Cell Organelles: The Nucleus

Front 1

The nucleus averages _____ in diameter.

Back 1

5 micrometers

Front 2

What are the three distinct regions of the nucleus?

Back 2

1. nuclear membrane
2. nucleolus
3. chromatin

Front 3

What is the colloidal fluid enclosed by the nuclear membrane?

Back 3

nucleoplasm

Front 4

T/F Most body cells have only one nucleus.

Back 4

True

Front 5

T/F The nuclei of muscle cells, osteoclasts, and some liver cells are multinucleate.

Back 5

True

Front 6

What type of body cell is NOT nucleated?

Back 6

Red Blood Cells

Front 7

The nucleus is bounded by the _____ or envelope

Back 7

Nuclear Membrane

Front 8

T/F The nuclear membrare is double layered

Back 8

True

Front 9

Which organelle's membrane is similar to that of the nucleus?

Back 9

Mitochondria

Front 10

T/F The nuclear membrane is a lipid bilayer.

Back 10

False (a phospholipid bilayer)

Front 11

What is the space between the outer and inner nuclear membranes called?

Back 11

Cisternae

Front 12

T/F The outer nuclear membrane may have ribosomes on it.

Back 12

True

Front 13

The outer nuclear membrane is continuous with the _____.

Back 13

Endoplasmic reticulum

Front 14

The two layers of the nuclear membrane fuse in the region of the nuclear _____.

Back 14

Pores

Front 15

T/F the nuclear pores are 3- 10 nm in diameter.

Back 15

False (30-100nm in diameter)

Front 16

The nuclear membrane is selectively permeable.

Back 16

True

Front 17

_____ are dark staining spherial bodies foud in the nucleus.

Back 17

nucleoli

Front 18

T/F The nucleoli are made up of aggregates of t-RNA and proteins.

Back 18

False (ribosomal r-RNA )

Front 19

T/F Nucleoli are not membrane bound.

Back 19

True

Front 20

How many nucleoli are typically found in a cell's nucleus?

Back 20

1-2

Front 21

T/F There are never more than two nucleioli in a cell's nucleus.

Back 21

False ( there may be more than 2)

Front 22

T/F Large nucleoli correlate with cells in growing tissues.

Back 22

True

Front 23

Nucleoli are associated with _____ regions

Back 23

chromatin

Front 24

Why are nucleoli associated with chromatin dense regions?

Back 24

these regions of DNA issue instructions for synthesizing ribosomal RNA

Front 25

Such DNA segments are called _____ _____ regions.

Back 25

nucleolar organizing (regions)

Front 26

RNA must be combined with proteins to form the _____ kinds of ribosomal subunits.

Back 26

2

Front 27

T/F Protein components of the r-RNA subunits are made by assembled ribosomes in the nucleus

Back 27

False ( the protein is "imported" from ribosomes
outside the nucleus in the cytoplasm).

Front 28

T/F The ribosomal subunits are made in the nucleus and "exported" via the nuclear pores into the cytoplasm

Back 28

True

Front 29

T/F The 2 ribosomal subunits are assembled together before leaving the nucleus.

Back 29

False (they are not assembled into functional ribosomes until the reach the cytoplasm)

Front 30

Viewed closely, _____ is a system of bumpy threads weaving their way through the nucleoplasm.

Back 30

chromatin

Front 31

Chromatin is comprised of roughly ____ amounts of DNA and globular histone proteins.

Back 31

equal

Front 32

The fundamental unit of chromatin is called the ____.

Back 32

nucleosome

Front 33

Nucleosomes are spherical clusters of _____ globular histone proteins connected like beads on a string by DNA.

Back 33

eight (8)

Front 34

The DNA molecule winds around one _____ then moves on the the next.

Back 34

nucleosome

Front 35

Conformational changes in a nucleosome alters the shape of its histones and expose different _____ on the DNA

Back 35

genes (linear DNA segments)

Front 36

Prior to cell _____ the chromatin coils and supercoils
into short bar-like bodies. LAST CARD

Back 36

division