Lecture 5 Microbes 2

Question 1

2 links between information and metabolic pathways are

Answer 1

Transcription and translation

Question 2

Transcription is (1) and its process (2)

Answer 2

mRNA synthesis. RNA polymerase synthesizes mRNA from antisense strand of DNA, producing a copy of “working” strand. It stops at termination sequence.

Question 3

What does ribosome consist of? (4)

Answer 3

Large 50S subunit, small 30S subunit; ribosomal RNA and protein.

Question 4

Does bacterial genome contain a single copy of ribosomal gene?

Answer 4

No. 1-15.

Question 5

Translation process (6)

Answer 5

Question 6

Two theories for why there are 20 kinds of amino acids utilized

Answer 6

A “frozen accident” theory by Crick; optimal biochemistry for versatility and cost of synthesis

Question 7

Genetic (3) and physiological (1) attributes of organisms to distinguish between rocks and life

Answer 7

Genetic: self-replication, heritability for sake of evolvability
Physiological: metabolism causing complexity.

Question 8

Two theories of origins of life

Answer 8

Panspermia and Spontaneous generation (and Special Creation)

Question 9

Background of panspermia

Answer 9

Genome size and complexity increase over time, size doubles every 400 million yrs. The begining stage of life took a “jumpstart” in genomes.

Question 10

Three types of panspermia

Answer 10

1. Undirected: dispersal of microbes among planets.
2. Directed: deliberate seeding by aliens
3. Misdirected: pollution by spacecraft

Question 11

What are evidence and objections to undirected panspermia (2+1)

Answer 11

Pro: Relates to short interval between appearance of permanent oceans and first signs of life.
Bacteria could be transported by meteors.
Con: low local star density, low probability of capture

Question 12

What are evidence and objections to directed panspermia (1+3)

Answer 12

Pro: solves means of dispersal
Con: time scale, no evidence of intelligent life, why only bacteria?

Question 13

What is evidence to misdirected panspermia

Answer 13

NASA spacecraft has 300,000 spores

Question 14

Background of spontaneous generation (2)

Answer 14

Flies, lice, mice were thought to arise from putrefaction. Simple creatures could be reproduced.

Question 15

Two premises for spontaneous generation to happen

Answer 15

complex bacteria arise by natural self-organization.
Or, continuous series of entities linking chemicals with evolution through natural selection take over self-assembly

Question 16

Three stage processes of spontaneous generation

Answer 16

Growth - exergonic material available
Reproduction - fraction that continues to grow.
Inheritance - reproduction results similar to parents over random members.

Question 17

Two branches of spontaneous generation

Answer 17

Genetics first or metabolism first

Question 18

Background of Genetics first theory (3) and example

Answer 18

RNA is both capable of replicating and metabolizing.
With raw materials and replicase, it can replicate itself.
Can act as enzymes called ribozymes to modify other RNA
Ex: self-splicing introns.
Thus, theory states that early ocean with RNA leads to organisms now.

Question 19

Background of metabolism first theory

Answer 19

Metabolism evolves from photosynthesis to cyanobacteria (oxidizing atmosphere) to respiration.

Question 20

Energy source of metabolism for early metabolism

Answer 20

hydrothermal vent (CO2 reduced by H2 to form organic mcls, anoxic)

Question 21

Bacterial metabolism is based on

Answer 21

Redox reactions

Question 22

How does the redox chart work

Answer 22

Oxidation side on top left and reduction on bottom right

Question 23

Explain first stage of metabolism of metabolism first theory (3)

Answer 23

General fermentation: sugar to alcohol/acids + ATP under lightning/UV
Glycolysis: glucose into two 3-C pyruvate + ATP + NADH (reducing power)
Fermentation: When anoxic, pyruvate oxidize NADH into NAD+ and ethanol, do not produce energy.

Question 24

Explain second stage of metabolism of metabolism first theory (5)

Answer 24

Oxidation of pyruvate into acetyl group attached to CoA.
Citric acid (TCA, Krebs) cycle gives off 1 ATP and 3 NADH.
Electron transport chain: energy of electrons into work. Electropositive to negative
When aerobic, electrons from NAD+ to NADH to eventually O2 into H2O, or eventually to (what’s in the chart).
Chemiosmotic energy storage by membranes:
Lipid bilayer membranes separate charges produced redox from ETC pumping H+ from inside to outside.(ETC created electrochemical gradient)
When H+ return through ATP synthase channel, ADP into ATP (a water mill)

Question 25

Third, fourth, and fifth stages of metabolism

Answer 25

3. Photosynthesis
4. Oxygenic photosynthesis (cyanobacteria) boost atmospheric oxygen to 21%
5. Aerobic respiration

Question 26

What does winogradsky column do

Answer 26

separating and visualizing metabolic systems of prokaryotes