BSCI 201 WEEK 3 CLASS NOTES
BSCI 201 WEEK 3 CLASS NOTES BSCI201
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This 4 page Class Notes was uploaded by Salma Notetaker on Thursday September 22, 2016. The Class Notes belongs to BSCI201 at University of Maryland taught by Justicia Opoku-Edusei in Fall 2016. Since its upload, it has received 15 views. For similar materials see Human Anatomy and Physiology 1 in Biology at University of Maryland.
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Date Created: 09/22/16
BSCI 201 CLASS NOTES FOR THE WEEK 9/19/16 Cell organelles: structure and function: The Endoplasmic Reticulum: two types Rough Endoplasmic Reticulum (RER) Smooth Endoplasmic Reticulum (SER) -‐Prominent in a cell that secretes -‐Prominent in a cell involved in drug proteins or cell active in exocytosi or a detoxification or in stereologenic. cell involved in phagocytosis: requires -‐ Lipids synthesis starts at the surface of lysosomes. the SER. -‐Golgi Apparatus: a cytoplasmic organelle that modifies, packages and tags proteins synthesized by bound-‐ribosomes.on the surface of the RER. These proteins are moved from RER to Golgi via vesicular trafficking. Summary: Secretory cells: cells that secrete proteins=>ribosome bound=>prominent RER=>prominent Golgi. -‐Phagocytes: parfake in phagocytosis=>ribosome bound=>prominent RER=> prominent golgi=>abundant lysozomes. -‐Lysozomes are vesicles that bud off Golgi. They are the “demolition crew”. -‐Lysozymes contained in lysozomes digest non useful or unwanted tissue substances or cells. -‐Peroxisomes: abundant in metabolically active cells where free radicals are produced as a by product of catabolism. They are then converted by oxidase into hydrogen peroxides (H2O2), then these are converted by catalase into water(H2O). Vitamin E and C give electrons so free radicals won’t harm you. Cytoskeleton: 3 types: microtubules Intermediate microfilam filaments ents Function: Function: Function: -‐act as trucks for vesicles trafikking and as a basis for Resist tension -‐are centrioles which are required for mitosis (mitose: placed on everywher separation/division of DNA). tissues such as e. -‐ act as basis for 2 types of cellular extensions: the -‐Unique to desmosomes. each cell cilia flagella Structural differences -‐occur in large numbers on -‐the only flagellated cell is the apical surface of the cell. sperm. -‐are shorter. -‐ are longer. Functional differences Beat to create unidirectional Beat to propel the cell itself. current that propel substances across the surface of the cell. -‐The nucleus: control center of the cell. Has 3 parts: Boundary nuclear membrane nucleolus Chromartin in nucleoplasm plasma membrane vs nuclear Assembles the rRNA Composed of structural membrane. with proteins to form units(repeated structures) called Plasma Nuclear the: nucleosomes. Anucleosome consists membrane membrane 1-‐small ribosomal of 8 histone proteins with thread-‐ -‐glycocalyx -‐glycocalyx subunit. like DNA wrapped around them. present. absent. 2-‐large ribosomal There are 2 forms of chromatin: -‐membrane -‐nuclear pores subunit. proteins act allow Both subunits will be heterochromatin euchromatin as carrier substances to exported through molecules be imported or the nuclear pores -‐DNA is -‐DNA is into the cytoplasm. wrapped around unraveled by that show exported based clusters of histone proteins specificity on size. At the time of histone proteins so it is active and and translation, a small saturation. ribosomal subunit so it is inactive. is involved in: -‐ if the fuses with the large 1-‐DNA number of one to form a replication. functional ribosome. 2-‐protein proteins for synthesis. a specific So cells producing substance proteins will have increases, several nuclei in the rate their nucleus doesn’t (secretory proteins). increase. Function of histone proteinsin chromatin: 1-‐ regulate DNA activity. 