Genetics and DNA

Learning Objectives

By the end of this lesson, the learner should be able:

• Describe the structure and features of the nuclear membrane
• List the contents of the nucleus
• Explain the organization of the DNA molecule within the nucleus
• Describe the process of DNA replication

Introduction

Deoxyribonucleic acid (DNA):

• The genetic material
• Molecule that stores information on its sequence of nucleotides, that instructs a cell to how synthesize certain proteins
• The proteins coded for on DNA function as:
  • Enzymes
  • Blood proteins
  • Structural proteins of muscle and connective tissue
  • Antibodies
  • Cell membrane components

Genetic Information

• Genetic information: Instructions to tell cells how to construct proteins; stored in D N A sequence
• Gene: Sequence of D N A that contains information for making 1 protein
• Genome: Complete set of genetic information in a cell
• Exome: Small portion of the genome that codes for proteins
• Gene Expression: Control of which proteins are produced in each cell type, in what amount, and under which circumstances

Structure of D N A

Double helix: 

• Double-stranded molecule, consisting of 2 chains of nucleotides
• DNA resembles ladder twisted into a spiral
• Backbone of each strand is a sugar-phosphate chain
• Bases from the 2 complementary strands are linked together by hydrogen bonds: C  ̶  G, A  ̶  T

Nucleotides are building blocks of DNA, and consist of:

• 5-carbon sugar, deoxyribose
• A phosphate group
• A nitrogenous base (adenine, cytosine, guanine, or thymine)

Nucleotide Structure

The Structure of D N A

D N A and Chromosome Structure

• 2 nucleotide chains of the double helix are antiparallel: point in opposite directions
• Complementary Base Pairing:  Bases pair only with specific (A ̶ T and C ̶  G)
• A and G are purines, and C and T are pyrimidines
• A purine only binds to a specific pyrimidine
• DNA wraps around histone proteins to give double helix a compact form in chromatin and chromosomes

D N A and Chromosome Structure

D N A Replication

When cell divides, each daughter cell must receive identical D N A

DNA Replication: process that produces an exact copy of a D N A molecule; occurs during interphase

Steps in D N A replication:

• • Hydrogen bonds break between base pairs
  • Strands unwind and separate
  • New nucleotides pair with exposed bases, under direction of D N A polymerase
  • Other enzymes connect new sugar-phosphate backbone

DNA Helicase: Unzips and Unwinds DNA strand

DNA Primase: Generates RNA Primer. Act as a template for starting point of DNA Replication

DNA Polymerase: Synthesize new DNA molecules by adding nucleotides to leading and lagging DNA strands in 5'€3' direction

Topoisomerase: Prevents supercoiling

DNA Ligase: Joins DNA fragments together by forming phosphodiester bonds between nucleotides

Okazaki Fragment: Short, newly synthesized DNA fragments that are formed on the lagging strand

Single Strand Binding Protein: Stabilize structure during replication

Leading Strand: Replicated continuously in the 3' to 5' direction

Lagging Strand: Replicated discontinuously in short sections

Learning Objectives

By the end of this lesson, the learner should be able:

• Describe the structure and features of the nuclear membrane
• List the contents of the nucleus
• Explain the organization of the DNA molecule within the nucleus
• Describe the process of DNA replication

Introduction

Deoxyribonucleic acid (DNA):

• The genetic material
• Molecule that stores information on its sequence of nucleotides, that instructs a cell to how synthesize certain proteins
• The proteins coded for on DNA function as:
  • Enzymes
  • Blood proteins
  • Structural proteins of muscle and connective tissue
  • Antibodies
  • Cell membrane components

Genetic Information

• Genetic information: Instructions to tell cells how to construct proteins; stored in D N A sequence
• Gene: Sequence of D N A that contains information for making 1 protein
• Genome: Complete set of genetic information in a cell
• Exome: Small portion of the genome that codes for proteins
• Gene Expression: Control of which proteins are produced in each cell type, in what amount, and under which circumstances

Structure of D N A

Double helix: 

