Components of nucleus (M1B1)

Question 1

Restricting protein synthesis to the cytoplasm helps in what?

Answer 1

ensure that newly made RNA molecules do not become involved in translation before processing is complete

Question 2

Typically the largest structure within a cell (nucleus), it consists of a nuclear envelope containing…………. ,the mass of DNA and its associated proteins, with one or more specialized regions of chromatin called………..

Answer 2

chromatin, nucleoli

Question 3

What forms a selectively permeable barrier between the nuclear and cytoplasmic compartments?

Answer 3

nuclear envelope

Question 4

The space between the nuclear and cytoplasmic is called?

Answer 4

perinuclear space

Question 5

Closely associated with the inner nuclear membrane is a highly organized meshwork of proteins called the…………… which stabilizes the nuclear envelope.

Answer 5

nuclear lamina

Question 6

Major components of the nuclear lamina layer are the class of intermediate filament proteins called………… that bind to membrane proteins and associate with chromatin in nondividing cells

Answer 6

lamins

Question 7

The inner and outer nuclear membranes are bridged at the?

Answer 7

nuclear pore complexes

Question 8

Various core proteins of a nuclear pore complex, called……………, display 8-fold symmetry around the lumen.

Answer 8

nucleoporins

Question 9

What consists of DNA and all of the associated proteins involved in the organization and function of DNA?

Answer 9

Chromatin

Question 10

In humans each cell’s chromatin (except that of eggs and sperm) is divided among how many chromosomes?

Answer 10

46 (23 pairs)

Question 11

Before cell division, each chromosome consists of two identical chromatin units called……………. held together by complexes of cohesin proteins

Answer 11

chromatids

Question 12

Chromatids are packaged within the nucleus around small basic proteins called…………

Answer 12

histones

Question 13

structural unit of DNA and histones is called the…………

Answer 13

nucleosome

Question 14

How many histones does a nucleosome have?

Answer 14

8 histones: two copies of H2A, H2B, H3, H4

Question 15

two categories of chromatin can be distinguished in nuclei of most nondividing cells are?

Answer 15

Euchromatin (appears lightly stained and Heterochromatin (appears heavily stained)

Question 16

Which is rich with genes Euchromatin or Heterochromatin?

Answer 16

Euchromatin

Question 17

What are the two types of Heterochromatin?

Answer 17

Constitutive heterochromatin and Facultative heterochromatin

Question 18

Facultative heterochromatin contains other regions of DNA with genes where transcription is variably inactivated in different cells by…………….. and can undergo reversible transitions

Answer 18

epigenetic mechanisms

Question 19

• Euchromatin predominates in active cells such as?

- Heterochromatin is more abundant in cells with little synthetic activity such as?

Answer 19

• large neurons

- circulating lymphocytes

Question 20

Facultative heterochromatin also occurs in the small, dense……………..which is one of the two large X chromosomes present in females but not males.

Answer 20

“sex chromatin” or Barr body

Question 21

Much heterochromatin tends to be concentrated near the?

Answer 21

nuclear lamina

Question 22

What’s an autosome?

Answer 22

Any chromosome that is not a sex chromosome

Question 23

Cells contain how many pairs of autosome chromosomes?

Answer 23

22

Question 24

The members of each chromosomal pair are called………… because, although from different parents, they contain forms (alleles) of the same genes

Answer 24

homologous

Question 25

When a cell contains two sets of chromosomes it is called ……….. example somatic cells

Answer 25

diploid

Question 26

When a cell contains only one set of chromosomes it is called………. example eggs and sperms

Answer 26

haploid

Question 27

-N is haploid number
In humans n =……..?

-2n is Diploid
In humans 2n =……..?

Answer 27

• 23

- 46

Question 28

what is a Medical screening that gives image of chromosomes. The optimal (favorable) viewing, Metaphase. Used to analyze the chromosomes. It provides information about the number & morphology of the chromosome

Answer 28

karyotype

Question 29

Constitutive heterochromatin is generally similar in all cell types and contains mainly repetitive, gene-poor DNA sequences, including the large chromosomal regions called?

Answer 29

centromeres and telomeres

Question 30

a generally spherical, highly basophilic sub-domain of nuclei in cells actively engaged in protein synthesis?

Answer 30

Nucleolus

Question 31

large complexes of protein and rRNA?

Answer 31

ribosomes