ANTH 204 ??? Week ??? Cavefish Biological basis for life Components of a cell Made up of proteins Nucleus- control center Mitochondria- powerhouse Ribosomes- manufactures proteins Types of cells in human Somatic cell- body cells comprise most tissues, bone, skin, brain, muscle Gametes- reproductive cells Chromosomes 22 autosomes and 2 sex chromosomes Human Cells Somatic are diploid 23 pairs= 46 chromosomes Gametes are haploid 23 chromosomes Each chromosome= 100?s and 1000?s of genes DNA Nuclear Contained within nucleus Make up chromosomes Complete set is the genome Mitochondrial In mitochondria Inherited from mother More prevalent in humans Deoxyribonucleic Acid Control center of cell Gene material Structure Sugar/Phosphate backbone Nucleotide Double helix Replication- during meiosis and mitosis Nucleotides Purines- adenine and guanine Pyrimidines- thymine and cytosine Base Pairing rule- A=T, C=G Cell division Mitosis Somatic cell division One cell- 2 daughter cells, 23 chromosomes each, diploid to diploid Wound healing Cell replacement Meosis Gametes 2 cycles One cell- 4 daughter cells Sex cell Diploid to haploid Steps of Mitosis 1.) 46 chromosomes line up in the center of the cell 2.) Chromosomes are pulled apart at the centromere 3.) The strands separate and are pulled to opposite ends 4.) Cell splits creating 2 cells Steps of Meiosis Oogenesis Females 1 round= 1 egg and 3 polar bodies Occurs before birth Spermogenesis Males 1 round= 4 sperm Starts at puberty and continues through life Evolutionary Significance of Meiosis Meiosis increases gene variation at a faster rate than mutation Offspring in sexual reproduction Protein Synthesis Proteins= chains of amino acids Transcription- DNA to RNA Translation- RNA to proteins Genes- A segment of a chromosome whose DNA codes for a specific protein Ribonucleic Acid Ribose Single Stranded Reads the DNA code Uracil not thymine 3 types- Transfer, Ribosomal, Messenger RNA rRNA Forms ribosomes Ribos anchor mRNA for protein synthesis tRNA Attaches individual amino acids Carries amino acid to ribos mRNA Transcription In nucleus DNA unwinds Single stranded mRNA form Translation mRNA moves out of nucleus mRNA processing Introns are exised- non-coding Exons are coded Amino Acid Anchored by ribosomes tRNA brings amino acid codons/anticodons Codons 3 nucleide sequence Each codon= amino acid (20) Codons pair with anticodons on tRNA Wobble position Proteins- chain of amino acids Functions Structure- Keratin and Collagen Hormones- myosis and actin= muscle contractions Enzymes- Energy activation Length size, function and shape depend on order of amino acids Genes and Inheritance of Traits Gene- segment of DNA that codes for a protein Alleles- alternate forms of gene Mendel?s 1st Principle Segregation Genes are discreet units Genes occur in pairs 1 gene comes from each parent Genotype= genetic makeup Plant height 2 possible (short/tall) 2 alleles T or t Dominance- allele that is observed in the heterozygote state Recessive- allele that is observed in homozygous recessive 3 possible genotypes Alleles= T or t TT= homozygous dominant Tt= heterozygous tt= homozygous recessive Phenotype= appearance Observable or detectable Tall or Short 2nd Principle Independent assortment Traits assort independently Presence of does not affect presence of 2 Mendilian traits Only certain traits follow rules Simple traits Qualitative traits 1 gene= one trait
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