Flashcards
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Questions and Answers

Why does DNA need to replicate before cells divide?

DNA replicates before a cell divides to give a complete set of genetic instructions to each daughter cell.

What is Deoxyribose?

A sugar derived from ribose by replacing a hydroxyl group with hydrogen.

What is a Nitrogenous base?

An organic molecule that has a nitrogen atom, along with chemical properties of a base. The function of this base is to bond nucleic acids together.

What holds the base pairs in place?

<p>Hydrogen bonds.</p> Signup and view all the answers

What is the function of Helicase?

<p>Unzips the DNA.</p> Signup and view all the answers

What role does DNA polymerase play?

<p>Builder - builds the DNA strand.</p> Signup and view all the answers

What is Primase?

<p>The start, what primes - tells the polymerase where to start.</p> Signup and view all the answers

What is the function of Ligase?

<p>Gluer - what glues the DNA together.</p> Signup and view all the answers

In what direction does polymerase build?

<p>5'-3'</p> Signup and view all the answers

In what direction does polymerase read?

<p>3'-5'</p> Signup and view all the answers

What is the leading strand?

<p>The strand of DNA that is being read and goes from 3'-5'.</p> Signup and view all the answers

What is the lagging strand?

<p>The second strand that is being built on second because it is going from 5'-3'.</p> Signup and view all the answers

What holds complementary bases (A & T) together?

<p>Hydrogen bonds.</p> Signup and view all the answers

What is the first step in DNA replication?

<p>To unzip the double helix.</p> Signup and view all the answers

The two separated strands will act as ____________________ for making the ___________________________________.

<p>Templates, new strands of DNA.</p> Signup and view all the answers

Why is DNA replication said to be semi-conservative?

<p>Because each helix that is created contains one strand from the helix from which it was copied.</p> Signup and view all the answers

What enzyme unwinds the DNA strands?

<p>Helicase</p> Signup and view all the answers

DNA pieces separated by primers in the lagging strand are called?

<p>Okazaki fragments.</p> Signup and view all the answers

List the 4 events that must occur in the lagging strand prior to completing its replication.

<p>Helicase 'unzips' the DNA strand, SSB proteins bond to DNA strands and pull it apart, Primase creates primes and tells DNA where/when to start, DNA polymerase begins to read from 3'-5' and then build 5'-3' on the leading strand.</p> Signup and view all the answers

Study Notes

DNA Replication Overview

  • DNA replication is essential before cell division to ensure each daughter cell receives a full set of genetic instructions.
  • The process is semi-conservative, resulting in each new helix containing one original strand and one newly synthesized strand.

Key Components

  • Deoxyribose: A sugar formed by replacing a hydroxyl group in ribose with a hydrogen atom.
  • Nitrogenous Base: Organic molecules with nitrogen that bond nucleic acids together, crucial for genetic coding.
  • Hydrogen Bonds: Bonds that hold the complementary nitrogenous base pairs (A & T) together.

Enzymes Involved

  • Helicase: Responsible for unzipping the DNA double helix, separating the two strands.
  • DNA Polymerase: Acts as the builder, adding nucleotides to form the new DNA strand.
  • Primase: Initiates DNA synthesis by creating RNA primers that indicate where DNA polymerase should start.
  • Ligase: Functions as the gluer, sealing gaps between DNA fragments to create a continuous strand.

Strand Characteristics

  • Leading Strand: Synthesized continuously in the 5'-3' direction; DNA polymerase reads the template in the 3'-5' direction.
  • Lagging Strand: Synthesized in segments called Okazaki fragments; built in the opposite direction (5'-3'), requiring the polymerase to work backwards, filling gaps as helicase unzips.

DNA Replication Process

  • The first step of DNA replication is to unzip the double helix.
  • The separated strands of DNA serve as templates for synthesizing new strands.
  • Lagging strand replication involves multiple steps: helicase unwinds the DNA, SSB proteins stabilize strands, primase synthesizes RNA primers, and DNA polymerase extends the strand from the primer.

Summary of Important Terms

  • Templates: The separated DNA strands that guide the synthesis of new DNA strands.
  • Okazaki Fragments: Short segments of DNA synthesized on the lagging strand.
  • SSB Proteins: Single-stranded binding proteins that help keep the DNA strands apart during replication.

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Description

This quiz covers essential concepts of DNA replication essential for cell division. Key terms include deoxyribose, nitrogenous bases, and the importance of DNA replication. Perfect for students studying molecular biology and genetics.

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