• Double-stranded molecule, consisting of 2 chains of nucleotides
• DNA resembles ladder twisted into a spiral
• Backbone of each strand is a sugar-phosphate chain
• Bases from the 2 complementary strands are linked together by hydrogen bonds: C  ̶  G, A  ̶  T

Nucleotides are building blocks of DNA, and consist of:

• 5-carbon sugar, deoxyribose
• A phosphate group
• A nitrogenous base (adenine, cytosine, guanine, or thymine)

Nucleotide Structure

The Structure of D N A

D N A and Chromosome Structure

• 2 nucleotide chains of the double helix are antiparallel: point in opposite directions
• Complementary Base Pairing:  Bases pair only with specific (A ̶ T and C ̶  G)
• A and G are purines, and C and T are pyrimidines
• A purine only binds to a specific pyrimidine
• DNA wraps around histone proteins to give double helix a compact form in chromatin and chromosomes

D N A and Chromosome Structure

D N A Replication

When cell divides, each daughter cell must receive identical D N A

DNA Replication: process that produces an exact copy of a D N A molecule; occurs during interphase

Steps in D N A replication:

• • Hydrogen bonds break between base pairs
  • Strands unwind and separate
  • New nucleotides pair with exposed bases, under direction of D N A polymerase
  • Other enzymes connect new sugar-phosphate backbone

DNA Helicase: Unzips and Unwinds DNA strand

DNA Primase: Generates RNA Primer. Act as a template for starting point of DNA Replication

DNA Polymerase: Synthesize new DNA molecules by adding nucleotides to leading and lagging DNA strands in 5'€3' direction

Topoisomerase: Prevents supercoiling

DNA Ligase: Joins DNA fragments together by forming phosphodiester bonds between nucleotides

Okazaki Fragment: Short, newly synthesized DNA fragments that are formed on the lagging strand

Single Strand Binding Protein: Stabilize structure during replication

Leading Strand: Replicated continuously in the 3' to 5' direction

Lagging Strand: Replicated discontinuously in short sections

Learning Objectives

By the end of this lesson, the learner should be able:

• Describe the structure and features of the nuclear membrane
• List the contents of the nucleus
• Explain the organization of the DNA molecule within the nucleus
• Describe the process of DNA replication

Introduction

Deoxyribonucleic acid (DNA):

• The genetic material
• Molecule that stores information on its sequence of nucleotides, that instructs a cell to how synthesize certain proteins
• The proteins coded for on DNA function as:
  • Enzymes
  • Blood proteins
  • Structural proteins of muscle and connective tissue
  • Antibodies
  • Cell membrane components

Genetic Information

• Genetic information: Instructions to tell cells how to construct proteins; stored in D N A sequence
• Gene: Sequence of D N A that contains information for making 1 protein
• Genome: Complete set of genetic information in a cell
• Exome: Small portion of the genome that codes for proteins
• Gene Expression: Control of which proteins are produced in each cell type, in what amount, and under which circumstances

Structure of D N A

Double helix: 

• Double-stranded molecule, consisting of 2 chains of nucleotides
• DNA resembles ladder twisted into a spiral
• Backbone of each strand is a sugar-phosphate chain
• Bases from the 2 complementary strands are linked together by hydrogen bonds: C  ̶  G, A  ̶  T

Nucleotides are building blocks of DNA, and consist of:

• 5-carbon sugar, deoxyribose
• A phosphate group
• A nitrogenous base (adenine, cytosine, guanine, or thymine)

Nucleotide Structure

The Structure of D N A

D N A and Chromosome Structure

• 2 nucleotide chains of the double helix are antiparallel: point in opposite directions
• Complementary Base Pairing:  Bases pair only with specific (A ̶ T and C ̶  G)
• A and G are purines, and C and T are pyrimidines
• A purine only binds to a specific pyrimidine
• DNA wraps around histone proteins to give double helix a compact form in chromatin and chromosomes

D N A and Chromosome Structure

D N A Replication

When cell divides, each daughter cell must receive identical D N A

DNA Replication: process that produces an exact copy of a D N A molecule; occurs during interphase

