BSC 215 Wk 5 Notes
BSC 215 Wk 5 Notes BSC 215
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This 8 page Class Notes was uploaded by Jordana Baraad on Thursday September 15, 2016. The Class Notes belongs to BSC 215 at University of Alabama - Tuscaloosa taught by Dr. Jason Pienaar in Fall 2016. Since its upload, it has received 36 views. For similar materials see Human Anatomy & Physiology I in Biological Sciences at University of Alabama - Tuscaloosa.
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Date Created: 09/15/16
9/13 Cellular Extensions Microvilli and pseudopods BOTH have actin filaments Cilia and flagella BOTH have microtubules LO4: Describe the structure and function of centrioles, microvilli, cilia and flagella Need to know why looking at microvilli Unorganized arrangement Plasma membrane extensions Increase absorptive surface area 15x 40x In absorptive structures o Intestinal epithelia (absorb food) o kidney tubules (absorb water) Actin filaments connected to terminal web. o “milking”—pull on actin fil w/n microvilli increased absorption **cilia v microvilli cross section of primary cilica Every human cell has one • Cell sensory function • “Monitors” surrounding conditions • E.g. Kidney primary cilia monitor fluid flow **microcilia for primary cilia v. secondary 9 rings for primary (9+0) secondary: 9 + 2 axoneme in center ( motility) • Secondary cilia (motile cilia) • Restricted to cells of respiratory tract, uterine tubes, brain ventricles, and testes • Motile cilia • Beat in waves to propel mucous, egg cells & cerebrospinal fluid Axoneme • 2 central, 9 peripheral microtubules (9+2 structure) • Peripheral microtubules extend as basal body into cell • Dynein arms use ATP energy to crawl up adjacent microtubule arms causes bending & power stroke if no dynein, you’re in trouble req saline solution; can’t move in mucus lack of saline solution CF Must beat in a nonviscous saline solution Chloride pumps: pump Cl though membrane Na+ follows by electrical attraction Water follows by osmosis CF happens when pumps not embedded in membrane Na won’t follow Cl so water won’t follow Sim to CF: Primary Ciliary Dyskinesia—same net result • Flagella • Only found in sperm cells in humans • Identical axoneme to secondary cilia (9+2) • Much longer and stiffer slightly different job—must move entire cell (luckily, small) • Beats in an undulating motion unlike propellerlike flagellum in bacteria Pseudopods Cytoplasm filled extensions of cell surface • Used by macrophages • Constantly appearing / retracting • *** Assembling / disassembling Actin protein scaffolds LO4: Describe the structure and function of centrioles, cilia and flagella Centrioles: Organize microtubules Direct cytoskeletal rearrangements e.g. mitotic spindle CQ 1. 3 main components cell: B. plasma membrane, cytoplasm, nucleus 2. Diff btwn active and passive transport is active uses proteins; passive doesn’t a. False—facilitated diffusion uses carrier proteins; is type of passive transport i. Not about protein use; about energy use 3. Na/K pump? b. 2 K ions in for 3 Na out reason: membrane almost impermeable to Na; only way in w/ channel 4. not part of endomembrane system a. cilia (ribosomes part of RER) 5. Which is secondary active transport? b. glucose symporter NOT Na/K pump—has secondarytransporterlike activity (but not secondary transport) Happens to antiport, but primary transport bc transport pump directly uses ATP Genetics LO1: Describe the structure & function of the nucleus, chromatin, chromosomes and nucleolus Enclosed by nuclear membrane Double membrane Continuous w/ SER SER folds = cistanae, NOT cristae (mitochondria folds) Largest organelle (DNA = 2 m) • Most cells have one • Mature red blood cells have none • Some muscle and liver cells have multiple nuclei nuclei are clones of one another • Control center of the cell • Contains all the Genes • Determines which proteins a particular cell will make does this by selectively expressing sets of genes doesn’t contain mitochondrial/ ribosomal DNA, but these aren’t considered yours LO1: Describe the structure & function of the nucleus, chromatin, chromosomes and nucleolus Nuclear envelope • Double membrane (4 phospholipid layers) • Outer membrane continuous with endoplasmic reticulum • Ribosomes embedded in cytoplasmic side of both • Inner membrane rests on intermediate filament scaffold (lamina) • Nuclear pores facilitate active transport of RNA (mostly mRNA out), proteins (in) & chemical messengers (in & out) Nucleoplasm • Salts, Nutrients, Nucleotides & Enzymes nucleotides = “building blocks” • Nucleolus (darker staining region) • Ribosomal factory (Ribosomal RNA (rRNA)) constantly need to make proteins constantly need rRNA, so constant transcription in nucleolus stains dark bc highly active • Chromatin • 30% DNA, 60% Histone protein, 10% RNA chromosomes are NOT the same thing as chromatin DNA is negatively charged RNA transcribed from DNA **chromosomes only made when need to move DNA to other cells mitosis/ meiosis other times, DNA in chromatin form—easily accessible LO1: Describe the structure & function of the nucleus, chromatin, chromosomes and nucleolus DNA wrapped around histone proteins = nucleosome 30 nm fiber Must move histone protein out of way to expose gene for transcription (“unwrap”) Most genes not being expressed at all times Chromosome has 4 copies of each gene (2 fr mom, 2 fr dad) LO1: Describe the structure & function of the nucleus, chromatin, chromosomes and nucleolus 2 arms of identical DNA sequence (sister chromatids) • Result of DNA replication • Chromatids joined at centromere • Each chromatid has a kinetochore at the centromere (on either side) function of kinetochore to interact w/ microtubules • Point of attachment for microtubule fibers during mitosis microtubules pull chromatids apart Human Karyotype Lots whole gene sequencing but still quickest way to look for certain things i.e. trisomy 21 Down’s syndrome (extra copy of chrom 21) banding patterns: dark patches = condensed DNA, not being transcribed light patches = looser DNA, highly active, so must always be transcribed ex. Na/K pump related genes 23 pairs 46 chromosomes (only nonpair = sex chromosomes: X/Y) look for abnormal numbers of chromosomes LO2: Recognize DNA / RNA structure, nucleotides, how they combine with phosphodiester & Hbonds Each nt has 3 basic components Ribose sugar (deoxy or oxy sugar) 1 of 4 diff bases (Adenine, Cytosine, Guanine, Thymine/ Uracil) oxygen on 2’ carbon is more imp distinction btwn DNA/ RNA than T/U purines: large, 2 rings, A/G pyrimidines: small, 1 ring, C/U/T Nitrogenous base (covalently linked to 1’ Carbon) 3’ carbon results in polarity of sugar 5’ carbon participates on phosphodiester bond process = dehydration synthesis Rules of genetics 1. purine on one side of DNA, means always linked to pyrimidine on other side 2. GC3 rule a. Guanine (purine) forms 3 Hbonds w/ Cytosine (pyrimidine) b. Adenine forms 2 Hbonds w/ thymine (AT2) LO2: Recognize DNA / RNA structure, nucleotides, how they combine with phosphodiester & Hbonds DNA polymerase can only add nt’s when hydroxyl group hanging off 3’ end True for DNA RNA polymerase can put down nt on template; doesn’t need existing –OH on 3’ end Always start w/ RNA primer to provide hydroxyl group for DNA Polymerase Both DNA and RNA can only grow 5’ 3’ end Each individual nt has 5’ and 3’ end st Last one will have 5’ end free; 1 one will have 3’ end free DNA opened at A/T seq, not C/G, bc 3 Hbonds stronger than 2 (2 in A/T) Hbond baseparing rules 5’3’ rules antiparallel rules If given… 3’AGCTTTCG5’ Need to grow in 5’ 3’ direction Put down at left (true for DNA or RNA) 5’TCGAAAGC3’ *OR* 1 base = U for RNA Pic in slide… what are the nt bases in the pic? Look at #bonds btwn bases to det G/C v. A/T Then look at ring structure to figure out which in bond is purine/ pyrimidine LO2: Recognize DNA / RNA structure, nucleotides, how they combine with phosphodiester & Hbonds Cellular DNA exists as long polymers of nucleotides connected by phosphodiester bonds • Each polymer associates with a partner based on specific hydrogen bonding patterns in an antiparallel orientation • 1 Purine :1 Pyrimidine • G ≡C • A = T 9/15/16 LO2: Recognize DNA / RNA structure, nucleotides, how they combine with phosphodiester & Hbonds DNA occurs as a double helix in cells • 2 strands twist around each other held by phosphodiester bonds • Most thermodynamically stable conformation Mutation happens mostly dur replicaion LO3: Describe and be able to use the genetic code Central dogma of molecular biology: Watson’s model DNA RNA protein Stored in nt’s transcription stored in nt’s translation amino acids Once gets to protein, can’t go farther Proteins are NOT genetic material—can’t pass it on LO3: Describe and be able to use the genetic code (whiteboard) Steps in writing nt sequence; describing replication 1. Form and open replication bubble a. write polarity: typ 5’ on top left (where phosphate hangs off) 3’ on top right (where –OH hangs) b. rule of antiparallel strands (true for DNADNA or DNARNA coming together 2. RNA polymerase puts down 3’ –OH that DNA polymerase can use a. RNA polym responsible for first phosphodiester bond b. DNA polymerase “cements” it 3. 