Presentation on theme: "Genetics Unit –Cell Reproduction Asexual reproduction – Binary fission – Mitosis Sexual reproduction – Meiosis Meiosis I, meiosis II gametes."— Presentation transcript:
Genetics Unit –Cell Reproduction Asexual reproduction – Binary fission – Mitosis Sexual reproduction – Meiosis Meiosis I, meiosis II gametes
Genetics Unit – Chpt. 9 Punnett Squares Probability Punnett square – Monohybrid, dihybrid – Dominant, recessive, homozygous, heterozygous – Incomplete, Co-dominant and x-linked traits
Genetics Unit – Gregor Mendel Father of modern genetics – 1 st to apply mathematics of statistics to crosses, 1840’s, Austria, monastery gardens Genetics field of biology devoted to understanding HOW characteristics are transmitted from parents to offspring Heredity the transmission of characteristics from parents to offspring
Mendel’s Laws 1. Law of Segregation : pair of factors is separated during the formation of gametes 2. Law of Independent Assortment : factors for different traits are distributed to gametes independently
Molecular Genetics Molecular genetics is the study of the structure and the function of the chromosomes and the genes. This would include mapping the genome, locating markers for diseases, making proteins and technology like cloning, genetic engineering and DNA fingerprinting.
Genetics Unit- Nucleic acids and protein synthesis DNA – organic compound made of repeating subunits called nucleotides. A DNA nucleotide has three parts – Sugar (deoxyribose) – Phosphate group (PO 4 ) – Nitrogen containing base (A,T,C,G) Adenine, thymine, cytosine and guanine
Watson and Crick James Watson and Francis Crick are the discoverers of the DNA double helix 1953, Cambridge, England Built a wooden model based on other research, including x-ray crystallography Other scientists involved where; Rosalind Franklin, Linus Pauling, Maurice Wilkins
Complementary Base Pairing Because of the exact shape and size of the DNA, the sugars and phosphates make the ‘sides of the ladder’ and the nitogenous bases make the ‘rungs. A and G (purines) are larger than C and T (pyrimidines) MUST PAIR UP with A-T and C-G so all rungs are the same length. A-T and C-G are hydrogen bonds.
DNA Replication During the S portion of interphase All DNA is copied so there are 2 complete sets, one set for each new cell p.188 DNA helix is untwisted by helicase enzyme DNA polymerase enzymes add new bases Get two identical strands of double helix
Mutations Change in the nucleotide sequence 1 error per 100,000 bases, VERY accurate Proof reading enzymes correct – allowing for 1 per billion nucleotide average Changes can also be caused by ‘mutagens’ like chemicals and radiation
RNA Single stranded Copies of DNA Can leave nucleus Takes DNA code to the ribosomes so that proteins can be manufactured Contains the sugar ribose, and the bases A, C, G and U (uracil). There is no T in RNA
RNA Transcription DNA is opened, only at the gene/region of interest. A “copy” is made by matching A-U and C-G The mRNA (leaves) and the DNA reseals. Original DNA is intact, undiluted, unchanged and in the nucleus. RNA strand is EDITTED to delete unnecessary regions called introns and the ‘good regions are spliced together (exons) and make the final mRNA
Types of RNA mRNA – messenger, carries DNA info from the nucleus to the cytoplasm tRNA – transfer (transport), short chain, highly folded, binds specific amino acids to the mRNA rRNA – ribosomal, most abundant version, ribosomes are made of protein and rRNA.
Translation of RNA into protein “protein synthesis” mRNA is read by the ribosome in chunks Each region of 3 bases on the mRNA is called a codon (p.194) Each codon signals a specific amino acid If you put the right amino acids in the right order you have ….. A protein.
Remember….. “Every thing, in every cell, is either made of a protein or run by a protein.” Functions of proteins include – muscle, structure, storage, immunity, identification, communication, and transport
Genetics Unit – Chpt 11 Gene Expression Gene expression – all genes are not ‘on’ all the time. The process of turning on the right genes at the right time is gene expression Genome – complete set of genetic material for an individual
Operons Found in bacteria cells – very different machinery from our cells Jacob and Monad Operon = structural genes + promoter + operater Operons can – 1. repress protein production (repressor) – 2. activate protein production (inducer)
More Chpt. 11 vocabulary Cell differentiation – the development of cells that have specialized functions ( muscle, nerve, skin, etc.) Morphogenesis – the formation of an organism, getting the tissues and organs in the right places Homeotic genes – regulatory genes that determine where anatomical features go
CANCER Malignant tumors are usually called cancer. Tumor – abnormal proliferation of cells, uncontrolled cell division Benign tumor – mass of cells Malignant tumor – uncontrolled cell division that invades and destroys healthy tissue Metastasis – spread of cancer to new sites
Cancer continued Oncogenes – genes that “cause” cancer, code for uncontrolled cell growth Tumor suppressor genes – code for proteins that prevented uncontrolled cell division. Mutation of tumor suppressor genes cause a predisposition to cancers Some cancers are now directly linked to viruses as their “cause”.