PPT 9 Bacterial Growth

Enzymes are

biological catalyst that increase the rate of a chemical reaction, are proteins but their make up can also include non protein molecules

Division of bacterial cells occurs mainly theough

binary fission

What occurs in binary fission?

parent cell enlarges, duplicates its chromosome (copies dna), and forms a central transverse septum dividing cell into two daughter cells

Usually dna replication in E. coli takes 40 minutes to completely copt the bacterial chromosome, however optimal reproduction for E. coli is?

every 20 min

How does bacterial dna replication allow for rapid division?

bacteria can start a new round of dna replication before the previous round is complete, enabling faster cell division

When a bacterial cell divides into 2 cells, each cell recives

a complete chromosome and an additional portion of the genome whose sythesis was initiated part way through the fission cycle

The cell must partition the dna and cytoplasmic membrane by synthesizing a

septum/crosswall

What is the initiation symbol for the septum?

invaginations of the cell evelope layers

What is responsible for the occurence of septation in E. coli?

two proteins

Generation time

time required for a complete fission cycle

What does each fission cycle increase the population by?

factor of 2; pop doubles each time

What is the avg generation time for bacteria under optimum conditions?

20-60 min

Leaving food at room temp even for a short time =

few bacteria can grow

E. coli grows every

20 min

Vibrio sp. grows every

10 min

What is the gt for Mycobacterium leprae (leprosy)?

14 days

Exponential growth=

pop 2x with each divisoin

Nf​=(Ni​)2^n. What does Nf mean?

final number of cells

Nf​=(Ni​)2^n. What does Ni mean?

initial number of cells

Nf​=(Ni​)2^n. What does n mean?

num of generations

Why don’t bacteria maintain their potential growth rate?

influenced by env factors

Increase in acids and waste =

decreased growth rate

Patients are most infective at which stage?

log stage

Describe the lag phase.

old and needs to make new enzymes; getting ready for division

Describe the log phase.

bacteria are growing and dividing at the max/optimum rate

In what stage of the growth curve is the pop most uniform in terms of chemical and physiological properties?

log phase

Actively growing cells are more vulnerable to conditions that disrupt binary fission and cell metabolism in?

the log phase

The generation time is always determined during

log phase

Bacteria is used by industry/medicine/research in the _ phase bc it is most uniform/reliable

log

Log phase is also known as

exponential growth phase; a perios of max growth

The log pahsed continues as long as cells have?

good env conditions and nutrients present

In what phase does growth eventually cease and the curve becomes horizontal

stationary

In the stationary phase, what remains constant?

the total number of viable microorgs

Since in the stationary phase the total of viable microorgs remains constant this may result?

a balance between cell division and cell death or the pop may simply cease to divide trough remaining metabolically active but at much reduced rate

Rate of cell growth equals rate of cell death

stationary phase

What causes the stationary phase?

decrease in nutrients, space and pH; and toxic accumulation of acids and wstes

Detrimental = decline in the number of viable characteristics of …

death pahse

Limiting factors intensity; loss of nutrients and low pH is not toxic

death

Compared to the death phase, microorgs in the log phase of growth are more?

infectious, virulent, metabolically active, rapidly growing

The shorter the generation time the more easily..

a pathogen can reach high numbers