2 template strands of replication—semiconservative replication a. top: top strand is from original molec; bottom strand is new (from RNA) b. bottom: bottom strand is from orig molec; top strand is new c. EACH STRAND IS 50/50 old/new 4. polymerases can only add at 3’ end a. smooth transcription on one side of bubble (leading strand) b. fragmented in opp direction (lagging strand) i. lagging strands have Okazaki fragments c. one of each, per template **KNOW ALL ENZYMES AND STEPS FOR TEST!! LO3: Describe and be able to use the genetic code (whiteboard): transcription Promoter (aka. TATA box): indicates where replication should start (which strand serves as template) *** Recognized by RNA polymerase RNA polymerase: protein catalyzes DNA replication Acts slightly downstream from promoter Lays down complementary nt’s –antiparallel Until reaches termination sequence Termination sequence on opp strand to promoter DNA opening continues L R Once DNA Polymerase “fixes” nt’s, mRNA falls of template DNA closes behind it; meanwhile, other side of bubble keeps opening LO3: Describe and be able to use the genetic code (whiteboard): transcription • Many different types of RNA • Usually single stranded sometimes folds back on itself to form partial double strands (complimentary base paring) forms stemloop structure of tRNA • Messenger RNA (mRNA) carries genetic information between nucleus and ribosomes stays long string of instruction; no folding • Ribosomal RNA (rRNA) component of ribosomes, enzymatic and mRNA orientation activity made in nucleolus—reason for dark stains proteins for laying down aa’s catalyzed by rRNA—enzymelike activity in sequencing • Transfer RNA (tRNA) transfers specific amino acids to specific mRNA sequences during translation one of loops in stemloop structure forms 3nt sequence called anticodon enzyme recognizes it and covalently links appropriate 1 of 20 aa’s 1:1 unique enzyme to anticodon ratio anticodon responsible for recognizing codons • MicroRNAs gene regulatory & defense functions don’t need to know LO3: Describe and be able to use the genetic code (whiteboard): transcription • Gene: Sequence of DNA that encodes for a sequence of RNA that plays a role in protein production • E.g. genes for mRNA (& proteins), tRNA, rRNA, regulatory microRNA • Genome: All the DNA contained within a typical cell • Human Genome is spread across 23, duplicated chromosomes (46 total) • 20 00025 000 genes, synthesize millions of different proteins • Typical gene ~ 3000bp long, (ranges up to 2.4 million bp) same length as nt’s; just described as bp’s bc complimentary bp’s is natural unit • Only 2% of genome are genes, rest is structural, regulatory or “junk” LO3: Describe and be able to use the genetic code (whiteboard): transcription DNA replication • DNA > DNA • (A=T, G≣C) • Transcription • DNA > RNA • (A=U, G≣C) • Translation • RNA > protein • triplet codons hydrogenbonding codon table refers to triplet codons on mRNA will be given this table on exam—KNOW how to use; DON’T memorize ex. codon 5’UCG3’ st 1 letter refers to 5’ end: U top row 2 letter: C 2 column 3 letter G Ser anticodon codes for Ser don’t need to know about degeneracy UCC codon (mRNA) AGG anticodon (tRNA) Ser again (fr mRNA codon) CAA codon Gln: glutamine KNOW 3 letter code to predict, NOT what 3 letter code means in full First aa in seq is Met: start codon AUG First step find 5’ end; 2 step find AUG Count in 3’s from there On ribosome, 3 sites E: Ejection site Where tRNA’s that have been used are ejected P: peptide site Contains growing aa chain at any given time A: amino site Where tRNA comes in w/ aa every time mRNA and tRNA pulled thru ribosome process continues until reaches 1 of 3 stop codons (UAA, UAG, UGA) no tRNA recognizes it; stops translation Ex’s • Example 1 • 5’AUGCCAUAGCUG3’ • MetPro • Example 2 • 5’AUGCUGGUCAAAUGA3’ • MetLeuValLys Histology Histology: study of normal tissues (abnorm—histopathology) LO1: Define histology and compare and contrast the general features of the four major tissue types Cells make ECM All tissues have in common—vary in amounts 4 classes epithelium—mostly cells function related to tight packing ex. skin look for: cell shape ECM doesn’t tell you much nuclei very close together connective—mostly ECM, not much else ex. cartilage is mostly collagen fibers, cells embedded 12 dark spots: fibroblasts nervous: distinct cell types very little extracellular protein look for axon/dendrite branches extending out muscular (ex. skinetal in “summary” slide) long, fibrous cells each long bar is cell; dark spots are nuclei (multinucleated) muscular and epithelium both mostly cells; not much ECM connective and nervous in common: connective almost all ECM
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