WEEK 1

Question 1

What is the Cell Theory

Answer 1

Cells are the smallest unit of life They arise from pre-existing cells They use free energy to maintain order, interact with the environment, and maintain internal homeostasis

Question 2

Approximate size of an atom

Answer 2

0.1- 0.5 nM (1-5 angstroms) 10

Question 3

Approximate size of lipids

Answer 3

1 -5 nM

Question 4

Approximate size of proteins

Answer 4

5-10 nM

Question 5

Approximate size of ribosome

Answer 5

20-30 nM

Question 6

~ size of most bacteria

Answer 6

1-10 uM

Question 7

~ size of plant and animal cells

Answer 7

10-100 uM

Question 8

prokaryotic structure Vs eukaryotic structure

Answer 8

Prokaryotes have no distinct nuclear compartment to house DNA, lack organelles, and usually have a cell wall surrounding the plasma membrane

Eukaryotes have organelles and use a membrane bound nucleus to house DNA Both have DNA, RNA, proteins, and ribosomes

Question 9

Structure of Cell envelopes: Gram positive vs Gram negative

Answer 9

Gram positive cell envelopes have multiple layers of peptidoglycan threaded by teichoic acids and an additional protective layer called the S-layer

Gram negative cell envelopes have a thin peptidoglycan layer and an outer and inner membrane. Outer membrane contains LPS and porins. Inner membrane have lipoproteins

Question 10

Differences in Structure: Bacteria vs Archaea

Answer 10

Archea have different membrane and envelope structures, also use ether-linked lipids

Bacteria use ester-linked lipids

Question 11

Types of Light microscopy

resolution: 0.2 uM

Answer 11

Standard

Phase contrast

Differential interference contrast

Question 12

Types of Electron Microscopy

Resolution: 2 nM

Answer 12

100x better than light microscopes

Uses a beam of electrons for illumination

Transmission (TEM)

Scanning (SEM)

Question 13

Gram stain Mechanism

Answer 13

Steps: Fix sample to slide, stain with crystal violet, add iodine to bind crystal violet to sample, wash with ethanol, counterstain with safranin

Gram positive cells will be purple

Gram negative cells will be pink since the thin cell wall only kept the safranin counterstain

Question 14

Criteria for Genetic material

Answer 14

1. Must contain information
2. Replication
3. Tranmission
4. Variation

Question 15

What was the result of Griffith’s Bacterial Transformation exeperiment

Answer 15

He found that genetic material from the heat killed S-strain had been transferred to the living R-strain that allowed them to develop a smooth capsle that was passed to their offspring and was able to kill the mouse.

Question 16

Which strain of S.pneumoniae in Griffith’s Bacterial transformation experiment was fatal? Which strain was benign?

Answer 16

The S-strain with the smooth capsle was fatal

The R-strain with the rough capsle was benign

Question 17

What was the result of the Hershey and Chase Experiment?

Answer 17

They discovered that the infected bacteria contained 70% of ³²P label, the phage coats contained 80% of ³⁵S label, and the progeny had 30% of ³²P

This confirmed that DNA held genetic information

Question 18

Whar were the labels used in the Hershey and Chase experiments?

Answer 18

³⁵S was used to label proteins since they contain more sulfur

³²P was used to label DNA since phosphates are abundant in DNA