Results for "Nitrogen"

6.2. Nitrogen Compounds, Polymers and Synthesis: Module 6: Organic Chemistry & Analysis Chemistry OCR A A Level

carbon and nitrogen cycles

Review for Nitrogen and Carbon Cycles

MCAT Organic Chemistry - Nitrogen- and Phosphorus-Containing Compounds

Nitrogen and Phosphorus Assimilation in Plants

Nitrogen cycle

Nitrogen cycle

SCIE- Earth Cycles: Nitrogen Cycle

Carboxylic Acids, Cyclic Carboxylic Acid Derivatives, and Nitrogen-Containing Compounds

Nitrogen cycle

Nonprotein Nitrogen

Renal Function/Non-Protein Nitrogen Activity

biology 2.1Unit 2.1: Mitosis and Meiosis Introduction By the end of this section, you should be able to: Define a chromosome. Define DNA as the genetic material. Define genes. Describe the structure of chromosomes. Describe the components of DNA. Define mitosis and describe its stages. Define meiosis and describe its stages. Relate the events of meiosis to the formation of sex cells. Compare mitosis and meiosis. Chromosomes, Genes, and DNA Almost all the cells of your body—except for mature red blood cells—contain a nucleus, which acts as the control center of the cell. The nucleus holds all the information needed to make a new cell and, ultimately, a new individual. Inside the nucleus are chromosomes, thread-like structures that store genetic information passed from parents to offspring. Chromosomes are made up of DNA (deoxyribonucleic acid), a molecule that carries the instructions needed to make all the proteins in your body. Many of these proteins are enzymes, which control the production of other chemicals and affect everything about how your body functions. Each species has a specific number of chromosomes: Humans have 46 chromosomes (23 pairs). Tomatoes have 24 chromosomes (12 pairs). Elephants have 56 chromosomes (28 pairs). Half of your chromosomes come from your mother, and the other half from your father. These chromosomes are arranged in homologous pairs, meaning they contain matching sets of genes. A karyotype is a special photograph that arranges chromosomes into their pairs. In humans, 22 pairs of chromosomes are called autosomes, which control most body functions. The 23rd pair is the sex chromosomes, which determine whether you are male or female: Females have two X chromosomes (XX). Males have one X and one Y chromosome (XY). DNA Structure DNA is a long, twisted molecule shaped like a double helix (a spiraled ladder). Each strand of DNA is made up of smaller molecules called nucleotides, which consist of: A phosphate group A sugar (deoxyribose) A nitrogen base The four nitrogen bases in DNA are: Adenine (A) → Always pairs with Thymine (T) Cytosine (C) → Always pairs with Guanine (G) Genes are small segments of DNA that carry instructions for making proteins. The sequence of these bases acts like a biological code, directing the cell to create specific proteins. In 1953, James Watson and Francis Crick, using data from Rosalind Franklin’s X-ray photographs, discovered the double-helix structure of DNA. Their discovery led to a huge increase in genetic research, including the Human Genome Project, which mapped all human genes. Mitosis (Cell Division for Growth and Repair) All body cells (somatic cells) divide using mitosis, a type of cell division that creates two identical daughter cells. Mitosis is essential for: Growth (producing new cells). Tissue repair (replacing damaged or old cells). Asexual reproduction (producing offspring with identical DNA). Stages of Mitosis Interphase The cell prepares for division by copying its DNA. Chromosomes are not visible under a microscope. Prophase Chromosomes condense and become visible. The nuclear membrane breaks down. Metaphase Chromosomes line up in the center of the cell. Spindle fibers attach to each chromosome. Anaphase The spindle fibers pull the sister chromatids apart to opposite ends of the cell. Telophase A new nuclear membrane forms around each set of chromosomes. The cell is almost ready to split. Cytokinesis The cytoplasm divides, forming two identical daughter cells. Mitosis is constantly occurring in areas like your skin and bone marrow, where new cells are needed regularly. Meiosis (Cell Division for Reproduction) Unlike mitosis, meiosis occurs only in the reproductive organs (testes in males, ovaries in females) and produces gametes (sperm and egg cells). Gametes have half the number of chromosomes (haploid, n=23) so that when fertilization occurs, the new cell has the correct chromosome number (diploid, 2n=46). Stages of Meiosis Meiosis consists of two rounds of cell division, resulting in four non-identical cells. Meiosis I: Prophase I – Chromosomes pair up and exchange genetic material (crossing over). Metaphase I – Chromosome pairs line up in the center of the cell. Anaphase I – Chromosome pairs separate and move to opposite ends of the cell. Telophase I & Cytokinesis – The cell splits into two haploid daughter cells. Meiosis II (similar to mitosis): 5. Prophase II – Chromosomes condense again. 6. Metaphase II – Chromosomes line up in the center. 7. Anaphase II – Sister chromatids separate and move to opposite sides. 8. Telophase II & Cytokinesis – Four unique haploid gametes are formed. Each gamete is genetically different due to crossing over and random chromosome distribution. Mitosis vs. Meiosis: Key Differences Importance of Mitosis and Meiosis Mitosis ensures that cells grow, repair damage, and replace old cells. Meiosis allows genetic diversity, which is essential for evolution and survival. Summary Chromosomes carry genetic information in the form of DNA. Genes are sections of DNA that code for proteins. Mitosis produces two identical daughter cells for growth and repair. Meiosis creates four non-identical sex cells for reproduction. Mitosis ensures genetic stability, while meiosis introduces genetic diversity

