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BIO 120- Notes 3

by: Whitney Marie Halaby

BIO 120- Notes 3 Bio 120-001

Whitney Marie Halaby
GPA 3.47

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Detailed notes from 2/19-2/26
Principals of biology
Class Notes
Bio, BIO 120, Biology, Genetics, cancer, Mitosis, MEOISIS, towson
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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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