BIO 120- Notes 3
BIO 120- Notes 3 Bio 120-001
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This 4 page Class Notes was uploaded by Whitney Marie Halaby on Sunday February 28, 2016. The Class Notes belongs to Bio 120-001 at Towson University taught by Partain in Spring 2015. Since its upload, it has received 30 views. For similar materials see Principals of biology in Biology at Towson University.
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Date Created: 02/28/16
BIO 120 Notes 2/19/162/16/16 Chromosomes: a structural unit containing parts of all of an organisms genome – consisting of DNA and its associated proteins o Pairs: one pair comes from dad, one comes from mom in sexually producing organisms > these are called homologous pairs Chromatids: one of two identical strands of chromatin OR half of replicated chromosome genes Genes: a segment of chromosome that carries specific information about a trait, contains info about anything your body needs, some genes carry mutations that cause disease or change traits instructions are carried by DNA (instructions for building all of the proteins that cells require each of these cells has a complete set of instructions (your genome) DNA (deoxyribonucleic acid): information molecules that are stored in the nucleus of eukaryotic cells & in the cytoplasm of prokaryotic cells composed of nucleotides o Only 2% of DNA codes for genes o 98% prevents genes from unraveling which helps mitosis Nucleotides: has 3 parts, phosphate, sugar (deoxyribose for DNA, and one of the 4 bases Adenine, Guanine, Thymine and Cytosine Complementary Bases: o Specific pattern of bases that connects 2 strands, called complementary base pairs that look like a spiral staircase o A T o C G o When one strand of DNA is known the other can be deciphered o One Side: ATCGGCA Other Side: TAGCCGT DNA Management of Info o Stores info o Protein synthesis o Duplicates information when needed o Transfers and decodes information when needed Protein Synthesis o RNA: only has one strand and has a different group of nucleotides – a molecules that carries information about proteins o Is a 2 stage process o 1. Transcription: copying of DNA gene into RNA o 2 Translation: RNA is translated into a protein (an enzyme is made) Mitosis: o Takes place in a body cell (somatic cell) o Happens all over the body except for the gonads o Responsible for growth and repair o Produces identical copies of parent cells o Asexual reproduction o 3 stage process called the Cell Cycle o 1. Interphase: DNA is copied, protein synthesis takes place, DNA replication takes place, cells can commit suicide, chromosomes are uncondensed (this is when chromosomes can be used), very time consuming – cells spend most of their time in interphase o 2. Mitosis: DNA splits equally – chromosomes become condensed/movable o Cytokinesis: parent cells divide in half Meosis o Begins at the end of interphase when there is double the DNA o Happens when diploid cells have been reduced to haploid cells o Meosis 1: homologous pairs split independently o Meosis 2: sister chromatids separate from each other o At the beginning there are diploid cells and the end there are 4 unique haploid daughter cells o Sex cells (germ cells) o Making gametes (eggs & sperm) o Testicles and ovaries are gonads o Unique cell production o DNA Replication: precedes cell division but occurs simultaneously o Each gamete is unique – 8 million gametes possible per person Life of Cells o Brain and nerve cells last a life time – drugs can kill brain cells o Bone marrow: divides rapidly – 20,000 new cells per minute where blood cells are made o Leaf cells: divide as young leaves, then stop dividing and increase in size Cancer o Unregulated cell growth (2 part failure) 1. When a cell should commit suicide but does not 2. Uncontrolled cell division o a benign tumor is unmutated cells o cancer is mutated cells o Tumor suppressor: mutation keeps growing o DNA replication can correct mutations o Metastasis: causes cells to migrate /move around o Cancer cells are immortal o Sometimes suppressor genes are unable to turn off growth, repair DNA, or cause cell suicide o Telomere: gets shorter until it dies in cancer telomere keeps growing this is why cancer is considered immortal o Cancer gets its name from the zodiac sign cancer o Causes: chemicals, sun exposure, nutrition and health, age, genetic testing (looking for mutations), detecting chemicals in blood, and biopsy o Treatment: Chemotherapy: therapy w/ chemicals Radiation therapy: high energy radiation that will destroy any DNA ( all cells) Cancer cells become resistant at 1 cell per million – average cells contains 1 billion cells o Signs: unusual bleeding, indigestion, nagging cough Asexual Reproduction o Advantages: more efficient, creates clone, single individual creates offspring, everyone can reproduce, no care for young, more offspring o Disadvantages: no genetic diversity, large amount of mutation, increased susceptibility to diseases or environmental change Sexual Reproduction o Advantages: 2 individuals (female & male), forms unique individuals unless there are twins, genetic diversity, fewer mutations, ability to fight diseases o Disadvantages: increased risk of spreading diseases (STD/STI), physically time consuming, only some individuals can reproduce Somatic cells: o 23 homogenous pairs > diploid cells (2 sets, one from mom and one from dad) > everywhere except gonads Germ Cells: o 23 total > haploid cell (egg or sperm cell) only in gonads Diversity: o Arises in 3 ways o 1.Sexual reproduction and random fertilization o 2.Independent assortment: homologous pairs that are situated at the metaphase plate the homologous orientation is as random as a flip of a coin o 3.Crossing over: beginning in Meosis 1: homologous pairs wrap around each other and they exchange genetic info – gene for gene – this was discovered by studying fruit fly DNA o 23 chromosome determines the sex o when there is an identical twin the zygote splits so the twins have the same genetic information o If there are fraternal twins one dad can father one zygote and another one can father another zygote o Vanishing twin syndrome: one twin is entirely absorbed by another twin so it has 2 sets of DNA Gregor Mendel o The father of genetics o Published his work on peas in 1865 o Mendel’s Ideas/Laws: 1. Law of Segregation: each gamete receives only one copy of a gene 2. Law of Independent Assortment: traits are in inherited independently of each other – same suite of genes Genotype: genetic composition of an individual Phenotype: physical traits ex. Right or left handed Allele: alternative versions of a same gene – phenotype of a gene Dominant: when one allele completely covers up the other allele for a gene represented by an UPERCASE letter on a pundit square Recessive: when one allele is completely covered up by the other alleles in a gene represented by a lowercase letter on a pundit square Homozygous: genotype where the alleles are the same Heterozygous: genotype where the alleles are different P p P PP Pp p Pp pp
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