Nitrogenous Waste

nitrogen cycle

Nitrogen Cycle Diagram | Quizlet

The Secret of Life Walter Sutton 1902 Chromosome theory: Genes are located on chromosomes, each gene occupies a specific place (locus) on a chromosome. A gene may exist in several forms (alleles) but each chromosome has just one allele for each gene. Mendel says traits controlled by genes, said they come in contrasting forms - differences in genetic sequence difference. Differences Genes: Mendel - Genes come in contrasting forms Theory - Simply minor changes in nitrogenous bases Dominance & Recessiveness Mendel: Some alleles are or are not expressed. Theory: Dominant Allele codes for function of protein, recessive doesn’t. Segregation Mendel: All plants have two alleles for every trait. Theory: Plants had two chromosomes, which come in pairs. Independent Assortment: Mendel: Segregation of one allele has nothing to do with segregation for other genes. Theory: Separation of chromosomes and chromatids is independent of others in meiosis. Genes on the same chromosome are said to be linked Linked genes are inherited together. They do not undergo independent assortment. Mendel was lucky he had chosen traits from different chromosomes. Thomas Hunt Morgan Fruit flies are ideal for genetic studies. He found that the gray body is dominant to black. Normal wings are dominant to small. Morgan’s Experiment: Crossed purebred gray normal wing flies (GGWW) with purebred black small wing flies (ggww) In F1, all are gray with normal wings (GgWw) He does not go to F2, but he takes F1 and does a test cross. He crossed something with a homozygous recessive. Results: 25% of each, 41.5 GW, 41.5 gw, 8.5 gW, 8.5 Gw X^2 is 43.56 at 3 df Conclusion: The two genes are linked/connected. They do not assort independently. They are on the same chromosome. Linkage Groups Groups of genes that tend to be inherited together. Fruit flies have 4 linkage groups. Fruit flies have 4 pairs of chromosomes. Corn has 10 linkage groups. Corn has 10 pairs of chromosomes. What about the 17% that did assort independently? Crossing over - most have blonde hair blue eyes, but crossing over can create blonde hair brown eyes. Produces individuals with rearranged linkage groups - “Recombinants” Frequency of crossing-over can be used to “map” genes. Sex Determination Autosomes - homologous pairs of chromosomes. Sex chromosomes Not necessarily homologous - X or Y Determines the sex of an individual XX = female XY = male Cannot live without X Sex-linkage Genes on the sex chromosome are “sex-linked” Usually on the X chromosome. Recessive X-linked traits are more often expressed in males. Morgan’s Experiment The gene for eye color is located on the X chromosome. Red eye color is dominant to white. Crossed white eyed male (XrY) with homozygous red eye female (XrXr) Conclusion: All F1 had red eyes - XRXr or XRY Gene Interactions Incomplete Dominance Active allele does not completely compensate for an inactive allele Carnations Red x White → Pink Pink X Pink → 1 Red, 2 Pinks, 1 White Codominance Both alleles are expressed. Cattle White X Red → Roan Roan X Roan → 1 Red, 2 Roan, 1 White Polygenic Inheritance Trait is controlled by many genes Tends to follow a gradient, not either/or Ex

