Chapter 3

Question 1

Nucleoid:

Answer 1

Location of DNA in Prokaryotic Cell. Coupled transcription and translation, most are single circular chromosome. Repository of genome, Transcription.

Question 2

Cytoplasm:

Answer 2

The substance inside the plasma/cell membrane.
The substance between a cell’s membrane (its outside layer) and its nucleus (its core).

Question 3

Cytosol:

Answer 3

The fluid part of the cytoplasm

Question 4

Polyribosomes:

Answer 4

A group of ribosomes bound to an mRNA molecule like “beads” on a “thread”. Increases the efficiency of protein production by a single mRNA.

Question 5

Cytoskeleton:

Answer 5

The cytoskeleton is a network of proteins that forms an internal framework for the cell. All cells have some type of cytoskeleton. The cytoskeleton is made of different proteins that facilitate many functions, from transporting materials to aiding in cell motility, anchoring the cell in place, and many more

Question 6

Gas vesicles:

Answer 6

In aquatic photosynthetic bacteria, filled with gas to create buoyancy, which allows bacteria to float. Shell is composed of protein, common in cyanobacteria.

Question 7

Plasmid:

Answer 7

A plasmid is a small circular DNA molecule found in bacteria and some other microscopic organisms

Question 8

How does DNA make it into a cell?

Answer 8

Contributors:
Ionic strength- cations
DNA folding proteins
Supercoiling
Supercoiling is very important!!
Enzymes involved:
Topoisomerases
DNA gyrase (introduce negative supercoils)
Topoisomerase I (introduces positive supercoils)

Question 8

Ribosomes:

Answer 8

Sites of protein synthesis
70S
50S + 30S subunits

Question 9

Supercoiling

Answer 9

Positive: Left-handed supercoiling
Negative: Right-handed supercoiling

Question 10

Do most organisms have positive or negative supercoiling?

Answer 10

Negative.

Question 10

DNA organization in the prokaryotic cell

Answer 10

Prokaryotes generally have a single circular chromosome that occupies a region of the cytoplasm called a nucleoid. They also may contain small rings of double-stranded extra-chromosomal DNA called plasmids

Question 11

DNA packaging:

Answer 11

DNA in nucleoid is organized in large loops held by protein. Prokaryotic DNA is organized into a single chromosome

Question 12

Nucleoid/Cytoplasm Interferface:

Answer 12

DNA is tightly packed, while still functioning.
Transcription of DNA only at nucleoid/cytoplasm interface. Writhing/wriggling DNA—experiments with
GFP show the DNA moves from interior of
nucleoid to interface (allowing transcription),
and then back again

Question 13

What are the three types of cytoskeleton proteins and what are their functions?

Answer 13

Spherical, Rod, and Vibroid.
FtsZ (spherical)
MreB and FtsZ (Rod)
FtsZ and MreB-crescentin (Vibroid)
The cytoskeleton of a cell is made up of microtubules, actin filaments, and intermediate filaments

Question 14

Cytosol Contents:

Answer 14

Writhing/wriggling DNA experiments with GFP show the DNA moves from interior of nucleoid to
nterface (allowing transcription), and then back again
Plasmids, polyribosomes.

Consists mainly of water, dissolved ions, small molecules, and large water-soluble molecules (like proteins).

Question 15

Ribosomes composition and function:

Answer 15

Sites of protein synthesis, made of protein and ribosomal RNA.
70S
50S + 30S subunits
Within the cytosol, polyribosomes.

Question 16

Specialized Structures in the Cytoplasm (5 things):

Answer 16

Inclusion bodies, gas vesicles, thylakoids, carboxysomes, magnetosomes

Question 17

Inclusion bodies/Storage granules:

Answer 17

Store carbon and energy.

Question 18

Gas vesicles:

Answer 18

Buoyancy for cyanobacteria

Question 19

Carboxysomes:

Answer 19

Fix carbon dioxide by autotrophs. Enhance fixing CO2, polyhedral protein shell, contain RuBisCo

Question 20

Thylakoids:

Answer 20

Photosynthesis Machinery (Plasma membrane folding). Stacks of interconnected membrane sacs, contain pigments, proteins and cofactors capture light energy for chemical energy.

Question 21

Magnetosomes:

Answer 21

Motile aquatic bacteria. Iron containing crystals within invagination of cytoplasmic membrane. Magnets that function in orientation

Question 22

Vesicles:

Answer 22

Vesicles are cellular organelles that are composed of a lipid bilayer. You can think of vesicles as cellular envelopes that are used to transport materials from one place to another. Vesicles also function in metabolism and enzyme storage as well