Unit 2: Biological basis of life, heredity, and genetics

Transcription

1 Unit 2: Biological basis of life, heredity, and genetics 1

2 Issues with Darwin's Evolutionary Theory??? 2

3 Cells - General Composition Organelles - substructures in the cell which do different things involved in the function of the cell, e.g. protein synthesis, nutrient conversion, energy storage and release, waste disposal, etc. Important Organelles Nucleus - houses both DNA and RNA molecules Ribosomes - organelles in part made up of RNA; involved in protein synthesis Mitochondria - powerhouse of the cell - produces energy; think: cell's engines; also has DNA: mtdna 3

4 Cells - Two types Somatic cells - body tissues eg organs, brain, bone, and muscle Sex cells (gametes) - unites with another gamete from another individual which forms a zygote. They transmit genetic information from parents to offspring. Zygote - Potential to develop into a new organism, contains all the chromosomes (46 for us) 4

5 Proteins Function - attach to various molecules to perform different functions Hemoglobin (Hb) - binds w/ oxygen and transports it around the body Collagen - (tissue composition) - most common protein in the body Enzymes - regulate chemical reactions; E.g., digestive enzyme lactase breaks down lactose into simpler sugars. Hormones - affect different tissues and organs. Insulin is made by specialized cells in the pancreas causes liver cells to absorb glucose from blood 5

6 DNA DNA (deoxyribonucleic acid) - Double-stranded host of the genetic code RNA (ribonucleic acid) - single-stranded molecule Three different compositions: messenger (mrna) transfer (trna) DNA + RNA houses genetic information responsible controlling the cell's functions 6

7 DNA Structure Nucleotides - 1. a sugar (deoxyribose), 2. a phosphate group, and 2.1 of 4 nitrogenous bases: Bases - adenine (A), thymine (T), guanine (G), and cytosine (C) Bonds: AT and GC Double helix Nucleotides: sugars and phosphates = ladder sides; bonded bases = rungs Codon = Triplet - 3 bases specify a given amino acid (e.g., CGA specifies arginine) 7

8 Protein Synthesis, an activity performed by DNA Starts with messenger RNA takes the copied DNA message out of the nucleus RNA - single-stranded and contains a different sugar and base uracil (U) instead of thymine. -Adenine usually binds with thymine but it also binds with uracil mrna is generated and peels away from DNA to leave the nucleus 8

9 Protein Synthesis DNA directs the assembly of proteins in cells Proteins structure - chains of amino acids Amino acids - 20 different amino acids 12 produced by cells but 8 are obtained by diet in humans. 9

10 Protein Synthesis, an activity performed by DNA mrna is decoded in ribosomes - mrna have triplets or codons code for specific amino acids trna goes to ribosomes where amino acids join wrt mrna codons potentially makes a protein or protein part. 10

11 Genes - structures and functions "a sequence of DNA bases that specifies the order of amino acids in an entire protein, a portion of a protein, or any functional product [like RNA]" (58p) Structure Composition: 100s-1000s of nucleotide bases Organization: coding and noncoding segments Function Regulatory genes - to switch on/off other DNA segments. E.g., Hox genes - direct body plan development and embryonic tissue segmentation. 11

12 Chromosomes Structure - Coiled DNA + proteins Locus - location of a gene on a chromosome. Types Autosomes - also paired and abnormal numbers of sex chromosomes can cause sterility or non-fatal consequences. Sex chromosomes = X and Y - X chromosome functions like autosomes; Y chromosome denotes an organism's sex in mammals. 12

13 Chromosomes Humans have 46 chromosomes, whereas gorillas and chimpanzees have 48. Karyotype - Chromosomes are visible during cell division 13

14 DNA replication -before cell division in the nucleus -Replication starts when a DNA molecule unzips exposing the bases -free-floating nucleotides pair with complementary bases --formulation of two new DNA molecules which packaged up to form the sets of chromosomes allotted to each daughter cell 14

15 DNA replication - Making copies of itself Enzymes - catalysts - breaks DNA base bonds which are able to connect to other DNA bases on DNA in the nucleus. Bonds: AT and GC - connects to another DNA strand to form two new DNA molecules A Train Goes Choo-choo Apples on Trees and Cars in Garage 15

16 Cell Division - Mitosis and meiosis Mitosis - creation of two cells from one -Somatic cells (muscles, brain, blood cells, etc) Phase 1: DNA replication - 46 single-stranded chromosomes become 46 double-stranded chromosomes. Phase 2: Cell division - 46 double-stranded chromosomes are split and make up the genetic material in two daughter cells. -Daughter cells are identical - 46 single-stranded 16

17 Cell Division - Meiosis Gametes -Two divisions - a reductive one a second cell division. Reductive division - similar to the process in mitosis; results in two cells each containing 23 double-stranded chromosomes. Second division - 23 double-stranded chromosomes align and pulled apart at the centromere also similar to mitosis; results with four daughter cells all possessing the haploid number of chromosomes. Haploid number = n = number of chromosomes in the gametes. For humans it is n =

18 Anthropology connections The Human Genome Project was made possible. -sequenced all 30,000 genes humans have in their genome. The Neandertal Genome has also been sequenced and same with the Chimpanzee genome other species as well. -compare and contrast the characteristics found among the genomes in order to better understand our own evolutionary history. Stem cells - Undifferentiated cells > able to divide and differentiate into other cell types (e.g., a cell that could become a blood, liver, or kidney cell) Need more background but here s a non-terrible video. 18