FINAL Unit 3 Flashcards
What is meant by growth and division of individual cells?
growth in cells = cell division = binary fission
What is meant by growth and division of a population?
growth in population = growth phases
What are 4 things bacteria can do?
- self-replicate
- store/transmit genetic info
- harness energy from environment
- maintain a separation between internal and external environment
How do bacteria grow and divide?
through binary fission
What is binary fission?
form of asexual reproduction with the result of two identical cells from one bacterial cell
Describe the process of binary fission.
- circular bacterial DNA molecule is attached by proteins to inner membrane
- DNA replication begins at a specific location and proceeds bidirectionally around the circle
- newly synthesized DNA molecule is also attached to inner membrane, near the attachment site of the initial molecule
- as replication proceeds, cell elongates symmetrically around the midpoint, separating DNA attachment sites
- cell division begins with synthesis of new membrane and wall material at midpoint
- continued synthesis completes the constriction and separates daughter cells
What is one round of cell division equivalent to?
one generation = one doubling of bacterial population
What are the 4 phases of population growth in a batch culture?
- lag —
- exponential /
- stationary —
- death \
Describe the lag phase in population growth.
- individual bacterial cells are growing but not readily dividing
- cells are making tools needed to thrive in new environment such as expressing protein-coding genes (for structural/integral membrane proteins, macromolecules)
- length of phase depends on difference in environment conditions (previous conditions –> present conditions)
- overall population does not display a net increase in growth
Describe the exponential phase in population growth.
- bacteria have fully adapted to their surrounding environment and maximized all benefits the can from nutrient media
- bacterial are at optimal conditions and want to replicate
- overall population of cells undergo binary fission at constant rate
- replication is at its maximum and cell number increases exponentially (2^n)
- cells are readily dividing and growth of population occurs exponentially
Describe the stationary phase in population growth.
- key nutrients are beginning to deplete, therefore bacteria begin to compete with other cells in order to obtain nutrients
- metabolic waste products released from bacterial cells begin to build up in environment and is toxic to cells
- net zero growth rate in overall population, which results from equal amount of individual cells actively dividing as there are cells dying
Describe the death phase in population growth.
- loss of nutrients, build-up of waste products, and lack of optimal conditions results in death of many cells
- in overall population, more cells are dying than actively dividing, therefore the growth of the overall population dramatically decreases
What is an anabolic reaction?
reaction that builds molecules from smaller units and require an input of energy (ATP)
ie. synthesis fo macromolecules
What is a catabolic reaction?
reaction that breaks down molecules into smaller units and produces ATP
ie. carbohydrates to sugars, fats to fatty acids and glycerol, proteins to amino acids
Why do cells need nutrients?
- are the building blocks of macromolecules
- used to make ATP
What type of nutrients are required for metabolic function of the cell?
- major bioelements: C, S, N, P, O, H
- minor bioelements: Fe, Ca, Mg
- vitamins
- electrons that are used to carry energy from food to electron transport system to make ATP
How do cells make ATP?
capture energy in bonds of food
What is ATP?
carries of energy, used for cells to do work
What is Gibbs free energy?
amount of energy available to do work
What is an exergonic reaction?
- ΔG
releases energy and proceeds spontaneously
catabolic
What is an endergonic reaction?
+ ΔG
requires input of energy and is not spontaneous
anabolic
What are reactants in terms of carbon?
reduced forms of carbon that are weakly bonded
What are products in terms of carbon?
oxidized forms of carbon that are strongly bonded
Describe an anabolic reaction in terms of the Gibbs free energy equation.
less disorder (-ΔS) and more chemical energy in bonds (+ΔH)