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Transcript

An exploration of the structural composition and functional significance of the DNA helix, the fundamental building block of genetic information.

UNRAVELING THE DNA HELIX: STRUCTURE AND FUNCTION

Class summary Class Topic: DNA Structure and Function Key Points: Historical DNA research figures (Miescher, Avery, Chargaff, Watson, Crick) DNA's double helix structure composed of nucleotides DNA replication process (helicase, primase, DNA polymerase) Mutations (point, frameshift, genetic disorders) Class Activities: Introduction and discussion Visual presentation on DNA structure DNA replication explanation QUIZ

In summary, DNA is the fundamental molecule that carries the genetic information necessary for the growth, development, and functioning of all living organisms. Understanding the structure and role of DNA is crucial for advancing our knowledge of biology, genetics, and various fields of scientific research.

DNA is responsible for the inheritance of traits from parents to offspring, and variations in the DNA sequence contribute to the diversity of living organisms.

Inheritance and Variation

DNA is composed of two strands that form a double helix structure, with each strand made up of nucleotides containing a sugar, a phosphate, and one of four nitrogenous bases: adenine, thymine, guanine, and cytosine.

DNA Structure

DNA (Deoxyribonucleic Acid) is the fundamental genetic material that carries the instructions for growth, development, function, and reproduction in all known living organisms.

What is DNA?

INTRODUCTION TO DNA

James Watson and Francis Crick propose the double helix structure of the DNA molecule, revolutionizing our understanding of genetics.

1953

Erwin Chargaff discovers that the four DNA bases - adenine, thymine, guanine, and cytosine - exist in a specific ratio within a DNA molecule.

1952

Oswald Avery, Colin MacLeod, and Maclyn McCarty demonstrate that DNA, not protein, is the genetic material.

1944

Swiss physician Friedrich Miescher isolates a phosphate-rich substance from the nuclei of white blood cells, which he calls 'nuclein' - the first discovery of DNA.

1869

THE DISCOVERY OF DNA

Erwin Chargaff, a prominent biochemist, made significant contributions to DNA research. Born in 1905 in Austria, he identified the base-pairing rules, known as Chargaff's rules: adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C). His work was crucial to Watson and Crick's 1953 double-helix model, forming a foundation for our understanding of genetics.

ERWIN CHARGAFF

DNA, or deoxyribonucleic acid, is the fundamental molecule that stores and transmits genetic information within living organisms. It is a complex macromolecule composed of two strands that wind around each other, forming a double-helix structure.

DNA AND GENETIC INFORMATION

A (Adenina) T (Timina) G (Guanina) C (Citosina)

"Aliens Took Gabo's Car"

DNA ligase enzyme joins the Okazaki fragments on the lagging strand, creating a continuous DNA molecule by sealing the gaps between the fragments.

DNA Ligase Seals Gaps

On the lagging strand, DNA polymerase synthesizes short, discontinuous DNA fragments called Okazaki fragments, which are later joined together by the enzyme ligase.

Okazaki Fragments Formation

DNA polymerase enzyme recognizes the RNA primers and uses them to initiate the synthesis of new DNA strands, adding complementary nucleotides to the exposed templates.

DNA Polymerase Extends Primers

Primase enzyme creates short RNA primer sequences on the exposed single-stranded DNA, providing a starting point for DNA synthesis.

Primase Synthesizes RNA Primers

Helicase enzyme separates the double-stranded DNA molecule by breaking the hydrogen bonds between the complementary base pairs, creating a replication fork.

Helicase Unwinds DNA

DNA REPLICATION

Effects of Germ Line MutationsNo effect or neutral effect:May occur in non-functional DNAMay not affect amino acid sequence in proteinsExample: Cat with slightly curled ears (no health impact)Detrimental effect:Harm organism's survival and reproductionExample: Marfan syndrome in humans (affects connective tissue)Lethal mutations: Disrupt critical DNA, causing deathBeneficial effect:Help organisms survive and reproduceExample: DDT resistance in insectsRare compared to neutral or detrimental mutations

Two main types:

  1. Somatic mutations: Occur in non-reproductive cells
Example: Yellow color on half of a red tulip petal Not passed to offspring
  1. Germ line mutations: Occur in reproductive cells (eggs and sperm)
Can be passed to offspring Important for large-scale evolution
S

DNA AND MUTATIONS

Info

  • Point Mutations
A single nucleotide in the DNA sequence is substituted with a different nucleotide, leading to changes in the amino acid sequence of the resulting protein.
  • Frameshift Mutations
An insertion or deletion of one or more nucleotides that disrupts the reading frame of the genetic code, resulting in a completely different amino acid sequence downstream.
  • Repeat Expansions
The number of tandem repeats of a DNA sequence is increased, which can lead to the development of genetic disorders such as Huntington's disease and Fragile X syndrome.

DNA AND MUTATIONS

  • Deletion Mutations
One or more nucleotides are removed from the DNA sequence, leading to a loss of genetic information and potential changes in the resulting protein.
  • Insertion Mutations
One or more nucleotides are added to the DNA sequence, disrupting the normal reading frame and potentially causing changes in the resulting protein.

DNA AND MUTATIONS

*National Institutes of Health (NIH)

An inherited blood disorder that causes red blood cells to become sickle or crescent-shaped. This results in reduced oxygen delivery to tissues and frequent episodes of pain.

Sickle Cell Disease

An inherited disorder that causes severe respiratory issues, digestive problems, and fertility problems. It is caused by a mutation in the CFTR gene that disrupts the function of the chloride channels in cells.

Cystic Fibrosis

Characteristics

Genetic Disorder

DNA AND GENETIC DISORDERS

Ongoing research in the field of genetics and genomics has led to significant advancements in areas such as personalized medicine, forensics, and biotechnology. These advancements have the potential to improve human health and enhance our understanding of the natural world.

Advancements in DNA Research

Mutations or changes in the DNA sequence can lead to genetic disorders, such as cystic fibrosis, sickle cell anemia, and Huntington's disease. Understanding the structure and function of DNA is crucial for diagnosing and treating these conditions.

DNA and Genetic Disorders

The process of DNA replication ensures that genetic information is accurately passed on from one generation to the next. This is a critical mechanism for the maintenance and continuity of life.

DNA Replication

The sequence of nucleotides in DNA serves as a blueprint for the synthesis of proteins, which are the building blocks of life. This genetic information is essential for the development and functioning of all living organisms.

Genetic Information Storage

DNA is a double-helix molecule composed of two complementary strands of nucleic acids. The structure of DNA is crucial for its function in storing and transmitting genetic information.

Understanding DNA Structure

CONCLUSION