DNA Helix Structure and Function.pptx
Diego Fernando Guillen
Created on September 21, 2024
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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:
- Somatic mutations: Occur in non-reproductive cells
- Germ line mutations: Occur in reproductive cells (eggs and sperm)
DNA AND MUTATIONS
Info
- Point Mutations
- Frameshift Mutations
- Repeat Expansions
DNA AND MUTATIONS
- Deletion Mutations
- Insertion Mutations
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