Lecture 4

Question 1

Directs all cell activities
Contains DNA
Separated by nuclear membrane

Answer 1

Nucleus

Question 2

Many nuclei

Answer 2

Multinucleate

Question 3

No nucleus

Answer 3

Anucleate

Question 4

Examples of multinucleate

Answer 4

Muscle

Some liver cells

Question 5

Examples of anucleate

Answer 5

Mature RBC

Question 6

Three main structures of the nucleus

Answer 6

Nuclear envelope
Nucleoli
Chromatin

Question 7

Double membran barrier suurpunds nucleus

Outer part continuous with Rough ER

Answer 7

Nuclear envelope

Question 8

Control entry/exit of molecules

Answer 8

Nuclear pores

Question 9

Dark-staining bodies in nucleus
1-2 per cell
Site where ribosomes are made

Answer 9

Nucleolus

Question 10

DNA + Proteins

Answer 10

Chromatin

Question 11

DNA wrapped around 8 histone proteins

Answer 11

Nucleosome

Question 12

Allow for compact and orderly packing of long DNA molecules

Answer 12

Histones

Question 13

Fundamental structural packing units of chromatin

Answer 13

Nucleosomes

Question 14

Complex of DNA tightly wrapped around basic proteins called histones

Answer 14

Nucleosome

Question 15

Consist of two tetramic molecules, each having four histone-subunits

Answer 15

Nucleosome Core

Question 16

Four histone-subunits

Answer 16

H2A
H2B
H3
H4

Question 17

Coils twice around the histone octamer

Answer 17

DNA helix

Question 18

External ninth histone added which holds the nucleosome structure together

Answer 18

H1 linker histones

Question 19

Nucleosome plus one H1-histone

Answer 19

Chromatosome

Question 20

Nucleosomes are separated one another by a

Answer 20

Linker segments of 20-200 nucleotides pairs

Question 21

Unfolded chromatin appearance

Answer 21

Beads-on-a-string appearance

Question 22

Nucleosomes with the aid of histone H1 packed together and wound into a regular coil called

Answer 22

Solenoid

Question 23

Contains six to eight nucleosomes per turn

Answer 23

Solenoid

Question 24

A solenoid forms

Answer 24

30nm nucleoprotein fibers

Question 25

Packaging DNA in nucleosomes and then in solenoid reduce its length by

Answer 25

A factor of about 50

Question 26

During cell division, chromatin condenses to form

Answer 26

Chromosomes

Question 27

Between cell divisions (interphase), chromatin exist as a tangle of fibers of

Answer 27

10-30 nm (10-9m) diameter

0.25-2 mm length

Question 28

The unfolded regions are reffered to as

Answer 28

Euchromatin

Question 29

More condensed unfolded regions are called

Answer 29

Heterochromatin

Question 30

Before cell division (Mitosis), the chromatin condense into

Answer 30

Metaphase chromosomes

Question 31

During this condensation, the DNA packaging factor increase dramatically from

Answer 31

50 to about 7000

Question 32

Folded and organized with specific non-histone proteins, into subdomains of coiled loops

Answer 32

Nucleoprotein chromatin fibers

Question 33

Two identical, symmetrical DNA molecules

Answer 33

Chromatids

Question 34

Made of chromatids

Answer 34

Chromosome

Question 35

Joined by a centromere which attach them to the mitotic spindle

Answer 35

Chromatids

Question 36

Each chromosome contains:

Answer 36

2 chromatids
1 centromere
4 telomeres (ends of DNA molecule)

Question 37

Copying of genetic material

Answer 37

Replication

Question 38

Process of duplication of the entire genome prior to cell division

Answer 38

DNA Replication

Question 39

Biological significance of DNA replication

Answer 39

Extreme accuracy of DNA replication

Only occurs during the S phase of the cell cycle