Microbial GrowthF08

El ongati on of cel l and dna dupl i cati on 2 cel l

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Unformatted text preview: GROWT H = or der l y pr ocess of the i ncr ease i n the n umber of i ndi vi dual mi cr obes – Ther e i s an i ncr ease i n si ze fol l owed by cel l di vi si on – BI N ARY FI SSI ON - m ost bacter i a di vi de i n thi s m anner – Some yeast r epl i cate by buddi ng – n ew cel l i s smal l er t han mother cel l • D I VI SI ON = 4 steps for 1 cel l to di vi de i nto 2 cel l s 1. El ongati on of cel l and DNA dupl i cati on 2. Cel l wal l & pl asma membr ane i ncr ease and star t f ol di ng i nwar d 3. For mati on of cr oss wal l between DNA r egi ons 4. Cel l s separ ate i nto 2 new i denti cal cel l s Bi na r y Fi ssi on Figure 6.12a Bi na r y Fi ssi on Figure 6.12b F i g. 6.2 Buddi ng Yea st G EN ERAT I ON or D OU BLI N G T I M E • L ength of ti me r equi r ed for a gener ati on of cel l s to d i vi de (doubl e) • L ength of ti me wi l l var y: – Depends on par ti cul ar or gani sm – Depends upon envi r onmental factor s – M i nutes to hour s (usual l y l ess than 1 hour ) • Because they doubl e i n number at ever y di vi si on i t i s di ffi cul t to pl ot cel l number s usi ng ar i thmeti c n umber s – Usual l y use a l ogar i thmi c scal e to gr aph bacter i al gr owth Cell Division Figure 6.13b Gener a ti on T i me • I f 100 cel l s gr owi ng for 5 hour s pr oduced 1,720,320 cel l s: ANI M ATI ON Binar y Fission Ba cter i a l Gr owth Cur ve Figure 6.14 B a cter i a l Gr owth Cur ve • Four phases for bacter i al gr owth i f an ol d cul tur e f r esh medi um – I ncr ease i n cel l si ze – I ntense i ncr eased metabol i c acti vi ty – Sensi ti ve to physi cal & chemi cal damage 1. LAG 2. LOG/EXPON EN T I AL – M axi mal gr owth and cel l di vi si on • Cel l s doubl i ng at the fastest r ate • Cel l si ze i s sl i ghtl y decr eased – I ncr eased metabol i c acti vi ty – Sensi ti ve to physi cal & chemi cal damage B a cter i a l Gr owth Cur ve (cont) 1. ST AT I ON ARY – – – – – Gr owth r ate eventual l y decr eases then stops # of new cel l s = # of dead cel l s Nutr i ent depl eti on M etabol i c bypr oducts (anti bi oti cs) Endospor es can be pr oduced 2. D EAT H (D ECLI N E) – Whol e cul tur e di es at fi r st sl owl y then exponenti al l y Pha ses of Gr owth ANI M ATI ON Bact er ial Gr owt h Cur ve Figure 6.15 M AT H : Ar i thmeti c vs Loga r i thmi c • PLOT : Cel l # vs Gener ati ons CALCU LAT I ON S: M f = ( M i ) 2n • M f = fi nal number of bacter i a M i = i ni ti al number of bacter i a – n = number of gener ati ons • I f you know any 2 of the 3 above number s we can sol ve...
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