ARE YOU

READY?

TONGUE TWISTER

• There with the weather-beaten weatherman.

• Imagine an imaginary menagerie manager imagining managing an imaginary menagerie.

• Three hundred thirty-three thousand three hundred thirty-three.

DISCOVERY OF

NUCLEUS

Oldest known depiction of cells and their nuclei by Antonie van Leeuwenhoek, 1719.

Robert Brown

- introduced the word areola or nucleus, in the cells of the flower's outer layer.

Matthias Schleiden

-name "Cytoblast" (cell builder).

Robert Remak and Rudolf Virchow propagated the new paradigm that cells are generated solely by cells ("Omnis cellula e cellula").

The function of the nucleus clear only later, after mitosis discovered and the Mendelian rules 20th century).

CELL NUCLEUS

CELL NUCLEUS

• Latin nucleus or nuculeus,

meaning kernel.

• The control center of the cell.

• It contains most of the cell's genetic material.

PRIMARY FUNCTIONS:

• Repository of genetic information

• Enables synthesis of nearly all proteins

• Houses the nucleolus

• Responsible for production of ribosomes.

• Selective transportation of regulatory factors and energy.

COMPOSITION

NUCLEAR ENVELOPE

separates the cell's genetic material from surrounding cytoplasm.

serve as a barrier between nucleoplasm and the cytoplasm.

NUCLEOPLASM

made up of water and other dissolved substances. act as a suspension for organelles maintains the shape of the nucleus.

NUCLEAR PORE

composed of multiple proteins allows the passage of molecules

from inappropriate entering or exiting the nucleus.

NUCLEAR LAMINA

• structural support for the nuclear envelope

• anchoring sites for chromosomes and nuclear pores.

PROGERIA

• Defective Lamina protein makes the nucleus unstable. That nuclear instability appears to lead to the process of premature aging in Progeria.

CHROMOSOMES

Multiple linear DNA molecules. During most of the cell cycle these are organized into chromatin During cell division the chromatin can

be seen to form the well-defined chromosomes.

NUCLEOLUS

synthesize rRna and assemble ribosomes.

HAVE

YOU LEARNED?

Which of the following parts of nucleus is responsible for the formation of the ribosomes?

nucleoplasm

nucleolus

nuclear envelope

chromosomes

A

B nucleolus

C

D

In the nucleus of eukaryotic cells, the genetic material is complexed with protein and organized into linear structures called:

centrioles

plasmidshistones

chromosomesA

B

C chromosomes

D

Provide structural support for the nuclear envelope and anchoring sites for chromosomes and nuclear pores.

Nucleoplasm

Cytosol

Nuclear Lamina

Nuclear MembraneB

CA

D

Nuclear Lamina

The space between the membranes is called:

perinuclear space

internuclear space

nuclear space

none of these

A

B

C

D

perinuclear space

It prevents larger molecules, such as nucleic acids and larger proteins, from inappropriately entering or exiting the nucleus.

nuleolus

nuclear envelope

nuclear lamina

nuclear pores

A

B

C

D nuclear pores

It serves as a barrier that prevent macromolecules from diffusing freely between the nucleoplasm and cytoplasm.

nuleolus

nuclear envelope

nuclear lamina

nuclear pores

A

B

C

Dnuclear envelope

ASSIGNMENT:

In 1 whole sheet of paper give a brief description of the following:

• DNA

• Histone

• Centromere

• Telomere