The Secret of Life Walter Sutton 1902 Chromosome theory: Genes are located on chromosomes, each gene occupies a specific place (locus) on a chromosome. A gene may exist in several forms (alleles) but each chromosome has just one allele for each gene. Mendel says traits controlled by genes, said they come in contrasting forms - differences in genetic sequence difference. Differences Genes: Mendel - Genes come in contrasting forms Theory - Simply minor changes in nitrogenous bases Dominance & Recessiveness Mendel: Some alleles are or are not expressed. Theory: Dominant Allele codes for function of protein, recessive doesn’t. Segregation Mendel: All plants have two alleles for every trait. Theory: Plants had two chromosomes, which come in pairs. Independent Assortment: Mendel: Segregation of one allele has nothing to do with segregation for other genes. Theory: Separation of chromosomes and chromatids is independent of others in meiosis. Genes on the same chromosome are said to be linked Linked genes are inherited together. They do not undergo independent assortment. Mendel was lucky he had chosen traits from different chromosomes. Thomas Hunt Morgan Fruit flies are ideal for genetic studies. He found that the gray body is dominant to black. Normal wings are dominant to small. Morgan’s Experiment: Crossed purebred gray normal wing flies (GGWW) with purebred black small wing flies (ggww) In F1, all are gray with normal wings (GgWw) He does not go to F2, but he takes F1 and does a test cross. He crossed something with a homozygous recessive. Results: 25% of each, 41.5 GW, 41.5 gw, 8.5 gW, 8.5 Gw X^2 is 43.56 at 3 df Conclusion: The two genes are linked/connected. They do not assort independently. They are on the same chromosome. Linkage Groups Groups of genes that tend to be inherited together. Fruit flies have 4 linkage groups. Fruit flies have 4 pairs of chromosomes. Corn has 10 linkage groups. Corn has 10 pairs of chromosomes. What about the 17% that did assort independently? Crossing over - most have blonde hair blue eyes, but crossing over can create blonde hair brown eyes. Produces individuals with rearranged linkage groups - “Recombinants” Frequency of crossing-over can be used to “map” genes. Sex Determination Autosomes - homologous pairs of chromosomes. Sex chromosomes Not necessarily homologous - X or Y Determines the sex of an individual XX = female XY = male Cannot live without X Sex-linkage Genes on the sex chromosome are “sex-linked” Usually on the X chromosome. Recessive X-linked traits are more often expressed in males. Morgan’s Experiment The gene for eye color is located on the X chromosome. Red eye color is dominant to white. Crossed white eyed male (XrY) with homozygous red eye female (XrXr) Conclusion: All F1 had red eyes - XRXr or XRY Gene Interactions Incomplete Dominance Active allele does not completely compensate for an inactive allele Carnations Red x White → Pink Pink X Pink → 1 Red, 2 Pinks, 1 White Codominance Both alleles are expressed. Cattle White X Red → Roan Roan X Roan → 1 Red, 2 Roan, 1 White Polygenic Inheritance Trait is controlled by many genes Tends to follow a gradient, not either/or Ex

Organic Nitrogen compounds