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Flashcards in bacterial growth and microbial genetics Deck (57)
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1

what is a pure culture

population of organisms descended from a single cell and is therefore separated from all other species

2

what did Robert Koch develop?

solid media (agar-agar derived from seaweed)
Contained in dishes invented by Kochs lab assistant Julius Richard Petri

3

What is Binary fission?

after a bacterial cell has increased in size and doubled all of its parts, it divides

4

Define microbial growth

an increase in the number of cells in a population

5

Define generation time

time it takes for a population to double in number

6

Bacterial growth in a lab (a closed system) follows a pattern of stages called _______

Growth curve

7

What are the 4 stages of the growth curve?

Lag phase (latent)
Exponential phase (log)
Stationary phase
Death phase

8

Describe the lag phase (latent)

Cells "ramp up" by synthesizing macromolecules required for division & ATP

9

Describe the exponential phase (log)

cells dividing at a constant rate, growth is balanced with available nutrients

10

Describe the stationary phase

cells have exhausted supply of energy and nutrients, number of cells remains relatively constant

11

Describe the death phase

population decreases as cells die off at a constant rate

12

What are the 2 methods to measure growth?

- direct count method using microscope and hemacytometer
- indirect cell counting using serial dilution

13

Adenine pairs with?

Thymine

14

Guanine pairs with?

Cytosine

15

A set of 3 nucleotides on a single strand =

a codon - this encodes a specific AA

16

Where does DNA replication begin?

replication origin (ori)

17

Is DNA replication semi-conservative?

Yes

18

What direction does DNA replication proceed in?

5' to 3'

19

Whats the difference between the leading strand & the lagging strand?

Leading strand= continuously synthesized
Lagging strand= discontinous, synthesized in pieces

20

What are the pieces of the lagging strand called?

Okazaki fragments

21

Describe the central dogma

DNA --> (transcription) --> RNA --> (translation) --> protein

22

Describe transcription

mRNA is synthesized from DNA via RNA polymerase
RNA nucleotides are adenine, uracil, guanine, cytosine
new mRNA is moved to ribosomes for translation

23

Describe translation

process of synthesizing proteins
occurs on ribosome
AAs are assembled into growing polypeptide chain (when folded= protein)

24

During transcription what acts as an on/off switch?

A regulatory region near the promotor which a regulatory protein can bind to

25

What is an operon?

a set of adjacent genes coordinately controlled by a regulatory protein and transcribed as a single RNA message

26

Is an operon inducible, repressible or both?

Both

27

Genes that are not always being transcribe must be ______ to function

Induced

28

Genes that are always being transcribed must be ______ to prevent proteins from being made

Repressed

29

An inducible operon requires what?

an inducer to prevent a repressor protein from binding to the operator

30

Where does spontaneous mutation occur?

natural environment