DNA and Genetics

DNA and Genetics : 

DNA and Genetics Anatomy and Physiology

What is DNA? : 

What is DNA? Contains the genetic information for making all the proteins in the cell

In the Beginning….. : 

In the Beginning….. The world of science debated on what the genetic material was Some thought it was protein Others believed it was DNA

Scientists looked for a Genetic “Factor” : 

Scientists looked for a Genetic “Factor” 1928 – Frederick Griffith’s “Transforming Factor” Experiment – he injected mice with various strains of bacteria, some heat-treated; he wanted to know what did it. 1944 – Oswald Avery and colleagues focused on two of the genetic factor candidates: protein and DNA – he repeated Griffith’s experiment but modified it by adding Proteases and DNases.

Final Proof that DNA is the Genetic Material : 

Final Proof that DNA is the Genetic Material 1952 – Hershey-Chase Experiment Virus = DNA (inside) + protein (outside) Conclusion: DNA was the genetic material due to viruses passing on DNA for reproduction

The DNA “Twist” : 

The DNA “Twist” DNA is a double helix Every 10 nucleotides there is a 360 degree rotation The structure of DNA is accredited to James Watson, Francis Crick and Rosalind Franklin

Frame of Reference : 

Frame of Reference Where is the DNA located in eukaryotes? Prokaryotes?

The Structure of DNA : 

The Structure of DNA DNA = deoxyribonucleic acid DNA is a polymer built up from monomers Monomers are called nucleotides

The Structure of DNA Continued : 

The Structure of DNA Continued Phosphate Group – provides the “backbone” of DNA 5’ end (5 prime end) Sugar – called a deoxyribose; also part of the DNA “backbone” 3’ end (3 prime end) Backbone of DNA called the sugar-phosphate backbone

Nitrogenous Bases of DNA : 

Nitrogenous Bases of DNA Nitrogenous bases of DNA Two Types Pyrimidines  Thymine (T)  Cytosine (C) Purines  Adenine (A)  Guanine (G) Purines are double ringed, pyrimidines are single ringed

Pairing of Bases : 

Pairing of Bases In DNA G hydrogen bonds with C T hydrogen bonds with A C G G T A C A T G C A T A G C C A T G T A C G T A T

Let’s Put the Structure Together : 

Let’s Put the Structure Together Notice the following: 5’ and 3’ ends A:T and G:C Hydrogen bond numbers Sugar-phosphate backbone Two strands are antiparallel

So how do we pass along our traits? : 

So how do we pass along our traits? At conception, the new human is called a zygote. Each zygote contains 46 chromosomes, 23 that came from its mother and 23 that came from its father. As cells multiply, each cell will contain 46 chromosomes – 23 pairs.

Mitosis : 

Mitosis

Meiosis : 

Meiosis We will go to the University of Leicester’s website for this diagram.

Words to Know : 

Words to Know Gene – the portion of a DNA molecule that contains the information for producing one kind of protein molecule. Chromosome – location of the DNA molecules (thus, the genes) Homologous pairs – chromosomes from both parents that contain similar genetic material (for example, hair color, eye color, attached ear lobes, rolling tongue)

Words to Know : 

Words to Know Alleles – genes that occupy corresponding positions on homologous chromosomes Homozygous – zygote that receives a pair of identical alleles Heterozygous – zygote contains a gene pair whose alleles differ

Words to Know : 

Words to Know Genotype – the combination of genes present in a zygote and its subsequent daughter cells Phenotype – the appearance of the individual that develops as a result of the ways the genes are expressed Dominant – gene of the pair that is expressed while its allele is not Recessive – gene that is not expressed while its allele is expressed

Dominant vs Recessive : 

Dominant vs Recessive Full lips Thin lips Dark hair Light hair Free ear lobes Attached ear lobes Bridge of nose convex Bridge of nose concave Dark eyes (brown iris) Light eyes (blue iris) Farsightedness Normal vision Astigmatism Normal vision Polydactyly Normal # of fingers, toes Freckles Lack of freckles Rolling tongue into a U Inability to roll tongue Dimples in cheeks Lack of dimples Normally-arched feet Flatfeet

Incomplete Dominance : 

Incomplete Dominance Sickle-cell anemia Green eyes ??? The jury is still out Wavy hair The slightly different Co-dominance Blood types – equally dominant genes Polygenic Inheritance Traits that are controlled by multiple genes such as body stature and the concentration of skin pigment

Gender Chromosomes : 

Gender Chromosomes XX – female XY - male Sex-linked Inheritance Traits determined by recessive genes located on X chromosomes Examples are color blindness and hemophilia

Chromosome Disorders : 

Chromosome Disorders Characterized by the presence of abnormal numbers of chromosomes (any number other than 46) If one pair of homologous chromosomes fails to separate during meiosis, both move into one daughter cell. If non-disjunction occurs during oogenesis, some of the resulting egg cells will have 2 X chromosomes and some have none.

X-Chromosome Disorders : 

X-Chromosome Disorders XXY – Klinefelter’s Syndrome – male sex organs (sterile), tall stature, feminine musculature, partial development of breasts XXX – relatively normal female, sometimes sterile XO – Turner’s Syndrome – female, fails to mature reproductively, short stature

Autosomal Disorders : 

Autosomal Disorders Down’s Syndrome – Trisomy 21 – mental disabilities, facial appearance, heart defects, short hands Edward’s Syndrome – Trisomy 18 – heart and kidney defects Patau’s syndrome – Trisomy 13 – blindness, heart defects, seldom lives longer than a few weeks Cri du chat (cat’s cry) – 5p- (5 p minus) missing part of chromosome 5

Other Hereditary Disorders : 

Other Hereditary Disorders Cystic fibrosis – thick mucus interfering with digestion and breathing Cretinism – lack of thyroid secretion Gout – accumulation of uric acid in the blood Huntington’s chorea – twitching, deterioration of mental function Marfan’s syndrome – long extremities, dislocation of lenses, heart defects Diabetes insipidus – production of large volumes of dilute urine, consequent dehydration Phenylketonuria (PKU) – inability to metabolize an amino acid called phenylalanine (in Diet Coke) – causes brain damage Muscular Dystrophy – atrophy of muscles Tay-Sachs Disease – causes blindness