Steps in D N A replication:

• • Hydrogen bonds break between base pairs
  • Strands unwind and separate
  • New nucleotides pair with exposed bases, under direction of D N A polymerase
  • Other enzymes connect new sugar-phosphate backbone

DNA Helicase: Unzips and Unwinds DNA strand

DNA Primase: Generates RNA Primer. Act as a template for starting point of DNA Replication

DNA Polymerase: Synthesize new DNA molecules by adding nucleotides to leading and lagging DNA strands in 5'€3' direction

Topoisomerase: Prevents supercoiling

DNA Ligase: Joins DNA fragments together by forming phosphodiester bonds between nucleotides

Okazaki Fragment: Short, newly synthesized DNA fragments that are formed on the lagging strand

Single Strand Binding Protein: Stabilize structure during replication

Leading Strand: Replicated continuously in the 3' to 5' direction

Lagging Strand: Replicated discontinuously in short sections

Learning Objectives

By the end of this lesson, the learner should be able:

• Describe the structure and features of the nuclear membrane
• List the contents of the nucleus
• Explain the organization of the DNA molecule within the nucleus
• Describe the process of DNA replication

Introduction

Deoxyribonucleic acid (DNA):

• The genetic material
• Molecule that stores information on its sequence of nucleotides, that instructs a cell to how synthesize certain proteins
• The proteins coded for on DNA function as:
  • Enzymes
  • Blood proteins
  • Structural proteins of muscle and connective tissue
  • Antibodies
  • Cell membrane components

Genetic Information

• Genetic information: Instructions to tell cells how to construct proteins; stored in D N A sequence
• Gene: Sequence of D N A that contains information for making 1 protein
• Genome: Complete set of genetic information in a cell
• Exome: Small portion of the genome that codes for proteins
• Gene Expression: Control of which proteins are produced in each cell type, in what amount, and under which circumstances

Structure of D N A

Double helix: 

• Double-stranded molecule, consisting of 2 chains of nucleotides
• DNA resembles ladder twisted into a spiral
• Backbone of each strand is a sugar-phosphate chain
• Bases from the 2 complementary strands are linked together by hydrogen bonds: C  ̶  G, A  ̶  T

Nucleotides are building blocks of DNA, and consist of:

• 5-carbon sugar, deoxyribose
• A phosphate group
• A nitrogenous base (adenine, cytosine, guanine, or thymine)

Nucleotide Structure

The Structure of D N A

D N A and Chromosome Structure

• 2 nucleotide chains of the double helix are antiparallel: point in opposite directions
• Complementary Base Pairing:  Bases pair only with specific (A ̶ T and C ̶  G)
• A and G are purines, and C and T are pyrimidines
• A purine only binds to a specific pyrimidine
• DNA wraps around histone proteins to give double helix a compact form in chromatin and chromosomes

D N A and Chromosome Structure

D N A Replication

When cell divides, each daughter cell must receive identical D N A

DNA Replication: process that produces an exact copy of a D N A molecule; occurs during interphase

Steps in D N A replication:

• • Hydrogen bonds break between base pairs
  • Strands unwind and separate
  • New nucleotides pair with exposed bases, under direction of D N A polymerase
  • Other enzymes connect new sugar-phosphate backbone

DNA Helicase: Unzips and Unwinds DNA strand

DNA Primase: Generates RNA Primer. Act as a template for starting point of DNA Replication

DNA Polymerase: Synthesize new DNA molecules by adding nucleotides to leading and lagging DNA strands in 5'€3' direction

Topoisomerase: Prevents supercoiling

DNA Ligase: Joins DNA fragments together by forming phosphodiester bonds between nucleotides

Okazaki Fragment: Short, newly synthesized DNA fragments that are formed on the lagging strand

Single Strand Binding Protein: Stabilize structure during replication

Leading Strand: Replicated continuously in the 3' to 5' direction

Lagging Strand: Replicated discontinuously in short sections