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Evolutionary Genetics

Evolutionary Genetics. Evolutionary Genetics. What are genes, and how do they produce the traits that make a pea plant or a human being? What do we know about the nature of the human genome? What are the basic laws of inheritance?

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Evolutionary Genetics

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  1. Evolutionary Genetics

  2. Evolutionary Genetics • What are genes, and how do they produce the traits that make a pea plant or a human being? • What do we know about the nature of the human genome? • What are the basic laws of inheritance? • What processes bring about the variation we see among members of a species and between parents and offspring?

  3. Evolutionary Genetics • How Genes Work • The gene is that portion of the DNA molecule that carries the codon sequence for a particular protein. FeatureAnalogueMeaning base letter codon word amino acid gene sentence protein

  4. definitions • Particulate • The idea that biological traits are controlled by individual factors rather than by a single all-encompassing hereditary agent. • Genes • Those portions of the DNA molecule that code for a functional product, usually a protein.

  5. definitions • Proteins • Molecules that make cells and carry out cellular functions. • Amino Acids • The chief components of proteins.

  6. definitions • Enzymes • Proteins that control chemical processes. • Chromosomes • Strands of DNA in the nucleus of a cell. • Deoxyribonucleic Acid (DNA) • The molecule that carries the genetic code. • Nucleotide • The basic building block of DNA and RNA, made up of a sugar, a phosphate, and one of four bases.

  7. definitions • Replication • The copying of the genetic code during cell division. • Codon • The three-base sequence that codes for a specific amino acid. Technically, the sequence on the mRNA.

  8. definitions • Protein Synthesis • The process by which the genetic code puts together proteins in the cell. • Messenger Ribonucleic Acid (mRNA) • The molecule that carries the genetic code out of the nucleus for translation into proteins.

  9. definitions • Transcription • The process during which messenger RNA is formed from the DNA code. • Translation • The process during which the mRNA code builds a protein using amino acids supplied by tRNA.

  10. definitions • Transfer Ribonucleic Acid (tRNA) • RNA that lines up amino acids along mRNA to make proteins. • Polygenic • a trait coded for by more than one gene. • Monogenic • A trait coded for by a single gene.

  11. Evolutionary Genetics • An Overview of the Human Genome • As of spring 2003, nearly the entire human genome has been sequenced. • We now have a baseline from which scientists will be able to further research the genome and compare other people and populations.

  12. Evolutionary Genetics • From Gene to Trait • Combinations of alleles give us genotypes. • These genotypes produce a trait. • The observable trait is the phenotype.

  13. The genotype for pea seed color is YG (heterozygous), the phenotype is yellow.  However, the dominant yellow allele does not alter the recessive green one in any way.   Both alleles can be passed on to the next generation unchanged

  14. definitions • Genome • The total genetic endowment of an organism. • Mendelian Genetics • The basic laws of inheritance discovered by Gregor Mendel in the nineteenth century. • Alleles • Variants of a gene. • Genotype • The alleles possessed by an organism.

  15. definitions • Homozygous • Having two of the same allele in a gene pair. • Heterozygous • Having two different alleles in a gene pair.

  16. definitions • Phenotype • The chemical or physical results of the genetic code. • Dominant • The allele of a heterozygous pair that is expressed in the phenotype.

  17. definitions • Recessive • The allele of a pair that is only expressed if homozygous. • Codominant • When both alleles of a pair are expressed in the phenotype. • Environmental • Here, any nongenetic influence on the phenotype. • Mutation • Any mistake in an organism’s genetic code.

  18. Evolutionary Genetics • How Inheritance Works • The variation between parents and offspring is the result of the processes of segregation and fertilization, and variation is the raw material of evolution.

  19. definitions • Mitosis • The process of cell division that results in two exact copies of the original cell. • Gametes • The cells of sexual reproduction, which contain only half the chromosomes of a normal cell.

  20. definitions • Zygote • The fertilized egg before cell division begins. • Segregation • In genetics, the breaking up of allele pairs in the production of gametes. • Meiosis • The process of cell division in which gametes are produced.

  21. definitions • Independent Assortment • When genes on different chromosomes segregate to gametes independently of one another. • Linkage • When genes occur on the same chromosome and are inherited together. • Crossing Over • When sections of chromosomes switch between chromosome pairs during meiosis. • Recombination • The exchange of genetic material between pairs of chromosomes during meiosis.

  22. Evolutionary Genetics • Summary • Evolutionary change is at its most basic level genetic change. • Segregation, independent assortment, crossing over, and mutation produces new genetic variation.

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