2-‐ Packaging of delicate thread-‐like DNA from twisting or breaking. DNA vs RNA DNA RNA -‐pentose sugar: deoxyribose. -‐pentose sugar: ribose. -‐contains nitrogenous bases: A:adenine, -‐contains nitrogenous bases: A:adenine, G:guanine, C:cytosine, T:thymine. G:guanine, C:cytosine, U:uracil. -‐ double stranded and helical. -‐ single stranded. -‐confined to nucleus inside cell. -‐in nucleus and in cytoplasm. -‐1 type of DNA. -‐3 type of RNA: rRNA, mRNA, tRNA. Transcription takes place in the nucleus whereas translation takes place in the cytoplasm, cells grow or divide. DNA contains genes. Gene: a DNA sequence that can be transcribed and translated to form a particular protein. Somatic cells not sex cells undergo cell growth and cell division=> 9 series of events from the time a cell is produced until it divides. Cell’s life cycle: 2 major phases: I) interphase G1 S G2 -‐the longest of all phases -‐some structural proteins -‐globular functional proteins -‐synthesis of structural -‐synthesis and growth occur. required for proteins (fibrous proteins) -‐DNA replication. initiation/maintenance of cell for cell growth. Semiconservative division ex:maturation replication. promoting factors(MPF): 1-‐unwinding of helical DNA: cyclin and cyclin-‐dependent 2 polynucleotide chains. kinase (CDK) 2-‐separation of 2 polynucleotide chains: new polynucleotide chain against each DNA template. -‐2 copies of DNA with each DNA consisting of an old strand (template) and a new strand. II Cell division mitosis cytokinesis Prophase Metaphase Anaphase telophase Division of the -‐heterochromatin: Chromoso the chromosomes -‐chromatin is cytoplasm of the parental condensed to form mes move away from assuming the chromosomes attached one another to euchromatin form cell into two -‐nucleoli disappear to the opposite poles of to enter into G1 daughter cells. -‐disintegration of new spindle the spindle. phase of the new It occurs nuclear membrane. fiber. cycle. concurrently -‐sprouting of spindle -‐nucleoli reappear. with mitosis. fiber(mitotic spindle) -‐synthesis of a new nuclear membrane. -‐disintegration of Telophase undoes the spindle fiber. prophase. With DNA replicated in the S phase of interphase and with the production of proteins required for cell division (G0 proteins), the cell enter the first phase of cell division=>mitosis. 2 types of growth: hyperplasia hypertrophy Growth in the number of cells Growth in the size of cells -‐neoplasia: excessive proliferation of cells considered abnormal. Effective chempotherapeutic drugs based on cell life cycle: 1-‐inhibit S phase of interphase=>DNA replication does not occur and therefore cell division (mitosis) does not occur. 2-‐Drugs that inhibit the G0 proteins such as maturation promoting factors (MPF) which initiate/maintain cell division. 3-‐ Drugs that disrupt spindle fiber hence anaphase of mitosis is aborted. (sister chromatid are not divided) Protein synthesis: transcription in euchromatin form. Occurs in interphase=>chromatin=>euchromatin=>extended form of DNA not coiled around histone proteins. 1-‐ Transcription: in euchromatid form. 2-‐Translation: -‐DNA unwinds -‐Separates into 2 polynucteotide chains *Template: -‐used in transcription Triplet codon anticodon C G C C G C C G C T A U A U A C G C Triplet same as anticon except that T becomes U 3 base sequence in DNA polynucleotide chain: triplet 3 base sequence in mRNA polynucleotide chain: codon 3 base sequence in tRNA polynucleotide chain: anticodon attached to the tail of tRNA is a specific amino acid: proline *Coding strand: DNA sequence that is not transcribed Immediately after transcription=>pre mRNA (exons and introns) cannot fit through the nuclar pores so RNA processing/editing/splicing to remove introns mRNA contains only exons. Amino acids specifying codons. mRNA can exit the nucleosome through the nuclear pores into cytoplasm where mRNA attach to functional ribosomes (free or bound). Non essential amino acids are made from essential amino acids from diet. Genetic Code: refers to the codons in mRNA and how they specify for amino acids 64 codons to 20 naturally occurring amino acids hence each amino acid can be coded for by at least 2 types of codons=>exhibits redundancy in the genetic code=>it takes care of minor mistakes(mutations) typically involving the third base of codon
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